ISE 2214
Manufacturing Processes
Laboratory
V
d
f
LAB MANUAL
Fall 2023
John P. Shewchuk. Ph.D., P.Eng.
Associate Professor
Grado Department of Industrial
and Systems Engineering
©2023 by John P. Shewchuk
PREFACE
Of fundamental importance for any engineer involved in manufacturing is a hands-on
understanding of manufacturing processes and equipment. In addition, however, is the
need to understand how different processes are combined to obtain products, as product
manufacture is the goal of any manufacturing facility. Manufacturing processes are thus
best taught in relation to the “big picture” of how products are made on the shop floor.
This laboratory manual has been developed specifically with this “product-oriented”
view of teaching manufacturing processes in mind. Ten of the thirteen labs are concerned
with the manufacture of three different products: a switch box, a pulley, and a mounting
plate. While these laboratories cover a wide variety of manufacturing processes including
assembly, casting, machining, CNC (Computer Numerical Control) machining, manual
and robotic welding, and inspection, equal emphasis is placed on understanding product
flow and control. To this extent, the laboratories employ engineering drawings, route
sheets, work orders, and inspection forms, just as do real manufacturing facilities.
The goal of this laboratory manual is to allow you to obtain hands-on experience in
manufacturing processes, in the context of overall manufacturing facility operation. This
will not only teach you about manufacturing, but will better prepare you for future courses
in manufacturing and industrial engineering. It is my sincere hope that you enjoy this realworld oriented experience learning about manufacturing processes and product
manufacture.
John P. Shewchuk
August 2023
ii
ACKNOWLEDGMENTS
The original development of this lab manual was partially sponsored by an
Instructional Enhancement Grant from Virginia Tech’s Center for Excellence in
Undergraduate Teaching (CEUT), awarded to the author in Spring 2000. The author
wishes to thank Kelcie Bower, Phillip Ratcliff, Jeffrey Snider, Will Vest, and Randy
Waldron, all of the Grado Department of Industrial and Systems Engineering at Virginia
Tech, for their assistance in working out details and building the various tooling and
fixtures needed for the original laboratories.
The author also wishes to thank all those involved in keeping this manual up-to-date
over the years as facilities and equipment have been upgraded or replaced. This includes
the following individuals and revisions:

Kelly Snidow (Grado Department of Industrial and Systems Engineering): MP-NC1
and MP-NC2 (Background and Procedure for both, new Haas vertical milling
machines), Spring 2023.

Kelly Snidow, Randy Waldron, Will Vest, William Monk, and Brian Burgess (Grado
Department of Industrial and Systems Engineering), Aditya Kulkarni (PhD student,
Grado Department of Industrial and Systems Engineering):
-
P-C: Figures 2, 3.
P-M: Figures 1, 4, and 5, Procedure.
P-I: photos p. 37.
MP-M: Figure 3.
MP-NC1: Background, Procedure (new EXPERTMILL vertical milling
machines).
MP-NC2: Background, Procedure (new FeatureCAM® software).
MP-I: Procedure (new Brown & Sharp coordinate measuring machine, Fowler
hardness tester).
MP-W2: Procedure (new Fanuc robot).
EDM: Background, Procedure (new Fanuc EDM machine).
TRN: Procedure (new data acquisition system)
All prior to Spring 2015.
iii
TABLE OF CONTENTS
Shop Floor Operation Fundamentals .............................................................................. 1
Safety Regulations .......................................................................................................... 3
Laboratory Report Format ............................................................................................... 4
Guide to Graphing for Laboratory Reports ...................................................................... 5
Laboratory Instructions:
SB-A:
SWITCH BOX – ASSEMBLY ...................................................................... 6
P-C:
PULLEY – CASTING ................................................................................ 16
P-M:
PULLEY – MACHINING ............................................................................ 23
P-I:
PULLEY – INSPECTION........................................................................... 33
MP-M:
MOUNTING PLATE – MACHINING AND RELATED PROCESSES ........ 42
MP-NC1: MOUNTING PLATE – NC MACHINING VIA MANUAL PART
PROGRAMMING ...................................................................................... 48
MP-NC2: MOUNTING PLATE – NC MACHINING VIA CAM SOFTWARE ............... 58
MP-I:
MOUNTING PLATE – INSPECTION ........................................................ 82
MP-W1:
MOUNTING PLATE – MANUAL ARC WELDING ..................................... 92
MP-W2:
MOUNTING PLATE – ROBOTIC ARC WELDING .................................... 97
F/PM:
SHEET METAL FORMING AND POWDER METALLURGY................... 103
EDM:
WIRE ELECTRICAL DISCHARGE MACHINING .................................... 108
TRN:
CUTTING FORCE AND TEMPERATURE IN TURNING ........................ 112
Appendix A: Geometric Dimensioning and Tolerancing .............................................. 118
Appendix B: Engineering Drawings, Route Sheets, and Inspection Forms
Switch Box ............................................................................................................. 122
Pulley ..................................................................................................................... 124
Mounting Plate ....................................................................................................... 128
Base Plate ............................................................................................................. 131
Forward Fix Plate ................................................................................................... 134
Aft Fix Plate ........................................................................................................... 137
iv
Shop Floor Operation Fundamentals
1
Shop Floor Operation Fundamentals
Introduction
Shop floor operation refers to the overall way in which things are done on the shop
floor to manufacture products. This section gives a very brief overview of shop floor
operation, in the context of what is covered in this laboratory manual. The information
will help you recognize and appreciate the various aspects of shop floor operation you
will encounter while performing the labs.
Product Specification and Manufacturing Plans
The manufacture of any product begins with a detailed specification of the product –
its size, shape, material, etc. Typically, this specification is provided in an engineering
drawing of the product. An engineering drawing may describe a product which is to be
made via fabrication (applying a series of manufacturing processes, such as machining),
or to a product which is to be made via assembly (combining other products together). If
the product is an assembly, the engineering drawing often contains a list of the individual
items comprising the product. A bill of materials (BOM) is sometimes also used to show
the individual items and their relationships.
The next thing which is needed is instructions telling us how to make the specified
product. For fabricated items and simple assembled items, the instructions are specified
via a route sheet. The route sheet lists the activities, or operations, which are needed to
make a product, the sequence in which the operations must be performed, and what
resources (machines, tooling, etc.) are needed for each operation. For more complex
assembled items, where the required activities can be performed in different sequences,
a task list and precedence diagram (or list) are employed. The task list specifies the
assembly activities, or tasks, which are needed to make the product, along with what
resources are needed for each task. The precedence diagram specifies which tasks must
be done before which other tasks.
Whenever a product is to be manufactured, it is essential to be able to monitor and
check the parts to ensure that the drawing requirements are being met. This function is
known as inspection. In order to document inspection results, part inspection reports are
often completed.
Flow Shop Operation
A flow shop is where products are made via one or more flowlines. A flowline is a set
of stations (machines, robots, or human workers) located right next to one another,
usually in a straight line. The stations are those required to produce a particular product
(or possibly several products), arranged in the order needed for production. Each station
is assigned one operation (fabrication) or one or more tasks (assembly). In the case of
assembly, a precedence diagram is used to help in the assignment.
1
2
Shop Floor Operation Fundamentals
Flowlines operation is very simple. Parts start at one end of the line, and move oneat-a-time from one station to the next for processing. Control of flowlines is also very
simple. Each station does the same thing over and over again, so once the stations are
set for a given product (machines setup, operators trained, etc.) little else is needed.
When manual assembly lines are used, assembly diagrams are often located at (near)
each station to help operators learn what they must do.
In this laboratory manual, flowline operation is investigated via the SB-A (Switch Box
– Assembly) lab. This lab involves running a manual assembly line in the Manufacturing
Processes Laboratory to produce a simple electrical item called a switch box.
Job Shop Operation
A job shop is where products are made by moving the parts through different
departments in the facility for processing. Each department handles a different type of
manufacturing process. For example, drilling is done in the drilling department, and
grinding in the grinding department. Thus, machines are grouped together based upon
what they do, unlike in flowlines where they are grouped based upon what they make.
Job shops operate as follows. Parts are first grouped together into batches for
processing. A batch (or job) is a set of parts, of the same type, which are processed
together. The batch will move to the machine needed for the first operation, and that
operation will be performed on all parts in the batch. The batch will then move to the
department/machine needed for the second operation, etc. Unlike flowlines, where
individual parts moved from one machine to another, parts in job shop production must
move together as a batch.
Control of job shops is more complex than flowlines. Because there may be many
batches at various places in the facility at any time, it is necessary to keep track of each
batch. This is typically done via work orders. A work order is a document which
accompanies each batch, specifying the part type, process plan, release date, due date,
and other information. There is usually a space to “sign-off” each operation when done,
so that we can keep track of what batches are where in the facility. In many cases, this
is done electronically (e.g., bar codes). The work order travels with the batch as the batch
moves through the facility. Once the last operation on the work order is completed, the
batch is done (i.e., all parts are finished). Any part inspection reports which have been
completed during processing are often attached to the work order, so that they may be
easily traced to the parts which were produced.
In this laboratory manual, job shop operation is investigated via the manufacture of
two products – a pulley (P) and a mounting plate (MP). The pulley is made via casting,
machining, and inspection operations. The mounting plate consists of three other items
– a base plate, a forward fix plate, and an aft fix plate. Each of these is fabricated via
machining and inspection operations, and the items are assembled into a mounting plate
via welding. Each of the operations needed to make pulleys and mounting plates is
performed in a different “department” in the Manufacturing Processes Laboratory.
Safety Regulations
3
Safety Regulations
The following regulations must be adhered to by all students for every lab. Students
who violate these regulations will not be allowed to perform/complete their lab.
This will result in a zero grade for that laboratory with no make-up opportunity.
1. Dress criteria for each lab is as follows:
LABORATORY
DRESS CRITERIA
SB-A P-C P-M
Safety goggles1
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Long pants with no frays or
holes
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Leather type shoes with
socks covering entire foot
NO ties, loose clothes (e.g.,
oversize sweatshirts), cloth
with fuzzy texture or lint
(e.g., inside-out sweatshirts)
NO rings, watches, bracelets, long necklaces, etc.
Long hair kept above the
neckline (cap, rubber band)
SHORT sleeves
P-I MP-M MP- MP- MP-I MP- MP- F/PM EDM TRN
NC1 NC2
W1 W2
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LONG sleeves
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NO contact lenses
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Safety welding gloves
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1
These can be checked-out from the toolroom.
2. During machining, the machine or cutter should not be in motion unless you are cutting or
preparing to cut. Keep hands away from the cutter, moving machinery and chips.
3. During welding and casting, do not handle metal parts directly (even with safety gloves on).
4. No eating, drinking, smoking, or use of cell phones in the laboratory.
5. Do not operate equipment without proper training and authorization.
6. Do not operate equipment until the machine area is clear of people.
7. Turn machines off before attempting to make any adjustments.
8. Never leave an operating machine unattended.
9. Report any damaged equipment or measuring instruments to the lab instructor.
4
Laboratory Report Format
Laboratory Report Format
Laboratory reports must consist of a title page plus seven sections as described below. Each
section should be titled, and the title style should be different (e.g. bold) in order to make it stand
out. All sections should be written in the third person (e.g. ‘It was found that...’). All tables and
figures must be numbered and referred to in the text before they appear. Number all pages
(except the title page), placing numbers in the upper right-hand page corners of pages.
1. Title Page (5 points). This must contain the following items, in order: (i) the title ‘ISE 2214 Manufacturing Processes Laboratory’, (ii) the title ‘Laboratory Report’, (iii) the laboratory
abbreviation and full name, (iv) the names of all students, (v) the index number, and (vi) the
submission date. Center-justify and space these items accordingly.
2. Table of Contents (5 points). This must list all sections following the title page and their
corresponding page numbers (note: the title page is page 1).
3. Introduction (10 points). Describe what the laboratory is about and the lab objectives, e.g.,
to obtain some fundamental knowledge, gain familiarity with a certain process, learn to
operate certain equipment, etc. The goal is to present the ‘big picture’ only: avoid too much
detail. This section should be written using the present tense.
4. Equipment (10 points). This section lists all of the items used for the laboratory, in sufficient
detail so that the reader could reproduce the laboratory. This will include processing
equipment (e.g., milling machine), tooling and fixtures (e.g., drill bits, milling fixtures),
measuring instruments and specimens (e.g., calipers, gage blocks), computer equipment and
associated hardware/software, raw materials for producing parts, and any consumables used
(e.g., cutting fluid, consumable electrodes). Use the ‘Equipment’ sections of the laboratory
instructions as a starting place for writing this section. Ask your lab instructor if you are unsure
of how to specify a machine, what material was used, etc.
5. Procedure (15 points). This section describes what was done. This includes both a textual
description, plus any numerical data (e.g., cutting conditions). Tables should be used when
a large amount of numerical data exists, or when grouping data aids in explaining the
laboratory procedure. Given all of the equipment, the reader should be able to reproduce the
laboratory based upon this section. This section should be written in the past tense, and
presented in as concise a manner as possible.
6. Presentation of Results (20 points). This section presents the results of all experiments,
tests, etc., described in the Procedure section. Use figures, graphs, and tables whenever
appropriate: graphs must be made following the guidelines on p. 5. This section should be
written in the present tense: be sure to follow any specific laboratory instructions provided.
7. Discussion of Results (20 points). This section serves to interpret and elaborate on the
results in light of the reasons the laboratory was performed. This should be done as clearly
and concisely as possible. Use the present tense in writing this section, and again make sure
to follow any specific laboratory instructions for each lab.
8. Conclusions (15 points). This section presents the major findings of the laboratory and your
conclusions on how well the objectives of the laboratory were met. The past tense should be
used for this section. Comments on usefulness of theory vs. real-world manufacturing issues
are appropriate in this section.
Guide to Graphing
5
Guidelines for Preparing Graphs for Laboratory Reports
• Title for each graph.
• Label axes. The x-axis is used for the independent variable and the y-axis for the
dependent variable(s). For example, in SB-A (WIP calculations), the x-axis represents
time and the y-axis represents # of items as a function of time.
• Show units of measurement.
• Choose scale appropriately or use full scale. When using graphing software, be sure
to choose X-Y or scatter chart to make sure the data points are shown correctly.
• Show each data point, using a different symbol for each series if there are multiple
series of data.
• Where there are multiple series of data, clearly label each series.
• DO NOT USE smoothing software to fit curves to data points, unless you clearly state
your assumptions and justify your choice of smoothing method. It is preferable to
simply join data points by hand than to try fitting a smooth curve to data which does
not support it.
• Hand-drawn graphs are acceptable ONLY if neatly drawn on graph paper and trueto-scale. All labels must be printed legibly.
• Layout your graph(s) on the page to allow for margins, i.e., DO NOT PRINT TO THE
EDGE OF THE PAGE.
6
SB-A Laboratory
SB-A: SWITCH BOX – ASSEMBLY
Purpose
To learn how products are made via assembly and basic assembly line concepts.
Overview
Product assembly is investigated by making switch boxes using assembly lines. A
switch box is a simple electrical component produced from various items.
An engineering drawing of a switch box is given on p. 122: a list of the tasks
needed to make switch boxes and a precedence diagram (showing what order the
tasks must be done in) are given on p. 123. The assembly line is comprised of
students, each of whom performs one or more assembly tasks.
Five
different assembly line configurations are investigated.
Equipment
Five-station assembly line, switch box components, stopwatches.
Background
Assembly is one of the most common manufacturing processes. Practically all items
– from light bulbs to toasters to computers to aircraft engines – are made via assembly.
When production volume is high (i.e., the item must be made repeatedly), assembly
lines are often used. An assembly line is simply a set of stations, arranged in a line,
where each station is responsible for performing a different set of tasks needed to
assemble the item. Parts start at one end of the assembly line and are successively
built-up as they flow down the line. Five important objectives for assembly lines where
stations are reliable (no breakdowns) but processing is unreliable (tasks not always
done correctly or completed) are as follows:
1. Maximize throughput, λ. Throughput is often measured in parts per hour (pph).
2. Minimize reject %, R. If λ = 10 pph and R = 0.20, there are only 8 good items
coming off the line each hour.
3. Minimize work-in-process, WIP. This is the average # of parts on the assembly
line at any given time.
4. Minimize line imbalance, B. This indicates the extent to which work is evenly
divided amongst the stations. If every worker has the same amount of work, the
line is perfectly balanced (B=0): as workloads become uneven, B increases.
5. Minimize idle time %, D. This indicates the extent to which the total capacity of
the line is utilized. A line where all workers are busy all the time has D = 0; a line
where each worker, on average, is idle one-quarter of the time has D = 0.25, etc.
SB-A Laboratory
7
Assembly lines can be either paced or unpaced. Let’s briefly look at each.
Paced Lines
In a paced line, each station is allotted exactly the same amount of time to perform its
assigned tasks. This amount of time is called the cycle time, C. Once the cycle time
has elapsed, all items are advanced to the next station simultaneously. Figure 1 shows
an example of a 4-station paced assembly line.
Work carrier
Base part
Conveyor
Figure 1. Paced assembly line.
For a paced line with M stations, operating for a total of C TOT cycles, the
performance measures can be calculated as follows:
1. λ = throughput = 1/C.
2. R = reject % = (# of rejects)/ C TOT
3. WIP = average work-in-process level = M (one item at each station)
M
4. B = line imbalance =
∑ (b − b )
2
j
M
j =1
where b j = total task time at station j for one unit; b is the average of all b j ’s.
5. D = idle time % = =
M ⋅ C − TTOT
M⋅C
M
where T TOT = total assembly time =
∑ bj , b j = total task time at station j
j =1
8
SB-A Laboratory
For example if M = 3 stations, b 1 = 1.5 min., b 2 = 1.8 min., b 3 = 1.2 min., C = 2
minutes, C TOT = 5 cycles, and # rejects = 1,
λ=
1 1
=
item/min.= 30 pph
C 2
R=
1
= 0.2= 20%
5
WIP = M = 3 items
B
=
D
2
2
2
1.5 − 1.5 ) + (1.5 − 1.8 ) (1.5 − 1.2 )
(
=
3
3 ⋅ 2 − (1.5 + 1.8 + 1.2 ) 6 − 4.5
=
= 0.25
=
3⋅2
6
0.24
25%
Unpaced Lines
In unpaced lines, completed items are immediately moved from one station to the next.
Thus, stations operate independent of one another. In order to account for differences
in total task time at each station in an unpaced line, buffer queues are used. A buffer
queue (or buffer) is simply some space between two stations where completed items
can be stored temporarily. Two problems can arise with unpaced lines due to buffers:
• A completed item cannot be moved because the following (downstream) buffer is
full. The station is blocked – forced idle even though there may be parts to work on.
• A completed item is moved, but no items are found in the preceding (upstream)
buffer. The station is starved – forced idle even though it is ready and able to work
on parts if they were available.
For an unpaced line with M stations, operating for T minutes, the performance
measures can be calculated as follows:
1. λ = throughput = (# of departed items) ⋅
60
T
2. R = % rejects = (# of rejects)/ (# of departed items)
T
3. WIP = average work-in-process level =
∫0 w(t)
, where w(t) is the # of items on
T
the line at time t, 0 ≤ t ≤ T. We can calculate the integral by recording item arrival
times (a i ’s) and departure times (d i ’s), plotting these values to obtain w(t), then
determining the area under the curve. For example, consider a line with 3
stations, where an item is ready to start at each station at t = 0 (i.e., w(0) = 3). If
we then observe line operation for 12 minutes and record arrivals at 2 and 6
minutes and departures at 4, 9, and 11 minutes, we obtain the following:
SB-A Laboratory
w(t)
9
5
4
3
WIP =
2
1
0
0
2
4
6
9 11 12
a1
d1
a2
d2 d3
t
M
4. B = line imbalance =
3(2) + 4(2) + 3(2) + 4(3) + 3(2) + 2(1)
12
40
=
= 3.33
12
∑ (b − b )
2
j
M , as before
j =1
5. D = idle time % = =
M ⋅ bmax − TTOT
M ⋅ bmax
For example, if M = 3 stations, b 1 = 1.5 min., b 2 = 1.8 min., b 3 = 1.2 min, T = 12
minutes, arrival times (a j ’s) are 2 and 6 minutes, departure times (d j ’s) are 4, 9 and 11
minutes, and # rejects = 1,
λ= 3⋅
R=
60
= 15 pph
12
1
= 0.33= 33%
3
WIP = 3.33 items (calculated above)
B = 0.24 (same as for paced line example)
=
D
3 ⋅ 1.8 − (1.5 + 1.8 + 1.2 ) 5.4 − 4.5
= 0.167
= 17%
=
3 ⋅ 1.8
5.4
Procedure
The procedure for this lab consists of performing five assembly line experiments
(Table 1). Experiments 1, 2, and 3 use paced lines, while Experiments 4 and 5 use
unpaced lines. The procedures for both paced and unpaced experiments are given
below. Data collected during the experiments is to be recorded on pp. 13-14. Different
students will be responsible for recording different data. Do not record the data in your
lab manual: copies of pp. 13-14 will be provided.
The lab instructor will divide each group (A, B, C, and D) of students into two teams
for the purpose of report writing. He/she will then demonstrate the assembly process by
assembling a unit, and the basic operation of paced and unpaced lines. The
experiments will then be performed. Once all five experiments are complete, the
instructor will make copies of the data forms and distribute them.
10
SB-A Laboratory
Table 1. Assembly Line Operation Experiments.
Assignment of Tasks to Stations
Experiment
No.
Line
Type
Buffer
Capacity
Cycle
Time
1
2
3
4
5
1
Paced
-
1 min 45
a,b
c,d
e,f
g
h
2
Paced
-
(TBA)
a
b,c
d,e,f
g
h
3
Paced
-
(TBA)
a
b,c
d,e,f
g
h
4
Unpaced
3
-
a
b,c
d,e,f
g
h
5
Unpaced
3
-
c
a
b
d,e,f,g
h
Experiments 1, 2, and 3: Paced Lines
1. Five students, one at each station, will be assigned to operate the assembly line.
Each student will be responsible for performing the tasks listed for that experiment at
his/her station. Another five students, one at each station, will be assigned to
measure and record observations of total task time (i.e., observations of b j ).
Students will be provided with stopwatches and clipboards for these tasks:
observations should be recorded in the appropriate table on p. 13.
NOTE: each b j value for a given experiment is the average of all the observations
you take at that station for the experiment. For example, if you recorded the values
0:16 (16 seconds), 0:20, 0:25, 0:18
at Station 1 for an experiment, then b 1 =
16 + 20 + 25 + 18 79
=
= 19.8 seconds.
4
4
The lab instructor will start and stop assembly line operation, and will pace the line.
This setup is shown in Figure 2.
Line
operators
#5
#4
#3
#2
#1
Task time
recorders
Lab
instructor
Figure 2. Paced Lines Experimental Setup.
SB-A Laboratory
11
2. The instructor will place an item (at the proper stage of assembly) at each station.
3. Students will be given a few minutes to familiarize themselves with their
assignments. Line operators should practice their assigned task(s), leaving the item
in front of them completed.
4. The line will then operate as follows. The lab instructor will give a START signal,
then a MOVE signal whenever the cycle time has expired. Upon the START and
each MOVE signal,
i.
All line operators still working an item (from the previous cycle) must stop.
- each such station: task time recorder stops stopwatch, records task time,
resets stopwatch.
- station #5 only: operator moves item.
ii. Each line operator then takes the unit to their left (preceding station), moves it to
their station, and starts working on it.
- task time recorders start stopwatches once move complete.
iii. When an operator finishes his/her item,
- task time recorder stops stopwatch, records task time, resets stopwatch.
- stations #1-4: operator waits (with item in front of him/her).
- station #5 only: operator moves item, then waits.
The lab instructor will continue to give the MOVE signal until the desired # of cycles
have been completed. Line operation will then stop. The instructor will then make
sure that one of the task time recorders records the general experiment information
(top of p. 13) on his/her form.
Experiment 4, 5: Unpaced Line
1. The unpaced line will use the same setup as before, except that two additional
students are needed to record data. One student will note and record item arrival
times (a i ’s)– the times items are removed from the input queue at station #1.
Another student will note and record departure times (d i ’s) – the times items are
moved from station #5. Students will be provided with stopwatches and clipboards
for these tasks: readings should be recorded on p. 14. The lab instructor will start
and stop assembly line operation. This setup is shown in Figure 3.
