21. The abrasive recommended for grinding materials of high tensile strength is

A. silicon carbide
B. aluminum oxide
C. sandstone
D. diamond

22. The factor responsible for the formation of continuous chips with built up edge is

A. low cutting speed and large rake angle
B. low cutting speed and small rake angle
C. high cutting speed and large rake angle
D. high cutting speed and small rake angle

23. An important geometrical quantity in the cutting of metals which can be used as a criterion for machinability of metals is

A. cutting speed
B. feed rate
C. shear angle
D. tool geometry

24. In centreless grinding, the surface speed of regulating wheel is

A. 5 to 15 m/min
B. 15 to 60 m/min
C. 60 to 90 m/min
D. 90 to 120 m/min

25. In metal cutting, use of low feeds and high cutting speeds is desired when the objective is

A. high metal removal rate
B. dry machining
C. use of soft cutting tool
D. surface finish

26. The angle on which the strength of the tool depends is

A. rake angle
B. cutting angle
C. clearance angle
D. lip angle

27. Larger than 15° side cutting edge angle

A. increases tool life
B. decreases tool life
C. produces chipping and decreases tool life
D. results in excessive stress concentration and greater heat generation

28. Which of the following statement is correct for orthogonal cutting system?

A. The cutting edge of the tool is perpendicular to the direction of tool travel.
B. The cutting edge clears the width of the workpiece on either ends.
C. The chip flows over the tool face and the direction of the chip flow velocity is normal to the cutting edge.
D. all of the above

29. The angle made by the face of the tool and the plane parallel to the base of cutting tool is called

A. rake angle
B. cutting angle
C. clearance angle
D. lip angle

30. In case of turning, as the machining proceeds, the spindle speed must __________ with the decrease in diameter of work.

A. decrease
B. increase