IME 241 Manufacturing Processes Laboratory
Revised October, 2007
LABORATORY REPORT WRITING
Skill in effective report writing is important to the professional life of engineers.
Reports should be clearly and concisely written to direct the reader's attention to the major
points in an experiment. Organization, good grammar, and overall neatness are the essential
ingredients of an effective report.
An engineering report is typically divided into the following sections:
(a)
TITLE PAGE - including experiment name, name(s) of engineer(s), date
experiment completed, and date reported.
(b)
TABLE OF CONTENTS - with page numbers
(c)
OBJECTIVE - the goal of the experiment with a brief explanation of any
necessary background theory and a justification for the experiment if
necessary.
(d)
PROCEDURE - including special equipment and instrument diagrams where
necessary.
(e)
DATA, PRINT-OUTS, OBSERVATIONS GATHERED - Note: Tabulated
data and observations, where appropriate, are easier to read than "listed" data.
(f)
ANALYSIS/MANIPULATION OF DATA - Equations, plots, etc.
(g)
GENERAL DISCUSSION OF EXPERIMENTAL RESULTS - Refer to the
Raw Data, Analyzed Data, and any other "qualitative" results. Try not to draw
conclusions in this section- save them for the "OVERALL CONCLUSIONS"
section. Here, comment on the significance of the results and on the existing
theory which supports the results. If existing theory does not support or
address the results, comment on reasons why. For experimental work on the
"leading edge" of technology, try to identify and develop, if possible, some of
the theory necessary for proper discussion of the experimental results.
(h)
OVERALL CONCLUSIONS - Address the objective here - i.e., was the
objective met?
(i)
APPENDIX - for large volumes of data, computer programs, and the like.
(j)
BIBLIOGRAPHY/REFERENCE LIST - Number the list and use the numbers
as references in the body of the report. The reference number follows the text
and is enclosed in brackets - e.g." [5]” after some text in one's report would
indicate that the preceding text was based on or quoted from reference number
five found in the reference list.
The appearance of the report is very important. The text of the report should be
typewritten (double-spaced) on plain, white paper (no lines). Data, plots, calculations, and
illustrations may be neatly handwritten and/or drawn on appropriate paper (white, column
(DATAFORM), or graph). Finally, the entire report should be bound in an appropriate report
cover.
GENERAL SAFETY PRECAUTIONS
& RULES FOR CLEAN-UP
1.
Keep your mind on your work; watch the tool; and shut off the machine if in doubt as
to the operation.
2.
Wear safety glasses at all times in the Laboratory.
3.
PROPER FOOTWEAR IS REQUIRED. No sneakers or open toe shoes allowed in
the Laboratory.
4.
Do not wear loose clothing, ties, watches, rings, or other articles which can become
entangled in moving machinery. Long hair must be secured with a hair net or elastic
band. Shorts are not allowed in warm weather.
5.
DO NOT LEAVE THE MACHINE WHEN IT IS RUNNING.
6.
Do not lean across a moving cutter or table. Stop the machine to make all
adjustments.
7.
Keep the fingers away from the tool and work while the machine is running.
8.
Do not point and operate any air hose at a student in the Laboratories.
9.
All tools and instruction material must be returned to their proper places.
10.
All machinery MUST BE CLEANED and chips disposed of in trash can.
EVALUATION OF SURFACE FINISH
1.
MP1
OBJECTIVE
To study the effects which variations in the parameters of the primary machining
process of turning have on the surface finish of a workpiece.
2.
EQUIPMENT
Federal Products Surfanalyzer, carbide cutting tool insert mounted on shank, Logan
Engine Lathe, mild steel workpiece, hand tachometer, and safety glasses.
3.
DISCUSSION
Primary machining uses heavy roughing cuts to remove large amounts of material.
Secondary machining follows primary machining taking lighter cuts to improve surface finish
and dimensional accuracy. The allowable surface roughness of a part to be machined
depends on factors such as functions and size of the part, fit and dimensional accuracy
required, loading requirements, and required motion and wear characteristics.
