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19 Reasons Why Taps Break and Fail

There is a plethora of reasons why Taps fail in the workplace. Here are a few common reasons why, from our friends at ‘The Tap and Die Company:’


 1.  Tap out of alignment with the hole or tap not running true

 2.  Feed pressure incorrect producing thin or deformed threads

 3.  Core hole too small

 4.  Incorrect tap for the material.

     a) Cutting rake too great b) Incorrect thread relief c) Chamfer lead too short

 5.  Incorrect sharpening eg. chamfer relief uneven or excessive

 6.  Tap hitting bottom of a blind hole

 7.  Tap reversed carelessly

 8.   Lubrication lacking or of wrong quality

 9.   Material too hard or abrasive of the type of tap

 10. Speed too fast leads to a poor thread finish

 11. Tap requires resharpening

 12. Tap flutes blocked with swarf

 13. Blind hole: Below 4mm if tapping depth is more than 3/4” thread length, tap may break by chip clogging or  tap may break by hitting bottom

 14. Deep hole tapping: If tapping depth is more than thread length, tap may break by chip clogging

  15. In a punched hole the diameter of the hole reduces from top to bottom  hence material tend to grip the tap resulting in breakage of the tap

 16. The tap may break while reversing if jerk is given while reversing

 17. It is recommended to use proper coolant while tapping, as use of coolant reduces friction during tapping & reduces heat generation during tapping which subsequently reduces the property of welding build-up edge formation

 18. Improper drill size – only ‘recommended tapping drills’ (shown on lefthand side) should be used

 19. Tap may break during tapping, if cutting load is going beyond torsional strength of the tap ie. due to excessive torque

Make sure you are careful and take time with your job to ensure you do not break equipment or compromise your safety. We get phone calls all the time from customers who break their taps! Do it once, do it well!

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