Thermal shock, caused by sudden heating and cooling, is the cracking and checking of a tool that leads to breakage (Figure F-32). This condition is most likely to occur when an inadequate amount of coolant is used. It is better to machine dry if the work and tool cannot be kept flooded with coolant. If edge wear occurs:
1. Decrease the machining speed.
2. Increase the feed.
3. change to a harder , more wear-resistant carbide grage.
If the cutting edge is chipped or broken:
1. Increase the speed.
2. Decrease the feed and/or depth of cut.
3. Change to a tougher grade carbide insert.
4. Use a negative rake.
5. Hone the cutting edge before use.
6. Check the rigidity and tool overhang.