Surface roughness can be measured by using a profilometer (Federal Products
Surfanalyzer) which uses a diamond tracer similar to a phonographic pickup. The tracer
reciprocates over the surface at a speed of about 1/8" per second and generates a voltage
which is proportional to the surface irregularities and is calibrated to express the arithmetic
average value in micro-inch or micro-meter.
In most cases the character of a machined surface depends upon the process used to
produce it. For example, there are several sources of roughness when machining with a
single point tool: (1) feed marks left by the cutting tool; (2) built-up edge fragments
embedded in the surface during the process of chip formation; (3) chatter marks from
vibration of the tool, workpiece, or machine tool itself. When a surface is turned at high
speed without chatter present, the primary surface roughness lies in an axial direction and
may be computed quite accurately from the feed and the tool geometry. (According to the
American Standards Association, ASA, the average roughness expressed in micro-inches for
a turned surface is approximately equal to feed/60.)
4.
PROCEDURE
1.
Understand the operating instructions for the lathe as presented to you by the
instructor.
2.
Observe the cutting edge of the carbide insert under a microscope to assure
that the cutting edge is free from flaws and defects.
3.
Divide the surface of the workpiece into nine 1.5" segments. Machine these
segments at the various combinations of feeds (0.004, 0.007, 0.010 ipr) and
speeds (150, 300, 450 sfpm), using a constant .020 inch depth of cut.
4.
After turning the surface of the given workpiece, clean off the workpiece (i.e.,
remove chips and oil from it) measure the surface roughness of the workpiece
using the portable surface analyzer. Take four readings for each segment by
rotating the workpiece 90 after each reading.
Record all data on the "Data Sheet" below.
Calculate the average surface roughness.
DATA SHEET FOR SURFACE FINISH EVALUATION
Cutting
Speed
(sfpm)
Feed
(ipr)
Surface Roughness (µin.)
1
2
3
4
Average
Roughness
(µin.)
0.004
150
0.007
0.10
0.004
300
0.007
0.10
0.004
450
0.007
0.10
5.
EVALUATION
1.
On one sheet of graph paper, plot the average surface roughness versus cutting
speed using feed as a parameter.
2.
On another sheet of graph paper, plot the average surface roughness versus
feed using speed as a parameter.
Discuss your results and the effects of any observed built-up-edge, chatter, etc. on the
average surface roughness.
BAR DRAWING
MP2
1. OBJECTIVE
To compare the work required per unit volume in the bar drawing process to the work
required per unit volume in the simple tension test to achieve the same extension of the bar
and from this determine the redundant work factor for the bar drawing.
2. EQUIPMENT
Tensile testing machine with a load capacity of 10,000lb. Hydraulic draw bench, fitted
with a load cell and dies for various finished bar diameters.
3. DISCUSSION
A perfectly efficient method of extending a cylindrical bar and decreasing its diameter is
through the application of simple tension. The disadvantage of this method is that about 25
percent elongation of the specimen will result in fracture. In contrast, bar drawing can be
performed over and over again, with smaller and smaller dies, to produce long lengths of bar,
rod and wire.
The efficiency of a bar drawing operation can be measured by comparing the work done
per unit volume (W/V) with the work per unit volume which would have been expended if
the process was as efficient as simple tension. The measure of efficiency is the redundant
work factor , which satisfies the equation:
W/V =  (W/V)st
where
W/V=actual work per unit volume expended in the process
(W/V)st = work per unit volume expended in simple tension
= redundant work factor
The purpose of this lab is to compare the work required per unit volume in simple tension
to achieve the same extension of the bar. To accomplish this goal a bar is pulled in simple
tension and three bars are drawn through different diameter dies. From the force and
extension data taken in the simple tension test an expression relating the strain of the bar ()
to the work done per unit volume (W/V)st can be derived. Next the drawing force, the
dimensions of the drawn bar and the die diameter is used to calculate:
1. The true strain in the drawn bar (dr)
2. Work per unit volume expended in the drawing process (W/V)dr
The work per unit volume that would have been done to extend the bar in simple tension
instead of through drawing is calculated by substituting (dr) into the equation for derived for
(W/V)st. Then can be calculated using:
 = (W/V)dr/(W/V)st
(1)
4. SIMPLE TENSION PROCEDURE
To determine the ideal work done per unit volume, the stress/strain properties of the
material need to be determined. Two methods based on tensile test results will be used.
