Q 28. In a single pass drilling operation, a through hole of 15 mm diameter is to be
drilled in a steel plate of 50 mm thickness. Drill spindle speed is 500 rpm, feed is
0.2 mm/rev and drill point angle is 
. Assuming 2 mm clearance at approach
and exit, the total drill time (in seconds) is
(A) 35.1
(B) 32.4
(C) 31.2
(D) 30.1
Answer: (A)
Explanation:
