Can nylon gall aluminum

[cobra46]

I am working an a design that involves a linear sliding interface. One of the surfaces is 6061-T6 and the other is MDS filled nylon.

I chose MDS filled nylon because I heard it was good for bearing surfaces. It turns out that the aluminum surface, which initially was smooth (~32), now looks like what can best be described as a galled surface.

Is it possible for nylon to gall aluminum? What materials would be better than MDS filled nylon? I can not use any lubrication nor can I use Teflon.

Thanks,

Kevin

 

[cobra46]

Wow...thanks for all of the feedback.

Some quick replies.

Teflon is ruled out because it is considered a contaminate in one of the environments we will operate.

That IGUS tool is awesome.

It is quite possible our loading PV is too high. I will follow up with that.

We must use aluminum because of weight. Hard anodizing while not optimal for us is not out of the question.

I'm not sure if the material I used contains graphite. The only description given was 'MDS filled cast nylon 6'.

MinyJulep - You mentioned corrosion caused by the combination of materials. Would this be a factor in just a couple of hours?

 

[MintJulep]

I don't know.

You've got all the parts - do a test.

 

[HDS]

one of the drawbacks of Mcmaster is that you don't know what you are getting. Try to get an MSDS for the material from them. That would list some of the ingredients. For production go to a regular supplier that will give you the details of what you are buying and you can complain if they switch grades or brands.

 

[FACS]

UHMW should be your first choice as a liner way bearing material on Anodized aluminum.

MDS filled Nylon would never even be on my list, neither would 6061 in a T6 only condition.

Use UHMW and anodize....

Charlie

http://www.facsco.com

 

[tbuelna]

cobra46,

"Teflon is ruled out because it is considered a contaminate in one of the environments we will operate."

Wow! That's a weird operating environment. One of the most desirable properties of PTFE is that it is the single most chemically inert and stable substance known to mankind.

As for filled nylon galling aluminum, that's what you would expect if debris is present in the contact area. The bits of debris embed themselves into the softer nylon surface and then abrade away the relatively harder aluminum mating surface. The aluminum surface exhibits the wear patterns since that is the joint component that is sliding relative to the debris particles. The nylon does not exhibit wear patterns since the debris particles are easily embedded into its soft surface.

You need to find the source of the debris. Nylon is corrosion resistant and chemically stable, so I doubt it's the source. Aluminum on the other hand, oxidizes very readily, and aluminum oxide is a very hard and abrasive compound.

Good luck.
Terry

 

[mighoser]

If you want to get fancy, coat the aluminum with diamond like carbon. We've done this before.

http://www.entegris.com

If it is just a corrosion issue coat the aluminum with Whitford's Xylan 1010 (Don't bake over 325F). Of course, Xylan is a fluoropolymer based coating which you can not tolerate. If you want to look at other polymers I would suggest a PPS. Try Techtron HPV. I've had good luck with it in high PV loading applications.