Step 1. Measure the initial diameter, Do of the test specimen. Use the extensometer to
measure the increase in length of the initial 2 inch gauge length. Note load reading, F, at
approximate extensions of .01, .02, .04, .06, .08, .10, .12, .14, .16, .18 and .20 inches. Take
care not to exceed the .25 inch range of the extensometer, as this will damage the instrument.
Step 2. Remove the extensometer from the specimen and continue the tensile test until
fracture of the bar. Record the peak load during the test Fmax and measure the final diameter
of the specimen, DF, some distance away from the neck that results in fracture.
Method 1
1. From the tensile test results determine the true stress (i) and true strain (i) for each load
(Fi) and extension (Li).
(Table provided).
2. The work done per unit volume in the tensile test is equal to the area under the
stress/strain curve. However the results of the tensile test need to be extrapolated up to the
strain produced in drawing, so a relationship between, (W/V)st and  needs to be found. An
approximate numerical integration can be used for this.
For each data point determine the work done per unit volume up to the current strain,
(W/V)sti. This is given by the following expression:
(W/V)sti=1/2 11 + 1/2(2 + 1)(2-1) + ½ (3 + 2)(3-2) + …1/2(i+ i-1)(i-i-1)
(2)
This equation approximates to the area under the true stress/true strain curve for strain i
(Figure 1). By plotting (W/V)st versus  on log-log scales or otherwise determine the
constants in the relationship:
(W/V)st = kb……………..…
(3)
Method 2
From the peak load and the final diameter of the tensile specimen (away from the neck)
determine the approximate stress/strain relationship:
 = Bεn ……….
(4)
from the following approximate method:
Exponent, n, is equal to the largest uniform strain and therefore is given by:
n = 2 Ln (Do/DF) …………
(5)
Applied stress at maximum load is:
 = Bnn
where
 = Fmax/(DF2/4)
Therefore
B = 4 Fmax/(DF2nn)………
(6)
By following this procedure an approximate stress strain relationship for the bar material is
found of the form:
 = Bεn ……….
(7)
The ideal work done per unit volume is given by the following expression:
(W/V)st = Bn+1 / (n+1)……………..…
(8)
This enables the ideal work done per unit volume to be calculated by substituting the true
strain for each reduction during the drawing tests. The redundant work factor is then
calculated by dividing the actual work done per unit volume by the ideal work done per unit
volume.
5. BAR DRAWING PROCEDURE
The drawing process is presented schematically in Figure 2. Draw specimens through the
.304, .321 and the .356 inch diameter dies. Note the average drawing force from the load cell
attached to the drawing bench and obtain force-time graphs from the attached computer and
printer.
Since the volume of metal does not change during the drawing process the length of the
bar (L1) after drawing can be found from the relationship:
Volume = (*Do2/4)*Lo=(*D12/4)*L1
(7)
Where L0= length of the bar before drawing (in)
D0= diameter of the bar before drawing (in)
D1 = diameter of the bar after drawing = die diameter
The work done, W = force x distance
W = Fd * L1
where Fd is the drawing force.
Therefore,
(W/V)dr =[Fd * L1]/[(*D12/4)*L1} = Fd/[(D12/4)]
(9)
which is numerically equal to drawing stress applied to the bar during the drawing operation.
The ideal true strain in bar drawing is given by:
DR = ln(L1/L0) = 2 ln (Do/D1)
(10)
Using the drawing strain in each case determine the equivalent (W/V)st, for simple tension
using methods 1 and 2 above. Equations (3) and (4) should be used. Put these values in the
table provided. For both methods calculate the redundant work factor , using equation (1).
A rule of thumb states that the drawing process is most efficient when the length of die
contact (Lc) is equal to the mean diameter of the drawn bar (D). The die geometry is
illustrated in Figure 3. When Lc is less than D, the amount of internal distortion of the metal
during deformation increases and efficiency drops. When Lc is larger than D, the effect of
surface die friction increases and efficiency again falls. Determine Lc/D from the die
geometry with the following equations:
tan () = (Do-D1)/(2Lc)
Lc =. .5(Do-D1)/tan()
Where  is the die angle and in this case is equal to 7.5 degrees. Is the rule of the thumb
correct according to your data and calculations?
