Sandvik Coromant Heat resistant super alloys - Manual (Page 74)

72
f
z
h
ex
iC
Effect of feed per tooth, f
z
As with other workpiece materials, feed and depth of cut are also important for tool life
when machining HRSA materials. The feed per tooth value is calculated from the recom-
mended maximum chip thickness (h
ex
) – this deviates from the feed per tooth depending
upon the following two factors:
0.1 0.15 0.2
0.25 60° 1.16 0.12 0.17 0.23
0.2 53° 1.25 0.13 0.19 0.25
0.15 46° 1.4 0.14 0.21 0.28
0.1 37° 1.66 0.17 0.25 0.33
0.05 26° 2.3 0.23 0.34 0.46
Depth of cut
diameter ratio,
a
e
/D
c
Entering angle, α Modification value, f
n
f
z
mm/tooth for given
chip thickness in mm:
Round inserts
Max chip thickness h
ex
= f
z
× sin k
r
h
ex
= f
z
×
√
4a
p
–
(
2a
p
)
2
iC iC
This is the width of the component engaged
in cut in relation to the diameter of the
cutter. It is the distance across the sur-
face being machined covered by the tool.
When the a
e
is below half the diameter the
maximum chip thickness is reduced rela-
tive to the f
z
– therefore the feed can be
increased.
Radial immersion, (a
e
/D
c
)
The entering angle (
k
r
) applied
h
ex
h
ex
h
ex
For inserts with an entering angle of 45º
and round inserts there is a chip thin-
ning effect – this allows greater feed than
inserts with
k
r
90º.