Sandvik Coromant Silent tools - How to reduce vibration in metal cutting - Manual (Page 16)

Sandvik Coromant – How to reduce vibration in metal cutting 12
Threading
Choosing the correct tool for the application
Choice of tooling family:
T-MAX U-Lock for threading hole diameters from 12 mm
CoroCut MB for threading hole diameters from 10 mm
CoroCut XS for threading hole diameters from 4 mm
Chip evacuation:
Chip evacuation is also very important when internal threading, parti-
cularly the feed direction which should be from inside out giving better
chip control. This, combined with a modified flank infeed, will produce
spiral chips which are then led out towards the mouth of the hole. Over-
hang, blind holes and material type are also of great importance when
internal threading and should be given due consideration.
The infeed per pass should not be more than 0.2 mm and never less than
0.06 mm. Never run a final pass without infeed, and it is important to have
a firm force on the bar to minimize vibrations.
Overhang:
Compared with turning, threading is limited to a certain overhang due
to the increased side (radial) forces. For overhangs beyond 2.5 x D it is
recommended to use Silent Tools holders or carbide reinforced shanks to
minimize vibration and thus increase productivity.
2 - 2.5 x D solid steel boring bars
3 - 5 x D Silent Tools boring bars