IESK102-Tutorial 3 MEMO
18th /08/2022
Total:30 marks
Due date: 26th/08/2022
Important instructions: Only pdf documents will be accepted, include your
student number, module code, tutorial no. in your document
Question 1
Provide the answer of your choice in the following multiple-choice questions. [5]
1. Manufacturing processes that create geometry are classified as basic or secondary
processes; machining is classified as a:
[1]
(a) basic process
(b) secondary process
Answer
b
2. Which three of the following operations are classified as face milling rather than
peripheral milling:
[1]
(a) end milling
(b) plain milling
(c) pocket milling
(d) slab milling
(e) straddle milling
(f) surface contouring
Answer
a, c, f
3. In a planner, the tool component that moves relative to the column to achieve
feed motion and cut through the work part with forward stroke is called
[1]
(a) mandrel
(b) toolhead
(c) ram
(d) cross rail
(e) axle
Answer
c
4. Which three of the following are names given to the three regions in the typical
wear growth curve:
[1]
(a) abrasion region
(b) accelerated wear region
(c) break-in period
(d) diffusion region
(e) failure region
(f) temperature region
Answer
c, b, e
5. Which three of the following changes in cutting conditions should be taken to
reduce the possibility of a temperature failure of a single point cutting tool:
[1]
(a) decrease depth of cut
(b) decrease feed
(c) decrease cutting speed
(d) increase depth of cut
(e) increase feed
(f) increase cutting speed
Answer
a, c, e
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Additional questions for practice (do not count for marks)
6. Which one of the following drill types would be the most likely choice to drill a
hole with a 100 mm (4.0 in) diameter:
(a) gun drill
(b) spade drill
(c) straight-flute drill
(d) twist drill?
7. Which one of the following types of grinding wheel wear involves dulling of the
individual grains in the grinding wheel:
(a) attritious wear
(b) bond failure
(c) crater wear
(d) flank wear
(e) grain fracture
8. What grit size should be selected to achieve the best surface finish:
(a) small
(b) medium
(c) large
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Question 2
Indicate if the statement is true or false by ticking the right box, indicate with
either an X or √ the answer of your choice.
[5]
True False
Boring is performed on the inside diameter to create a new hole
√
Turning is performed on the outside diameter of an existing cylinder
√
The chip thickness ratio is always less than one
√
Wheel grade indicates the grinding wheel’s ability to retain abrasive grits
during cutting
Centreless grinding can only be used for grinding external cylindrical
surfaces
√
√
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Question 3
Provide answers to the following questions:
[12]
Identify two advantages and disadvantages associated with machining operations and
other material removal processes
1. Describe the difference between roughing and finishing cuts (mention two
differences) [4]
a. Roughing - removes large amounts of material from starting work part
i. Some material remains for finish cutting
ii. High feeds and depths, low speeds
b. Finishing - completes part geometry
i. Final dimensions, tolerances, and finish
ii. Low feeds and depths, high cutting speeds
2. What is an orthogonal cutting operation?
[1]
Simplified 2-D model of machining that describes the mechanics of machining
fairly accurately
3. What are the three basic forms of sawing operation?
(a) Power hacksaw, (b) band saw (vertical), (c) circular saw
[3]
4. What are some of the tool life criteria used in production machining operations,
mention 2?
[2]
• Complete failure of cutting edge
• Visual inspection of wear by the machine operator
• Fingernail test across cutting edge
•
•
•
•
•
•
Changes in sound emitted from operation
Chips become stringy and difficult to dispose
Degradation of surface finish
Increased power
Workpiece count
Cumulative cutting time
5. What are the two principal locations on a cutting tool where tool wear occurs? [2]
___________
______________________________
Additional questions for practice (do not count for marks)
6. Mention and describe two types of milling operations and (include description of
the tool and work part axis)use their axis
7. What are the four principal operations for machining gear teeth
8. What are the five basic parameters of a grinding wheel?
9. What is dressing, in reference to grinding wheels?
10. Mention three popular machining operations
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Question 4
Complete the following calculations:
1. Chip thickness before the cut = 0.012 mm. After the cut, the deformed chip
thickness = 0.028 mm, calculate the chip thickness ratio.
𝒕𝒐
𝒓 = =0.012/0.028
𝒕𝒄
[8]
[2]
2. If the cutting speed is 9.86m/s and the feed= 0.50 mm/rev, while the depth of the
cut is 4.0mm, determine the material removal rate. (Remember to be mindful of
SI units)
[3]
v=9.86m/s x 1000mm
f=0.50mm/rev x 1 rev
d=4mm
RMR = v f d
=19720 mm3/min
3. The workpiece rotates at a surface speed of 25 m/min, the wheel rotates at 1800
rev/min, infeed (depth of cut) = 0.05 mm, and traverse feed = 0.50 mm/rev,
determine the material removal rate.
[3]
3
3
RMR = vfd = (25 m/min)(10 )(0.50 mm)(0.05 mm) = 625 mm /min
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