Spring 2020 EML4321 Manufacturing Engineering HW-8
(Due on April 22, 2020)
Q1. An orthogonal cutting operation is performed on an aluminum workpiece. The depth of cut
t0=0.1 mm, width of cut w=2.5 mm, rake angle α=10°, and cutting speed V=2 m/s. Estimate
the cutting temperatures using the properties shown in Table 1.
Table 1
Flow stress
126 MPa
Thermal diffusivity
97 mm2/s
Volumetric specific heat 2.6 N/mm2·°C
Q2. List four basic characteristics required for cutting tool materials.
Q3. True or False? Negative rake angles are generally not preferred for ceramic, diamond, and
cubic boron nitride tools.
Q4. Explain the consequences of using a cutting tool coating that has a different coefficient of
thermal expansion than the substrate.
Q5. Which material is more suitable for machining steels: diamond or cubic boron nitride?
Explain why.
Q6. Describe the consequences of exceeding the allowable wear land (see Table 8.5) for cutting
tools.
Q7. What are the functions of a cutting fluid?
Q8. Tool temperatures start low at low cutting speeds and are higher at higher cutting speeds, but
they decrease when the cutting speed is increased beyond a threshold value. Explain why.
Q9. Can high-speed machining be performed without the use of cutting fluids? Explain.
Q10. Explain the effect of cobalt content on the properties of carbides.
Q11. Which of the following operating parameters has the greatest effect and which has the
smallest effect on tool life in practice?
(a) depth of cut (b) cutting speed (c) feed rate
Q12. A 75 mm-diameter stainless steel cylindrical part is turned on a lathe at 450 rpm in one
pass. The depth of cut is 2 mm and the feed is 0.5 mm/rev. What should the minimum power
[W] of the lathe be?
Q13. A 200-mm-long, 75-mm-diameter titanium-alloy rod is reduced to a diameter of 73 mm by
turning on a lathe in one pass. The spindle rotates at 380 rpm, and the tool travels at an axial
velocity of 200 mm/min. Calculate the cutting speed [m/min] at the outer surface and at the
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Spring 2020 EML4321 Manufacturing Engineering HW-8
(Due on April 22, 2020)
machined surface, material removal rate [mm3/min], time of cut [min], power required [W],
cutting force [N], and work [N·m] for this operation. Use the average value of the specific
energy required for machining titanium alloys given in Table 8.3 in the textbook.
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