2. The instructor will place an item (at the proper stage of assembly) at each station.
3. Students will be given a few minutes to familiarize themselves with their
assignments. Line operators should practice their assigned task(s), leaving the item
in front of them ready to start.
12
SB-A Laboratory
Line
operators
#5
#4
#3
#2
#1
Task time
recorders
Lab
instructor
Departure time
recorder
Arrival time
recorder
Figure 3. Unpaced Lines Experimental Setup.
4. The line will then operate as follows. Upon the lab instructor’s START signal,
i.
Each line operator begins working on the item in front of him or her. Once the
item is completed, the operator will immediately move it to the downstream
buffer if room is available. If there is no room, the operator must wait idle for
room to appear (station blocked). Once the completed item has been moved,
the operator can take a new item from the upstream buffer to work on. If there
are no items, the operator must wait idle for an item to work on (station starved).
ii. Each task time recorder takes and records observations at his/her station.
iii. The arrival and departure recorders watch stations #1 and #5, respectively, and
record arrival and departure times. NOTE: these students must keep their
stopwatches running for the entire duration of the experiment, taking point
readings when necessary (SPLIT function on stopwatch).
iv. Students not involved in line operation or recording of data should observe each
station with respect to blocking and starving.
Once the desired time interval has elapsed, the lab instructor will give the STOP
signal to stop the line. The instructor will then make sure that
• one of the task time recorders records the general experiment information (top of
p. 13) on his/her form.
• one of the arrival/departure time recorders records the blocking/starving
observations on his/her form.
SB-A Laboratory
Experiment
#
13
Cycle time, C
Total # of
cycles, C TOT
Total time, T
# of rejects
1
2
3
4
5
Experiment
#
1
2
3
4
5
Observations of b j (total task time at station j), j =
1
2
3
4
5
14
SB-A Laboratory
Experiment #
Arrival times (a i ’s)
Departure times (d i ’s)
4
5
Experiment
#
4
5
Blocking/starving observations at station j, j =
1
2
3
4
5
SB-A Laboratory
15
Lab Requirements
A lab report is required of EACH TEAM of students. The report MUST be prepared
according to the ‘Laboratory Report Format’ instructions (p. 4), and be submitted at the
START of the next lab. The Procedure should include the table from p. 10 (make a
new table: do not photocopy), with the missing cycle time values added. In the
Presentation of Results, include the following:
• The data sheets you obtained from the experiments (five copies of p. 13, two of p.
14).
• A table showing the task time values (b j ’s) for each experiment. These must be
calculated (average values) based upon the observations recorded in the data
sheets.
• The values of λ, R, WIP, B, and D for each experiment. Present the results in a
table, and SHOW YOUR CALCULATIONS for experiments 1 and 4 only. For
experiment 4, be sure to show a graph of w(t), as demonstrated on p. 9. Follow
the guidelines on p. 5 in preparing this graph.
In the Discussion of Results, answer the following questions:
1. Which of the paced line experiments – 1, 2, or 3 – do you feel had the best line
performance? Justify your response.
2. Which of the unpaced line experiments – 4 or 5 – do you feel had the best line
performance? Justify your response.
3. Compare the best paced line configuration (found in Question 1) to the best unpaced
line configuration (Question 2). Which of these do you feel is better? Justify your
response.
4. Where did starving and blocking occur (i.e., at what stations) in Experiment 4?
Experiment 5? Why do you think this occurred in each case?
5. Based upon the experiments performed, describe some conditions under which you
feel a paced line would be preferred over an unpaced line.
16
P-C Laboratory
P-C: PULLEY – CASTING
Purpose
To learn the basics of sand casting and permanent mold casting.
Overview
The sand casting process is investigated by casting a pulley.
An
engineering drawing of the pulley is given on p. 124: casting corresponds to
operation 10 on the route sheet for this item (pp. 125-127). The permanent mold
casting process will be demonstrated separately.
Equipment
Furnace, aluminum alloy, green molding sand, sand casting tools, permanent molds.
Background
Casting is one of the oldest manufacturing processes. In casting, molten metal is
poured into a mold, the metal is allowed to solidify, and the part is removed. Casting is
used to produce parts that have complex shapes (even internal cavities), and/or are
very large, in a single step. Examples of cast items include engine blocks, pistons,
railroad wheels, and crankshafts.
There are two main categories of casting processes: non-permanent (expendable)
mold and permanent mold. In expendable mold casting, the mold has to be destroyed
in order to remove the part. Thus, expendable mold casting is economically feasible
only if the items are needed in small quantities. Sand casting, in which the mold is
made of sand, is a good example of expendable mold casting. In sand casting, a
pattern of the part to be produced is placed in sand to make an imprint, removed from
the sand, and molten metal then poured into the cavity. The mold used for sand casting
typically consists of a top half (known as the cope) and a bottom half (known as the
drag). The molten metal is poured into the pouring basin, following which it flows down
the sprue and into one or more runners, which lead to the cavity. One or more vents
often lead from the cavity to the outside to allow air (and hot gases) to escape. To
account for the fact that the molten metal shrinks during solidification, risers are often
used. These are cavities that supply additional metal to the mold cavity as required.
Figure 1 illustrates the basic components of sand molds, while the basic sand casting
process is illustrated in Figure 2.
P-C Laboratory
17
Part cavity
Riser
Pouring basin
Sprue
Flask
Cope
Runner
Drag
Mold
Figure 1. Sand Casting Mold.
Figure 2. Sand Casting Process.
In permanent mold casting, the mold can be opened to remove the cast part without
damage: such molds can be used to make thousands of identical parts quickly and
easily. In the simplest case, permanent molds consist of two mold halves hinged
together at one end (Figure 3). The mold halves are closed together, molten metal is
poured in and allowed to solidify, the mold is opened, and the part is removed.
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P-C Laboratory
Permanent mold casting is best suited to large production runs, where the higher cost of
the molds can be justified.
Figure 3. Permanent Mold.
Procedure
The procedure for sand casting the pulley is given below. The lab instructor will first
demonstrate the procedure up to the pouring stage (Step 7a, p. 21). Following the
demonstration, the instructor will divide you into two to three teams. Each team will
then perform the sand casting operation, using a single sand mold and making one
pulley for each team member. While the molten metal is solidifying, the instructor will
demonstrate the permanent mold casting process.
Once you have completed the casting operation, be sure that someone in your
group signs-off the operation on the work order.
Pulley Op. 10 – Sand Casting
1. Fill Drag
a. Riddle the sand, using a mechanical riddle, to filter out the
large chunks, leaving small, fine particles.
b. Place the drag upside down (i.e., handles facing bottom)
on a wooden board.
c. Place the patterns on the wooden board, inside the drag,
with the large end down (boss end up). Space the
patterns as evenly as possible from the sides of the drag
(and from each other). Lightly dust the patterns with
parting compound.
P-C Laboratory
19
d. Place the hand riddle on top of the drag and fill it with
sand.
Hand-riddle the sand until the patterns are
covered, then dump the remaining sand in the riddle on
the patterns.
This process ensures that fine sand
contacts the patterns.
e. Shovel sand directly into the drag until it is heaping over
the sides. Using the pinging side of a bench mallet, ram
the sand into the drag. Start at one corner and work all
the way around the edge, then work in towards the
center. This will drop the sand level in the drag to about
half-full. NOTE: do not ram the sand too hard. The sand
must be able to breathe.
f. Again shovel sand directly into the drag until it is heaping
over the sides. Move the sand by hand to create mounds
at the corners, adding more sand if necessary (i.e., if not
heaping over sides everywhere). Using the mallet side of
a bench mallet, ram the sand into the drag. Again start at
one corner, work around the edge, then work towards the
center.
g. Remove excess sand from the top of the drag, using a
striking bar, to make the sand level with the top edge.
h. Lightly draw an outline of the patterns, in their actual
locations, in the sand surface using a vent wire. Then,
make several vent holes above each pattern, where each
hole goes halfway to the pattern (do not touch the
patterns). These holes help allow gases to escape during
casting. Then create additional vent holes over the rest of
the sand surface, going three-quarters of the way down to
the board.
i. Finally, sprinkle sand over pattern vent holes, then smooth the sand out by hand.
This sand prevents liquid metal from flowing out of any vent holes that have
contacted a pattern. Then slam a wooden board over the top of the drag (watch
fingers!).
j. Holding the boards and drag together, rotate the unit 90°
on the table. Then slowly flip the unit over so the patterns
are at the top. Remove the top wooden board, then lightly
level the sand surface with a hand trowel (be careful
around the patterns!).
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P-C Laboratory
2. Fill Cope
a. Place the cope onto the drag, lining up the alignment
holes. Sprinkle parting compound over the entire surface
of sand in the drag (this prevents the cope and drag from
sticking together). Then place a sprue cutter in the center
of the patterns and sink it down approximately 1 in. Place
a riser cutter over each pulley, off-center but covering the
center
b. Using a hand riddle, fill the inside of the cope with fine
sand. BE CAREFUL not to hit the sprue cutter. Don’t
worry if some sand goes into the sprue cutter.
c. Fill the cope with sand and pack it down as before (Steps
1e and 1f).
d. Remove excess sand and level the sand surface using a striking bar, as before.
e. Make several vent holes over the entire surface, going
three-quarters of the way down to the board. Then
remove the sprue cutter and riser cutters by slightly
shaking and rotating each cutter to loosen it, then pulling
it straight out.
3. Separate Cope and Drag
Separate the cope and drag by removing the cope
and laying it on its side on the table. Using a vent
wire, place an “x” on one corner of the mating
surfaces of both cope and drag. This helps ensure
correct orientation when reassembling the mold.
4. Prepare Cope Mating Surface
a. Lightly compact the sand surface around the sprue hole with your finger, to ensure
the sand at the lip doesn’t crumble during pouring.
b. Spin the cope around on the table so you can access the
mating surface. Using a hand trowel, create a pouring
cup about 3-4 inches in diameter where the sprue hole
meets the surface. Carefully remove excess sand from
the sprue hole with your finger, then lightly compact the
sand comprising the pouring cup surface with your finger.
Finally, blow the remaining sand out of the sprue hole
(front to back) using an air bellows.
P-C Laboratory
21
5. Prepare Drag Mating Surface
a. Loosen up any sand in the pattern draw spike holes using a vent wire (holding the
pattern securely by hand). Then blow any sand out of the draw spike holes using
air bellows.
b. Remove each pattern from the drag as follows: Place the
draw spike in the draw spike hole and lightly tap the draw
spike on top once with a rapping bar. Holding the top of
the draw spike with one hand, lightly tap the side of the
spike with the rapping bar to loosen the mold cavity
around the pattern. Then tap the top of the draw spike
once again to secure it in the pattern. Carefully pull the
draw spike straight up to remove the pattern.
c. Create runners and gates in the mating surface using a
gate cutter. Be sure to cut the sand from each cavity to
the sprue hole, sloping downwards as you go. The runner
should be no more than about 3/16-in. deep at the center.
Carefully compact the sand surface of each runner and
gate with your finger. Finally, blow excess sand from the
pattern cavities, gates and runners using an air bellows.
BE CAREFUL not to contact the sand with the air bellows
nozzle.
6. Assemble Cope and Drag
Place the drag/board assembly in the sandpit. Then place the cope over the drag,
ensuring proper alignment via the “x” ‘s created earlier (Step 3). Squeeze the cope and
drag together firmly by the handles. Repeat this step for each mold being made.
7. Pour Molten Metal
a. Pour molten metal into each mold until full. NOTE: the lab instructors will perform
this step.
b. Clean-up while waiting for the metal to solidify. The lab instructors will also
demonstrate the permanent mold process during this time.
c. Once the metal has sufficiently solidified, lift the cope straight up from the drag and
drop it onto the sandpit floor on its side. The parts will fall out. Carefully remove
the parts.
d. Remove the sand from the cope and drag, and place the boards, cope, and drag on
the table, with a hand riddle and mallet on top. Shovel the sand back to the rear of
the sandpit.
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P-C Laboratory
8. Finish Up
a. Cut the riser off of the top of your pulley. Be sure to cut as close to the pulley
surface as possible and that your cut is parallel to the surface.
b. File off the runner stub at the side of the pulley.
c. Hand file the pulley to remove rough edges
Lab Requirements
Each team of students is required to perform the casting operation as described.
For each team, the instructor will evaluate all pulleys made to obtain an average score
for how well the pulleys were cast (pattern reproduction, surface finish). This score will
be given to each team member. Each student will then be graded individually on how
well they finished their pulleys (Step 8 – Finish Up). The evaluation will be done as
follows:
Poor
Pattern reproduction (size/shape correct)1
Surface finish (fine sand over entire surface)1
Removal of riser, runner, rough edges2
1
25
25
4
Average score, considering all pulleys made by a team.
Individual score, each team member and their own pulley.
Fair
35
35
6
Good
40
40
8
Excellent
45
45
10
Total points: 100
2
Evaluation will be done by comparison with pulleys that have been properly cast and
finished.
P-M Laboratory
23
P-M: PULLEY – MACHINING
Purpose
To learn about some different types of machining processes used for rotational (i.e.,
round) items, and how to use various machine tools to perform the processes.
Overview
Machining processes commonly used for rotational items are investigated
by machining the pulleys cast in the previous lab. This correspond to operations
20-110 on the route sheet for this item (pp. 125-126). The processes covered
include turning, facing, chamfering, drilling, reaming, tapping, broaching, and
deburring. NOTE: Page 124 is required to complete this lab: bring a printout of this
page with you. A page will be provided for you if necessary BUT this will result in a
deduction of 20 points from your score.
Equipment
Cast pulley.
Lathe, drill press, hand press.
Various cutting tools, jigs, fixtures, and measuring instruments.
Hand file.
Background
Machining is a general term for manufacturing processes where a cutting tool is
moved relative to a workpiece to selectively remove material from the item. Machining
is one of the most fundamental and important categories of manufacturing processes.
This is because:
- Machining can create almost any shape (flat, round, etc.) or geometric feature
(pocket, boss, etc.).
- Machining can be applied to almost all metals and alloys, as well as to many other
materials (plastics, wood, etc.).
- Machining is capable of producing dimensions to very close tolerances (± 0.001 in.
or better), and of creating very smooth surface finishes (better than 16 µin.).
Machining is generally performed after the main shape of the item is obtained via a
bulk deformation process (such as casting, rolling, or forging). Successive machining
operations, using different types of machines and cutting tools, are very common.
The most common machining processes for rotational items are those performed on
a lathe. Figure 1 shows a basic or “engine” lathe. The workpiece is affixed to the
spindle, which is rotated by a drive motor in the headstock. The opposite end of the
part is usually held by a center located on the tailstock. The single-point cutting tool is
held by the tool post (tool holder), which is affixed to the compound rest. The
compound rest sits in a cross slide, which moves the tool into the workpiece (i.e.
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P-M Laboratory
radially). The cross slide in turn is attached to the carriage, which moves the cross slide
(and hence tool) parallel to the workpiece (i.e., axially). Each of the cross slide and
carriage can be moved manually (hand wheel) and automatically (i.e., power feed).
Figure 1. Engine lathe.
Machining processes performed on lathes include the following:
- turning: tool moves parallel to the axis of rotation, reducing the item’s diameter.
- facing: tool is fed radially into the rotating workpiece, creating a flat surface.
- chamfering: tool is fed against the edge of the workpiece, forming a “chamfer.”
- drilling: tool is held in the tailstock and fed into the workpiece to create a hole.
- reaming: similar to drilling, but the goal is to enlarge a hole and improve tolerance.
These processes are shown in Figure 2.
Turning
Drilling
Facing
Chamfering
Reaming
Figure 2. Some common machining processes performed on a lathe.
P-M Laboratory
25
Once the cutting tool has been selected for a lathe operation, three parameters (or
cutting conditions) must be established before the operation can be performed. These
are speed (or cutting speed, V), feed (f), and depth-of-cut (d). For lathe operations,
- speed is how fast the part surface travels past the tool. This depends upon both
how fast the spindle is rotating (N, rpm) and the diameter of the part.
- feed is how much the tool advances alongside the part for each part revolution.
- depth-of-cut is to how much material (thickness) is removed from the part at a time.
Figure 3 illustrates speed, feed, and depth-of-cut for a turning operation. For any
machining operation, speed is usually measured in surface feet per minute (sfpm), feed
in inches per revolution (ipr) or millimeters per revolution, and depth-of-cut in inches or
millimeters. Note also that we cannot set speed directly: we must set the rotational
speed N to get the desired speed.
Cutting speed, V
Depth-of-cut, d
Feed, f
Figure 3. Speed, feed, and depth-of-cut for turning on a lathe.
When a lot of material has to be removed, it is common to perform a lathe operation
using one or more roughing passes, followed by a finishing pass. A roughing pass is
one where the depth-of-cut is large, so as to remove material as quickly as possible. A
finishing pass is one where depth-of-cut is shallow, the objective being to obtain the
final dimensions. Cutting speed is often increased and feed decreased in finishing
passes to obtain the required surface finish.
If a rotational part requires a hole that cannot be created using a lathe, a drill
press must be used. A basic upright drill press is shown in Figure 4. The part is
affixed to the table, while the cutting tool (drill bit) is held in the spindle and driven by a
motor in the head of the unit. Moving a hand lever causes the rotating spindle and drill
bit to move down into the work piece, creating a hole. Drill presses can also be used
P-M Laboratory
26
for related processes such as reaming and
tapping. Tapping is used to create internal screw
threads on an existing hole, for the purpose of
assembly.
For drilling and related processes, speed is
how fast the outer edge of the tool moves relative
to the part (established via spindle speed N), feed
is how much the tool advances into the part for
each spindle revolution, and depth-of-cut is how
deep the hole is. As with turning, speed is not set
directly: it is established via setting the spindle
speed, N.
While lathes and drill presses can be used to
create round holes in work pieces, sometimes
other (i.e., non-round) internal features are
needed. Examples include a slot along the length
of a hole (also known as a keyway) and a square
Figure 4. Drill press for drilling
hole. In order to create such features, broaching
and related operations.
is used. In (internal) broaching, a multiple-tooth
cutting tool is moved linearly through an existing
hole, causing the hole to gradually take the shape of the broaching teeth. The cutting
tool (broach) can be either pushed into or pulled through the hole, as shown in Figure 5.
Finally, a common characteristic of practically all machining processes is that burrs
are formed. A burr is a sharp, thin protrusion of material, usually triangular in shape,
which develops along the edge of a surface following machining (and other)
metalworking processes. Burrs are both undesirable and unavoidable. They can
interfere with assembly of mating parts, reduce the fatigue life of components, and are a
safety hazard to personnel. In order to remove burrs, deburring is usually performed at
various times during machining. Manual deburring can be done using files, abrasive
belts, and/or wire brushes.
Figure 5. Push broaching (A) and pull broaching (B).
P-M Laboratory
27
Procedure
The basic steps for performing each machining operation are given below. The
equipment needed for each operation is specified on the pulley route sheet (work
order). For each operation, the lab instructor will first go through the required steps in
detail, following which each student will perform that operation on their part. KEEP
HANDS CLEAR OF THE TOOL DURING MACHINING. DO NOT ATTEMPT TO
BRUSH AWAY OR OTHERWISE REMOVE CHIPS WHILE THE TOOL IS IN MOTION.
(Page 124 is required to complete the operations of the Pulley)
Once the operations have been completed for all parts, be sure that someone in
your group signs-off the operations on the work order.
Pulley Op. 20 – Face Hub, Turn Hub Diameter
1. Rough Face Hub
a. Set the spindle rotational speed to 440 RPM.
b. Move the carriage to the right until the tool post is about 1 foot from the chuck.
Mount the RH face tool in the tool post.
c. Chuck the pulley by the boss end. (Ask Instructor for assistants if needed)
d. Turn on the spindle, then manually move the carriage left until the tool just touches the
end (Face) of the pulley hub (surface to be faced). Then move the cross slide to
back the tool away from the part radially (turning handle counterclockwise), until
it clears the hub diameter by about 1/8-inch. (There should be about 1/8” to be
removed from face.)
e. Now Zero the digital readout by pressing the soft key next the Z axis. Move the
carriage about 0.050-in. to the left, so that the tool overlaps the part axially. This
sets the depth-of-cut to about 0.050 in. (The digital readout should now display
0.050.)
f. As we are performing a roughing pass, the tool can be fed manually. Move the
cross slide to feed the tool radially into the part (turning the handle clockwise),
facing the hub. (Apply cutting fluid when needed. Note: applying excessive
amounts of cutting fluid make it difficult to clean machine.) Watch the tool tip
and stop feeding when it gets to the part centerline. Then back the tool away from
the part (turning counterclockwise) until it clears the hub diameter.
g. Turn off the spindle; raise Chuck Guard and measure the hub thickness using the
dial calipers. (The Chuck Guard will disenable the machine when in the up
position. Always raise the Chuck Guard when you are measuring or touching
the part!)
h. Repeat steps c-g above (i.e., perform more roughing passes), adjusting the depthof-cut as needed, until the hub thickness is about 0.65 inches (vs. a required
thickness of 0.625 in.). This leaves sufficient material for finishing this face (the
P-M Laboratory
28
opposite face of the hub will be left unfinished). Note that once you are finished
rough facing, the tool is in position for finish facing.
2. Finish Face Hub
a. Measure the Hub thickness to determine the amount of material to be removed for
finish cut. Now move the carriage to the left until you have the proper depth-of-cut.
(Should be about 0.020 in.)
b. For the finishing pass, the tool will be fed automatically so that the best finish is
obtained. Set the feed to 0.003 ipr. Then set the machine so that the tool, when
using power feed, moves radially towards the part centerline (vs. away from the
centerline). (Ask Instructor for assistants if needed)
c. Lower the Chuck Guard, Turn on the spindle, apply cutting fluid if needed and
engage the power feed. The cross slide will automatically move and feed the tool
radially into the part, facing the hub. Again watch the tool tip; you must disengage
the power feed when the tool gets to the part centerline.
d. Once the power feed has been disengaged, bring the tool away from the faced
surface by moving the carriage slightly to the right. (This will prevent you from
damaging the Hub face.)
3. Rough Turn Hub Diameter
a. Locate the tool at the axial center of the hub and about 1/4-in. from the hub diameter.
(Make sure the tool does not touch the part when the machine is turned on.)
b. Lower the Chuck Guard and Turn on the spindle, and move the tool radially
towards the part until it just touches the hub diameter. Then move the tool to the
right, until it clears the end of the hub by about 1/8-in.
c. Now Zero the X axis on the digital readout by pressing the soft key next to the X.
This will zero the tool on the hub diameter.
d. Set the feed to about 0.010 ipr. Then set the machine so that the tool (when using
power feed) moves left. (Ask Instructor for assistants if needed)
e. Using the cross slide hand wheel and digital readout, set the depth-of-cut to about
0.100 in. (The digital read should read 0.100) (There should be about 0.250
inches to be removed from part diameter.)
f. Lower the Chuck Guard, Turn on the spindle, apply cutting fluid if needed and
engage the power feed. The carriage will automatically move and feed the tool
axially, from right to left, turning the hub diameter. Watch the tool tip and disengage
the power feed when the cut has been taken. Then move the tool back to the right,
past the hub.
g. Turn off the spindle, raise Chuck Guard and measure the hub diameter using the
dial calipers.
h. Repeat steps e-f above (i.e., perform more roughing passes), adjusting the depthof-cut as needed, until the hub diameter is about 3.050 in. (vs. a required diameter
P-M Laboratory
29
of 3.00 in.). This leaves sufficient material for finish turning. Once you are finished
rough turning, the tool is in position for finish turning.
4. Finish Turn Hub Diameter
a. Set the feed to 0.003 ipr. (Ask Instructor for assistants if needed)
b. Measure the part diameter and calculate the material to be removed for the
finishing pass. For example, if you measured 3.058 in., the material to be removed
would be (3.058-3.00) = 0.058 in.
c. Lower the Chuck Guard, Turn on the spindle, apply cutting fluid and engage the
power feed. Watch the tool tip and disengage power feed when the cut has been
taken.
d. Once the power feed has been disengaged, move the tool away from the surface
radially (turning hand wheel counterclockwise) about 1/2-in. before bringing it
back to the right. This is to avoid scratching the surface you just cut.
e. Turn off the spindle and raise Chuck Guard.
Pulley Op. 30 – Machine Groove
1.
Move the carriage to the right until the tool post is about 1 foot from the chuck.
Remove RH facing tool and mount V-grooving tool in tool holder.
2.
Move the carriage to the left until the sharp point of the V-grooving tool line up with
the corner of the face and outside diameter of the part.