6. DISCUSSION
Present your results and calculations in a report, which should include any necessary
graphs. Comment on the differences between the values  determined and discuss the
reasons behind these differences.
True
Stress
σ
σ9
σ8
σ5
σ6
σ7
ε4
σ3
σ2
σ1
ε1
ε2
ε3
ε4
ε5
ε6
ε7
ε8
ε9
True Strain, ε
FIGURE 1
STRESS VERSUS STRAIN
α
D0
D
D1
Fd
Lc
FIGURE 2
DRAWING SCHEMATIC
(D0 –D1)/2
α
Lc
FIGURE 3
DIE GEOMETRY
Table 1
Tensile Test Results
True Stress
Reading #, i
Target extension
Actual extension
Force (lb)
∆Li
∆Li
Fi
1
0.01
2
0.02
3
0.04
4
0.06
5
0.08
6
0.10
7
0.12
8
0.14
9
0.16
10
0.18
11
0.20
σi
lb/in2
Work per unit
True strain
ε
vol.
(W/V)sti
Table 2
Die size
Drawing force
Actual work
(in)
(lb)
(W/V)dr
Drawing Test Data
Ideal work, (W/V)st
Redundant work factor,Φ
Lc/D
Method 1
Method 2
Method 1
Method 2
ORTHOGONAL METAL CUTTING
1.
MP5
OBJECTIVE
To observe the basic mechanics of metal cutting. Trends in the cutting process are
observed while varying cutting parameters and workpiece material. Chip formation is
also observed and studied.
2.
EQUIPMENT
Hardware

Horizontal Milling Machine. Adapted to carry out a slow spped orthogonal
planning operation

Combination Workpiece Fixture and Dynamometer. Used to hold the
three different workpiece materials during the cutting operation. The built in
dynamometer converts the applied force to a representative signal.

High Speed Steel cutting tool. Used to carry out the cutting process. This
wedge shaped tool is mounted in a special tool holder on the horizontal
milling machine.

Three workpiece materials (Aluminum, Brass, and Copper). The workpiece
material is varied to observe the effects of material properties on the cutting
process.

Video Microscope. Used to take a magnified picture of the cutting process.
It interfaces with the computer through a frame grabber video board.

Frame Grabber Video Board. Used to display the cutting process in real
time. A picture of the metal cutting process can be “frozen” when the student
desires. The still picture is then analyzed using the computer and Global Lab
Image software package.

Data Acquisition Board. Used to gather the horizontal and vertical force
signals from the dynamometer. These signals are then plotted and analyzed
using the Labtech Notebook and Microsoft Excel software packages.

Computer. Used to run the software necessary to acquire and analyze the
measured data.
Software

Global Lab Image. Used to process and analyze the still picture from the
frame grabber board.

Labtech Notebook. Used to acquire data from the data acquisition board.

Microsoft Excel. Used to display and statistically analyze the force
measurements from the Labtech Notebook software.
N
tc
F
R
φ
t0
FV
FH
R
Figure 1. Orthogonal Metal Removal Process
Tool
Rake angle, α
Feed direction
Material 3
Material 2
Material 1
Fixture
Figure 2. Experimental Set-up for Orthogonal Cutting
3.
DISCUSSION
The mechanism of metal cutting is quite complex but the basic theory can be
explained by a simplified two dimensional (orthogonal) model as given in Figure 1.
Orthogonal cutting is used as a model to approximate the force relationships in a real life
machining process. The two measured components of the cutting force are the horizontal
force (FH ) and the vertical force (FV). These force components are conveniently
measured using a dynamometer. Using these measured force components the forces
acting on the shear plane and along the face of the cutting tool can be calculated. The
effect of varying the cutting process parameters is determined by comparing these
calculated forces.
