Composite materials have been the go-to choice for bearing and bushing applications for the better part of the last century. This is due to their self-lubricating wear properties and also because they are much lighter and easier to handle than their metal counterparts. When using composites for these applications, however, there are some essential practices that one must consider. These include: running clearances, press fit interference, ID close-in, post curing effects, wall thickness, surface finish and lubrication. To give a better understanding of what these are and how to apply them to your application, we described them in this paper.
Limiting PV, Wear Factor and Coefficient of Friction
Limiting PV is a description of the capability of a bearing material to resist the pressures and velocities of use. It is defined as the product of the unit load P (psi) based on the projected bearing surface area and the velocity of the shaft expressed in feet per minute.
A glass transition temperature (Tg) describes the point at which a thermoset polymer changes its physical structure to a crystalline state and is an average of the temperature range those changes occurred. The actual glass transition temperature range depends upon the molecular structure of the material, the testing method, sample preparation, the cure schedule, and the degree of cure.