Page 676 - Manufacturing Engineering and Technology - Kalpakjian, Serope : Schmid, Steven R.

Quantitative Problems 657

23.6. Describe the differences between boring a workpiece 23.10. Describe the relative advantages of (a) self-opening
on a lathe and boring it on a horizontal boring mill. and (b) solid-die heads for threading.
23.7. How is drill life determined? 23.1 I. Explain how external threads are cut on a lathe.
23.8. Why are reaming operations performed? 23.12. What is the difference between a blind hole and a
23.9. Explain the functions of the saddle on a lathe. through hole? What is the significance of that difference?

QUALITATIVE PROBLEMS

23.13. Explain the reasoning behind the various design 23.24. Explain the reasons for the major trend that has been
guidelines for turning. observed in producing threads by thread rolling as opposed
23.14. Note that both the terms “tool strength” and “tool- to thread cutting. What would be the differences, if any, in
material strength” have been used in the text. Do you think the types of threads produced and in their performance char-
there is a difference between them? Explain. acteristics?
23.15. List and explain the factors that contribute to poor 23.25. Describe your observations concerning the contents
surface finish in the processes described in this chapter. of Tables 23.2 and 23.4, and explain why those particular
recommendations are made.
23.16. Explain why the sequence of drilling, boring, and
reaming produces a hole that is more accurate than drilling 23.26. The footnote to Table 23.11 states that as the hole
and reaming it only. diameter increases, speeds and feeds in drilling should be
reduced. Explain why.
23.17. Why would machining operations be necessary even
on net-shape or near-net-shape parts made by precision cast- 23.27. In modern manufacturing, which types of metal
chips would be undesirable and Why?
ing, forming, or powder-metallurgy products, as described in
preceding chapters? Explain. 23.28. The operational severity for teaming is much lower
23.18. A highly oxidized and uneven round bar is being than that for tapping, even though they both are internal ma-
turned on a lathe. Would you recommend a small or a large chining processes. Why?
depth of cut? Explain. 23.29. Review Fig. 23.6, and comment on the factors in-
23.19. Describe the difficulties that may be encountered in volved in determining the height of the zones (cutting speed)
clamping a workpiece made of a soft metal in a three-jaw for various tool materials.
chuck. 23.30. Explain how gun drills remain centered during drilling.
23.20. Does the force or torque in drilling change as the Why is there a hollow, longitudinal channel in a gun drill?
hole depth increases? Explain. 23.31. Comment on the magnitude of the wedge angle on
23.21. Explain the similarities and differences in the design the tool shown in Fig. 23.4.
guidelines for turning and for boring. 23.32. If inserts are used in a drill bit (see Fig. 23.21), how
23.22. Describe the advantages and applications of having a important is the shank material? If so, what properties are
hollow spindle in the headstock of a lathe? important? Explain.
23.23. Assume that you are asked to perform a boring oper- 23.33. Refer to Fig. 23.10b, and in addition to the tools
shown, describe other types of cutting tools that can be
ation on a large-diameter hollow workpiece. Would you use a
horizontal or a vertical boring mill? Explain. placed in toolholders to perform other machining operations.

QUANTITATIVE PROBLEMS

|l23.34. Calculate the same quantities as in Example 23.1 mechanical efficiency of 80%. The spindle speed is 500 rpm.
for high-strength titanium alloy and at N = 700 rpm. Estimate the maximum feed that can be used before the lathe
|]23.35. Estimate the machining time required to rough begins to stall?
turn a 0.50-m-long annealed copper-alloy round bar from a |]23.37. A 7.5-mm-diameter drill is used on a drill press
60~mm diameter to a 58-mm diameter, using a high-speed operating at 300 rpm. If the feed is 0.125 mm/rev, what is the
steel tool. (See Table 23.4.) Estimate the time required for an MRR? What is the MRR if the drill diameter is doubled?
uncoated carbide tool. |]23.38. In Example 23.4, assume that the workpiece mate-
u23.36. A high-strength cast-iron bar 200 mm in diameter rial is high-strength aluminum alloy and the spindle is run-
is being turned on a lathe at a depth of cut d = 1.25 mm. The ning at N = 500 rpm. Estimate the torque required for this
lathe is equipped with a 12-kW electric motor and has a operation.