Lubrication of special bearin 1

[alansimpson]

I have made up a special bearing for a piece of test equipment comprising 2.3mm Tu carbide ball spinning on a hardened flat surface at 2000-4000 RPM. Surface hardened steel or Tu carb. Loading along spinning axis should be fairly low 1-5 N.

Environment normal room conditions in lab. 20 deg. C.

I am happy with arrangement and have been unsuccessful with traditional bearing arrangements.

However I would like some advice on the best lubrication to use to reduce friction. Lubrication must be just applied to surface and left to work 1000 + hrs. of use.

Thanks in advance

 

[handleman]

If I understand lubrication theory correctly (granted, I may not), any lubrication that you add will actually end up increasing friction. Here comes some probably incorrect terminology: The idea of lube is that the parts in motion never actually touch due to a thin film of lube. This film is maintained by the relative motion between the parts and the lube's viscosity and other properties. The motion of the parts basically "pulls" the lube between the parts in motion. Lubrication breaks down if the load on the bearing is greater than the fluid pressure can bear, and the components force their way to contact.

What you have created with your hard ball and hard surface is essentially point contact. Even though your ball is spinning, there is (again, theoretically) zero relative motion at the interface between the ball and the plate. There is no mechanism by which any lube you add can be "pulled" into the contact interface. Any that is there will simply get "drilled" out of the way. Then it will add viscous drag to the portions of the spinning ball that are not touching the plate but are close enough that surface tension/wicking effect brings fluid in contact with both ball and plate.

Again... my theory based on pretty limited knowledge.

-handleman, CSWP (The new, easy test)