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STRESSES ON CUTTING EDGES WHEN MILLING

When milling each individual tooth is only in contact with the workpiece for a maximum of 180° per revolution. Consequently certain conditions affect the cutting edges.   For problem solving chart

A

 SUDDEN VARIATIONS
The sudden variation in cutting forces could lead to small gashes on the cutting edges.
  

B

 THERMAL EFFECT
Temperatures of up to 1000° can develop when the cutting edge enters the workpiece. The termal effects alter as the cut progresses, this combined with the effect of the insert being exposed to the air or coolant (in the non-cutting position) could lead to cracks appearing along the cutting edge.
  

C

 BREAKOUTS
Breakout or chipping develops through overworking the insert.   REMEDY:
* check edge condition
*check facets and/or radius
*use a tougher grade
  

D

 WEAR DOWN THE CLEARANCE FACE
Normal condition when milling for a period of time. REMEDY:
*increase feed
*use a more wear resistant grade
*lower cutting speed
  

E

 PLASTIC DEFORMATION
High cutting temperatures can lead to this condition.  REMEDY:
*reduce cutting speed
*use a grade which is more resistant to this condition
  

F

 SPLITERING
Change in temperatures and intermittent cutting conditions can lead to splitering of the cutting edge.  REMEDY:
*alter cutting data, reduce load
*use tougher grade carbide
*adjust entry and exit conditions
  

G

 CRATERING
Cratering in general is not a reason for short tool life.  REMEDY:
*reduce cutting speed
*use a more wear resistant grade
  

H

 BUILT UP EDGES
This condition occurs when the cutting speed is too low.  REMEDY:
*alter cutting data (increase)
*alter geometry, positive cutting angle