Thermal cracks

?Likely causes

• Interrupted cutting repeatedly heats and cools the cutting edgeAgreed by 2+ makers^[1][2][3][4]
• Wet cutting, or unstable application of cutting fluidAgreed by 2+ makers^{[1][2][3][4][5][6]}
• CVD coating is thickOne maker^[1]
• A large-diameter face mill is being usedOne maker^[5]

✓Fixes

Cutting conditions

• Reduce the cutting speedAgreed by 2+ makers^[1][7][8]
• Reduce the feed and depth of cutAgreed by 2+ makers^[7][8]

Tool

• Use a grade with high thermal shock resistance and toughnessAgreed by 2+ makers^{[2][3][7][5][8]}
• Reduce heat generation with a sharp edge geometryAgreed by 2+ makers^[3][5][7]

Coolant

• Use dry cutting, air blow, or MQLAgreed by 2+ makers^{[4][6][3][7][8][1]}
• If wet, apply a large volume without interruptionAgreed by 2+ makers^{[1][2][3][5][7]}

Where sources differ: In end milling of stainless steel and heat-resistant alloys, if wet cutting is insufficient, increase the fluid volume and reduce the speed (Mitsubishi e-learning).

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