Question

For a ball bearing made out of plastic inner and outer race and a stainless steel ball, which of these materials is likely to wear? What would the wear pattern be like? Which will eventually fail first?

Answer 1

Plastic ball bearing was developed inorder to use it in place of stainless steel ball bearing where chances of rusting is more or we can say where ball bearing are exposed to water and corroisive environment. Plastic ball bearing doesn't transfer heat to other surfaces whereas stainless steel ball bearing does. Plastic ball bearing is noiseless as well as self lubricating where as stainless steel ball bearings are not self lubricating and they do produce noise.

So ball bearing made up of plastic will take more time to wear. Stainless steel is likely to fail first.

Failure not only depends on the material of bearings, it also depends on which types of bearings we are using. As for example if we are using journal bearing then there will be a sudden failure without any indication whereas the Anti- Friction bearing gives indication before failures by creating more noises. Plastic bearings is noiseless so the failure pattern will be sudden there will be no any indication before failures, whereas stainless steel produces noise, so before failure there will be uneven noise as an indication.

Bearing mainly fails due to pitting, due to repeated stress under cyclic loading. But plastic ball bearings can absorb shocks better than that of stainless steel ball bearings, so plastic bearings will have more life.