5.6 TOOL WEAR

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Tool wear is still a significant problem in cutting.

Typical types of tool wear include,

- Flank wear

- 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,

- Complete Failure - the tool is unusable

- Flank Failure - this can be estimated with maximum lw values,

Roughing Cuts

0.03" for carbide tools

0.06" for high speed steel

Finishing Cuts

0.010" for carbides

0.015" for high speed steel

- Work surface finish is inadequate

- Work dimension outside tolerance

Flank wear can be discussed as a function of time,

General notes of concern are,

- The main factor in tool wear is temperature

- The main factor in tool life is cutting speed

- Critical temperatures for High Speed Steels are 1150°F and for carbides it is 1600°F

- A higher velocity will increase temperature more than an increase in feed for the same mrr

- A higher feed will increase the tool forces