Question

A 0-20 mm through hole is to be drilled in a 30
mm thick plate using a double fluted, 120° lip
angle drill. The drill tip is at a distance of 3 mm
from the plate surface when cutting is started
and an over travel of 2 mm is recommended as
a margin to ensure drilling through the full
thickness of the plate. If the drill rotates at 500
rev/min and the feed per tooth is 0.01 mm, the
machining time of the operation (in min) will be
(a) 4.5
(c) 9
(b) 7.5
(d) 10.5
​

Answer 1

Explanation:

9 maybe

please mark me as brainlisttt

Answer 2

Given:

A 0-20 mm through-hole is to be drilled in a 30  mm thick plate using a double fluted, 120° lip  angle drill. The drill tip is at a distance of 3 mm  from the plate surface when cutting is started  and an over travel of 2 mm is recommended as  a margin to ensure drilling through the full  the thickness of the plate. If the drill rotates at 500 rev/min and the feed per tooth is 0.01 mm

To Find:

The  machining time of the operation (in min) will be

(a) 4.5

(c) 9

(b) 7.5

(d) 10.5

​Solution:

Machine time is 4.5 min.

Please have a look at the attached image