Whether or not to grease a plastic bushing is a frequently asked question, or even just an assumption customers make (that they need to). While there are times where greasing is important, and times where it is absolutely critical, in most cases with many materials you will not need to. Avoiding the need to grease a bushing is a strong advantage plastics have over metal in application. Many plastics are self-lubricating and can come impregnated with solid or liquid lubricants. Certain bushings, such as the Rulons, will never require grease. In general, if you want to switch from a greases metal bushing and are flexible on material, an oil-filled option would be quoted. The cost difference between oil-filled and unfilled materials is about 30% so you need to judge how important it is not to grease.
In the case where an unfilled bearing grade material is required, grease grooves can be machined into the part. These would come with a “grease nipple” or small hole in the bushing to permit application of the grease. This is common for applications such as kiln wheel bushings or sprockets. That said, there is one case where you *must* grease and that is if the demands of your application exceed the P/V/PV ratio of the plastic. P/V/PV needs to be under all three maximum limits for the bearing material; however, that’s a discussion that requires it’s own article.
If you are looking for grease-less bearings or have questions on our Redco bearing materials please contact us.