3.
Now zero the Z axis by pressing the soft key next to the Z on the digital readout.
4.
Make sure the tool clears the part diameter about 1/8th inch. Move the tool to the left
.312 in. (this will display on the digital readout as such). Now your tool is in location
to cut the V-groove.
5.
Now zero the tool radially. Lower the Chuck Guard and turn on spindle. Move the
tool radially until it just touches the parts diameter (making a faint line on part
surface). Now zero the tool by pressing the soft key next to the X on the digital
readout. You are now ready to cut the V-groove.
6.
Move the tool radially (turning hand wheel clockwise) into the parts diameter until
the you read 0.500 inches on the digital readout. (This will make the V-groove
0.250 inches deep from the parts surface.) Add cutting fluid when tool chatter
becomes excessive.
7.
Move the tool away from the part radially when done (turning hand wheel
counterclockwise), and turn off the spindle and raise Chuck Guard.
Pulley Op. 40 – Center Drill, Drill, Ream
1.
Remove tool from tool holder. Mount a chuck in the lathe’s tailstock.
2.
Insert the center drill in the chuck and tighten.
30
P-M Laboratory
3.
Move the tailstock left (towards) the part, until the tool tip is about 1/2-in. away from
the end of the pulley hub. Secure the tailstock.
4.
Manually feed the center drill into the part until the tapered portion of the cutter is
about halfway into the part.
5.
Loosen the tailstock and move it to the right of (away from) the part.
6.
Repeat steps 2-5 above, using the drill and then the reamer, as follows:
- drill: feed the tool into the part using an intermittent motion (i.e., insert, feed,
remove, repeat). This will break the chips and help bring them out of the hole.
- ream: feed the tool into the part in one continuous motion.
7.
Remove the part from the chuck.
Pulley Op. 50 – Face Boss, Turn Boss Diameter
1.
Place the pulley on the arbor table, boss down. Locate the mandrel in the center
hole and press it into through the center hole. NOTE: the lab instructor will
perform this step.
2.
Chuck the mandrel (with part) in the lathe, with the boss facing the tailstock.
3.
Insert a live center in the tailstock, then slide the tailstock left (towards) the part until
the center touches the mandrel. Secure the tailstock.
4.
Set the required load on the live center. (Ask Instructor for assistants if needed)
5.
Face and turn the boss in the same manner as for the hub (Op. 20), noting the
following:
Face Boss
- Use a depth-of-cut of about 0.030-in. (or less), and passes as
required, to obtain the required total length of 1.375 in.
- Feed the tool manually, being careful not to hit the mandrel
with the tool.
Rough Turn
Boss Diameter
- Depth-of-cut of about 0.100 in (or less), passes as required to
obtain boss diameter of about 1.050 in.
- Power feed (f = 0.010 ipr), moving right to left (towards chuck).
Finish Turn
Boss Diameter
- Depth-of-cut as needed to get 1.000-in. dia. in a single pass.
- Power feed (f = 0.003 ipr), moving right to left. When done, be
sure not to drag the tool across the diameter you just cut.
Pulley Op. 60 – Deburr Machined Surfaces
1.
Mount the V-grooving tool into the tool holder.
2.
Lower Chuck Guard, Turn on the spindle, and move the grooving tool to lightly
contact the three machined edges of the pulley.
3.
Turn off the spindle and raise Chuck Guard. Remove the V-grooving tool from tool
holder. Remove the mandrel/part from the chuck.
P-M Laboratory
4.
31
Place the mandrel/part on the arbor table, boss side up, and remove the mandrel.
Pulley Op. 70 – Broach Keyway
1.
Insert the broach guide in the boss end of the pulley hole. Then insert the broach
into the guide (it will only go in one way). Press together by hand until snug.
2.
Place the part/broach assembly on the arbor table.
3.
Press down and broach the keyway.
Pulley Op. 80 – Deburr Center Hole
1.
Chuck the 1-in. countersink in the drill chuck. Mount the part in the drill press vise.
2.
Turn the spindle on.
3.
Manually move the pulley hole into location under the rotating countersink to
deburr. Repeat for the other end.
4.
Turn off the spindle.
Pulley Op. 90 – Center Drill, Drill, Tap Radial Hole
1.
The gang drill has three spindles. Chuck the center drill in the left spindle, the twist
drill in the middle spindle, and the tap in the right spindle.
2.
Set spindle speed: left spindle = 900 RPM, center spindle = 600 RPM, right spindle =
150 RPM.
3.
Insert the pulley into the pulley jig, with the keyway is at the top. Tighten the jig
screws.
4.
Secure the jig in the left vise.
5.
Turn on the spindles with the foot switch.
6.
Lower the center drill (tapered section) about half-way into the part, then remove
the tool.
7.
Remove the jig, move it to the center vise, and secure it.
8.
Lower the twist drill until completely through the boss wall. BE CAREFUL not to go
through both walls! Remove the tool.
9.
Remove the jig, move it to the right vise, and secure it.
10. Apply cutting fluid to the tap and to the hole. Lower the tap into the part: once it
begins to thread, the tool will lower at its own pace. Keep your hand on the lever
and watch the tool carefully: when the tool has gone through the wall, reverse the
direction of the lever. This will cause the tap to automatically reverse direction and
rise out of the hole.
11. Turn off the spindles.
12. Remove the part from the jig.
P-M Laboratory
32
Pulley Op. 100 – Deburr Keyway, Radial Hole
1.
Hand-file the top of the radial hole and the edges of the keyway.
Pulley Op. 110 – Mark S/N
1.
Using a suitable ink marker (wax pencil, etc.), mark the serial no. (S/N) on the hub
face of the pulley (your instructor will give you the S/N to use).
Lab Requirements
Each student is required to machine a pulley as described. Parts will be evaluated
based upon general conformance of dimensions and geometry to the drawing
requirements (i.e., marks will be deducted only if dimensions and/or geometry are
obviously incorrect). The evaluation will be done as follows:
Not
attempted
Poor
Fair
Good
Excellent
Hub face
Hub diameter
0
0
6
6
8
8
11
11
14
14
Groove
Center hole
0
0
4
3
6
4
8
5
10
7
Boss face
Boss diameter
0
0
6
6
8
8
11
11
14
14
Keyway
Radial hole
Deburr (all required items)
0
0
0
3
4
4
4
6
6
5
8
8
7
10
10
Total points: 100
where
poor
fair
good
excellent
⇒
⇒
⇒
⇒
feature mostly incomplete and/or incorrect.
feature somewhat incomplete and/or incorrect.
feature slightly incomplete and/or incorrect.
feature complete and entirely correct.
P-I Laboratory
33
P-I: PULLEY– INSPECTION
Purpose
To learn how to operate various measuring instruments used for inspection of
manufactured items.
Overview
Inspection is investigated by inspecting the pulleys which were machined in the
previous lab. This corresponds to operation 120 on the route sheet for this product (pp.
125-126). Be sure to read through Appendix A (Geometric Dimensioning and
Tolerancing) before the lab, if you have not already done so. NOTE: A
scientific calculator and page 127 (printout) are required to complete this lab: bring
these with you. A page will be provided for you if necessary BUT this will result in a
deduction of 20 points from your score.
Equipment
Machined pulley.
Various inspection instruments.
Background
As we have seen, the goal in manufacturing is to produce items according to the
design specifications. These specifications, which cover product dimensions, geometry,
and other properties (hardness, surface finish, etc.), are given in the engineering
drawing(s) for the product. Inspection is the process by which part attributes are
examined to determine whether or not the parts conform to design specifications. Parts
which pass inspection can usually move on to subsequent processing operations, while
parts which fail inspection must be reworked, scrapped, or otherwise dealt with.
Inspection is a critical component in any manufacturing facility. Not only does
inspection ensure that products are of the required quality, it provides information which
can be used to improve the manufacturing process. Many manufacturing firms have
separate inspection departments, with highly-trained inspectors.
The most common form of inspection involves measurement. The attribute of
interest is measured, and the resulting value compared with the design specifications to
see if it is acceptable or not. For example, we might measure the length of a part and
then compare the value obtained with that specified on the drawing to see if the length
is within tolerance. In direct measurement, the measurement is taken and read with the
same measuring instrument. In indirect measurement, the measurement is taken with
one instrument, then transferred to and read from another instrument.
In this laboratory, we will be using a variety of measuring instruments to perform final
inspection on our pulleys. These instruments include the following: dial caliper, outside
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P-I Laboratory
micrometer, telescoping gage, dial indicator, gage blocks, and optical comparator. Some
background on each of these instruments now follows.
Dial Caliper
A dial caliper (Figure 1) consist of a scale and two jaws, one moveable and one fixed.
The part to be measured is placed inside the jaws, the jaws tightened, and the
measurement taken. The measurement is established by reading the scale (each division
= 0.100 in.) and adding on the value read in the dial (each division = 0.001 in.). Dial
calipers are very commonly used for measuring length and diameter. They can also be
used for measuring the size and depth of internal features, such as holes and pockets.
INSIDE MEASURING JAWS
DIAL INDICATOR
LOCK SCREW
90
0
1
0
10
80
20
70
30
60
50
DEPTH ROD
4
5
6
40
FINE ADJUSTMENT WHEEL
OUTSIDE
MEASURING
JAWS
BEZEL CLAMP
Figure 1. Dial caliper.
Outside Micrometer
ANVIL
SPIND
LOCK
NUT
SLEEVE
0
FRAME
01 2 3
An outside micrometer consists of a threaded
spindle inside a C-shaped frame, as shown in Figure
2. A graduated thimble and sleeve are located at the
end of the spindle. Rotating the thimble causes the
spindle to move towards or away from the opposite
end of the frame. The part is placed inside the frame
against the anvil, and the spindle turned until it
contacts the part. The measurement is then taken via
a vernier on the sleeve and thimble. Outside
micrometers are very commonly used for direct
measurement of part thickness and outside diameters
of small parts. They are also used in conjunction with
telescoping gages for indirect measurement.
THIMBLE
Figure 2. Outside Micrometer.
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35
Telescoping Gage
A telescoping gage (Figure 3) is a “T”-shaped instrument having two spring-loaded,
retractable plungers. The device is used to take measures of internal features such as
holes and slots. The plungers are retracted and locked, inserted into the part feature,
then released. The plungers then extend to contact the sides of the feature, are locked
in position, and removed from the part. Another measuring instrument, such as an outside
micrometer, is then used to read the measure. Telescoping gages come in a wide variety
of sizes.
PLUNGERS
Figure 3. Telescoping Gage.
Dial Indicator
Dial indicators (Figure 4a) are simple mechanical devices which convert linear
movement to rotation of an indicator needle on a circular dial. The indicator is first zeroed
(i.e., indicator needle made to point to zero on the scale) with respect to some reference
surface, then the part is brought into contact with the contact point. The measurement is
read directly from the circular dial. Dial indicators are used with various holding fixtures
for measuring thickness (height), straightness, parallelism, roundness, flatness, and
runout. The fixture must be located on a solid, flat surface for such measurements to be
possible – items known as surface plates are especially designed for this function. Figure
4b shows an example of a dial height gage.
Gage Blocks
Gage blocks are square or rectangular-shaped blocks used for a variety of measuring
tasks. A set of blocks of different sizes is usually provided: blocks can also be “stacked”
to obtain additional sizes. Gage blocks are precision-made and are usually dimensionally
accurate and parallel within several millionths of an inch, and are sometimes traceable to
national standards. Because of their high accuracy, they are often used to check or
calibrate other measuring instruments. Gage blocks can also be used for indirect
measurement.
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P-I Laboratory
THUMB
WHEEL
DIAL
INDICATOR
DIAL
BEZEL
CLAMP
INDICATOR
LOCK
INDICATOR
NEEDLE
BASE
CONTACT
POINT
(a)
SCRIBER
(b)
Figure 4. (a) Dial indicator, and (b) dial height gage.
Optical Comparator
An optical comparator is a machine used for checking surface profiles and
measuring dimensions of small, intricate parts. The part is fixed on a table, and a
projection system casts a magnified shadow outline of the part on a screen.
Measurements are taken by moving the part (table) and measuring the movement of the
shadow image with respect to reference lines on the screen. Digital readouts are often
used to improve resolution and repeatability.
Procedure
The pulley inspection operation consists of a set of inspection steps, each which
involves inspecting one or more attributes. For each attribute, measurements are taken
to determine one or more disposition values. These values are then compared to the
drawing requirements to determine whether or not the attribute is acceptable. The
entire procedure is recorded on a part inspection report form.
The lab instructor will give you a pulley to inspect, and will explain and demonstrate
each inspection step. You are to inspect your pulley and complete the inspection
form in your lab manual (p. 127). For each attribute inspected,
• record all measurements and show all calculations and the disposition value(s) in
the RESULTS column.
• check the ACC (accept) or REJ (reject) column to indicate the disposition.
If an attribute on your pulley is incomplete (and hence cannot be inspected), write
“INCOMPLETE” in the RESULTS column for that attribute, check the REJ column, and
notify your instructor. He/she will give you another pulley to use for that attribute.
P-I Laboratory
37
Record your measurements, disposition value(s), and disposition for that attribute at the
bottom of the inspection form (and on the back, if necessary).
Once all steps have been performed and the inspection form completed, determine
the final disposition of your pulley and record this on the work order. When all
disposition results have been recorded, be sure to sign-off the inspection operation on
the work order. As this is the last operation on the work order, the job is now complete.
In practice, the inspection forms would be stapled to the work order or otherwise
carefully stored.
Pulley Op. 120 – Inspection
1. Hub Diameter
Equipment: dial caliper.
a. Take three equally-spaced readings of the hub diameter.
b. Record each measurement, and calculate and record the average (as the
disposition value), on the pulley part inspection report form.
2. Boss Diameter
Equipment: outside micrometer.
a. Take three equally-spaced readings of the boss diameter.
b. Record each measurement, and calculate and record the average (as the
disposition value), on the inspection form.
3. Concentricity of Hub and Boss
Equipment: dial indicator with base, bench center, surface plate, tapered mandrel.
a. Place the pulley on a mandrel, either by hand or with an arbor press.
b. Place the mandrel on bench center on the surface plate as shown below:
Bench Center
Bench Center with part
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P-I Laboratory
c. Raise the dial indicator contact point above the part height, then locate the contact
point at point ‘a’ on the hub (above). Zero the indicator, using the bezel.
d. Rotate the mandrel (and part) and note the range of dial indicator movement. This
is known as T.I.R. (Total Indicator Reading). Record this value on the inspection form.
e. Repeat steps c – d using point ‘b’ on the boss (above).
f. Remove the mandrel from the part.
g. Calculate the concentricity of the boss with the hub, C, as follows:
C=
T.I.R.(hub) − T.I.R.( boss)
2
Record this as the disposition value on the inspection form.
4. Hub Thickness
Equipment: gage blocks totaling 0.625 inches (e.g., 0.300, 0.120, 0.105, 0.100), dial
bench gage.
a. Stack the gage blocks together and place them on the bench gage table, under the
dial gage contact point.
b. Zero the indicator, using the bezel, and lock it. Remove the gage blocks.
c. Lift the contact point with the hand lever, and slide the pulley underneath as shown
below. Record the measurement.
d. Repeat step c two more times to obtain three measurements total, 120° apart.
e. Calculate the average based upon the three readings, add this value to 0.625, and
record the resulting disposition value on the inspection form.
5. Parallelism of Hub Face and Shoulder
Equipment: dial bench gage.
a. Lift the contact point and slide the pulley underneath as before.
b. Zero the indicator.
P-I Laboratory
39
c. Rotate the part 360°, keeping the contact point in the same radial location (about
mid-way between boss and hub diameters) at all times. Note the total range of dial
indicator movement (T.I.R). This is the amount within which the hub face and
shoulder are parallel.
d. Record T.I.R. as the disposition value on the inspection form.
6. Overall Length
Equipment: dial height gage, surface plate.
a. Place the dial height gage on the surface plate. Move the contact point down until it
rests on the surface plate, and zero the dial using the bezel.
b. Lift the dial slide (assembly which slides along the vertical bar) up until the
measuring tip is about 2-3 inches above the surface plate.
c. Move the pulley underneath. Then lower the dial slide down by hand until the
contact point is about 1/16-in. above the top of the boss, and lock the slide in place
with the thumbscrew (left side of dial slide). Then use the fine height adjustment
nut (right side of dial slide) to lower the contact point until it contacts the top of the
boss. Slide the pulley back and forth while lowering to determine when contact has
been made.
d. Take reading.
e. Take additional readings by raising/lowering the dial slide using the fine height
adjustment nut. Take 3 equally-spaced readings total.
f. Record each measurement, and calculate and record the average (as the
disposition value), on the inspection form.
7. Center Hole Diameter
Equipment:
1
2
− 34 telescoping gage, outside micrometer.
a. Retract the plungers on the telescoping gage and lightly tighten the thumbscrew to
lock the plungers.
b. Insert the gage (plunger end first) into the pulley hole at the boss end, as shown in
figure (a) on the next page. Be sure the setscrew hole does not interfere with the
plungers.
c. Set the telescoping gage length as follows: loosen the thumbscrew to release the
plungers, lightly tighten the thumbscrew, rotate the gage to about 30° with vertical,
and then straighten the gage out and retract it. See figures (b) and (c) on the next page.
d. Measure the length between the plungers with the outside micrometer. Record this
as the disposition value on the inspection form.
40
P-I Laboratory
~30°
(a)
~30°
(b)
(c)
8. Groove Dimensions
Equipment: Deltronic Optical Comparator DH-124.
a. Turn on the optical comparator (top rocker switch, front of comparator underneath table),
then set the PROFILE rocker switch (same area) to LOW to set the light intensity. Turn
on the DRO (digital read-out) unit on top of the comparator (rocker switch at back).
b. Both the DRO display and comparator LED display (to lower right of projection screen)
will be flashing. Hit “X” (or “Y”) on the DRO, then “RESET” next to the LED display.
c. Load the part in the vise with the boss facing right. A shadow image of the part will
appear on the projection screen.
d. Center the “V” of the groove on the vertical crosshair, and the top edge of the part
on the horizontal crosshair, using the right hand crank (X table movement), large
left hand crank (Y table movement), and comparator screen rotation knob (screen
angle). The comparator screen rotation knob is located at the lower right corner of
the screen. The display should now appear as follows:
a
b
e. Zero the DRO by pressing the X and Y buttons, and the comparator LED display
by hitting RESET .
f. Measure the axial distance from groove center to part edge. Rotate the X table
movement hand crank counterclockwise to move the part right (part image
moves left), until point ‘a’ (figure above) lines up with the vertical crosshair. Read
and record the DRO X display as the axial location disposition value, then move the
part back to the center of the screen.
g. Measure groove depth. Rotate the Y table movement hand crank counterclockwise
to move the part towards the screen (part image moves up), until point ‘b’ lines up
P-I Laboratory
41
with the horizontal crosshair. Read and record the DRO Y display as the depth
disposition value, but DON’T move the part back.
h. Measure groove angle. Rotate the comparator screen knob counterclockwise until
the vertical crosshair lines up with the right-hand edge of the groove on the screen.
Read and record the comparator LED display value in the last row (“Width”) of the
inspection form. Then calculate groove width, based upon groove angle and depth,
and record this as the width disposition value.
i. Remove your part and shut down (power switch, PROFILE switch) and DRO.
Lab Requirements
Each student is required to inspect a pulley as described. The evaluation will be
done on a per-attribute basis as follows:
Not
attempted Poor
Fair
Good Excellent
1. Hub Diameter
2. Boss Diameter
0
0
4
4
6
6
8
8
10
10
3. Concentricity of Hub and Boss
4. Hub Thickness
0
0
4
4
6
6
8
8
10
10
5. Parallelism of Hub Face and Shoulder
6. Overall Length
0
0
4
4
6
6
8
8
10
10
7. Center Hole Diameter
8. Groove Axial Location
0
0
4
4
6
6
8
8
10
10
9. Groove Depth
10. Groove Width
0
0
4
4
6
6
8
8
10
10
Total points: 100
where
⇒ measurement(s) incorrect, disposition value(s) calculated incorrectly,
and disposition incorrect.
fair
⇒ any two of the above done incorrectly.
good
⇒ any one of the above done incorrectly.
excellent ⇒ measurement(s) correct, disposition value(s) calculated correctly,
and disposition correct.
poor
42
MP-M Laboratory
MP-M: MOUNTING PLATE – MACHINING AND RELATED
PROCESSES
Purpose
To learn about some different types of machining and related processes used for
prismatic (i.e., box-shaped) items, and how to use various machine tools to perform the
processes.
Overview
Machining and related processes commonly used for prismatic items are
investigated by producing base plates, which in turn will be used to make
mounting plates. An engineering drawing of a base plate is given on p. 131:
machining and related processes encompass operations 20-70 of the route sheet for
this item (p. 132). The processes covered include horizontal milling, vertical
milling, punching, and deburring. (See p. 129 for an engineering drawing of a
mounting plate and p. 128 for a mounting plate bill-of-materials.)
Equipment
Steel plate 6-1/2” x 3” x 1/2”.
Vertical milling machine, horizontal milling machine, punch press, drill press.
Various cutting tools and fixtures, hand file.
Background
Machining is a general term for manufacturing processes where a cutting tool is
moved relative to a workpiece to selectively remove material from the item. Machining
is one of the most fundamental and important categories of manufacturing processes.
This is because:
- Machining can be used to create almost any shape (flat, round, etc.) or geometric
feature (pocket, boss, etc.).
- Machining can be applied to almost all metals and alloys, as well as to many
other materials (plastics, wood, etc.).
- Machining is capable of producing dimensions to very close tolerances (± 0.001
in. or better), and of creating very smooth surface finishes (better than 16 µin.).
Machining is generally performed after the main shape of the item is obtained via a
bulk deformation process (such as casting, rolling, or forging). Successive machining
operations, using different types of machines and cutting tools, are very common.
One of the most common category of machining processes for prismatic items is
milling. Milling is where a workpiece is moved relative to a rotating, multiple-edge
cutting tool to remove material. To perform milling, horizontal milling machines
or vertical milling machines are used (Figure 1). As shown in the figure, the terms
MP-M Laboratory
43
horizontal and vertical refer to the orientation of the tool axis. With either type of
machine, the part is affixed to the work table, which sits in a saddle. The saddle can
move transversely, allowing the part to be moved relative to the tool. The cutting tool
(milling cutter) is attached to a spindle (via an arbor on horizontal milling machines)
which is rotated by a drive motor. Milling is accomplished by rotating the tool, lowering
the tool down until it contacts the part, then moving the work table (and hence part)
transversely.
Overarm
Head
Tool
Arbor
Tool
Column
Column
Saddle
Saddle
Work table
Work table
Base
Base
(a)
(b)
Figure 1. (a) Horizontal and (b) vertical milling machines.
Once the cutting tool has been selected for a milling operation, three parameters
known as cutting conditions must be established before the operation can be
performed. These are speed (or cutting speed, V), feed (f), and depth-of-cut (d). For
milling operations,
- speed is how fast the outer edge of the tool moves relative to the part. This
depends upon both how fast the spindle speed is rotating (N, rpm) and the
diameter of the tool.
- feed is how much the part moves for each revolution of the tool.
- depth-of-cut is how much material (thickness) is removed from the part at a time.
Figure 2 illustrates speed, feed, and depth-of-cut in milling. For any machining
operation, speed is usually measured in surface feet per minute (sfpm), feed in inches
per revolution (ipr) or millimeters per revolution, and depth-of-cut in inches or
millimeters. Note also the following:
- Speed cannot be set directly. The spindle rpm N must be set to get the desired
speed.
- Instead of feed, a related parameter called feed rate (f r ) is often specified. This is
how much the part moves relative to the tool per unit time, rather than per tool
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MP-M Laboratory
revolution. Feed rate is commonly expressed in inches per minute (ipm) or
millimeters per minute.
Tool
Speed
Speed
Tool
Workpiece
Workpiece
Depth-of-cut
Depth-ofcut
Feed
Feed
Side milling
(Horizontal milling machine)
Face (end) milling
(Vertical milling machine)
Figure 2. Speed, feed, and depth-of-cut in milling.
When a lot of material has to be removed, it is common to performing the machining
operation using one or more roughing passes, followed by a finishing pass. A roughing
pass is one where the depth-of-cut is large, so as to remove material as quickly as
possible. A finishing pass is one where depth-of-cut is shallow, the objective being to
obtain the final dimensions. Cutting speed is often increased and feed decreased in
finishing passes to obtain the required surface finish.
