brass bushing issue 2

[subsearobot]

Hi all,
I have a sliding interface with low very PV and I am looking at options for materials. It is a handheld application, so friction must me minimized. We started with ultem for concerns other than friction, but it turns out that ultem is a *terrible* sliding component. It has very high friction, and because of that, it suffers from adhesive wear.
We like the performance of brass for some of the requirements for this part, but strangely, sliding friction is not one of them. the sliding interface is noisy- it sounds like 2 parts sliding against eachother. i want it to feel and sound as smooth as butter. The brass parts are machined, so have a typical cnc finish (16 to 32?) currently. the brass slides against a stainless 316 cylinder and potentially another ultem part.

I have not used brass much for this type of application, and where i have, it has been pre-made bushings from oil-filled stock...

I suspect that our problem is surface finish- related. For that oh-so buttery brass-feel, what is a good way to finish brass? these are production parts, so I don't want labor if i can help it. Can we tumble the brass parts to get a good sliding finish? any recommendations are welcome!!
what is a good surface finish to call out on prints for said buttery action? Do I need a specific brass alloy? (my experience is with polymers, stainless steels and aluminums. pretty ignorant with brass, as you can tell)


thanks!

 

[Tmoose]

I bet you mean bronze. There are MANY flavors of bronze.
One of the leaded bronzes is generally required when lubrication is scanty.

Have you tried any of the PTFE filled materials? Some claim the PTFE etc is transferred to the shaft after the first dozen or so revolutions.

Nye used to have some grease that supposedly provided the "large flywheel" feel on high end audio control knobs

 

[TugboatEng]

PTFE filled or, if there isn't impact loading, Graphite bushings such as those available from Graphalloy might do the trick. Graphalloy is expensive but I think there are knock-off versions available. There is another type of PTFE composite bushing mounted on a steel backing that can't remember the name of. It's used for sliders on motorcycle forms and is very slippery.

 

[DAVIDSTECKER]

Try these guys or similar.

http://www.cipcomposites.com/

 

[hydtools]

Garlock may have something you may like.

http://bearing-solutions.isostatic.com/category/sleeve-bearings

Ted