During this experiment it will be noticed that the chip thickness is considerably
larger than the depth of cut. This large chip thickness indicates a small shear angle is
present and relatively inefficient metal removal occurs. The metal removal is inefficient
because energy has been wasted deforming the discarded chip. The forces required to cut
the metal also increase as the shear angle decreases. This increase in force is due to the
large shear area that accompanies the small shear angle. A larger force is required to
shear more material.
Metal cutting becomes more efficient as the chip thickness decreases and the shear
angle increases. The metal removal is efficient because energy has not been wasted
deforming the discarded chip. The most efficient machining process takes place when the
chip thickness equals the depth of cut because no unnecessary deformation of the chip
occurs. The forces required to cut the metal also decrease as the chip thickness decreases
and the shear angle increases. This decrease in force is due to the small shear area that
accompanies the large shear angle. A smaller force is required to shear less material.
The shear angle will be calculated using the cutting ratio (rc)(rc = tc/t0) and the tool
rake angle () as shown in Figure 1. Both the cutting ratio and the tool rake angle are
measured from the image of the chip formation obtained in the experiment.
tan  
r sin 
1  r cos 
The power required for the orthogonal metal cutting operation is given by the following
equation:
HP 
FH v
33000
where:
v = the cutting speed in feet per minute (This is the feed rate setting on the
horizontal milling machine).
FH = the horizontal force in lbs. This is measured using the dynamometer.
33000 = the conversion from ft lb/min. to horsepower.
Notice from the equation above that the horsepower required to cut the metal
decreases as the horizontal cutting force decreases. Less power is used and metal cutting
is more efficient when the chip thickness is reduced because the horizontal cutting force
decreases.
The chip thickness is reduced by using a tool with a large rake angle. Unfortunately,
large rake angle tools are weaker and fail faster than small rake angle tools.
If a small rake angle tool is used the tool will last a longer time but more energy for
cutting the metal is required. If a large rake angle tool is used then less energy for cutting
the metal is required, but the tools will wear out quickly. This situation implies an
optimum rake angle exists. At this optimum rake angle the sum of the cutting power
costs and the tool replacement costs will be a minimum. Optimum rake angles and
corresponding optimum shear angles have been determined for various tool/work
combinations. This information is commonly available in manufacturing engineering
handbooks. If some new tool/work combination is used it is necessary to perform an
experiment to determine the optimum rake angle to use.
The friction force (F) of the chip sliding on the tool face and the normal force (N)
perpendicular to the tool face, as shown in Figure 1, may be calculated from the following
relationships.
F  FH sin    FV cos 
N  FH cos   FV sin  
where  = the tool rake angle.
The resulting coefficient of friction between the tool face and the chip is the tangent
of the friction angle, , as shown in Figure 1. The coefficient of friction, μ, is given by
the following equation.
  tan  
4.
PROCEDURE
F
N
1.
Understand milling machine safety and operating instructions.
2.
Clean workpieces and fixture to remove all chips.
3.
Ensure that the work is firmly clamped within the fixture.
4.
Clamp the +150 rake angle tool securely in the tool holder so the cutting
edge is orthogonal to the feed motion.
5.
Ensure the cutting tool straddles the workpieces with an equal overhang
on each side.
6.
Hand feed the milling table longitudinally across the workpieces to ensure
the tool clears all lighting equipment and fixture components.
7.
Set the milling machine feed to the first feed rate specified in the data
sheets.
8.
Return the tool to the starting position and establish a reference plane by
removing a light chip from the three workpieces.
9.
Clean workpieces and fixture to remove all chips.
10.
Open the Global Lab Image software package.
11.
Note the force readings from the voltage indicators and collect a sample
chip for each material. Measure the chip thickness of each chip with the
micrometer.
12.
Return tool to starting position and adjust milling machine for a depth of
cut of .004 inches. Begin cutting the workpieces.
13.
Use the Global Lab Image software to capture one picture of the cutting
process for each workpiece.
14.
Close the Labtech Run-Time Data Acquisition Module to stop acquiring
data.
15.
Repeat steps 12 through 16 for each of the remaining feed rates specified
in the data sheets.
16.
Using the Global Lab Image software to measure the depth of cut, the
chip thickness, and the shear angle for each of the stored images or
measure from the printed images. Record all data.
