Orientation Effects in Filled Plastics Bearing Materials

The development of antifriction materials based on lamellar solid lubricants dispersed as fillers in thermoplastic compounds is briefly reviewed. Experimental evidence is offered to account for the wide variations in friction and wear properties reported, in terms of flow orientation and cross-flow migration of the filler particles. These findings confirm the importance of finish machining operations on the rubbing surfaces. Preliminary evidence is also offered for the disruption of particle orientation by polymer crystallization processes where the particles are small. Experimental methods used are: image analyzing microscopy, X-ray diffraction, and a specially developed friction testing machine for molded plastics samples.