Acetal Gear on Anodize Boss

[i2xtreme]

I am curious if anyone has had any experience what the wear characteristics of using Acetal gear on an anodized aluminum boss. The forces are very light ~4in-oz.

I have a acetal gear with a 10 mm bore and instead of using bearings it would be nice to just machine the boss in the existing aluminum component slip the gear over and volia.

It would have to last for about at most 100k revolutions. It would be best to be non-lubed. if the boss wears an additional .002 it will not be a problem.

Estimating the wear using wear = kpvt... suggests it will not be a problem. Any thoughts?

 

[MikeHalloran]

The tribology is different for running an acetal gear on an anodized boss, or on a boss that's machined after anodize. So I'm curious about which combination you are proposing.

Frankly, it doesn't matter; I don't like it either way.



Mike Halloran
Pembroke Pines, FL, USA

 

[DesignerGuy16]

It all depends on the formulation of acetal, RPM, etc.

IGUS bearings for example use a base delrin blend and mix in a lubrication additive. Most bearings you'll see will do this. Light load, low RPM isn't bad, but you'll get better wear if you can press in something like a 17-4 PH1150 boss. As the plastic bearings life is also very dependent on the shaft material, finish, and hardness.

James Spisich
Design Engineer, CSWP