5.
EVALUATION
1.
Calculate the shear angle for each cutting condition using the measured cutting
ratio. Compare the calculated value with the shear angle you measured on the
stored image.
2.
Calculate the mean horizontal and vertical cutting forces for each workpiece and
feed. Calculate the standard deviation of the cutting forces for each workpiece
and feed.
3.
Calculate the friction force (F) and the normal force (N) at the tool-chip interface
for each cutting condition. Determine the friction angle () and the coefficient of
friction () for each cutting condition.
4.
Calculate the horsepower required for each of the cuts taken.
5.
Plot the following using a separate graph for each work material:
a. Shear angle () versus cutting speed,(table speed), v.
b. Coefficient of friction () versus cutting speed.
c. Required Horsepower versus cutting speed.
Draw some conclusions on the above graphs.
ORTHOGONAL METAL CUTTING DATA SHEET
Tool rake angle = _____.
Shear
Work
Table feed
Depth of
Material
(ipm)
cut (in)
Vertical
Horizontal
angle (φ)
deg
Aluminum
Brass
Copper
0.6
0.004
1.5
0.004
2.3
0.004
0.6
0.004
1.5
0.004
2.3
0.004
0.6
0.004
1.5
0.004
2.3
0.004
force, FV
force, FV (lb)
(lb)
TOOL WEAR AND TOOL LIFE
1.
MP4
OBJECTIVE
To study the effect of cutting velocity on the wear and life of a cutting tool used for
turning.
2.
EQUIPMENT
Engine lathe; cylindrical workpiece; toolmaker's microscope; carbide insert (cutting tool)
with geometry specifications of -5, -5, 5, 5, 15, 15, 3/64.
3.
DISCUSSION
Machineability describes the relative difficulty encountered in cutting various
metals. Hardness, shear strength, microstructure, rate of strain hardening, formation of a
built-up edge (BUE), and other properties of a material determine the limit on cutting
speed for a given tool-work combination. The relative machineability of an alloy may be
determined by comparing the tool life obtained when it is machined under certain
conditions with that obtained when machining SAE B1112 steel under the same
conditions. However, that type of machineability rating leaves much to be desired
because it is too general and fails to account for variations in physical properties,
microstructure, workhardenability, surface finish, cutting conditions, etc. The dominant
machining parameter affecting tool life for a given tool/work combination is the cutting
speed, v. It has been found experimentally that the relationship between tool life, T, and
cutting speed is of the general form vTn = C. This equation is known as the Taylor tool
life equation, after F.W. Taylor who first observed this relationship in the early 1900’s.
Since the Taylor Equation plots as a straight line on logarithmic coordinates,
considerable predictive information can be obtained by fitting a least squares trend line to
relatively few (5 or 6) experimental points. By using different feed rates, a family of
curves can be determined which can be used to predict the approximate cutting speed and
feed for the most economical rate of metal removal. However, the latter problem is
beyond the scope of this experiment. The criterion for tool life is a particularly important
aspect of the experimental procedure for using Taylor's empirical tool life equation.
Experience has shown that tool materials wear differently depending upon the chemical
nature and physical properties of the work material and the relative velocity and thus the
frictional heat generated at the tool-chip interface. In general, when the flank wear is
plotted as a function of minutes of tool life, the curve shows three portions: a rapid initial
rise, a reduced slope of approximately constant value, and finally, a rapid rise which
becomes nearly vertical as the point of failure is approached. At relatively high cutting
speeds, the central portion of the curve disappears and tool life is very short (1 min. or
less). At lower than normal speeds, tool life is much prolonged, but the rate of metal
removal is small (Figure 1). In some cases, particularly with the cast iron cutting grades
of carbides, a built-up edge (BUE) is produced at low cutting speeds. Therefore, tool life
curves for carbide tools should not be extrapolated below 200 fpm, because the BUE
formed when carbides are used at low speed causes a catastrophic failure in about 1
minute. Triple carbides, i.e., TiC, TaC and WC must be used to machine steel
successfully.
