Ball and socket joint - socket material 1

[AMMoyer]

I am working on a ball and socket joint.

The ball stud is made from SAE 4135-4140 steel with the ball end being induction hardened to 55-60 Rc with a nearly polished surface finish. There are no surface finish spec's on this currently.

I am looking for some guidance with material selection for the female socket side of the joint. My major concerns are wear resistance and impact strength. I would like to use a sintered powder metal with enough porosity to aid in lubrication. The joint will be greaseable. From what I've learned about metal to metal wear, the microhardness and the macrohardness should be similar in the materials to maximize the wear. Would a stainless or C/Cu powder metal be appropriate for this application if the hardness was near 55 Rc? I ask about the C/Cu since the softer copper would wear into any of the surface abnormalities and minimize any problems associated with using similar materials. Is there any validity to my theory here?

Would any PVD coatings such as Chromium Nitrate be of any benefit in this situation or would that be overkill?

Any suggestions are welcome. Thanks.

 

[CoryPad]

It is possible that your proposal could work.

Current high-volume parts use either metallic or polymeric ball seats. For metallic ones, simple low carbon steels that have been carbonitrided or carburized are used. For polymeric ones, acetal is used.

 

[TVP]

AMMoyer,

Can you give a little more detail on the female socket side of the joint? Will this be a one-piece/monolithic part, or is the socket subsequently joined to a larger part? Also, is the socket side of the ball stud straight or conical? Have you calculated the contact stress? Will this socket have internal threads, or will a nut be used to tighten the joint? No matter what the answers are to the above, a PVD coating is overkill. Personally I would not use a PM part, especially if the socket is going to be internal threaded, but it may be a acceptable design choice.

 

[AMMoyer]

Thank you for the feedback. I will look at not using a PM socket and going with the acetal or treated mild steel.