Through-holes are a common feature of many prismatic components. These can be
produced via machining (drilling), but an alternative is to shear the unwanted material
from the part via a sheet metal forming process called punching. In punching, the
workpiece (sheet) is placed on a die, and punch is brought down with sufficient force to
shear the material it contacts into the die (Figure 3). A hole is created when the punch
is circular and the die contains a hole (other shapes are of course possible as well).
Punching is an attractive alternative to drilling because it is much faster. Additionally,
the waste produced from punching (round slugs) is much easier to clean up than that
Figure 3. Punching of sheet metal.
MP-M Laboratory
45
produced from drilling (metal chips). The disadvantage is that the force needed to
punch can be very high, and increases with increasing workpiece thickness. This
results in the need for very large machines (e.g., punch presses).
Both milling and punching processes result in the formation of burrs. A burr is a
sharp, thin protrusion of material, usually triangular in shape, which develops along the
edge of a surface following machining (and other) metalworking processes. Burrs are
both undesirable and unavoidable. They can interfere with assembly of mating parts,
reduce the fatigue life of components, and are a safety hazard to personnel. In order to
remove burrs, deburring is usually performed at various times during machining.
Manual deburring can be done using files, abrasive belts, and/or wire brushes.
Procedure
The first operation (op. 10 – cut to length) has already been performed on your
parts. The basic steps for performing the remaining machining operations on the base
plate are listed below. The equipment needed for each operation is specified on the
base plate route sheet (work order). For each operation, the lab instructor will first go
through the required steps in detail, following which each student will perform that
operation on their part. KEEP HANDS CLEAR OF THE TOOL DURING MACHINING.
DO NOT ATTEMPT TO BRUSH AWAY OR OTHERWISE REMOVE CHIPS WHILE
THE TOOL IS IN MOTION.
Once the operations have been completed for all parts, be sure that someone in
your group signs-off the operations on the work order.
Base Plate Op. 20 – Punch Mounting Holes
1.
Place the base plate on the punch press table. Slide the part under the punch and
against the jig stops along two edges. This will locate the plate in the correct
position for the hole.
2.
REMOVE YOUR HAND FROM THE PART, AND KEEP IT AWAY DURING
PUNCHING.
3.
Depress the foot pedal to bring the punch down through the part, creating a hole.
4.
Wait for the punch to fully retract. Then remove the part, rotate it 180°, and repeat
steps 1-3.
Base Plate Op. 30 – Deburr Holes
1.
Chuck the 82° countersink in the drill chuck.
2.
Turn the spindle on.
3.
Manually move the base under the rotating countersink to deburr each hole.
4.
Turn off the spindle.
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MP-M Laboratory
Base Plate Op. 40 – Side Mill Longitudinal Slot
1.
Check that the fixture is to the left of the tool, then set the base plate in the fixture.
Push the part against the two locating pins with one hand while installing and handtightening the two cap screws with the other. Then tighten the screws securely with
an allen wrench.
2.
The longitudinal slot will be cut in a single pass. Set the cutting conditions as
follows: spindle speed (N) = 50-55 rpm, feedrate = 1/2-1 ipm, depth-of-cut = 0.100
in. Your lab instructor will give you exact settings and show you how to set the
machine.
3.
Turn the machine spindle on (tool starts rotating). Apply
cutting fluid to the tool and adjacent work surface, then
SLOWLY rotate the manual feed wheel clockwise to make
the table and part move right (i.e., towards the tool). Stop
when the part just contacts the tool, then feed the part just
a little more (1-2 turns). Then engage the power feed: the
table and part will continue to move towards the rotating
tool, cutting the slot. Add cutting fluid whenever the tool
appears dry.
4.
Once the slot has been cut, disengage the power feed. Then rotate the manual
feed wheel clockwise until the part is at least 1 inch past (to the right of) the tool.
5.
Remove the part from the fixture and clean it.
Then rotate the feed
wheel counterclockwise until the fixture is back at the starting position, i.e., about 2
in. to the left of the tool.
Base Plate Op. 50 – End Mill Transverse Slot
1.
Check that the fixture is in front of the tool, then set the base plate in the fixture.
Push the part against the three locating pins with one hand while installing and
hand-tightening the cap screws with the other. Then tighten the screws securely
with an allen wrench.
2.
The transverse slot will be cut using both a roughing and a finishing pass. Set the
cutting conditions as follows for the roughing pass: spindle speed (N) = 300-375
rpm, feedrate = manual feed (see below), depth-of-cut = 0.060-0.080 in. Your lab
instructor will give you exact settings and show you how to set the machine.
3.
Turn the machine spindle on, and apply cutting fluid to
the tool and work surface. Then rotate the manual feed
wheel clockwise to move the table and part back until the
part contacts the tool. Continue turning the wheel to cut
the slot, adding cutting fluid whenever the tool appears
dry.
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47
4.
Once the roughing pass is complete, increase the depth-of-cut until the total depth
is 0.10 in (i.e., giving a finishing cut of 0.02-0.04 in.). Now rotate the manual feed
wheel counterclockwise to make the finishing pass by feeding the table and
part forward, adding cutting fluid as necessary.
5.
Once the final pass is complete, remove the part from the fixture and clean it. The
fixture should now be back at the starting position.
Base Plate Op. 60 – Deburr Slots
1.
Using a hand file, deburr the machined edges of each slot.
Base Plate Op. 70 – Mark S/N
1.
Using a suitable ink marker (or wax pencil), mark the serial no. (S/N) on the bottom
face of the base plate (your instructor will give you the S/N to use).
Lab Requirements
Each student is required to machine a base plate as described. Parts will be
evaluated based upon general conformance of dimensions and geometry to the drawing
requirements (i.e., marks will be deducted only if dimensions and/or geometry are
obviously incorrect). The evaluation will be done as follows:
Not
attempted
Poor
Mounting holes
Longitudinal slot
0
0
8
8
Transverse slot
Deburr (holes and slots)
0
0
16
8
Fair
Good
Excellent
12
12
16
16
20
20
24
12
32
16
40
20
Total points: 100
where
poor
fair
good
excellent
⇒
⇒
⇒
⇒
feature mostly incomplete and/or incorrect.
feature somewhat incomplete and/or incorrect.
feature slightly incomplete and/or incorrect.
feature complete and entirely correct.
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MP-NC1 Laboratory
MP-NC1: MOUNTING PLATE – NC MACHINING VIA MANUAL
PART PROGRAMMING
Purpose
To learn about Numerically Controlled (NC) Machining and how it can be done by manual
part programming.
Overview
Numerically controlled machining is investigated by manually preparing and validating an
NC program for a part. The parts of concern are forward fix plates, which in turn will be
used to make mounting plates. An engineering drawing of a forward fix plate is shown on
p. 134: NC machining encompasses operation 20 on the route sheet for this item (p. 135).
The NC program will be validated using wax blocks and a small NC milling machine.
NOTE: you must prepare your NC program individually BEFORE the lab, and
bring both a softcopy AND a hardcopy (print-out) of your program to the lab.
The program must be saved as a text (.txt) file on a USB memory stick OR a
data CD. Each student must bring his/her own storage device (i.e., no sharing).
MARKS WILL BE DEDUCTED if these requirements are not met (see p. 57).
Note: If documents are provided for you there will be 20 points deducted from
your score.)
Equipment
Wax blocks 3” x 3” x 1”, steel plate 3” x 3” x 1/4”.
Haas Desk Top vertical milling machine, HURCO vertical milling machine.
Various cutting tools and fixtures.
Background
Numerically Controlled (NC) Machining is the use of coded instructions, in the form
of alphanumeric data, to control the movement of a cutting tool relative to a part. A
computer program (NC program) is prepared, which contains all the instructions needed
for the operation. This includes speed, feed, and depth-of-cut data, what tools to use
and when, the tool path, and when to turn cutting fluid and/or coolant flow on and off.
The NC program is entered into a controller, which reads the program and sends the
necessary control signals to the machine.
Numerically controlled machining is of great importance in modern manufacturing.
Before NC machining, every machining operation had to be done manually. Skilled
machine operators were needed, and the repetitive, tedious nature of the work often
resulted in low product quality. Changing from one product to another was very time
consuming, as the operator had to manually adjust the work table, load the required
MP-NC1 Laboratory
49
tools, etc. Numerical control reduces the need for skilled machines operators, and allows
one operator to handle several machines at the same time. Quality is vastly improved:
the same program is executed each time and hence parts are practically identical to one
another. Finally, changing from one product to another can be done quickly by simply
loading different NC programs.
Before NC programs can be used for production, they must be validated, i.e.,
checked to make sure they are working properly. A program that has not been validated
may have errors that can damage the tool, part, and possibly even the machine. Thus,
validation is essential in NC machining. This process can take a lot of time, however,
and tie-up production machinery. One way to minimize the time is to validate NC
programs using wood, wax, or even Styrofoam parts. This allows the use of very high
feed rates, thus reducing the time needed for validation.
NC programs can be generated in several ways. The most straightforward method is
to manually calculate the tool path and then write the NC program directly based upon
this (and other) information. This is known as manual part programming. This laboratory
is concerned with manual part programming using the Haas Desk Top mill programming
language, and using the NC programs with Haas Desk Top vertical milling machines.
Haas Desk Top Coordinate System
There are three axes of movement on the Haas Desk Top mill. The machine spindle
moves up and down (Z axis), while the part table moves both left and right (X axis) and
towards and away from (Y axis) an operator facing the machine. Thus, the tool can move
in three dimensions with respect to the table. The tool tip position is then expressed in
terms of the coordinates (X, Y, Z, point C in Figure 1).
The tool tip position is always defined relative to a specified origin (0, 0, 0). There are two
possible origins: home zero and reference zero (Figure 1).
Machine table
(in limiting position)
+Z
+Y
A
B
+X
Part
Figure 1: Coordinate system origins for the Haas Desk Top Mill.
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MP-NC1 Laboratory
Home zero (point A) is the upper right-hand corner of the machine table when the
table is at its limiting position along both X and Y axes and Z will be at its highest limit
(i.e., the table will be as far left and forward as possible and the machine head as high
as possible).
Reference zero (point B) is the main reference point within a program. It can be
anywhere within the working envelope of the machine (e.g., corner of part), and is
established when the machine is setup to run a program.
Clearance Plane
In order to move the tool from one cutting location to another on a part, a clearance
plane must be established. This is an imaginary XY plane, above the highest point on the
part, in which the tool can move freely. The tool typically starts in the clearance plane. It
is then moved (in the clearance plane) to the first cutting location, lowered into the part,
the cut taken, the tool raised to the clearance plane and moved to the next cutting location,
etc. Figure 2 shows an example of a clearance plane.
+Z
+Z
+Y
Clearance
plane
+X
Y
+X
Part
Figure 2. Clearance plane.
Manual Part Programming for the Haas Desk Top
A Haas Desk Top part program consists of a sequence of program statements, each of
which uses G-code or M-code. G-codes specify the general (G) operations performed on
a machine (type of motion, speed or feed mode, etc.), while M-codes specify
miscellaneous (M) commands (changing the cutting tool, turning coolant flow on or off,
setting spindle speed, etc.).
G and M codes that may be used in this lab are as follows:
- G00 – Rapid Traverse (move the tool to a location at the machines fastest feed rate,
only use G00 when tool is in the clearance plane). Example: (G00 X1.000 Y2.500).
- G01 – Move the tool to a location, at a controlled feed rate, using linear interpolation.
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51
The destination location is set via the letters X and Y, while the letter F indicates the
feed rate (note: a decimal point is needed). Use G01 when the machine is cutting
material. Example: (G01 X1.000 Y2.500 F10.0).
- G02 – Move the tool in a clockwise motion using circular interpolation. ‘X’ and ‘Y’
specify the tool location after the move, ‘I’ and ‘J’ specify the x and y coordinates of
the circle center (relative to the tool’s location before the move), and ‘F’ indicates
feed rate (note: a decimal point is needed). Use G02 when the machine is cutting
material. Examples: (G02 X1.500 Y1.500 I0.500 J0.500 F10.0), (G02 X1.500
Y1.500 R.500 F10.0).
- G03 – Move the tool in a counterclockwise motion using circular interpolation. Same
syntax as G02.
- G20 – Inch: Specifies inches as the unit of measure for the part program.
- G28 – Set reference point: Commands machine to return to home origin.
- G40 – Cancel cutter compensation: All commands are taken from the tool center.
- G43 – Tool length compensation positive must be used with a H # referencing tool
being used.
- G54 – Coordinate offset (Reference Zero from Home Position).
- G90 – Absolute programming mode: All coordinates are relative to origin of the
current coordinate system.
- G91 – Incremental programming mode: Each motion to a new coordinate is from
the current tool location.
- M02 – Set machine spindle speed. M02 is followed by the letter S and then spindle
speed in RPM. Example: (M02 S8000).
- M03 – Spindle motor on: Activated concurrently with motion specified in the program
block; remains in effect until superseded by M05.
- M05 – Spindle motor Off: Activated after the motion specified in the program lock;
remains in effect until superseded by M03.
- M06 – Tool change: Used in conjunction with a T (for tool) code to perform multiple
tool operations.
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- M30 – End a n d r e s e t program: Turns off drive motors, spindle and accessory
outlets: prepares for the next program cycle.
The FIRST FOUR statements of a program should always be the following:
G00 G54 G90 G40 G20
M06 T1
M03 S8000
G43 H01 Z.200
(“Rapid Traverse” (G00), “Coordinate Offset” (G54),
“Absolute Programming Mode” (G90), “Cancel Cutter
Compensation” (G40), “Inch” (G20))
(Tool change: insert tool #1 into the spindle).
(Turn spindle on, set RPM to 8,000)
(Height offset positive (G43), tool reference 01 (H01), Z
movement to 0.200)
The LAST THREE statements of a program should always be the following:
M05
G28
M30
(Turn the spindle off)
(Return the tool to the home origin)
(End, reset program)
Rectangular Motion
Rectangular motion commands are those where tool movement (center of tool’s
diameter) is specified in terms of x, y, and z moves. There are two types of movement:
absolute (tool moves relative to the reference zero) or incremental (tool moves relative
to its last location). Absolute movement is set via the G90 command, while G91 is used
to specify incremental movement. For example, if the tool is located at point A (X = 0.5,
Y = 1, Z = 2), the following rectangular motion commands would generate the shape
shown (in the plane Z = 2), using a feed rate of 10 inches per minute (IPM):
G90
(All command will move from absolute zero)
G01 X2.5 F10.0
(Moves the tool from A to B)
G01 Y1.75 F10.0
(B to C)
G01 X1.5 Y2.5 F10.0
(C to D)
G01 X0.5 F10.0
(D to E)
G01 Y1.0 F10.0
(E to A)
The G91 command moves the tool relative to its
current location. The same shape as before can also be
generated via G91 commands as follows:
G91
G01 X2.0 F10.0
G01 Y0.75 F10.0
G01 X-1.0 Y0.75 F10.0
(All command will move from the previous point)
(Moves the tool from A to B)
(B to C)
(C to D)
MP-NC1 Laboratory
G01 X-1.0 F10.0
G01 Y-1.5 F10.0
53
(D to E)
(E to A)
Though either G90 or G91 commands can be used for Z axis movement, it is always
safer to use G90 commands. Assuming the part surface is at Z = 0, clearance plane
moves are then always positive and moves to bring the tool down into the part are always
negative.
Circular Motion
When cutting a radius, the tool (center of tool’s diameter) moves from an XY starting
point to an XY ending point as it rotates around a specified center point (designated by
I and J). As previously specified, the G02 command rotates the tool in a clockwise
movement while G03 results in a counterclockwise movement. Note that to specify
circular motion, you need to know both the starting and ending (destination) XY locations
of the tool and the XY center point of the circle along which the tool will travel. The circle
center point is specified either by its x and y coordinates (I and J) relative to the tools’
starting location, or by the circle radius (R). For example, if the tool is located at point A
(X = 0.8660, Y = 0.500, Z = 2.0), the following circular and angular motion commands
would generate the shape shown (in the plane Z = 2.0):
90
75
60
C
45
30
D
B
15
A
0
1
2
3
0
G90
(All command will move from absolute zero)
G01 X2.1650 Y1.25 F10
(Moves the tool from A to B)
G03 X0.6470 Y2.4148 I-2.165 J-1.25 F10.0
(B to C moving counterclockwise)
G91
(All command will move from the previous point)
G01 X-0.3882 Y-1.4488 F10.0
(C to D)
G02 X0.6072 Y-0.4659 I-0.2588 J-0.9659 F10.0 (D to A moving clockwise)
Alt. (G02 or G03 X ending location Y ending location R radius of arc)
(Note: When using G90 and G91 command, (I and J) will be located from the
starting point of the arc.)
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MP-NC1 Laboratory
EXAMPLE
The Haas Desk Top G-code program on the following page will cut the VT logo
below (tool path = center of tool’s diameter), from a 7 x 12 in. work piece. The reference
zero is at the bottom lower left corner of the work piece, and the clearance plane is 0.20
in. above the part. A 0.25-in. diameter end mill is to be used. Depth-of-cut is 0.10 in.
throughout.
G00 G54 G90 G40 G20
(Starting statement)
M6 T1
(Tool change Tool # 1)
M3 S8000
(Spindle on at 8000 RPMs)
G43 H01 Z.200
(Height offset positive, tool reference 01, Z movement to 0.200)
G00 X6.00 Y1.00
(Move to center of lower straight-line segment)
G01 Z-.1 F10.0
(Feed tool into material)
G01 X8.500 F10.0
(Cut first half of lower straight-line segment)
G03 Y6.000 I0.0000 J3.5000 F10.0 (Cut RH semi-circle)
G01 X3.500 F10.0
(Cut upper straight-line segment)
G91
(Change from Absolute to Incremental programming)
G03 Y-5.00 R2.50 F10.0
(Cut LH semi-circle)
G01 X2.500 F10.0
(Cut second half of lower straight-line segment)
G90
(Change from Incremental to Absolute programming)
G00 Z.200
(Move tool to clearance plane)
G00 X3.000 Y5.000
(Move tool to the starting point of “V”)
G01 Z-.1000 F10.0
(Feed tool into material)
G01 X4.000 Y2.000 F10.0
(Cut first half of “V”)
G01 X6.000 Y5.000 F10.0
(Cut second half of “V”)
G00 Z.200
(Move tool to clearance plane)
G00 X7.000
(Move tool to the starting point of “T”)
G01 Z-.100 F10.0
(Feed tool into material)
(Program continues on the following page)
MP-NC1 Laboratory
G91
G01 X2.00 F10.0
G01 X-1.000 F10.0
G01 X-1.5 Y-3.00 F10.0
G90
G00 Z.2000
M05
G28
M30
55
(Change from Absolute to Incremental programming)
(Cut top segment of “T”)
(Move tool to the center of top segment of “T”)
(Cut bottom segment of “T”)
(Change from Incremental to Absolute programming)
(Move tool to clearance plane)
(Turn off spindle)
(Command machine to return to home origin)
(End and reset of Program)
Procedure
Each student will prepare a Haas Desk Top G-code part program for the forward fix
plate (p. 140). Programs are to be validated using the Haas Desk Top vertical milling
machines and wax blocks. A depth-of-cut of 0.250 inch is to be used for the entire cutting
operation.
The feed rates for cutting wax parts are to be 10.0 inches/minute for the X, Y, and Z
axes respectively. You must prepare your NC program individually BEFORE the lab,
and bring both a softcopy AND a hardcopy (print-out) of your program to the lab.
The program must be saved as a text (.txt) file on a USB memory stick OR a data
CD. Each student must bring his/her own storage device (i.e., no sharing). MARKS
WILL BE DEDUCTED if these requirements are not met (see p. 57).
At the start of the lab, the lab instructor will describe the operation of the Haas Desk
Top vertical milling machine. He/she will then go through the steps to download a
program, load a part, and run the program. These steps are described below. Following
the demonstration, you will load your program on a PC in the laboratory. Modify your
program as necessary, then run it (i.e., attempt to cut a part). Continue working with your
program and running it, using only one side of your wax block and obtaining extra blocks
from your instructor, as necessary. NOTE: NC programs must be prepared
individually. If you need help, ask the lab instructor. No student help is permitted.
Once you are satisfied with your program, notify your lab instructor. He/she will watch
you go through the procedure and then evaluate your part. Only the final run of the
program on the wax part will be graded. Full marks can be obtained only by cutting
the part correctly on the first attempt (see p. 57). Common mistakes are: Letter O
used instead of a zero (0), All Destination or value numbers must have a decimal
behind it (example X2.0 and F10.0), and using G00 instead of a G01 with a
controlled feed for mill operations.
Once the programs have been prepared for all parts, be sure that someone in your
group signs-off the NC PROGRAM VALIDATED portion of the operation on the work
order. The lab technicians will then use a validated NC program to cut the actual forward
fix plates you will use for your mounting plate.
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Forward Fix Plate Op. 20 – Cut Radial Slot, Mounting Holes, and “X” Slot
Reset Key
Cursor Keys
List Program
Memory Key
Select Program
Graphics Key
Cancel
TO LOAD AND RUN PROGRAM:
1. Press List Prog Key.
2. Toggle up and over to run from USB.
3. Press Select Prog Key.
4. To run Graphics press Memory Key, Graphics Key, Then Cycle start
Button. (Green button lower left of control panel)
5. To run Program press Memory Key, and Press Cycle Start Button. (Green
button lower left of control panel)
TO UNLOAD PROGRAM:
1. Pull you USB out of the controller.
2. Press Cancel Key.
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57
Lab Requirements
Each student is required to produce the part as described. Your final part will be
evaluated as follows:
Not
attempted
0
0
0
Arc
“X” slot
2 holes
Poor
25
25
8
Fair
30
30
12
Good
35
35
16
Excellent
40
40
20
Total points: 100
where
poor
fair
good
excellent
 feature mostly incomplete and/or incorrect.
 feature somewhat incomplete and/or incorrect.
 feature slightly incomplete and/or incorrect.
 feature complete and entirely correct.
IN ADDITION to the above,
• 20 points will be deducted from your part score if you do not prepare your program
in advance, as specified on p. 48 and p. 55.
• 4 points will be deducted from your part score for each additional cutting attempt
made.
In other words, full marks (100 points) can be obtained only by preparing the program in
advance as described and cutting the part correctly on the first attempt.
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MP-NC2 Laboratory
MP-NC2: MOUNTING PLATE – NC MACHINING VIA CAM
SOFTWARE
Purpose
To learn how Numerically Controlled (NC) Machining can be accomplished via
Computer Aided Machining (CAM) software.
Overview
Numerically controlled machining is investigated by preparing and validating an
NC program using CAD/CAM software. The parts of concern are aft fix plates, which
in turn will be used to make mounting plates. An engineering drawing of an aft fix
plate is shown on p. 137: NC machining is operation 20 on the route sheet for this
item (p. 138). The NC program will be validated using wax blocks and a small NC
milling machine. A quiz will be given at the end of this lab. Note: the entire lab
manual (hardcopy) is needed for this lab: bring this with you. A manual will be
provided for you if necessary BUT this will result in a deduction of 20 points from
your score.
Equipment
Wax blocks 3” x 3” x 1”, steel plate 3” x 3” x 1/4”.
Haas Desk Top vertical milling machine, HURCO vertical milling machine.
Various cutting tools and fixtures.
CAM software (FeatureCAM®).
Background
Numerically controlled (NC) machining, as we have seen, is where a computer
program (NC program) is used to control the movement of a cutting tool relative to a part.
In the previous lab (MP-NC1), manual part programming was used to generate NC
programs. There are several disadvantages to manual part programming:
- Manual calculation of the tool path and writing the NC program line-by-line are
both tedious, time-consuming, and error-prone processes.
- Because programming errors are common, validation to take a substantial amount
of time.
- Validation must be performed on-line, i.e., employing the actual machine to be
used. This can tie-up equipment which would otherwise be used for production.
- Each NC program is written for a specific machine and controller. Thus, if either
of these change, the NC program must be rewritten from scratch.
- Programs are difficult to modify.
An alternative to manual part programming, which addresses each of these
disadvantages, is CAM (Computer Aided Machining) Part Programming. In this method,
MP-NC2 Laboratory
59
the user first specifies the product geometry, then specifies the tool path based upon the
product geometry. This is done by interacting with graphical computer software (often
called CAM software) to generate a part program. A part program is a set of coded
instructions in general (i.e., non-equipment specific) terms. The part program is then
simulated and post-processed to obtain the set of coded instructions for a specific
machine/controller combination (i.e., an NC program). In CAM part programming, the
part geometry is represented by a CAD (Computer Aided Design) model of the part, which
is either generated directly (via an integrated CAD software package) or generated
separately and imported into the CAM software package. Either way, the tool path is then
generated based upon the CAD model.