Tool failure usually occurs either because of excessive crater wear or from flank wear to
such an extent that cutting ceases and excessive tool-work contact generates so much
frictional heat that the tool softens and erodes to destruction. In production practice, this
occurs soon after 0.030" flank wear. Therefore, in the United States, a limit on flank
wear of 0.030 in. is usually standard. The ISO Standard for tool life testing for sintered
carbide tools specifies a maximum flank land width of 0.3 mm or 0.012 inches.
Carbide cutting inserts are very brittle, so considerable care must be taken to be
sure no chips are in the seat before locking the tool in place. Also, all traces of the built-
up edge must be removed from the first side of the insert before turning it over to use the
last four edges.
Figure1 Typical Tool Wear Curves
Figure 2 Wear in Cutting Tools
4.
PROCEDURE
1.
Observe each cutting edge under a microscope before using it to be sure
that there are no nicks or cracks which could cause premature failure. Be
sure that the carbide tool holder seat is clean; then, mount the tool and
clamp it securely in the seat of the tool holder. Set the machine properly
for the first cut. The following speeds, depth-of-cut, and feed will be used:
Cutting speed
Depth of cut (in.)
Feed (ipr)
(sfpm)
Material: 1045 Steel
2.
0.015
800, 700, 600
0.0024
STOP THE FEED; BACK OFF THE TOOL; and THEN, STOP THE
SPINDLE. Remove the tool and use the toolmaker's microscope to
measure the flank wear-land. Use 30 sec. cutting time increments for the
first minute and then every few minutes, as listed under 4, of cutting time
until a 0.012 in. wear land has developed. Note that more than three
points (at least 5 or 6 usually) are needed to determine the Taylor Equation
from the data. Record the wear-land values in Tables 1 to 3. Use care to
align the undamaged surface of the insert with the cross-hair in the
eyepiece before measuring the wear-land.
3.
Index the carbide insert 90 in the tool holder and gather a new set of data
for each of the other speeds.
4.
Take measurements of the tool wear at the following time intervals:
a) At 600 fpm take measurements at 1 minute and 2 minutes from the start
of cutting and then every 4 minutes after this until a wear land width of
0.012 inches is obtained.
b) At 700 fpm take measurements at 1 minute and 2 minutes from the start
of cutting and then every 4 minutes after this until a wear land width of
0.012 inches is obtained.
c) At 800 fpm take measurements at 1 minute and 2 minutes after the start
of cutting and then every 3 minutes after this until a wear land width of
0.012 inches is obtained.
5.
EVALUATION
1.
Develop a tool life curve for the supplied carbide tool insert by plotting the
measured flank wear-land for each cutting edge as a function of cutting
time (in minutes).
2.
The tool life is assumed to be when the flank wear land reaches width
0.01”. Determine the tool life in minutes for each cutting speed.
3.
Sketch the final flank wear and crater wear patterns developed on the tool
insert at each cutting speed.
4.
How do you think the use of a cutting fluid would affect the results
observed?
5.
What limits, if any, are there to the extrapolation of the tool life curve in
either direction?
6.
Plot tool life against cutting speed using log scales and from this determine
C and n for Taylor’s equation.
Table 1 Data Sheet for Tool Wear
Tool Material: Tungsten Carbide Work Material: 1045 Steel
Feed, f: 0.024 ipr
Cutting time (min), t
Volume removed = fdvt
Cutting speed, v: 600 fpm
Depth of Cut, d: 0.015 in
Volume removed (in3)
Flank land wear (in)
Table 2 Data Sheet for Tool Wear
Tool Material: Tungsten Carbide Work Material: 1045 Steel
Feed, f: 0.024 ipr
Cutting time (min), t
Volume removed = fdvt
Cutting speed, v: 700 fpm
Depth of Cut, d: 0.015 in
Volume removed (in3)
Flank land wear (in)
Table 3 Data Sheet for Tool Wear
Tool Material: Tungsten Carbide Work Material: 1045 Steel
Feed, f: 0.024 ipr
Cutting time (min), t
Volume removed = fdvt
Cutting speed, v: 800 fpm
Depth of Cut, d: 0.015 in
Volume removed (in3)
Flank land wear (in)