Tap Failure
Tap Cuts Oversize
1. Tap out of alignment with the hole or tap not running true.
2. Feed pressure on tap producing thin or deformed threads.
3. Drilled core hole too small, see thread charts.
4. Incorrect tap for the material e.g. :
(a) Cutting rake too great,
(b) Incorrect thread relief,
(c) Chamfer lead too short.
5. Incorrect sharpening e.g. chamfer relief uneven or to excessive.
Tap Cutting Edges Chip
6. Tap hitting the bottom of a blind hole.
7. Tap reversing with swarf trapped.
8. Lubrication lacking or wrong quality or specification.
9. Material too hard, or abrasive for the tap type.
Rapid Tap Wear
10. Speed too fast also consider items 3, 4, and 8.
Poor Thread Finish
11. Tap has reached the extent of its life. Consider type of tap used, or items 3, 4, and 8.
Tap Breaks
12. Tap blocked with swarf, is it the correct type of tap? look at items 1, 3, 4c, 5, 6, 7, 8, 9, 10, and 11