
118 Fundamentals of Machining Processes
5.2.4 Cutting Forces, Power, and Removal Rate
The main (tangential) cutting force F
v
(Newton) in the direction of the cutting
speed V can be calculated from
c
where k
s
is the specic cutting energy in N/mm
2
. Therefore, the cutting
power N
c
in kW becomes
N
c
v
=
3
The motor power N
m
required is given in kW by
N
m
v
=
×
3
η
where η
m
is the mechanical efciency of the machine tool used in the cut-
ting operation. The rate of material removal (VRR) in mm
3
/min is also
given by
=
or
av
where d
av
is given in mm by
d
av
f
=
In turning, three components of force are shown in Figure 5.6