Reply With QuoteI've specified copper grease for non moving parts before but not for gears, bearings etc. Not sure on the suitability for this type of application.
I have been reading the essays on Engineers Edge about gear lubrication. I don't think they quite address my exact situation. We are using fractional horsepower shaded pole motors with 3200 RPM and gearboxes with varied configurations. The one I am working on has a 23 rpm output with 3 powdered metal gears (including pinion gear).
The gearbox is mounted to a 2 or 3 inch plastic valve in either a normally open or closed position. The motor drives the valve one direction and the spring returns it when the cycle is complete.
Historically, the gears were bathed in oil prior to assembly and the gearboxes saturated the shipping containers with excess oil. Presently we are using a green automotive style grease applied with precision to the gear pins and at the output shaft; minimal grease is applied to the teeth in an effort to reduce back-drive friction resistance.
In testing I am observing fretting on the gear pins and the grease drying out to a thick hard film. Some fail with the gearbox seizing, others have had the pin seize on the gear but continue operating until the pin chews its way out of mesh with the other gears.
The question I have is what is an optimal grease or lubrication for our system? I am considering a copper grease but have not looked deep enough to know if it would be economically feasible.
Drew K
I've specified copper grease for non moving parts before but not for gears, bearings etc. Not sure on the suitability for this type of application.
I have used it on the brakes and fairing panel bolts on my bikes for years (CBR 600 F x reg). I recall someone using it on a non-o-ring chain drive on an older bike and claiming it lasted very well. I know the hazards of using near rubber components on brakes and o-ring chains but that is not a concern in our gearbox application.
I think I am just going to need to build a few and test them to destruction and see where they fail.
Drew K
Testing is always the forward. When the proper mechanical guys turn up, they should have a better answer for you.
Just as a general suggestion, you might try a modern automotive wheel bearing/CV Joint synthetic grease, I have used one that has a very low viscosity and no liquefication issues on a number of general lubrication applications including highly loaded paper shredder gears.
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