In a single pass drilling operation, a through hole of 15

Home » Materials Science and Manufacturing Engineering » Materials Science and Manufacturing Engineering Miscellaneous » Question

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 118°, Assuming 2 mm clearance at approach and exit, the total drill time (in seconds) is

1. 35.1
2. 32.4
3. 31.2
4. 30,1

Correct Option: A

T_c =	(L_h + A + O + H)
	Nf

Here, L_h = 50 mm; A = O = 2 mm;

C =	D	cot		β		= 7.5 × cot(59) = 4.5 mm
	2			2

N = 500 rpm; f = 0.2 mm/rev
T_c = 0.585 min or 35.1 seconds