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I have an issue with some parts. T

I have an issue with some parts. T

I have an issue with some parts. T

(OP)
I have an issue with some parts.  The internal thread M14 x 1.5 has been produced with an oversized tap.  The pitch diameter results in a 13.71 mm (out by over .5 mm) diameter that tapers down to 13.05 mm.  The external thread pitch diameter is ok.  I checked a couple of parts, and the thread pullout strength for these parts is approximately 16000 lbs.  I checked good parts as well, and their pull out strength was 19000 lbs.  My question, is there a relationship between the pullout strength and the torque retention over time?  How will this part behave after cycle loading of 50,000 cycles? 1000000 cycles?  Thanks for any help.   

RE: I have an issue with some parts. T

It is unlikely that there is a useable correlation between pullout strength and torque retention.  As far as long-term durability, I think you have a problem due to the oversized internal threads.  A recent article [Engineering Failure Analysis 8 (2001) 49-56] showed problems with static properties of fasteners with non-conforming pitch dimensions, so the cyclic behavior would be even worse.  My advice is do not use these suspect parts.

Cory
cpadfield@omnimetalslab.com

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