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Aluminum-on-SS thread galling

We need to build a sensor that must be made from stainless steel, most likely 304L and it is to be threaded into a female aluminum thread by our customer. Because we can't control their thread condition we need to apply a coating to our stainless steel part to prevent galling failure of the aluminum. Our pressure port has a straight 12mm thread and uses a copper seal ring. The requirement is for 6 assembly sequences at 20 N-M torque without failure. Without a coating about half the parts tried fail the test by severely galling and failing the aluminum threads. Our SS threads will be machine-cut (not rolled). What would be a good coating to apply in our factory prior to shipping?

Gary Casey
Product designer - Moorpark, California, USA
January 2, 2008

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I know that silver plating of stainless steel fasteners for insertion in aluminum is a common approach in the electronics fabrication business, but I don't know offhand how many cycles they are good for.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 2, 2008

Maybe too simplistic but, have you considered helicoils?

Guillermo Marrufo
Monterrey, NL, Mexico
January 5, 2008