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TOOL WEAR AND DAMAGE

CAUSES AND COUNTERMEASURES

Tool Damage Form		Causes	Countermeasure
Flank wear		- Tool grade is too soft. - Cutting speed is too high. - Flank angle is too small. - Feed rate is extremely low.	- Tool grade with high wear resistance. - Lower cutting speed. - Increase flank angle. - Increase feed rate.
Crater wear		- Tool grade is too soft. - Cutting speed is too high. - Feed rate is too high.	- Tool grade with high wear resistance. - Lower cutting speed. - Lower feed rate.
Chipping		- Tool grade is too hard. - Feed rate is too high. - Lack of cutting edge strength. - Lack of shank or holder rigidity.	- Tool grade with high toughness. - Lower feed rate. - Increase honing. (Round honing is to be changed to chamfer honing.) - Use large shank size.
Fracturing		- Tool grade is too hard. - Feed rate is too high. - Lack of cutting edge strength. - Lack of shank or holder rigidity.	- Tool grade with high toughness. - Lower feed rate. - Increase honing. (Round honing is to be changed to chamfer honing.) - Use large shank size.
Plastic Deformation		- Tool grade is too soft. - Cutting speed is too high. - Depth of cut and feed rate are too large. - Cutting temperature is high.	- Tool grade with high wear resistance. - Lower cutting speed. - Decrease depth of cut and feed rate. - Tool grade with high thermal conductivity.
Welding		- Cutting speed is low. - Poor sharpness. - Unsuitable grade.	- Increase cutting speed. (For DIN Ck45, cutting speed 80m/min.) - Increase rake angle. - Tool grade with low affinity. (Coated grade, cermet grade)
Thermal Cracks		- Expansion or shrinkage due to cutting heat. - Tool grade is too hard. * Especially in milling.	-Dry cutting. (For wet cutting, flood workpiece with cutting fluid) - Tool grade with high toughness.
Notching		- Hard surfaces such as uncut surface,chilled parts and machining hardened layer. - Friction caused by jagged shape chips. (Caused by small vibration)	- Tool grade with high wear resistance. - Increase rake angle to improve sharpness.
Flaking		- Cutting edge welding and adhesion. - Poor chip disposal.	- Increase rake angle to improve sharpness. - Enlarge chip pocket.
Flank Wear Fracture *Damage for polycrystallines		- Damage due to the lack of strength of a curved cutting edge.	- Increase honing. - Tool grade with high toughness.
Crater Wear Fracture *Damage for polycrystallines		- Tool grade is too soft. - Cutting resistance is too high and causes high cutting heat.	- Decrease honing. - Tool grade with high wear resistance.