21. It is required to cut screw threads of 2 mm pitch on a lathe. The lead screw has a pitch of 6 mm. If the spindle speed is 60 r.p.m., then the speed of lead screw will be
A. 10 r.p.m.
B. 20 r.p.m.
C. 120 r.p.m.
D. 180 r.p.m.
22. The tool life in case of a grinding wheel is the time
A. between two successive regrinds of the wheel
B. taken for the wheel to be balanced
C. taken between two successive wheel dressings
D. taken for a wear of 1 mm on its diameter
23. In which of the following machine, the work is usually rotated while the drill is fed into work?
A. Sensitive drilling machine
B. Radial drilling machine
C. Gang drilling machine
D. Deep hole drilling machine
24. In twist fluted drills, chips do not move out automatically.
A. Correct
B. Incorrect
25. Mild steel during machining produces __________ chips.
A. continuous B. discontinuous
26. Crater wear is mainly due to the phenomenon known as
A. adhesion of metals
B. oxidation of metals
C. diffusion of metals
D. all of these
27. The cutting speed for drilling aluminium, brass and bronze with high speed steel drills varies from
A. 10 to 20 m/min
B. 18 to 30 m/min
C. 24 to 45 m/min
D. 60 to 90 m/min
28. Flank wear depends upon the
A. hardness of the work and tool material at the operating temperature
B. amount and distribution of hard constituents in the work material
C. degree of strain hardening in the chip
D. all of these
29. The tool may fail due to
A. cracking at the cutting edge due to thermal stresses
B. chipping of the cutting edge
C. plastic deformation of the cutting edge
D. all of these
30. The operation of machining several surfaces of a workpiece simultaneously is called
A. profile milling
B. gang milling
C. saw milling
D. helical milling
31. The grinding wheel speed (surface speed in m/min) usually varies from
A. 500 to 1000
B. 1000 to 1500
C. 1500 to 2000
D. 2000 to 2500
32. The factor considered for evaluation of machinability is
A. cutting forces and power consumption
B. tool life
C. type of chips and shear angle
D. all of these
33. In oblique cutting system, the tool may or may not generate a surface parallel to the workface.
A. Yes
B. No
34. The plunge grinding requires very __________ speed.
A. high
B. low
35. In conventional milling, the cutting force tends to lift the work.
A. True
B. False
36. In machining metal, cutting force at the cutting edge is measured by a
A. wattmeter
B. dynamometer
C. hydrometer
D. pyrometer
37. With the same tool life, the maximum material per minute is removed by
A. increasing the cutting speed
B. decreasing the cutting speed
C. increasing the depth of cut
D. increasing the feed rate
38. The process of removing metal by a cutter which is rotated against the direction of travel of workpiece, is called
A. up milling
B. down milling
C. face milling
D. end milling
39. A feed gear box for a screw cutting lathe is designed on the basis of
A. geometric progression
B. arithmetic progression
C. harmonic progression
D. none of these
40. In American Standard Association (A S A) system, if the tool nomenclature is 8-6-5-5-10-15-2 mm, then the side rake angle will be
A. 5°
B. 6°
C. 8°
D. 10°