
128 Fundamentals of Machining Processes
The specic cutting energy is
k
s
Cutting force, F
v
, is
v
The machining time, for l ≥ 200 mm, l
a
= l
o
= 0
t
f
m
ao
=
=
×
=
05 500
10
.
.min
Specic power consumption = 2.5/785 × 60 = 5.3 × 10
−5
kWh/mm
3
The surface roughness R
t
R
S
t
m==
××
×
=
2
05 05 1000
25
..
µ
5.3 Drilling
Drilling is a method of machining by cutting used for making holes by
means of twist drills. The process involves two basic motions: the primary
rotary motion and the auxiliary linear feed motion. In the horizontal drill-
ing operation, the workpiece performs the rotary motion, while the tool
undergoes the linear ...