-----

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

---

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
(Ted is available for instant or longterm help)

January 2, 2008

Maybe too simplistic but, have you considered helicoils?

Guillermo Marrufo
Monterrey, NL, Mexico
January 5, 2008

---