As previously stated, CAM part programming does not suffer from the disadvantages
of manual part programming. Once familiar with the CAM software, NC programmers
can generate part programs relatively quickly. Laborious, repetitive, and error-prone
calculations and tasks (such as tool path generation) can be handled by software
routines, reducing programming time and errors. Validation can be done off-line, i.e.,
away from the machine, via computer simulation. Changes to equipment (i.e., machine
and/or controller) can be handled easily by simply using the same part program and a
different post-processor. Programs can be modified relatively quickly using the CAM
software. And, finally, importing and using CAD files as the basis for tool path generation
saves the NC programmer substantial time and effort.
In this laboratory, the CAM part programming approach is employed using
FeatureCAM® software and Hass Desk Top vertical milling machines. The CAD model
will be created first, following which the part program will be generated, simulated, and
post-processed for a Haas machine. The remainder of this section gives a brief overview
of FeatureCAM® software and how it works. Detailed instructions on how to create the
CAD model and part program are given in the next section.
Basic Concepts behind FeatureCAM®
Views
In FeatureCAM®, there are seven views for looking at parts: Isometric, Top, Bottom,
Front, Back, Left, and Right. In this lab, we make use of at least two of these: Isometric
and Top. These views are shown in Figure 1.
Coordinate System
The coordinate system axes are referred to as X, Y, and Z. View coordinates are
specified relative to a particular view. The coordinate frame appears in the lower left
corner of any view: in the top view X points right on the screen, Y points up, and Z points
out of the screen towards the user. Figure 1 also illustrates coordinate system (X = 0, Y
= 0 and Z = 0). This location is known as the Reference Zero.
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MP-NC2 Laboratory
Figure 1. Views (select) and coordinate systems used in FeatureCAM®.
Steps in FeatureCAM®
FeatureCAM® employs several steps for creating part programs for a specified
machine/controller. These steps are shown in Figure 2.
Stock
Feature from
geometry
Geometry
Feature from
dimensions
Geometry is a
single entity (line,
circle)
Curves
Features
Toolpaths
NC Code
Figure 2. Steps in FeatureCAM®.
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61
Step 1: Stock. Stock refers to the initial piece of material you will use to make your part.
The Stock wizard (Figure 3) steps you through entering the shape and dimensions of the
stock, the stock material, part program zero and the coordinate system for modeling. The
stock is the initial material from which you cut your part. It can be rectangular, circular, a
more general extruded shape, or other solid item. The stock shape is used for 3D toolpath
simulations and to control the extent of milling features like bosses. FeatureCAM® has
embedded feed/speed tables for many different stock materials, so that feeds and speeds
can be automatically calculated based on the stock material. The Stock wizard provides
step-by-step instructions for specifying or modifying the general stock shape, specific
stock dimensions, fixture IDs, part program zero, and the origin of your modeling
coordinate system.
Figure 3. Stock wizard.
Step 2: Geometry. Points, arcs, lines and other shapes are used to describe the overall
shape of parts. Many different geometry tools are available. Geometry can also be
imported from CAD systems. Each part starts with an initial design. You may already have
an engineering drawing, a part sketch or you may want to use FeatureCAM® to draw your
part design from scratch. The geometry step gives you methods of creating points, lines,
arcs, and circles. You can also clip (remove) geometry. If you want to create multiple
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objects, select the Create more than one option at the bottom of the Geometry
Constructors dialog box (Figure 4) before selecting the type of object you want to create.
Figure 4. Geometry Constructors dialog box.
Step 3: Curves. Shapes that involve more than a single line or arc are described as
curves. This step groups arcs and lines into curves by automatically tracing smooth paths.
If you want to make a feature from more than a single line, arc or circle, you must connect
the geometry into a curve. Curves are produced via the Curve Creation dialog box (Figure
5).
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Figure 5. Curve Creation dialog box.
The various options for creating curves are as follows:
Used to create closed curves (curves that form a closed boundary) by clicking
on one piece of geometry in a single mouse click. This will create a closed loop
by following smooth paths. If this method does not result in the correct pieces,
click the Clear Pieces button in the Feature/Geometry Edit bar, select the
Curves step again, and use the Pick.
Used to create curves manually by clicking on segments of the curves. To
create an open curve (curves that do not form a loop), click the beginning of
the curve and then click the end. If the resulting curve is not correct, click a
number of intermediate positions to guide the process of creating curves.
Closed curves can also be created with this technique by clicking back to the
initial piece of geometry.
Opens the Curve wizard that provides step-by-step instructions for creating
curves using a variety of methods.
Used to chain projections of vertical surfaces into curves using mouse clicks.
Step 4: Features. Features are commonly-used shapes like pockets, threads, or bosses
(Figure 6). These objects, created from curves and dimensions, are used to both describe
your part in 3D and generate toolpaths. For example, if you want a hole in your part,
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choose the Hole feature. If your part has a pocket, choose the Pocket feature. The New
Feature wizard (Figure 7) walks you through the process of creating features.
Figure 6. Feature examples.
Figure 7. New Feature wizard.
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One category of features are those that can be created solely from dimensions. These
features include holes, rectangular-shaped pockets, threads, and round pockets (called
step bores). Other features require curves to describe their shape. They are listed under
the From Curve category. These features include pockets, bosses, grooves, chamfers,
rounds, sides, and faces. If you want to create a pattern of features, select the Make a
pattern from this feature check box. Clicking Next steps you through the wizard via the
following:








Selecting the feature type.
Optionally entering pattern dimensions.
Positioning the feature.
Specifying the manufacturing strategy.
Reviewing the automatically selected tools.
Reviewing the automatically calculated feeds and speeds.
Overriding the tooling and feed/speed values.
Changing manufacturing attributes.
To modify a feature either double-click on it or select it and click the Properties button
to open the Properties dialog box.
Step 5: Toolpaths. Toolpaths are generated from collections of features. You can
simulate them in FeatureCAM® using toolpath centerlines, 2D unshaded. This step uses
the simulation toolbar at the bottom of the screen. It is also recommended to run a
simulation in ‘Sim Mode’ located in upper left corner of screen (Figure 8). This provides
a 3D simulation of the cutting process.
Figure 8. Sim Mode selection.
Step 6: NC Code. Machine-specific G-codes are generated from the toolpaths.
Translators (post-processors) are provided for many different NC controls and a program
is included for creating new translators or post-processors. This step is used to generate
NC code in FeatureCAM® via the NC Code dialog box (Figure 9).
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Figure 9. NC Code dialog box.
The various options used for generating NC code are as follows:
The Feed Optimization button evens out the load on the tool by adjusting the
feed rate of each NC block.
The View the NC Code button displays the code in the Results window. You
can also display the tooling lists and operations sheets by clicking the tabs
located at the bottom of the Results window.
The Save NC button opens the Save NC dialog and lets you save the NC code
to disk. You can also save additional documentation like tool lists, operations
list and part databases.
The Tool Mapping button lets you change the locations of the selected tools
in the tool changer.
Procedure
Each student will use FeatureCAM® software to prepare an NC program for the aft fix
plate (p. 137), following the instructions given below. Programs are to be validated using
the Haas Desk Top vertical milling machines and wax blocks, using the depth-of-cut as
specified on the engineering drawing (p. 137). The feedrates for cutting the parts are
calculated by the software: these may be modified, however. NOTE: NC programs must
be prepared individually. If you need help, ask the lab instructor. No student help
is permitted.
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Once you are satisfied with your program, notify your lab instructor. He/she will watch
you download and run your program, then evaluate your part. Only the final wax part
will be graded. Full marks can be obtained only by cutting the part correctly on the
first attempt (see p. 81).
Once the programs have been prepared for all parts, be sure that someone in your
group signs-off the NC PROGRAM VALIDATED portion of the operation on the work
order. The lab technicians will then use a validated NC program to cut the actual aft fix
plates you will use for your mounting plate.
Aft Fix Plate Op. 20 – Cut Top Edge, Slot, Mounting Holes, and Pocket
Open FeatureCAM® by double-clicking the icon on the Desktop (if required). The
Available Document Types dialog box (Figure 10) will appear. Answer the question
(What do you want to do?) by selecting Mill, check units to Inch, check initial stock dialog
to Wizard, and leave Machine Configuration to Mt Configuration. Then select Create New
Document: the Stock step (Steps panel, left side of screen) should then start
automatically.
Figure 10. Available Document Types dialog box (partial).
Now you are ready to complete the steps in FeatureCAM® programming process (Stock,
Geometry, Curves, Features, Toolpath and NC code). These steps are located in the
Steps panel (left side of the screen).
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Step 1: Stock
After you have finished completing the steps in the New Part Document wizard, the Stock
page should automatically appear (Figure 11). If not, select the Stock icon in the Steps
panel on the left side of the screen.
Figure 11. Stock wizard in main FeatureCAM® window (partial).
Set up Stock properties by progressing through the required dialog boxes (via the Next
button at the bottom of the Stock window) as follows:
 Stock (Dimensions): select Block for stock shape, then enter the dimensions for
stock width, length and thickness as follows (from the engineering drawing on p.
143):
Thickness: 0.250 inches
Width:
3.0 inches
Length:
3.0 inches
Be sure to enter these values: correct if necessary.
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 Stock - Material: The material for
the Aft Fix Plate is 1018 CRS: this
is established by selecting
STEEL-10XX from the drop-down
box. Once you’ve made this
selection, the unit horsepower
and hardness will be calculated
and
displayed
automatically
(Figure 12).
 Multi-axis positioning: We only
need 3 axes to machine this part,
so select No to the question on
this page.
 Setup – Definition: Enter Aft Fix
Plate for Setup Name. Ensure 54 is
entered for Fixture ID, and enter your
own name for Part Name.
Fig 12. Stock - Material dialog box.
 Setup – Part Program Zero: The X, Y and Z zero will be at the fixed location on the
Haas Desk Top vertical milling machine: this is also the lower left corner of the
engineering drawing. This will be known as the Reference Zero. For ‘What method
do you want to use to define the part program zero location for Aft Fix Plate?’, select
Use current location.
 Stock Properties – stock1: This page is an overview of what you have just
completed and can be change if needed. After reviewing the page and making any
necessary corrections, click OK. (NOTE: use current set up page and names if
option appears).
Step 2: Geometry
Now you are ready to start creating your CAD drawing of the Aft Fix Plate from the
dimension stated on the engineered drawing (p. 143). In FeatureCAM®, the Aft Fix Plate
consists of circle and lines. Using the Circle, Line and Edit/Clip Geometry constructors,
you can complete the entire CAD drawing. There are other ways to produce the Aft Fix
Plate in FeatureCAM®, but in this lab we will manually generate the CAD drawing.
Specify geometry for the Aft Fix Plate via the following steps:
 Create Circles. The Aft Fix plate will be based on eight circles – two for the throughholes, two radius ends for the slot, and four radius corners for the pocket. Select
the Geometry icon in the Steps panel (left side of screen) to open the Geometry
Constructors dialog box (Figure 4). To create the first circle (left through hole):
i. Select the Circle from Rad, Center icon (Figure 13a), then hit OK.
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ii. You are then prompted, at the bottom of the screen, for the data necessary to
define the circle. For R (radius), enter 0.188 and for XYZ Center (location of
circle center) enter 0.500 (X), 1.375 (Y), and 0.000 (Z) – the data prompt should
now appear as shown in Figure 13b. If you made a mistake, use the undo
icon (
) in the top tool bar and then re-enter the correct data.
(a)
(b)
Figure 13. (a) Selection of ‘Circle from Rad, Center’ icon for drawing
a circle, (b) Radius and XYZ data for first circle.
Once the circle is correct, select the Create icon (or hit the Enter key): the circle
should now appear on the part drawing (Figure 14a).
Create the remaining seven circles in a similar manner, using the Aft Fix Plate
engineering drawing to determine the circle locations and radii. After completing
all eight circles, your part drawing should appear as shown in Figure 14b.
(a)
(b)
Figure 14. Part drawing after creating first circle (a) and all
eight circles (b).
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 Create Lines. The Aft Fix plate requires seven lines – one for the top edge, two for
the slot, and four the pocket. Select the Geometry icon to open the Geometry
Constructors dialog box (Figure 4). To create the first line (top edge):
i. Select the Line from 2 Pts icon (Figure 15a), then hit OK.
ii. The data prompt will again appear at the bottom of the page. When drawing a
line from 2 points, FeatureCAM® needs to know the beginning point (known as
XYZ 1) and ending point (XYZ 2) of the line (if you do not know the exact point,
FeatureCAM® will do addition and subtraction calculations for you). To create
the line for the top edge, enter the following values:
- Point XYZ 1: X = 0.000, Y = 3 - 0.188, Z = 0.000.
- Point XYZ 2: X = 3.000, Y = 3 - 0.188, Z = 0.000.
The data prompt should now appear as shown in Figure 15b. As before, be
sure to correct any mistakes you make. Once the line is correct, select the
Create icon: the top edge should now appear on the part drawing.
(a)
(b)
Figure 15. (a) Selection of ‘Line from 2 Pts’ icon for drawing a line,
(b) Starting and ending point data for top edge.
To create the remaining lines for the slot and pocket, you must connect circles. To
create the top line of the slot:
i. Select the Line from 2 Pts icon, then hit OK.
ii. Select the edge of the left slot circle as shown in Figure 16(a). A square with
a line will appear and be connected to the circle: the square indicates that you
are at the correct point on the circle. If a circle with a connected line appears,
press the Undo icon and try again.
iii. Connect the line to the right slot circle. The drawing should appear as shown
in Figure 16(b).
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(a)
(b)
Figure 16. Part drawing after selecting left slot circle (a) and
joining to right slot circle (b).
Connect the remaining circles to complete the slot and pocket. After completing
all seven lines, your part drawing should appear as shown in Figure 17.
Figure 17. Part drawing after creating all seven lines.
The final step is to ‘clip’ (remove) the circle arcs which are not a part of the slot.
Select the Geometry icon, followed by the Clip icon in
the Edit/Clip window (Figure 18). Then click on each arc
which is not a part of the slot or pocket, as shown in
Figure 19a. Once completed the part drawing should
appear as shown in Figure 19b.
Fig 18. Edit/Clip window.
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Clip internal
arcs
Clip internal
arcs
(a)
(b)
Figure 19. (a) Arcs to clip (remove) from slot, pocket.
(b) Part drawing after arcs removed.
Step 3: Curves
Recall that individual lines, arcs, circles, etc., must be grouped together into curves.
Select the Geometry icon in the Steps panel (left side of screen) to open the Curve
Creation dialog box (Figure 5). In response to the question ‘Which method do you want
to use?’, select the Closed Curve icon ( ): this enables you to select the geometry for
a specific curve with a single mouse click. A data prompt will appear the bottom of the
screen: create a curve for the left through hole circle as follows:
i. Select the left through hole on the part drawing.
ii. Name the curve Left Hole in the data prompt.
iii. Click on Create: the geometry will change color. You have now turned the left
through hole circle into a curve!
Repeat the above process to create the remaining curves, i.e., Right Hole, Top Edge,
Slot, and Pocket.
Step 4: Features
The next step is to turn the five curves into features. Click on the Features icon in the
Steps panel: the New Feature wizard (Figure 7) will appear. In response to the question
‘What kind of feature would you like to make?’, select Side. Then click Next. The New
Feature – Curves window (Figure 20) will appear. If there is any unwanted data in the
data prompt, select the data and then click on the Delete from the selected items icon
( ) to remove the unwanted curves.
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Figure 20. New Feature – Curves window.
To create features from curves, you must first select curves you would like to change. As
the left hole, right hole, and slot all have the same depth of cut (0.250 in.), we can save
time by creating their corresponding features all at the same time. From the New Feature
– Curves window, select the Pick curve or geometry icon (
), then select the left
hole. The Select window appears (Figure 21a): select the left hole object, then click OK.
The New Feature – Curves window will reappear with the left hole object. Repeat this
process for the right hole and slot: the window should then appear as in Figure 21b.
(a)
(b)
Figure 21. (a) Select window for selecting curves, (b) New Feature – Curves
window following selection of left hole, right hole, and slot.
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The features are now completed by progressing through the required dialog boxes (via
the Next button at the bottom of the New Feature – Curves window). This is done for
the left hole, right hole, and slot as follows:
 Set Machining Side: The New Feature – Machining Side window is used to
determine which side of a feature you would like to machine on – inside or outside.
By using the Switch Machining Side icon (
), you can change the side the cutter
will cut on. Make sure that all features are cut on the inside (Normal is selected).
 Set Cutter Offset: The
New Feature – Location
window
(Figure
22)
appears next.
Ensure
that Offset from curve z
location is 0.0.
 Define Feature Depth:
The New Feature –
Dimensions window is
used to define feature
depth. The left hole, right
hole, and slot are 0.250
in. deep, which is a
through cut. The draft
angle,
chamfer
and
bottom radius can be left
at their default values (0.0).
The resulting window is
shown in Figure 23.
Figure 22. New Feature – Location window.
 Establish Machining Process: The
New Feature – Strategies window is
where you specify how your part will be
machined. The Aft Fix Plate will be
machined with a finishing pass only
(no roughing pass) and climb milling
will be employed. A finishing pass only
is used here because a roughing pass
would necessitate a different tool and
there are no tool changes. Deselect
Rough Pass to ensure that a single
pass is used. The resulting window is
shown in Figure 24.
Fig 23. New Feature – Dimensions window.
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Figure 24. New Feature – Strategies window.
 Select tool crib: The New Feature – Operations window opens next.
FeatureCAM® can automatically select a tool from the tool crib for your program.
You will not be using the FeatureCAM® tool crib, however: instead you will select a
tool from the MP-NC2 Lab tool crib. No selections are required here.
 Default tool: The New Feature – Default Tool window now appears. The option ‘I
want to search for another tool or make a new one’ is automatically selected.
Check the box next to the only tool listed (0.3750 diameter, 2 flute endmill). The
window should appear as shown in Figure 25.
Figure 25. New Feature – Default Tool window.
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 Set machining parameters: The New Feature – Feed/Speed page appears as
shown in Figure 26. This is where spindle speeds (RPM) and feed rates (IPM) will
be specified. FeatureCAM® automatically recommends spindle speed and feed
rate: this can be changed if desired, however. To make the Haas Desk Top milling
machine to run at the proper feed/speed, set spindle speed to 8000 RPM and feed
to rate to 10 IPM. Also, we will not be using coolant in this process, so deselect the
coolant list window.
Figure 26. New Feature – Feed/Speed window.
 Finish Up: The New Feature – Summary page appears as shown in Figure 27.
Review all settings, then click on Finish. The Side Properties page appears: this
is where you can change certain properties of this feature. If satisfied, click OK.
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Figure 27. New Feature – Summary window.
Repeat all of the above (Step 4: Features) for the top edge and pocket. Note the
following:
 The depth of cut for the top edge and pocket is not the same as that for the left hole,
right hole, and slot.
 When completing the Features for the top edge and pocket, you will be finishing the
bottom of each feature. In the New Feature – Strategies window (Figure 24), be
sure to check Finish bottom.
Step 5: Toolpaths
You must simulate toolpaths in FeatureCAM® in order to produce the NC code for your
part. Using the proper Translator (post-processor) for your machine controller,
FeatureCAM® will write the correct code for the Haas Desk Top (your computer is set-up
to use the Haas VF post-processor), Toolpath simulations also helps you check for
gouges and manage tool load. To generate the tool path, click on the Toolpaths icon
( ) in the Steps panel, then press the Play icon ( ).
It is also recommended to run the simulation in Sim mode as described on p. 67. Select
the simulation icon of your choice and then the Play icon: the Ordering window will
appear as shown in Figure 28. Click OK and the machining of your part will be simulated.
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Figure 28. Ordering window.
Step 6: NC Code
After you have simulated the machining of your Aft Fix Plate, you are ready to save your
program. Insert the USB memory stick (which will be provided) into your computer. Select
the NC Code icon (
) in the Steps panel: the NC Code window (Figure 9) will appear.
 To save your NC code, select ‘Save the NC code on my computer’s disk drive’. The
Save NC window will appear as shown in Figure 29. Select ‘Save to other
directory’, then choose the proper USB drive. Use your initials as the file name
(make sure you save the file as a .txt file) and then select OK.
 Save the FeatureCAM® part file to your USB memory stick: select File, Save As,
Computer, and USB drive. For file name, enter Name and select Save. Your file
will have the extensions ‘.fm’.
The closing window of Figure 30 will appear: select No. Then close FeatureCAM® and
remove your USB drive.
Setup and Run
Go through the steps to load program into the Haas Desk Top controller, load your part,
and run your program as before (MP-NC1 lab, p. 56).
Modify as Required
If you need to modify your program ask instructor for help.
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Figure 29. Save NC window.
Figure 30. Closing window.
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Lab Requirements
Each student is required to produce the part as described and take the quiz given
afterwards. The part is worth 80 points and the quiz 20 points. Your final part will be
evaluated as follows:
Not
attempted
0
Poor
6
Fair
10
Good
13
Excellent
16
Slot
0
6
10
13
16
2 holes
0
6
10
13
16
Pocket
0
12
20
26
32
Top edge
Part points: 80
where
poor
fair
good
excellent




feature mostly incomplete and/or incorrect.
feature somewhat incomplete and/or incorrect.
feature slightly incomplete and/or incorrect.
feature complete and entirely correct.
IN ADDITION to the above, 4 points will be deducted from your part score for each
additional cutting attempt made.
In other words, full marks for your part (80 points) can be obtained only by cutting the part
correctly on the first attempt.
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MP-I: MOUNTING PLATE – INSPECTION
Purpose
To learn how to operate various measuring instruments used for inspection of
manufactured items.
Overview
Inspection is investigated by inspecting the base plates, forward fix plates,
and aft fix plates machined in the previous three labs. This corresponds to
operations 80, 40, and 40 on the route sheets for these items (pp. 132, 135
and 138), respectively. Be sure to read through Appendix A (Geometric
Dimensioning and Tolerancing) before the lab, if you have not already done so.
NOTE: A scientific calculator and pages 133, 136, and 139 (printouts) are required
to complete this lab: bring these with you. Pages will be provided for you if
necessary BUT this will result in a deduction of 20 points from your score.
Equipment
Machined base plate, forward fix plate, aft fix plate.
Various inspection instruments.
Background
As we have seen, the goal in manufacturing is to produce items according to the
design specifications. These specifications, which cover product dimensions, geometry,
and other properties (hardness, surface finish, etc.), are given in the engineering
drawing(s) for the product. Inspection is the process by which part attributes are
examined to determine whether or not the parts conform to design specifications. Parts
which pass inspection can usually move on to subsequent processing operations, while
parts which fail inspection must be reworked, scrapped, or otherwise dealt with.
Inspection is a critical component in any manufacturing facility. Not only does
inspection ensure that products are of the required quality, it provides information which
can be used to improve the manufacturing process. Many manufacturing firms have
separate inspection departments, with highly-trained inspectors.
The most common form of inspection involves measurement. The attribute of
interest is measured, and the resulting value compared with the design specifications to
see if it is acceptable or not. For example, we might measure the length of a part and
then compare the value obtained with that specified on the drawing to see if the length
is within tolerance. In direct measurement, the measurement is taken and read with the
same measuring instrument. In indirect measurement, the measurement is taken with
one instrument, then transferred to and read from another instrument.
A second form of inspection is gaging. In gaging, the attribute of interest is
compared directly with one or more standards (gages) which are known to be
acceptable or rejectable with respect to that attribute. For example, if we have a gage
whose length is that desired for a part, we can compare the part length to the gage
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length to establish whether or not the length is correct. Such gages are often referred
to as go-no gages, as they indicate directly whether the attribute is acceptable (go) or
not (no-go). Gaging does not give as much information as measuring, but is faster.
In this laboratory, we will be using a variety of measuring instruments to perform final
inspection on base plates, forward fix plates, and aft fix plates. These instruments
include the following: dial caliper, depth micrometer, dial indicator, plug gage, hardness
tester, and coordinate measuring machine. Dial calipers and dial indicators are
discussed on pp. 34-35. Some background on the remaining instruments now follows.
