Polymer bearings are an alternative to metal

Lubricant and maintenance free xiros polymer ball bearings can be used at temperatures above 300F, are highly corrosion resistant, can be washed and cleaned, are non-magnetic, and are lightweight in comparison to traditional metal bearings.  They are an economic alternative for many applications where the use of conventional metallic bearings are not suited, such as in washdown environments, around chemicals, or in liquid media.
 In such applications, lubricants often wash out of metallic, sealed, and permanently lubricated ball bearings, so that corrosion becomes a problem. Polymer bearings are also lighter and unaffected by magnetic fields. The line includes general purpose, high-temperature, and low-cost versions. More than 100 shapes, sizes, and styles are available, including radial and axial bearings, bearings for linear and rotational movement, rotary and pedestal bearings, as well as flange, ball, and dust-shielded ball bearings.http://www.igus.com