Inhouse processes haven't changed. We have to import blanks from two outside sources. I Will check on their end. We were using GH-4.5, I'm sending in H-6's to see if that helps.

The holder isn't rigid it will spring open when too much torque is applied. As far as too much difference he stated that it looked electroplated coating on top of the usual black oxide process. You're right, there might be something there. Coolant was one of the first things they looked at (forgot to mention). They use a water-based coolant run through all tappers (central system) and stated that if it works on other tappers with no issues, it couldn't be the problem. I will suggest a change of coolant or a flush. Thanks for the input.

New to the forum, have been scratching my head for weeks. Been using M22 taps with Black Nitride for years with few issues. We get in a new lot of taps in and the tool life is cut in half. Initially thought the taps were smaller than marked but had them checked and no changes. We found out the coating company changed a process but had it checked by a metallurgist and didn't see too much of a difference. Have tried different coatings, TIN, TICN, with better results but not enough for the cost. We get three different parts to be tapped that are all hardened steel and thought maybe there was a difference there but tested all parts and were all in range. The machine is a San Shing...Any Ideas would be welcome.