Depth Micrometer
THIMBLE
98 7
0
BASE
0
A depth micrometer consists of a
threaded spindle inside a T-shaped
frame, as shown in Figure 1. A
graduated thimble and sleeve are
located at the end of the spindle:
rotating the thimble causes the
spindle to move down and the depth
rod to protrude from the bottom of
the frame. The micrometer base is
placed over the feature to be
measured, and the spindle turned
until the depth rod contacts the
bottom of the feature.
RATCHET
STOP
SLEEVE
DEPTH ROD
Figure 1. Depth Micrometer.
Plug Gage
A plug gage is used for inspecting hole diameters. The gage consists of a round bar
having a small diameter A and large diameter B (Figure 2). If diameter A can pass
through (into) the hole while diameter B cannot, the hole diameter is acceptable.
Otherwise, the hole is too small (A can’t pass through) or too big (B passes through).
A
B
Figure 2. Plug Gage.
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Hardness Tester
Hardness, the resistance of a material or item to permanent indentation, is often
used in manufacturing to give a general indication of the strength of a material or item.
Hardness is determined by pressing an indenter into the surface of a material, with a
predetermined load, and then measuring some characteristic of the resulting
indentation. The measurement is then converted to corresponding hardness value.
Several different hardness tests have been developed, each characterized by a different
type of indenter and/or indentation measure. It is important to note that unlike
dimensional and geometric measurements, hardness measurements as described
result in some damage to the workpiece. The indentations are very small, however, and
can often be done on an inconspicuous surface.
Coordinate Measuring Machine
A coordinate measuring machine (CMM) is a machine that can perform a variety of
dimensional and/or geometrical inspection tasks. The machine consists of a rigid table
upon which the part rests, and a measuring probe attached to a head which can move
from side-to-side (x), back and forth (y), and up and down (z). The probe is first zeroed
with respect to the workpiece, and is then moved to contact the workpiece at various
locations as established by the inspection task. By tracking the movement of the probe
in three-dimensional space and relating this movement back to the zero point, attribute
dimensions and/or geometry can be established. Figure 3 illustrates the general
structure of a CMM.
Probe
z
x
y
Figure 3. Coordinate measuring machine (CMM).
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Coordinate measuring machines can be controlled in four different ways:
1. Manual Control – the operator physically moves the probe from one location to the
next, records the measurements, and then manually calculates dimensions/
geometry based upon the measurements.
2. Manual Computer-Assisted Control – the operator again moves the probe, and
records dimensions/geometry (calculated by the machine).
3. Motorized Computer-Assisted Control – the operator uses a joystick (or similar
device) to control the motion of the probe, and records dimensions/geometry.
4. Direct Computer Control – the movement of the probe, recording of measurements,
and calculation of dimensions/geometry are all performed automatically via
execution of a computer program. The CMM in this case acts like an NC milling
machine, with the cutting tool replaced by a probe.
Coordinate measuring machines are very accurate and versatile machines, capable
of measuring complex parts that would be difficult to inspect otherwise. A further use of
CMMs is for reverse engineering: generating the dimensions/geometry of a part, then
using this information to create an engineering drawing.
Procedure
The inspection operation for each item (base plate, forward fix plate, and aft fix
plate) consists of a set of inspection steps, each which involves inspecting one or more
attributes. For each attribute, measurements are taken to determine one or more
disposition values. These values are then compared to the drawing requirements to
determine whether or not the attribute is acceptable. The entire procedure is recorded
on a separate part inspection report form for each item.
The lab instructor will give you a base plate, forward fix plate, and aft fix plate to
inspect, and will explain and demonstrate each inspection step. You are to
inspect each item and complete the inspection forms in your lab manual (pp.
133, 136, and 139). For each attribute inspected,
• record all measurements and show all calculations and the disposition value(s) in
the RESULTS column.
• check the ACC (accept) or REJ (reject) column to indicate the disposition.
If an attribute on your base plate is incomplete (and hence cannot be inspected),
write “INCOMPLETE” in the RESULTS column for that attribute, check the REJ column,
and notify your instructor. He/she will give you another base plate to use for that
attribute. Record your measurements, disposition value(s), and disposition for that
attribute at the bottom of the inspection form (and on the back, if necessary).
Once all steps have been performed and the inspection forms completed, determine
the final disposition of each item and record this on the corresponding work order.
When all disposition results have been recorded, be sure to sign-off the inspection
operations on the work orders. As this is the last operation on each work order, the jobs
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are now complete. In practice, the inspection forms would be stapled to the work orders
or otherwise carefully stored.
Base Plate Op. 80 – Inspection
1. Overall Length
Equipment: dial caliper.
a. Take three readings of the base plate length: one at the center, and one about 1/4inch in from each end.
b. Record each measurement, and calculate and record the average (as the
disposition value), on the base plate part inspection report form.
2. Mounting Hole Diameter
Equipment: dial caliper.
a. Take two readings of each hole, 90° apart, using the internal measuring jaws of the
dial caliper.
b. Record each pair of measurements, and calculate and record the averages
(disposition values) on the inspection form.
3. Longitudinal Slot Depth
Equipment: dial caliper.
a. Using the dial caliper depth probe, take readings of longitudinal slot depth at
locations a, b, c and d as shown in sketch (a) below. Be sure to keep the caliper
width parallel to the end of the plate, as shown in sketch (b).
e
a
b
c
d
f
(a)
(b)
b. Record each measurement, and calculate and record the average (disposition
value), on the inspection form.
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4. Transverse Slot Depth
Equipment: depth micrometer.
a. Take readings of transverse slot depth at locations e and f, as shown in the
previous sketch (a).
b. Record each measurement, and calculate and record the average (disposition
value), on the inspection form.
5. Flatness
Equipment: dial indicator with base, surface plate.
a. Place the base plate top face down on the surface plate.
b. Position the dial indicator contact point so it is about 1/8-inch above the part
surface, Then move it to a position about 1/4-inch from the right end of the plate,
along the axial centerline (point a below).
d
b
c
a
c. Move the dial down, by rotating the arm, until the contact point just touches the
plate, then move the dial down about 1/16-inch more.
d. Zero the dial by turning the bezel.
e. Slide the plate longitudinally until the contact point is at the opposite end, i.e., the
contact point ends up at point b as shown above. Watch the indicator while moving
the plate and note the total range of movement or T.I.R. (Total Indicator Reading).
Record this value on the form.
f. Repeat steps b-e above, but measuring T.I.R. from point c to d (i.e., transversely).
g. Record the larger of these two measurements as the disposition value on the
inspection form. (Note: in measuring flatness in this manner, we are assuming that
the two surfaces are parallel).
Forward Fix Plate Op. 40 – Inspection
1. Location of “X” Slot, Mounting Holes, Radial Slot; Slot Radius
Equipment: Brown & Sharp Coordinate Measuring Machine (CMM).
a. Fix the forward fix plate in the CMM vise, with the S/N facing up.
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MP-I Laboratory
b. From the PC DMIS screen select the execute button (the red ! Icon upper left).
c. PC DMIS message will appear: (Please rotate to ID = T1A0B0) Select OK.
d. The Input Comment widow will appear
Who are you?
1) staff
2) Student
Type in 2 for Student and select OK.
e. The Input Comment window will appear again:
Please Choose:
1) Calibrate Tip
2) DCC Inspect
3) Exit
Type in 2 for DCC Inspect and select OK.
f. PC DMIS message will appear:
***Automatic moves begins next***
Position the probe well above the part
Look at the probe, if above part, select OK.
The CMM goes through a zeroing routine, then measures the part features
and records them. (Approximant time: 2 minutes)
g. After the CMM stops the Input Comment window will appear:
Please Choose
1) Calibrate Tip
2) DCC Inspect
3) Exit
Type in 3 for Exit and select OK.
h. Minimize the entire PC DMIS screen to get back to the desktop.
Click on the Forward Fix Plate Icon (on the desk top) and print chart.
Use chart to fill out your inspection sheet.
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MP-I Laboratory
7
5
6
2
1
4
3
i. Record the X and Y measurements for each of features 1-7 on the inspection form,
as well as the diameter (DIA) measurement for feature 7. The X and Y
measurements are the disposition values for establishing the location of the “X” slot,
mounting holes, and radial slot. The disposition value for the radial slot radius is
(DIA measurement–0.375)/2.
Aft Fix Plate Op. 40 – Inspection
1. Slot Location
Equipment: dial caliper.
a. Measure and record a L , a R , b, and c as shown in the sketch below.
c
b
aL
aR
b. Calculate and record the location of the left end of the slot = (X L ,Y L ) and the right
end of the slot (X R ,Y R ,) from the following:
TD ,
XL = b + TD , YL = aL + TD , XR = b + c −
YR = aR + TD
2
2
2
2
where TD = tool diameter.
c. The distance ε L between the desired location of the left slot end and the actual
location can then be found from
εL =
(XL − 0.5)2 + (YL − 2.438)2
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MP-I Laboratory
Calculate ε L , then develop a similar expression for ε R and calculate the value.
Record ε L and ε R as the disposition values on the inspection form.
2. Mounting Hole Diameter
Equipment: 0.375-in. diameter plug gage.
a. Attempt to pass the small (green end) diameter of the plug gage through the left
mounting hole. If the diameter passes, record the disposition value “L: GO – √” on
the inspection form (L ⇒ left hole), otherwise record “L:GO – ×.”
b. Attempt to pass the large (red end) diameter of the plug gage through the left
mounting hole. If the large diameter does not pass, record the disposition value “L:
NO GO – √” on the form, otherwise record “L:NO GO – ×.”
c. Repeat a–b for the right hole.
3. Hardness
Equipment: Fowler Bench top Digital Hardness Tester (Rockwell B Scale).
a. Lower the specimen Table using the Black Hand Wheel (about 3/8” gap between
the indenter and table) turning counter-clockwise.
b. Lay the aft fix plate on the specimen table, pocket up. Then slide the plate until the
indenter is positioned to contact the part surface just outside (i.e., about 1/4-inch
away from pocket, holes and edge) the pocket. Hold the part with one hand while
turning the hand wheel to raise the specimen table with the other. Raise the part
until it just contacts the indenter.
c. Apply preload. Rotate hand wheel (clockwise) until the indenter touches plate.
Now apply load by slowly turning hand wheel (clockwise). While looking at the
display above, you will see an arrow move to the right, once an alarm sounds stop
turning. The hardness tester will automatically load and unload the pressure on the
indenter. (Takes about 15-20 seconds).
d. Read and record value. After the hardness tester unloads it will display the
hardness reading. Record the value (value is hardness on the Rockwell B scale).
e. Remove plate. After you have recorded the reading turn hand wheel (counterclockwise) to release all pressure on plate and indenter, now you can remove plate.
f. Repeat steps a – e to take 3 readings total at various locations.
g. Remove the part, and calculate and record the average hardness (disposition
value) on the inspection form.
MP-I Laboratory
91
Lab Requirements
Each student is required to inspect a base plate, forward fix plate, and aft fix plate as
described. The evaluation will be done on a per-attribute basis as follows:
Not
attempted Poor
Fair
Good Excellent
Base Plate
1. Overall Length
2. Mounting Hole Diameter
3. Longitudinal Slot Depth
4. Transverse Slot Depth
5. Flatness
0
0
0
0
0
4
4
4
2
4
6
6
6
3
6
8
8
8
4
8
10
10
10
5
10
Forward Fix Plate
1. “X” Slot Location
2. Mounting Hole Location
3. Radial Slot Location, Slot Radius
0
0
0
4
4
4
6
6
6
8
8
8
10
10
10
Aft Fix Plate
1. Slot Location
2. Mounting Hole Diameter
3. Hardness
0
0
0
4
2
4
6
3
6
8
4
8
10
5
10
Total points: 100
where
⇒ measurement(s) incorrect, disposition value(s) calculated incorrectly,
and disposition incorrect.
fair
⇒ any two of the above done incorrectly.
good
⇒ any one of the above done incorrectly.
excellent ⇒ measurement(s) correct, disposition value(s) calculated correctly,
and disposition correct.
poor
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MP-W1 Laboratory
MP-W1: MOUNTING PLATE – MANUAL ARC WELDING
Purpose
To learn the basics of manual arc welding.
Overview
Manual arc welding is investigated by performing the manual welding operations
required to create a mounting plate, using the shielded metal-arc welding (SMAW)
process. This consists of tack-welding and then double fillet-welding a forward fix
plate (p. 134) to a base plate (p. 131), then tack-welding an aft fix plate (p. 137) to
the base plate.
An engineering drawing of a mounting plate is given on p. 129:
manual arc welding covers operations 10-30 on the route sheet for this item (p. 130).
Equipment
Forward fix plate, aft fix plate, base plate.
AC or DC arc welding machine, 1/8” diameter E7014 electrodes.
Metal tongs, chipping hammer.
Background
A common problem in producing many manufactured items is how to permanently
join together two or more large, heavy, metallic components. In many such items
(machinery, ships, and pipelines, etc.), the components are structural and must be able
to withstand heavy loads. One of the most common methods for joining such
components together is arc welding. In arc welding, parts are joined together by using
an electric arc to heat the area of contact between the items until they melt together.
The arc results from making the items part of a high-voltage electric circuit via an
electrode. It is created by bringing the electrode into contact with one of the items. By
quickly withdrawing the electrode to a small, predetermined distance above the items,
the arc can be maintained. The resulting electric energy produces temperatures in the
range of 10,000 °F, hot enough to melt any metal.
Arc welding can be performed in several ways, the most widely used of which is
shielded metal-arc welding (SMAW – Figure 1). In this process, the electrodes are long,
thin sticks coated with chemicals that provide flux and shielding gas during the welding
process. Flux is a material that melts during welding and covers the weld surface to
prevent the formation of oxides and other contaminants (this covering is called slag).
Shielding gas refers to a gas intended to shield (surround) the electrode tip, arc, and
molten weld pool from air during welding. This is necessary as at high temperatures,
metals are highly reactive to oxygen and other elements in air. Such reactions, if
unimpeded, could seriously degrade the quality of the weld.
MP-W1 Laboratory
93
Electrode holder
Electrode
Shielding gas
Slag
+
Workpiece
AC (DC)
Power
Source
–
Figure 1. Shielded metal-arc welding (SMAW) process.
In SMAW, the electrodes are consumable. This means that they are consumed
during the process, i.e., the electrode actually melts and becomes a part of the weld
pool. The additional metal that is added to the weld joint is called filler metal.
Consumable electrodes are beneficial in that the filler metal helps increase the size of
the weld pool and provide a stronger joint. A drawback, however, is that the electrodes
must be replaced as they are used up. Either alternating current (ac) or direct current
(dc) can be used for SMAW, with current typically ranging from 50-300 A. The power
required is usually less than about 10 kW.
The SMAW process is widely used due to its simplicity and versatility. The only
equipment needed is a power supply, cables and clamps, and an electrode holder and
electrode. Drawbacks of the process include the need for highly skilled operators and
to clean the slag from the welded joint.
Types of Weld Joints and Welds
Figure 2 shows the five basic weld joint types and the two most common types of
welds used for such joints. Each of these can be made via SMAW. In this lab, a double
fillet T-joint is used to join the forward fix plate to the base plate.
Several different methods are available for holding two items together in the required
position and orientation for welding. One method is to use a fixture. Another is to tack
weld the two parts together. A tack weld is nothing more than a fusion weld applied to
a single point. Through use of a set of tack welds, two items can be secured together
for a subsequent groove or fillet welding operation. In this lab, tack welds are used to
secure a T-joint for double fillet welding, as shown in Figure 3.
Properties of Welded Joints
Properties of welded joints include fusion, depth-of-penetration, and bead
appearance. These terms are described as follows:
- Fusion refers to the extent to which the items (and filler metal) have melted (or
fused) together. Good fusion is indicated by the lack of any discernable line
between the items and the weld pool, i.e., the two items should appear as one.
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MP-W1 Laboratory
groove weld
BUTT JOINT
EDGE JOINT
fillet weld (single or double; single shown)
T JOINT
LAP JOINT
CORNER JOINT
Figure 2. Types of weld joints and welds.
Figure 3. Tack-welds used for a T-joint.
- Penetration (or depth-of-penetration) refers to the depth to which the materials
have fused together. High penetration results in a strong weld.
- Appearance of the weld is a good way to judge weld quality. A good weld bead is
characterized by a uniform width, a smooth, even ripple pattern, and a uniform
weld surface (or fillet angle) throughout its length.
MP-W1 Laboratory
95
Procedure
The lab instructor will first familiarize you with the SMAW procedure by showing you
how to strike an arc, lay a weld bead on a flat surface, and butt-weld two steel plates
together. He/she will then show you how to tack-weld two steel plates in a T-joint, then
fillet weld the plates together. Tacking and fillet welding a T-joint are the types of
welding operations needed for your parts, so pay careful attention. Details on each
welding operation are given below.
The instructor will then show you a forward fix plate/base plate weldment (welded
assembly) having good fillet welds, and three weldments having poor welds. These
weldments will be used to evaluate your work, so pay careful attention so you know
what is expected.
Following the demonstration, you will first practice striking an arc and laying a weld
bead on scrap steel plates. You will then practice performing the required tacking and
fillet welding operations, again using scrap steel plates. You can use up to 3 sets of
steel plates for practice: refer to the four weldments previously described to evaluate
your work. Once you are satisfied with your ability to perform the required welding
operations, tell your lab instructor. He/she will observe you perform the three welding
operations, and will then evaluate your work. Only the final weldment will be graded.
MARKS WILL BE DEDUCTED if additional welding (i.e., Op. 40) is performed – see
p. 96.
Once the welding operations have been completed for all parts, be sure that
someone in your group signs-off the operations on the work order.
Mounting Plate Op. 10 – Tack Weld Forward Fix Plate to Base Plate
1.
Set the control unit to 135-140 amps.
2.
Locate the forward fix plate in the base plate as per the drawing.
3.
Strike the arc at one end of the joint, using one of the following two methods:
- Tapping Motion Method. Tap the electrode against the workpiece surface and
immediately withdraw it to a distance of about 1/16-inch and an angle of about
75-80° with the workpiece surface.
- Scratching Method. Tilt the electrode at an angle and contact the workpiece
surface while simultaneously rotating the electrode in a brisk manner (as if
striking a match). Immediately withdraw the electrode to a distance equal of
about 1/16-inch and an angle of about 75-80° with the workpiece surface.
4.
After striking the arc, hold the electrode at that location for a brief moment to form a
small weld pool, then withdraw the electrode. Remember to feed the electrode
forward as it is consumed, in order to maintain a constant arc gap.
5.
Repeat steps 3-4 for the other end of the joint.
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MP-W1 Laboratory
Mounting Plate Op. 20 – Double Fillet-Weld Forward Fix Plate to Base Plate
1.
Set the control unit and strike the arc at one tack, as described above (Op. 10).
2.
While maintaining the specified distance and angle, move the electrode slowly to
the other tack, using a weaving (or similar) motion, to form a continuous bead.
Feed the electrode forward as it is consumed to maintain a constant arc gap. Also
note the following:
- Moving too slow will result in excessive penetration and possible burning, while
moving too fast will result in a thin bead and weak weld.
- If the arc length (distance from workpiece surface to electrode) is too short, the
workpiece will not receive sufficient heat and penetration and fusion will be poor.
- If the arc length is too long, excessive spatter will occur and the bead will be
irregularly shaped.
3.
Following welding, use the metal tongs to pick up the hot workpiece and hold it
underwater for about 15 seconds to cool it.
4.
Remove slag from the weld bead using a chipping hammer.
5.
Repeat steps 1-4 above to create a fillet weld on the other side of the T joint.
Mounting Plate Op. 30 – Tack Weld Aft Fix Plate to Base Plate
This operation is performed identically to Op. 10 above, but using the Aft Fix Plate.
Lab Requirements
Each student is required to perform the manual welding operations as described.
Parts will be evaluated as follows:
Incomplete
Welding operations completed
(% completed)
Bead width (about 3/8-in., uniform over
over length)
Ripple pattern (smooth even pattern
over length)
Fillet angle (about 45° over length)
Poor
Fair
Good
30
35
(26-50) (51-75)
12
16
Excellent
0
(0)
0
25
(1-25)
8
40
(76-100)
20
0
8
12
16
20
0
8
12
16
20
Total points: 100
Evaluation of each attribute will be done by comparison with forward fix plate/base
plate weldments having good welds and welds which are deficient in the attributes.
IN ADDITION to the above, 20 points will be deducted from your part score if the
final welding operation (Op. 40) is performed manually as well.
MP-W2 Laboratory
97
MP-W2: MOUNTING PLATE – ROBOTIC ARC WELDING
Purpose
To learn the basics of robotic arc welding.
Overview
Robotic arc welding is investigated by performing the robotic welding operations
required to create a mounting plate, using the gas metal-arc welding (GMAW)
process. This consists of double fillet-welding an aft fix plate (p. 137) to a base
plate (p. 131). An engineering drawing of a mounting plate is given on p. 129:
robotic arc welding is operation 40 on the route sheet for this item (p. 130). A quiz
will be given at the end of this lab.
Equipment
Base plate/forward fix plate assembly, aft fix plate.
Fanuc Robot ARC Mate 100i Be.
Lincoln welding unit, gas supply system, welding table.
Welding fixture, metal tongs.
Background
As demonstrated in the previous lab (MP-W1), manual arc welding is a difficult
process to perform. Considerable operator skill is required: in many instances manual
welding operations can only be performed by certified welders with many years
experience. This in turn makes manual welding operations expensive and difficult to
schedule due to limited qualified personnel. A final disadvantage of manual arc welding
is that it is easy to make mistakes when production volume is high due to the difficulty of
maintaining the level of concentration required.
The above situation is in many ways similar to machining operations, where skilled
machine operators are necessary. Consequently, the concept of numerical control –
the use of coded instructions to control the movement of tool – can be used to similar
advantage in welding. Because of the size of components and complexity of the tool
(electrode) path in many cases, robots are often employed. Thus, the use of computers
to control the motion of a welding electrode is referred to as robotic arc welding.
In employing a robot to perform arc welding, several improvements in the process
can be made. The first is to employ a continuous spool of electrode wire and an
automated wire feeder, rather than sticks. This allows the welding process to continue
uninterrupted for much longer intervals of time. The second is that shielding gas can
now be provided from a separate source and delivered to the weld zone by the same
robotic arm holding the electrode. This is not only a more reliable way of providing
shielding, but eliminates the need for the electrode to be coated and hence lessexpensive electrode material. This modified process is known as gas metal-arc welding
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MP-W2 Laboratory
(GMAW – Figure 1). Though GMAW can also be done manually, the process is
especially well suited to robotic arc welding.
Wire feed
Electrode wire
(from spool)
Nozzle
in
out
Shielding
gas flow
Shielding
gas
+
Workpiece
AC (DC)
Power
Source
–
Figure 1. Gas metal-arc welding (GMAW) process.
Robotic arc welding systems typically consists of (i) a robot, with an end effector
capable of holding both an electrode and shielding gas line, (ii) a power supply, (iii) a
wire holder (spool) with automatic wire feeder, and (iv) shielding gas line and nozzle.
Shielding gas is typically, argon, carbon dioxide, or some mixture of these or other
gases. Robotic arc welding can typically be performed in either semi-automatic or fullautomatic modes. In semi-automatic mode, only the electrode wire feed is controlled –
movement of the electrode and starting/stopping the wire feed, shielding gas flow, and
weld current are all controlled by the operator. In full-automatic mode, the entire
process is performed automatically via a computer program. This program, of course,
must be prepared for each robotic arc welding operation to be performed.
To aid in programming, three different operating modes are usually provided in
robotic gas arc welding systems. Step-by-step operation allows for programming the
robot, low speed operation is used for verifying a program, and high-speed operation is
used for actual part production. Four programming methods are commonly available:
1. Path Following – the robot is guided along the weld joint and “remembers” the
path.
2. Teach In/Menu Guiding – the robot is moved from one position to the next via a
teach box (a portable control for robot programming). Position and other
instructions are stored via commands from the teach box.
3. Teach In/Text Edit Guiding – similar to teach in/menu guiding, but where
additional instructions are manually entered at the controller input panel.
4. Teach In/Menu Guiding with Text Editing – combines most of the above features.
MP-W2 Laboratory
99
In this laboratory, robotic arc welding is performed using a Fanuc robot system. This
consists of a Fanuc ARC Mate 100i Be articulated robot, the robot controller, and a
teach box. The teach in/menu guiding method is used for robot programming with this
system. The robot’s end effector is a GMAW welding head. Power for welding is
provided by a Lincoln Electric welding unit, and a gas supply system provides a 75%
argon/25% CO 2 shielding gas mixture to the welding head. A small welding table is
also provided for fixturing parts at a convenient work height.
