Sandvik Coromant Heat resistant super alloys - Manual (Page 92)

90
Tool holding
One of the main criteria when deciding both
the tool and holding device is to have as
small a run out as possible. This keeps
a uniform chip thickness on each cutting
edge and hence has an even load distribu-
tion. The total indicator run out (TIR) should
not be more than 10 microns.
A good rule of thumb is that ‘For every
10 microns in added run out the tool life
reduces by 50%’!
A CoroGrip ® power chuck or shrink fit
should be used due to:
Minimised run out
- increased tool life.
Stability
- reduced vibrations allowing higher
depths of cut.
Clamping forces
- resists pull out with high helix cutters.
Programming feed rate (peripheral and central feed of the tool)
When programming with the feed applied to the tool centre, the feed must be reduced
when producing an internal radius or a circular motion (G2 or G3) if not using radius
compensation. Due to the fact that the periphery has to travel further than the tool centre
for the same angular rotation.
Tool life
TIR
Constant tool centre feed Reduced feed for radius
v
fm
= n x f
z
x z
n
D
vf
= D
m
– D
c
D
vf
D
m
v
f
= x v
fm