POM/PA Plastic Bearings (precision plastic Bearings) POM and PA have excellent mechanical strength and wear resistance. They are suitable for manufacturing precision plastic bearings with good self-lubrication performance and low friction coefficients. In addition and high speed application. Plastic bearing made with POM is the most extensive sort of all the plastic bearings. Generally the inner and outer rings are made with POM or PA, Cage are made with PA and the balls are made with glass, stainless or ceramic. These bearings could be used in some alkali environment but not proper to some acid environment.