Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

5.6 TOOL WEAR

 

· Tool wear is still a significant problem in cutting.

 

· Typical types of tool wear include,

  1. - Flank wear
  2. - Crater wear

 

· Flank wear - the point of the tool degrades

 

 

 

· Crater wear also decreases tool life

 

 

· Tool failure can typically grouped under one of the following categories,

  1. - Complete Failure - the tool is unusable
  2. - Flank Failure - this can be estimated with maximum lw values,
    1. · Roughing Cuts
      1. 0.03" for carbide tools
      2. 0.06" for high speed steel
    2. · Finishing Cuts
      1. 0.010" for carbides
      2. 0.015" for high speed steel
  3. - Work surface finish is inadequate
  4. - Work dimension outside tolerance

 

· Flank wear can be discussed as a function of time,

 

 

· General notes of concern are,

  1. - The main factor in tool wear is temperature
  2. - The main factor in tool life is cutting speed
  3. - Critical temperatures for High Speed Steels are 1150°F and for carbides it is 1600°F
  4. - A higher velocity will increase temperature more than an increase in feed for the same mrr
  5. - A higher feed will increase the tool forces