
189Cutting Flat Surfaces
Solution
Given d = 30 mm, Z
c
= 8, t = 4 mm, S
z
= 0.1 mm/tooth, f = 120 mm/min,
k
s
= 1000 N/mm
2
, and l = 300, the machining time in face milling is calculated
as follows: For slot milling,
y =−=() ()15 15 0
22
mm
The total length of the workpiece travel
L
l
m
mm=+ += +×+ −=
2
23300 11 321∆
t
L
f
m
m
min===
321
120
268.
The milling cutter rotational speed N
N
==
×
=
rpm
150
F
mt
s
=
F
mt
N=
=
1019
V
==
=
14 13
.m/min
The mean cutting power, N
c
,
N
c
mt
kW=
×
=
=
024
3
.
The motor power, N
m
, becomes
N
m
c
kW== =
η
027
.
6.3.3