Tap wears quickly or welds

?Likely causes

• Work hardening of the tap drill holeAgreed by 2+ makers^[1][2][3][4]
• Cutting speed is highAgreed by 2+ makers^[1][2][3]
• Insufficient lubrication or degraded cutting fluidAgreed by 2+ makers^[1][2][3]
• Tap drill hole is smallAgreed by 2+ makers^[1][2]
• Surface treatment or tool material does not suit the applicationAgreed by 2+ makers^[1][2][3]

✓Fixes

Cutting conditions

• Reduce the cutting speedAgreed by 2+ makers^[1][2][3]

Tool

• Use a wear-resistant surface treatment or powder HSS (CPM, etc.)Agreed by 2+ makers^[1][2][3]
• Avoid grinding burn when regrindingOne maker^[2][3]

Setup

• Prevent work hardening of the tap drill hole and make it largerAgreed by 2+ makers^[1][2][3]

Coolant

• Review the type and supply method of the cutting fluid (replacement timing, filtration, preventing contamination by other oils)Agreed by 2+ makers^[1][2][3]

▦Notes by material

• Stainless steel: The main cause of short tool life is work hardening of the tap drill hole. If there is a hardened layer of 0.1-0.2 mm, a normal stainless steel tap cannot machine it^[4][5]
• Cast iron (FC250, etc.): Chips are fine, so evacuation with a spiral tap is unstable. If durability is needed, use a powder HSS or carbide tap^[6][7]

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