Procedure
The lab instructor will first go through the robotic arc welding operation for the given
parts (below). The instructor will demonstrate the procedure up to performing a practice
run (Step 6), and will then explain the remaining steps. Everyone in your group will then
go through the entire operation once (this will result in all parts being welded). Once all
parts are complete, the lab instructor will evaluate them. When finished, be sure that
someone in your group signs-off the operation on the work order.
Mounting Plate Op. 40 – Robotic Arc Welding
1. Fixture Part
Insert a base plate/fix plates assembly in the welding fixture.
2. Power up Robot
a. Locate the Fanuc System Wall Power Control Box: Turn the black switch to the
on position.
b. On the power control box turn the key switch to the T1 position.
c. Pick-up the Teach Box, slide left hand through the side strap. Your fingers will feel
a dead man switch on the back, squeeze the switch lightly and hold.
d. On the Teach Box, turn the on-off switch to the on position. (Switch is located next
to your thumb.)
e. At the top left hand side of teach box there will be a red fault light. Press the Reset
button on the teach box to remove this fault light. (If the light doesn’t go out release
the dead man switch, squeeze, then press reset again.)
3. Program (Teach) Robot
a. Press the white Select key in the middle of the teach box. A new display
screen will appear.
b. Press F-2 for Create and then press F-1 for program. Put in a new program
number between 1to10. Press enter 2 times; a new display screen will appear.
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MP-W2 Laboratory
c. To move the robot: Press and hold down the blue Shift key, then press the (X, -X
J1), (Y, -Y, J2) or (Z, -Z, J3) key to move the robot. Now move the robot to about
6 inches about the part using the X, Y or Z key. (The blue Shift key must be held
down at all times while moving the robot.)
75°-80°
Welding nozzle
Fixture
Part
BEND
TWIST
Welding
table
(a)
(b)
d. Once you are in position, set a point above the work piece; press F-1 then enter.
e. Release the Shift key and press the Coord key in the middle of teach box until
you see the JGFRM Job frame symbol.
f. Now move the robot to the starting point of the weld. Press and hold Shift key
(using Z negative key) move welding nozzle to the starting position, about ¾ of
an inch away from the plate. (This will be from the welding nozzle not the wire
sticking out.)
About 3/4-in.
g. Now start the weld. Press F-2 for Arc Start then enter.
h. Now move the robot to the end of the weld. Move robot slowly to the stopping
position (using the X, -X, Y or -Y key), press F-4 key for Arc End and then enter.
This will turn the welder off at this point.
i. Use the Z positive key to move robot upward from part to about 6 inches away.
j. Press the F-1 for an end point then enter. (Teaching is now complete.)
MP-W2 Laboratory
101
4. Practice run:
a. To run a practice run, (make sure the JGFRM is at 100%) press and hold the
Shift Key and press the FWD Key. (You may need to do this after each step.)
b. If program is correct: Turn the welder and gas on and step outside of the welding
area.
5. Weld the part:
a. Reset the light curtain, press green button on the control panel (located on the
wall). If light curtain is set, a green light will appear. (If you break light curtain, reset
again.)
b. Now turn the key switch on the wall control to the Auto position.
c. Turn the switch on the teach box to the off position
d. Reset the fault light on the teach box. (Make sure JGFRM is at 100%, if not use
the % key on the teach box to set at 100%). Now the robot will run at full speed.
e. Press the shift key and then Weld ENBL key, this will activate the welder to weld.
f. Slide the welding curtain in place and view the robot through the curtain (Do not
look directly at welding arc.)
g. Press the green cycle start button and the robot should start welding. After it stop
turn the Weld ENBL off.
h. Remove part and repeat until everyone’s parts are welded. (Make sure you use
metal tongs remove parts, parts will be HOT! Place parts underwater for about ten
seconds to cool it.)
6. Re-Fixture Part
Remove the part and move it to the other side of the moveable fixture plate, then
slide the plate toward the robot until it stops. The part is now in the proper position and
orientation to weld the other side, using the same program.
7. Perform Practice Run and Weld
On the Wall Control Box, turn the Key Switch back to the T1 position. Pick-up the
Teach Box once again and squeeze the dead man switch and hold. Turn the teach
box to the on position, now reset the red fault light.
Repeat steps 4 and 5 to practice and weld the part. If correct weld remaining parts.
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MP-W2 Laboratory
8. Remove Part and Cool
Put on welding gloves, then remove the part from the fixture plate and grab it with a
pair of metal tongs. Then place the part underwater for about ten seconds to cool it.
9. Shut Down
Locate the Fanuc System Wall Power Control Box: Turn the black switch to the
off position. Now turn the arc welder off and close the gas flow.
Lab Requirements
Your group is required to use the robotic arc welding system to weld everyone’s
parts as described. Each student must then take the quiz given afterwards. The part is
worth 80 points and the quiz 20 points.
The instructor will evaluate all parts to obtain an average part score, which will then
be given to each student in the group who was present. Parts will be evaluated as
follows:
Welding operations completed
(% completed)
Correct weld length (from tack to tack)
Poor
Fair
Good
Excellent
0
(0)
0
30
(1-50)
30
35
(51-75)
35
40
(76-100)
40
Part points: 80
F/PM Laboratory
103
F/PM: SHEET METAL FORMING AND POWDER METALLURGY
Purpose
To learn the fundamentals of sheet metal forming and powder metallurgy.
Overview
Sheet metal forming is studied by performing deep drawing tests for two different
materials, to study the effect of material properties on formability. Powder metallurgy
processing is investigated by creating a “coin” via this process. A quiz will be given at the
end of this lab.
Equipment
0.031-in. thick type 3033 and type 1100 aluminum sheet, bronze alloy powder.
Hydraulic press, arbor press.
Sheet metal and powder metallurgy forming die sets.
Heat treat furnace, foil sheets.
Background
Sheet metal forming refers to cutting, bending, and forming operations performed on
relatively thin sheets of metal. Such processes date back to 5000 BC, when jewelry and
cooking utensils were hammered or stamped out of malleable metals such as copper,
gold, and silver. Today, sheet metal forming is used extensively in the manufacture of a
vast array of goods such as automobile bodies, aircraft panels, small and large
appliances, file cabinets, and beverage cans. Parts made via sheet metal forming have
good dimensional accuracy, high strength, good surface finish, and low cost.
One of the most specialized sheet metal forming processes is deep drawing. In this
process, a sheet (or blank) is placed over a die and then pushed into the die using a
punch, as shown in Figure 1. The blank is held against the die during the process with a
blankholder. One load (Fb) is first applied to the blankholder to secure the blank, then a
separate load (Fp) is applied to the punch to form the item. The result is that the blank
takes the shape of the die. Parts made in this manner include sinks, cooking pots,
beverage cans, and automobile body panels.
In order for deep drawing to be possible, the material must be ductile enough to thin
and elongate during the process, but have sufficient strength to avoid tearing and rupture.
The formability of a material for deep drawing is often specified by the limiting drawing
ratio (LDR):
Db(max)
LDR  maximum blank diameter 
punch diameter
Dp
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F/PM Laboratory
Punch
Fb
Fb
Fp
Blankholder
Blank
Die
Figure 1. Deep drawing process.
where a circular punch and die are assumed. The larger the LDR, the higher the
material’s formability. To determine the Db(max) , a deep drawing test is performed.
Powder metallurgy processing is where parts are produced from metal powders. The
process is simple and consists of two main steps: compacting and sintering. In
compacting, the powder is placed in a die and compressed into the desired shape,
typically via a set of punches. The die and/or one or both punches may have patterns on
their surfaces. The compressed part at this stage is known as a green compact. Sintering
consists of heating the green compact to a temperature below the materials melting point,
where the individual particles bond together via diffusion. The powder metallurgy
process is illustrated in Figure 2.
Upper
punch
Furnace
Powder
Die
Lower
punch
Green
compact
Compacting
Sintering
Figure 2. Powder metallurgy process.
Powder metallurgy processing has several unique advantages as compared to other
manufacturing processes:
F/PM Laboratory
105
- Parts can be produced to (or nearly to) the final dimensions in one step, eliminating
subsequent processing. This is called net shape or near net shape processing.
- Metal alloy combinations that are not possible with other methods (e.g., casting) can
be used (by simply mixing the different powders together).
- Certain metals which are difficult to work with using other methods can be handled
using powder metallurgy (e.g., tungsten filaments in incandescent light bulbs).
- The inherent porosity of parts formed by powder metallurgy can be exploited to
produce porous components such as filters and self-lubricating bearings.
- Scrap is negligible: about 97% of the raw material is used in the process.
As a result of these advantages, the powder metallurgy process is widely used.
Typical products made using powder metallurgy include gears, cams, automotive
components, porous products, and cutting tools.
Procedure
Sheet Metal Forming: The sheet metal forming process of interest in this lab is deep
drawing. This process is studied by conducting deep drawing tests, which are used to
determine the limiting drawing ratio (LDR) for each of two different materials:
- Material A: Type 3003-0 aluminum sheet, 0.031-in thick (YS = 6 ksi, UTS = 16 ksi,
elongation = 30%).
- Material B: Type 5052-H32 aluminum sheet, 0.031-in thick (YS = 28 ksi, UTS =
33ksi, elongation = 25%).
The steps for conducting a deep drawing test are below. The lab instructor will setup
the press, then demonstrate the test procedure. Your group will then perform the test for
each material type. Record the necessary data in the table below, and calculate and write
the LDR for each material in the space provided.
Deep Drawing Test
1. Move the deep drawing die into place on the press (if necessary).
2. Cut blanks of the material having the following diameters: 3-5/8”, 3-3/4”, and 3-7/8”.
Select the 3-5/8” diameter blank for drawing.
3. Lightly lubricate both sides of the blank, and place the blank (centered) on the die.
4. Start the press and run it through the drawing cycle. The blank will be drawn into a
cup. Pop the cup out of the die via the hand lever.
5. Record the condition of the cup – OK or torn.
6. If the cup was OK, repeat from step 3 using the next larger-diameter blank. Otherwise,
calculate the LDR for the material, based upon the largest blank diameter which was
OK and the punch diameter of 2 in.
106
F/PM Laboratory
Material A
Blank
Diameter
Results (OK, torn)
Material B
Blank
Diameter
Results (OK, torn)
LDRA =
=
LDRB =
=
Powder Metallurgy Processing: The two steps in powder metallurgy processing are
compacting and sintering. The procedures for these steps are given below.
The instructor will first demonstrate the compacting stage. Each student in the group
will then perform the compacting stage to obtain two parts. Once all parts have been
compacted, the instructor will sinter all parts together (i.e., in the same furnace load).
Compacting
1. Move the powder metallurgy forming die into place on the press (if necessary).
2. Measure the correct amount of powder and pour it into the die. NOTE: DO NOT use
any extra powder – this can damage the equipment.
3. Start the press, and stop the press once a force of 35 tons (equivalent to about 1800
psi on the gage) has been reached.
4. Remove the die, place it face down on the arbor press, and apply force to push the
item (green compact) out of the die.
Sintering
1. Set the furnace to 825 C and switch on the furnace (this will be done already).
2. Place the parts on carbon blocks in a sheet of heat treat foil. Fold the foil and doublewrap the edges.
3. Place the foil bag in the furnace and allow it to soak for 20 min. NOTE: use a timer!
F/PM Laboratory
107
4. Following soaking, remove the foil bag from the furnace and place it on an aluminum
block. NOTE: your instructor will do this.
5. Once the bag has sufficiently cooled (at least 30 minutes), it can be opened and the
parts examined. (Your instructor will likely show you completed parts from a previous
lab to avoid having to wait).
Lab Requirements
Sheet metal forming: Your group is responsible for performing the deep drawing test
on the two materials and calculating the LDR for each. Part scores will be determined as
follows:
a. Deep drawing tests not done
b. Test done for one material only, LDR missing or incorrect
c. Test done for one material only, LDR correct OR
test done for both materials, LDR’s missing or incorrect
d. Test done for both materials, LDR’s correct
0 points
30 points
35 points
40 points
Powder Metallurgy Processing: Each student is responsible for compacting two
parts as described. Parts will be evaluated as follows:
a. No parts compacted
b. One part compacted, but incorrectly
c. One part compacted correctly OR two parts compacted incorrectly
0 points
30 points
35 points
d. Two parts compacted correctly
40 points
Quiz: Each student must take the quiz given at the end of the lab. The quiz will be
worth 20 points.
108
EDM Laboratory
WIRE ELECTRICAL DISCHARGE MACHINING
Purpose
To learn the fundamentals of the Wire Electrical Discharge Machining (Wire EDM)
process and the effects of various process parameters on surface finish.
Overview
This laboratory consists of burning material from a stainless steel workpiece, to
produce five (5) different indentations in the workpiece, by using the Wire EDM process.
Each indentation is created using a different combination of cutting technologies, gap
voltage, and working current. The surface roughness of each indentation is measured
and the data gathered is analyzed to determine (i) how surface roughness is affected by
different wire offsets (ii) how surface roughness is related to voltage, current, and
machining time.
Equipment
Stainless steel workpiece.
FANUC EDM ROBOCUT α - C400iA.
Profilometer.
Background
Electrical discharge machining (EDM) is a process where electric sparks, generated
repeatedly at a high frequency, are used to selectively remove material from a
workpiece. There are two types of EDM in this Lab, the first type is called the Plunge
EDM, and the second type is called the Wire EDM. In both cases the workpiece is
mounted on a platform that induces a positive charge to the workpiece. The electric
sparks are generated because of the potential difference between the workpiece and
the wire (or an electrode in the case of Plunge EDM). The workpiece is submerged in
dielectric fluid (which in this case is distilled water) that ionizes when there’s sufficient
potential difference between the workpiece and the wire, thus generating a spark. This
spark burns a small amount of the workpiece into particles. Flushing of excess particles
from the workpiece is critical since accumulation of the particles around the work piece
can cause premature arcing (which leads to a short circuit). The dielectric fluid is then
filtered to remove these particles.
Though the amount of material removed is small, thousands of sparks are generated
every second. This results in a steady removal of material from the zone between the
wire and the workpiece. The main difference between the Plunge EDM and the Wire
EDM is that in Plunge EDM the electrode is “plunged” into the workpiece repeatedly to
burn small amounts of the workpiece and thus the slot machined is dependent on the
shape of the electrode, whereas in Wire EDM spools of wire (brass in this case) is fed
continuously into the work zone to generate the spark and burn the material, thus
109
EDM Laboratory
allowing the user to machine complex contours while ensuring the part is under little
or no stress. Figure 1 shows a wire EDM machine.
Figure 1. FANUC wire EDM machine.
The two most important parameters in EDM are spark frequency and discharge
(working) current. Increasing spark frequency (discharge current held constant) or
decreasing discharge current (spark frequency held constant) decreases surface
roughness, but increases machining time. Note that the spark frequency is directly
proportional to gap voltage, e.g., increasing gap voltage increases spark frequency.
We are also interested in the total energy consumed by the Wire EDM machine to
make an indentation in the workpiece. As mentioned before, the sparks that burn the
material from the workpiece are generated when there is sufficient potential difference
between the wire and the workpiece. This potential difference causes a current to run
through the wire. The Wire EDM machine measures both the potential difference
(voltage reading), and the current (amperage reading) of the wire. Let 𝑉 denote the
voltage reading, and let 𝐴 denote the current reading. Then the power (𝑃) consumed by
the Wire EDM machine to the make an indentation is given by the equation
𝑃 = 𝑉 ∗ 𝐴.
(1)
Since power is energy used per unit time, we know that the total energy consumed by
the machine (𝐸 ) to make an indentation is given by the equation
𝐸 = (𝑉 ∗ 𝐴) ∗ 𝑡,
where 𝑡 is the machining time in seconds.
(2)
Electrical discharge machining is a nontraditional machining process, because it
doesn’t remove material in the traditional manner (i.e. via a cutting tool). The user has to
ensure that the workpiece can conduct electricity in order to use EDM. Cases where
traditional machining processes such as turning (p. 24), milling (pp. 42-44), and drilling
(pp. 25-26) are unsuitable, nontraditional processes such as EDM must be employed.
Typical features produced via EDM include deep, small-diameter holes, stepped
110
EDM Laboratory
cavities, narrow slots, and shallow holes, or pockets. Products include die cavities for
automotive components and turbine blades.
Procedure
The Wire EDM experiment consists of burning material to produce 5 different indentions
in the workpiece. The instructor will first present the details of the working of the Wire
EDM machine and the various machine parameters that will be of interest during the
experiment. The instructor will then give an overview of the different cutting
technologies, working current, gap voltage, and time involved in producing each
indentation. The instructor will proceed to assign each member of the group the
responsibility of recording the readings for one parameter that affects the indentation in
Table 1. The students with the assistance of the instructor will then operate the
machine.
Once all indentations have been created, remove and clean the part. Proceed to
measure the surface roughness of each indentation using a profilometer (Surfometer).
The profilometer gives a variety of readings: you are interested in the average surface
roughness (Ra - which will be recorded in micro inches or µ inches). Record these
values in the table as well.
Table 1. Data collection for Wire EDM experiments.
Experiment
Number
Pass
Number
1
1
2
1
2
1
3
2
3
1
4
2
3
4
1
2
5
3
4
5
Voltage
Reading (V)
Current
Reading
(A)
Wire Offset
(inches)
Time (t)
(seconds)
Surface
Roughness
(micro
inches)
EDM Laboratory
111
After the completing the surface roughness measurements, calculate the energy
consumed by the Wire EDM machine on each pass and record it in Table 2.
Table 2. Energy calculations for Wire EDM experiments.
Experiment Number
Pass Number
1
1
2
Power = V*A
(watt)
Energy
consumed
=V*A*t
(joule)
Total Energy per
experiment
1
2
1
3
2
3
1
4
2
3
4
1
2
5
3
4
5
Lab Requirements (prepare items based on the data that YOUR TEAM collected)
A lab report is required of EACH TEAM of students. The report MUST be prepared
according to the ‘Laboratory Report Format’ instructions (p. 4), and be submitted at the
START of the next lab. In the Presentation of Results, include the following items, in
the given order:
• A copy of Table 1 and Table 2 with all readings and calculated values.
• On the same graph, plot the curve Surface Roughness (y-axis) vs. Experiment
number (x-axis) and Closest Wire Offset in each experiment (y-axis) vs Experiment
number (x-axis).
• On the same graph, plot the curve Surface Roughness (y-axis) vs. Experiment
number (x-axis) and Energy consumed in each experiment (y-axis) vs Experiment
number (x-axis).
Follow the guidelines on p. 5 in preparing each graph. Be sure that surface roughness,
being the dependent variable, is on the y-axis (i.e., vertical).
In the Discussion of Results, describe the relationships between the variables
shown on the graphs. Do these trends agree with your understanding of the EDM
process? Comment on possible sources of error.
112
TRN Laboratory
TRN: CUTTING FORCE AND TEMPERATURE IN TURNING
Purpose
To study the effects of cutting conditions on cutting force and temperature, and to
learn to develop empirical models.
Overview
This laboratory consists of performing a series of turning experiments on the outer
diameter of a single workpiece on a lathe. Each experiment consists of a particular
combination of cutting conditions (speed, feed, and depth-of-cut values) and cutting fluid
flow (on or off). Cutting force and temperature data are recorded for each experiment,
and analysis performed to determine the relationship between (i) cutting force and
cutting conditions, and (ii) temperature and cutting conditions.
Equipment
Rotational steel specimen.
Lathe with variable speed drive.
Dynamometer (force measurement), thermocouple (temperature measurement).
Data acquisition system, hand-held tachometer.
Background
Machining is where a cutting tool is moved relative to a workpiece to selectively
remove material from an item. Machining is one of the most fundamental and important
categories of manufacturing processes. Parts of almost any shape (flat, round, etc.)
can be produced via machining, as can almost any geometric feature (pocket, boss,
etc.). Almost all metals and alloys, as well as various other materials such as wood and
plastics, can be machined. As a result of this versatility, machining is very widely used
in the production of manufactured goods. Examples of machining processes include
turning (p. 24), milling (pp. 42-44), and drilling (pp. 25-26).
In order to perform a machining operation with a given cutting tool, three parameters
known as cutting conditions must be specified. The first of these, speed (or cutting
speed, V), is how fast the part surface travels past the tool. The second, feed (f), is the
rate at which the tool is advanced into the workpiece. Finally, depth-of-cut (d) is how
much the cutting tool penetrates below the original work surface during the operation.
Speed is usually measured in surface feet per minute (sfpm), feed in inches per
revolution (ipr) or millimeters per revolution, and depth-of-cut in inches or millimeters. It
should also be noted that speed cannot usually be set directly: we set the rotational
speed N (rpm), of either the tool or workpiece, to get the desired speed.
Two important machining variables which are dependent upon cutting conditions are
cutting force and cutting temperature. Cutting force (F C ) is the force needed to move
the tool against the workpiece. This force is in the direction of cutting, i.e., the same
TRN Laboratory
113
direction as the speed V. It is desirable to be able to determine cutting force in advance
because this parameter establishes
- the power needed for a machining operation. Power can be calculated from
P =
Fc V
hp (horsepower)
33,000 ⋅E
where F C is in lb, V in sfpm, and E = mechanical efficiency of the machine
(typically around 90%).
- the load which the tool, machine and workpiece must be able to withstand during
machining. The inability to withstand this load can result in a broken tool, a
damaged part, and/or deflection in the machine (and hence the inability to
accurately machine items).
In general, we find that cutting force increases with increasing feed and/or depth-ofcut. Increasing cutting speed alone has little effect on cutting force.
Cutting temperature (θ) is the average temperature at the tool-workpiece interface.
At the start of a machining operation, the tool-workpiece interface is at ambient (room)
temperature. During machining, the friction between the cutting tool and work surface
generates a great deal of heat, causing the cutting temperature to rise drastically.
Approximately 98% of the total energy used for cutting ends up being converted into
heat: temperatures over 1000° F are common. It is desirable to be able to determine
cutting temperature in advance because excessively high temperatures can have
detrimental effects. These include
- increased tool wear.
- altered properties at the workpiece surface (localized heat treatment).
- rougher surface finish.
- reduced dimensional accuracy due to thermal stresses.
In general, cutting temperature increases with increasing speed, feed, and/or depthof-cut. Increasing speed has the greatest effect and increasing depth-of-cut the
smallest. One simple way to reduce cutting temperature is to employ cutting fluid. This
is a fluid which is applied to the tool/workpiece interface (e.g., via a spray nozzle) to cool
and lubricate the area (and to carry off the machined chips).
In this laboratory, cutting force and cutting temperature are studied for turning, a
common machining process used for rotational (i.e., round) items. In turning, the
workpiece is held in a lathe (p. 24) which rotates the item at a predetermined speed. As
the workpiece rotates, the cutting tool is moved parallel to the axis of rotation, reducing
the diameter of the item. Figure 1 illustrates cutting force, speed, feed, and depth-of-cut
for a turning operation. Note that for a lathe, F C = vertical cutting force = F(z). Not
shown in the figure are two other forces which are present during cutting on a lathe, F(x)
and F(y).
114
TRN Laboratory
Figure 1. Cutting force, speed, feed, and depth-of-cut in turning.
For turning operations, cutting force F C and cutting temperature θ can be calculated
using the following empirical equations:
Fc = K ⋅ f x ⋅dy
where K, x, and y are constants, and
θ = C ⋅ Vn ⋅ fm
where C, n, and m are constants. To solve for the three unknowns in each case, three
equations are needed. Different equations can be obtained by measuring cutting force
F C and cutting temperature θ for different combinations of cutting conditions. Consider
first solving for K, x, and y (F C expression). If we have two experiments a and b where
speed (V) and feed (f) are constant, we can solve for y via the expression
Fc (experiment a)
Fc (a )
K ⋅ fa x ⋅da y
=
=
K ⋅ fb x ⋅db y
Fc (experiment b)
Fc (b )
x
by canceling the K and f terms, taking logs of both sides, rearranging terms, and
plugging in values. Similarly, if we have an additional experiment c, where speed and
depth-of-cut (d) are constant for experiments a and c, we can solve x via the expression
Fc (a)
K ⋅fax ⋅ da y
=
Fc (c)
K ⋅ fc x ⋅ dc y
Once both x and y are known, we can solve for K by using Fc = K ⋅ f x ⋅dy , our values
of x and y, and the values of F C , f and d from experiment a, b, or c. We can solve for
the cutting temperature parameters C, n, and m in similar manner (where the depth-ofcut is constant for all three experiments).
In the lab, cutting force Fc (=F(z)) is measured, along with F(x) and F(y), using a
dynamometer. Temperature is measured by placing a temperature measuring device
known as a thermocouple in close proximity to the tool/workpiece interface. To record
force and temperature data, an automated data-acquisition system is used.
115
TRN Laboratory
Procedure
The lab instructor will divide you into teams of two or three students. He/she will
then demonstrate the procedure to be used for each cutting force and temperature
measurement experiment. This procedure is given below.
Following the demonstration, your group will go through the procedure eight times,
once for each experiment. The values to use for the various parameters which must
be set each experiment are given on the table on p. 116. Record the average cutting
force and average cutting temperature values in this table as well. NOTE: the
cutting force values you will record are in newtons (N). To convert to lb., multiply by
0.2248.
1. Setup the computer (data-acquisition system)
a. From the Desktop double click the “Turning Lab” icon (LabVIEW).
b. From the LabVIEW screen enter data for each cutting condition.
CUTTING CONDITIONS
-
SURFACE Speed (surface feed/min)
<per table p.116>
-
FEED (inches/rev)
<per table p. 116>
-
DEPTH OF CUT (inches)
<per table p. 116>
c. SCALE VALUE (factor) for F(z)
<per table p. 116>
2. Setup the amplifiers for force measurement
a. Set the gain (rotary knob) on each amplifier to match the scale value (factor) you
input to the computer for F(z), plus F(x) and F(y). However we are only recording
the force of F(z). (Step 1d).
b. Set the run mode toggle switch on each amplifier to “operate.” NOTE: data will not
record if this is not done.
3. Setup the lathe for the experiment
a. With the lathe OFF, set the feed using the selector knob.
b. Turn the lathe ON (i.e., spindle turning). Set the spindle rotational speed (N),
using a hand-held tachometer, to obtain the required cutting speed (V).
c. With the lathe ON, set the depth-of-cut.
116
TRN Laboratory
4. Measure cutting force and temperature
a. Engage the clutch to start the tool feed. The tool will start to move into the part.
b. Wait until you have full depth of cut (i.e., the tool edge is fully cutting into the
shoulder of the part). Then signal the computer operator to hit the ENTER key to
start collecting force and temperature data. The readings will display on the
screen (NOTE: the force readings given on the screen are in newtons, N).
c. Once all readings are taken, the average values appear on the screen. At this
point the computer operator can signal the machine operator to stop the tool feed.
Turn the lathe OFF if the feed needs to be changed.
d. Record the “Average Z force” and “Average Temperature” values shown on the
screen in Table 1 below.
e. Set the run mode toggle switch on each amplifier back to “Reset.”
Table 1. Data collection for turning experiments.
Experiment Speed (V),
Depth of
Cutting
Feed (f),
cut (d),
fluid
Scale
#
(sfpm)
ipr
in,
flow
factor
1
450
.0030
.025
off
5,000
2
350
.0030
.025
off
5,000
3
250
.0030
.025
off
5,000
4
250
.0060
.025
off
10,000
5
250
.0120
.025
off
10,000
6
250
.0120
.0375
off
20,000
7
250
.0120
.050
off
20,000
8
250
.0120
.050
on
20,000
Average Z force
Average
( = cutting force F c )
temperature
N
lb.
(θ), oC
TRN Laboratory
117
Lab Requirements
A lab report is required of EACH TEAM of students. The report MUST be prepared
according to the ‘Laboratory Report Format’ instructions (p. 4), and be submitted at the
START of the next lab. In the Presentation of Results, include the following items, in
the given order:
1. A copy of the above table, showing the data recorded by your group.
2. Six graphs, based upon the data in the above table, as follows:
a) Cutting force (F C , in lb) vs. speed (V), based upon experiments 1, 2 and 3.
b) Cutting force (F C , in lb) vs. feed (f), based upon experiments 3, 4 and 5.
c) Cutting force (F C , in lb) vs. depth-of-cut (d), based upon experiments 5, 6 and
7.
d) Cutting temperature (θ) vs. speed (V), based upon experiments 1, 2 and 3.
e) Cutting temperature (θ) vs. feed (f), based upon experiments 3, 4 and 5.
f) Cutting temperature (θ ) vs. depth-of-cut (d), based upon experiments 5, 6 and
7.
Follow the guidelines on p. 5 in preparing each graph. Be sure that cutting force
and temperature, being the dependent variables, are on the y-axis (i.e., vertical).
In the Discussion of Results:
1. Describe the relationships between F C and each cutting condition, and θ and
each cutting condition. Do these relationships agree with your understanding of
cutting tool theory? Discuss possible sources of error.
2. Derive empirical equations for F C and θ, as described on p. 120, where F C values
are in lb. SHOW YOUR WORK.
3. Use your equations to predict F C (in lb) and θ for the following conditions: V =
500 sfpm, f = 0.0030 ipr, and d = 0.125 in.
4. Calculate the horsepower required for these same cutting conditions and your
value of F C . Assume a machine efficiency of 90% for your calculations.
5. Answer the following: What effect does cutting fluid have on cutting temperature?
On cutting force?
118
Appendix A
APPENDIX A: GEOMETRIC DIMENSIONING AND
TOLERANCING
Introduction
An important step in designing any product is to establish the desired dimensions,
geometry, and other properties. For example, we may desire that a rotational part may
have a certain length and diameter, and be round to a certain extent. The desired
specifications then become the goal in manufacturing the product. No matter how we
decide to make the product, there are two fundamental principles of manufacturing
which always hold:
1. No desired specification (dimension, etc.) can ever be obtained exactly.
2. No two parts can ever be exactly the same.
The first principle results from the fact that any manufacturing process can only be
performed within a certain level of accuracy. Some machines are more accurate than
others, so they will be able to get closer to desired specifications when producing parts.
The second principle results from the fact that all manufacturing processes are subject
to process variability. No matter how hard we try, we can never perform a
manufacturing process exactly the same way twice. Machines are accurate only to a
certain extent, machines and tools wear, operators perform tasks differently from time to
time, etc. Even machines which are highly accurate can never do the same operation
exactly the same way twice.
While the above two fundamental principles of manufacturing may appear to be a
problem, this is not in fact the case. First of all, there is seldom a need for items to be
made exactly to desired specifications. For example, it makes little difference if a pencil
which is desired to be 6.0 inches long is actually 6.02 inches long, but 8.0 inches is
clearly too long. Thus, it is only necessary that the item be made within specified
bounds. Similarly, there is seldom a need for any two parts to be exactly identical: they
only need be close enough such that one part can be substituted for another if
necessary. This concept of interchangeable parts is one of the cornerstones of modern
society. For example, as long as all light bulbs are made within a certain range of
diameter, such that the largest bulb can still fit in the smallest socket and the smallest
bulb securely in the largest socket, the bulbs are close enough to being identical.
Therefore, it is necessary for product designers to establish and specify acceptable
bounds on what is desired when designing products. Such bounds are known as
tolerances, from the Latin tolerare – to endure or put up with. Tolerances apply to any
and all desired specifications in manufacturing. They must be stated, along with what is
desired, on the engineering drawings and other relevant documents. Of particular
importance in manufacturing are tolerances on dimensions and geometry. The manner
in which such tolerances are specified in manufacturing is known as geometric
dimensioning and tolerancing (GD&T). In this section, we present those GD&T
concepts you will need to understand to perform the laboratories in this manual.
Appendix A
119
Dimensional Tolerances
Dimensional tolerances are used to specify bounds on any desired or nominal
dimension (length, width, height, diameter, angle). There are three ways to specify
dimensional tolerances:
i. Bilateral tolerance – the nominal dimension is given, along with an upper and
lower bound.
ii. Unilateral Tolerance – the nominal dimension is given, along with an upper or
lower bound.
iii. Limit Dimensions – only the bounds are specified
Each of these types of tolerance is shown, applied to linear dimensions, in the figure
below.
Bilateral tolerances
2.00
+ 0.05
– 0.05
0.99 – 1.01
Limit
dimensions
0.50 ± 0.05
1.00
+ 0.00
– 0.01
Unilateral tolerance
Geometric Tolerances
Geometric tolerances are used to specify bounds on the geometry of part features.
The two most important categories of geometric tolerances are form tolerances and
location tolerances. Form tolerances are bounds on geometric attributes such as
flatness, parallelism, straightness, circularity, and cylindricity. Location tolerances are
bounds on the position of features.
In order to apply geometric tolerances, we must first be able to specify the part
edges (lines) and surfaces (planes) upon which the tolerances will be based. Such
items are called datum references.
Examples of datum references and their
specification:
120
Appendix A
A
-ADatum = plane A
Part and datum reference
C
-CDatum = plane C
Part and datum reference
Example of form tolerances and their specification:
0.010
//
-A-
0.005
Flatness (
). The top surface of the part
must be at the correct height (nominal
dimension + tolerance, not shown), and
must lie between two parallel planes 0.010
inch apart.
Parallelism ( / / ). The top surface must be
at the correct height, and must lie between
two planes 0.005 inches apart which are
each parallel to datum plane A (bottom of
the part).
-A-
0.010
Cylindricity ( ). Every point on the larger
cylinder must be within the specified
diameter (nominal dimension + tolerance,
not shown) and lie between two concentric
circles at that axial location, one 0.010
inches larger than the other.
Appendix A
121
Examples of location tolerances and their specification:
Toleranced Location. The true location of
the center of the hole must be within a
square having corners established by the
toleranced locating dimensions, i.e.,
0.50 ± 0.05
+ 0.00
1.00
– 0.01
∅ 0.010 S
(0.99, 0.55)
(1.00, 0.55)
(0.99, 0.45)
(1.00, 0.45)
True Position ( ). The true location of the
center of the hole must be within a circle
centered at the nominal dimensions (1.0,
0.50) and having a diameter of 0.010
inches, i.e.,
(1.00, 0.50)
0.010
0.50
(The S
means “regardless of feature
size”: the hole center must be located as
above no matter what it’s actual diameter
is)
1.00
C
-C-
∅ 0.02
Concentricity ( ). The axis of the larger
cylinder must be within a cylindrical zone
having a diameter of 0.02 inches and
whose axis coincides with the datum axis,
i.e., the axis upon which the smaller
cylinder is located.
9
8
10
3
2
13
12
11
4
1
5
6
7
BOX COVER
2
REQ’D
1
1
2
1
1
1
1
1
1
1
SCALE: AS NOTED
DR. BY: J. SHEWCHUK
ITEM NO: 2214-001
REV: A
DATE: AUG. 1, 2000
DRWG. NO. 72085
SWITCH BOX
INDUSTRIAL & SYSTEMS ENGINEERING – VPI & SU
NO.
ITEM
BOX SCREW
3
BOX
SPST TOGGLE SWITCH
4
1
SPST SWITCH FACE PLATE
5
SPACER
8
6
9/16-IN. NUT
9
1/2-IN. NUT
3/8-IN. NYLON GROMMET
10
LAMP ASS’Y
WIRE ASS’Y A (BL)
11
7
1
WIRE ASS’Y B (BK)
12
1
1
WIRE ASS’Y C (RD)
13
122
Appendix B
Appendix B
123
TASK LIST
SWITCH BOX – ITEM NO. 2214-001
Description
Task
Items
Tools
a
Install switch in box
Switch, face plate, 1/2-in.
nut, box
–
b
Install lamp ass’y in box
Lamp ass’y, spacer, 9/16in. nut
–
c
Insert grommet in box
Nylon grommet
–
d
Attach wire ass’y C to lamp ass’y
and run through grommet
Wire ass’y C (RD)
–
e
Attach wire ass’y B to switch and
run through grommet
Wire ass’y B (BK)
–
f
Attach wire ass’y A between
switch and lamp ass’y
Wire ass’y A (BL)
–
g
Attach box cover
Box cover, box screw (4)
h
Test
- electrical (light must come
on).
- assembly: both switch and
lamp secure; two screws
used for box cover.
Phillips screwdriver
–
Test unit
PRECEDENCE DIAGRAM
SWITCH BOX – ITEM NO. 2214-001
a
e
c
f
b
d
g
h
1
– 20 UNC
B
∅ 0.010
SCALE: FULL
REV: A
DATE: JUNE 20, 2000
DRWG. NO. 41562
PULLEY
INDUSTRIAL & SYSTEMS ENGINEERING – VPI & SU
DR. BY: J. SHEWCHUK
1.0
4
0.020
MAT’L: 713 ALUMINUM.
1.365
1.385
0.289
0.75
A
ITEM NO: 2214-002
-B-
0.625 ±0.001
//
0.625 ±0.025
ALL DIMENSIONS ± 0.015 IN. UNLESS OTHERWISE NOTED.
NOTES
3.0
0.25
0.312
-A-
124
Appendix B
Appendix B
125
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
ROUTE SHEET
ITEM NO:
1 OF 2
NAME:
2214-002
Pulley
MAT’L:
713 Aluminum
DRWG. NO:
41562
REV:
PLAN NO:
PP-235
PLANNER:
Collins, A.
DATE:
June 29, 2023
Op.
Description
Dept.
Machine
A
Tooling,
gages
Setup,
min.
Run,
min.
10
Cast pulley
C
6’ x 8’ sand
box, Speedy
Melt furnace,
mechanical
riddler
Sand mold,
sand casting
tools, 1”
sprue cutter,
1-1/2” riser
cutter
30
45
20
Chuck boss; rough
& finish face
hub, rough &
finish turn hub
dia.
T
South Bend
2HP or Mazak
10HP lathe
RH face, dial
calipers
5
20
30
Machine groove
T
"
Grooving
tool, hook
divider, 6"
steel rule
5
5
40
Center drill,
drill, ream
center hole
T
"
No. 5 center
drill, 37/64"
twist drill,
5/8" reamer
2
10
50
Remove, insert
mandrel, reverse.
Face boss, rough
& finish turn
boss dia.
P, T
5/8" steel
mandrel, live
center, dial
calipers
10
20
60
Deburr machined
surfaces, remove
mandrel
P, T
Grooving tool
2
5
70
Broach keyway
1/8" keyway
broach
2
2
P
Famco arbor
press, South
Bend 2HP or
Mazak 10HP
lathe
"
Famco arbor
press
126
Appendix B
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
ROUTE SHEET
ITEM NO:
2 OF 2
NAME:
2214-002
Pulley
MAT’L:
713 Aluminum
DRWG. NO:
41562
REV:
PLAN NO:
PP-235
PLANNER:
Collins, A.
DATE:
June 29, 2023
Dept.
Machine
A
Tooling,
gages
Setup,
min.
Run,
min.
1
1
45
5
Hand file
5
5
Marker
0
1
Dial caliper,
outside mic.,
telescoping
gage, dial
indicator,
gage blocks
(0.625-in.)
5
25
Op.
Description
80
Deburr center
hole
D
Orbit drill
press
1"
countersink
90
Center drill,
drill, tap radial
hole
D
Leland
Gilford gang
drill
Pulley jig,
vise and
mounting
plate (3),
No. 3 center
drill, No. 7
twist drill,
1/4-20 tap
100
Deburr keyway,
radial hole
M
–
110
Mark S/N on hub
face
M
–
120
Inspect to drwg.
I
Deltronic
optical
comparator
DH-124
Appendix B
127
PART INSPECTION REPORT
ITEM NO:
NAME:
2214-002
MAT’L:
Pulley
DRWG. NO:
713 Aluminum
INSPECTOR:
ATTRIBUTE
1. Hub Diameter
2. Boss Diameter
3. Concentricity of
Hub and Boss
4. Hub Thickness
5. Parallelism of
Hub Face and
Shoulder
6. Overall Length
7. Center Hole
Diameter
8. Groove Axial
Location
9. Groove Depth
10. Groove Width
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
41562
REV:
A
DATE:
RESULTS
1 OF 1
S/N:
W/O #:
AC
C
REJ
128
Appendix B
BILL-OF-MATERIALS
MOUNTING PLATE – ITEM NO. 2214-003
INDENTED BOM:
MOUNTING PLATE, 2214-003
BASE PLATE, 2214-004
FORWARD FIX PLATE, 2214-005
AFT FIX PLATE, 2214-006
EXPLODED BOM:
MOUNTING PLATE
BASE PLATE
FORWARD FIX PLATE
AFT FIX PLATE
(1)
(1)
(1)
SCALE = 2:3
2214-005
2214-006
SCALE: AS NOTED
DR. BY: J. SHEWCHUK
ITEM NO: 2214-003
REV: B
DATE: JULY 13, 2000
DWG. N0. 74893
MOUNTING PLATE
INDUSTRIAL & SYSTEMS ENGINEERING – VPI & SU
2214-004
3
16
Appendix B
129
130
Appendix B
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
ROUTE SHEET
ITEM NO:
1 OF 1
NAME:
2214-003
Mounting Plate
MAT’L:
(Assembly)
DRWG. NO:
74893
REV:
PLAN NO:
PP-320
PLANNER:
Culver, S.
DATE:
July 15, 2023
Op.
Description
Dept.
Machine
Hobart arc
welder
B
Tooling,
gages
Run,
min.
10
2
10
Tack weld forward
fix plate 2214005 to base plate
2214-004
W
20
Double fillet
weld forward fix
plate 2214-005 to
base plate 2214004
W
"
"
10
10
30
Tack weld aft fix
plate 2214-006 to
base plate 2214004
W
"
"
10
2
40
Double fillet
weld aft fix
plate 2214-006 to
base plate 2214004
W
Fanuc Robot
ARC Mate 100i
welding unit,
Argon/C02 gas
Robot station
weld fixture,
metal tongs
30
2
supply
E7014
electrode
Setup,
min.
0.25
0.10
0.125
1.50
3.0
SCALE: FULL
DR. BY: J. SHEWCHUK
REV: –
DATE: JUNE 22, 2000
DWG. NO. 71653
BASE PLATE
INDUSTRIAL & SYSTEMS ENGINEERING – VPI & SU
0.010
MAT’L: 1018 CRS.
0.562 DIA. (2 PLCS)
0.50
ITEM NO: 2214-004
1.25
(2 PLCS)
0.25
ALL DIMENSIONS ± 0.015 IN. UNLESS OTHERWISE NOTED.
NOTES
0.50
0.875
(2 PLCS)
3.25
6.50
Appendix B
131
132
Appendix B
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
ROUTE SHEET
ITEM NO:
1 OF 1
NAME:
2214-004
Base Plate
MAT’L:
1018 CRS, 3” x 1/2” bar
DRWG. NO:
71653
REV:
PLAN NO:
PP-301
PLANNER:
Lancaster, S.
DATE:
July 8, 2023
–
Tooling,
gages
Setup,
min.
Run,
min.
–
5
5
PPJ-1 jig
15
1
Orbit drill
press
82°
countersink
10
2
M
Cincinnati
2MH or Van
Norman 26SU
MF-2 fixture
30
15
End mill
transverse slot
(0.50-in. width)
M
Bridgeport
VMM or
Cincinnati
Toolmaster
MF-3 vise
15
10
60
Deburr slots
D
-
Hand file
2
5
70
Mark S/N on
bottom face
D
-
Marker
0
1
80
Inspect to drwg.
I
-
Dial caliper,
depth mic.,
dial indicator
w/base,
surface plate
5
10
Op.
Description
10
Cut to length
S
Marvel Mark
II vertical
band saw
20
Punch mounting
holes
P
Scotchman
FI60/130
punch press
30
Deburr holes
D
40
Side mill
longitudinal slot
(0.25-in. width)
50
Dept.
Machine
Appendix B
133
PART INSPECTION REPORT
ITEM NO:
NAME:
2214-004
MAT’L:
Base Plate
DRWG. NO:
1018 CRS
INSPECTOR:
ATTRIBUTE
1. Overall Length
2. Mounting Hole
Diameter
3. Longitudinal Slot
Depth
4. Transverse Slot
Depth
5. Flatness
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
71653
REV:
–
DATE:
RESULTS
1 OF 1
S/N:
W/O #:
AC
C
REJ
0.875
(2 PLCS)
1.00
(2 PLCS)
0.50
2.00
1.00
(2 PLCS)
2.00
(2 PLCS)
1.00
(2 PLCS)
45°
MAT’L: 1018 CRS.
45°
1.25 R
ALL DIMENSIONS ± 0.015 IN. UNLESS OTHERWISE NOTED.
NOTES
3.00
1.50
3.00
SCALE: FULL
DR. BY: J. SHEWCHUK
ITEM NO: 2214-005
REV: –
DATE: JUNE 25, 2000
DWG. NO. 71669
FORWARD FIX PLATE
INDUSTRIAL & SYSTEMS ENGINEERING – VPI & SU
1.375
(3 PLCS)
0.375 DIA. (2 PLCS)
0.188 R (4 PLCS)
0.188 R (2 PLCS)
0.250
134
Appendix B
Appendix B
135
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
ROUTE SHEET
ITEM NO:
1 OF 1
NAME:
2214-005
Forward Fix Plate
MAT’L:
1018 CRS, 3” x 1/4” bar
DRWG. NO:
71669
REV:
PLAN NO:
PP-303
PLANNER:
Slusser, J.
DATE:
July 8, 2023
Op.
Description
10
Cut to length
S
Marvel Mark
II vertical
band saw
20
Cut radial slot,
mounting holes,
and “X” slot.
M
Hurco
machining
center
30
Mark S/N on back
face
M
–
40
Inspect to drwg.
I
Brown & Sharp
Coordinate
Measuring
Machine
Dept.
Machine
–
Tooling,
gages
Setup,
min.
Run,
min.
–
5
5
3/8” end mill
15
8
Marker
0
1
6” vise
5
10
136
Appendix B
PART INSPECTION REPORT
ITEM NO:
NAME:
2214-005
MAT’L:
Forward Fix Plate
DRWG. NO:
1018 CRS
INSPECTOR:
ATTRIBUTE
1.”X” Slot Location
2. Mounting Hole
Location
3. Radial Slot
Location, Slot
Radius
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
71669
REV:
–
DATE:
RESULTS
1 OF 1
S/N:
W/O #:
AC
C
REJ
0.50
0.875
(2 PLCS)
1.00
(2 PLCS)
2.00
1.00
(2 PLCS)
2.00
(2 PLCS)
1.00
(2 PLCS)
3.00
PART TO HAVE FINAL HARDNESS OF AT LEAST 55 (ROCKWELL B).
MAT’L: 1018 CRS.
ALL DIMENSIONS ± 0.015 IN. UNLESS OTHERWISE NOTED.
NOTES
3.00
2.438
0.188
S
0.100
SCALE: FULL
DR. BY: J. SHEWCHUK
ITEM NO: 2214-006
REV: A
DATE: JUNE 29, 2000
DWG. NO. 71672
AFT FIX PLATE
INDUSTRIAL & SYSTEMS ENGINEERING – VPI & SU
1.375
(2 PLCS)
0.375 DIA. (2 PLCS)
0.188 R (4 PLCS)
∅ 0.010
0.188 R (2 PLCS)
0.375
0.100
Appendix B
137
138
Appendix B
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
ROUTE SHEET
ITEM NO:
1 OF 1
NAME:
2214-006
Aft Fix Plate
MAT’L:
1018 CRS, 3” x 1/4” bar
DRWG. NO:
71672
REV:
PLAN NO:
PP-312
PLANNER:
Snidow, K.
DATE:
July 10, 2023
Op.
Description
10
Cut to length
S
Marvel Mark
II vertical
band saw
20
Cut top edge,
slot, mounting
holes, pocket
M
Hurco
machining
center
30
Mark S/N on back
face
M
40
Inspect to drwg.
I
Dept.
Machine
–
Fowler
Hardness
Tester
(Rockwell B)
A
Tooling,
gages
Setup,
min.
Run,
min.
–
5
5
3/8” end mill
15
8
Marker
0
1
Dial caliper,
0.375” plug
gage
5
10
Appendix B
139
PART INSPECTION REPORT
ITEM NO:
2214-006
MAT’L:
NAME:
Aft Fix Plate
DRWG. NO:
1018 CRS
INSPECTOR:
ATTRIBUTE
1. Slot Location
2. Mounting Hole
Diameter
3. Hardness
INDUSTRIAL & SYSTEMS
ENGINEERING – VPI & SU
71672
REV:
A
DATE:
RESULTS
1 OF 1
S/N:
W/O #:
AC
C
REJ