Show description

The most common wear mechanism for thermoplastics is adhesive wear. Adhesive wear occurs when opposing/mating surfaces slide against each other, and fragments of one surface pull off and adhere to the other. The adhesive forces between the polymer and the counterpart are sufficient to inhibit sliding at the original interface. The harder of the opposing surfaces scrapes or abrades away the mating part. The adhesive junctions which form at the real points of contact rupture within the polymer itself and a layer of polymer is deposited on the counterpart.

When an application calls for plastic on plastic, dissimilar polymers should be used and incorporated with one or more wear-resistant additives. Reinforcements such as glass, carbon, and aramid fibers enhance wear resistance by increasing the thermal conductivity and creep resistance, thus improving the LPV and working PV of the part. PTFE has the lowest coefficient of friction of any internal lubricant. Its particles shear during operation to form a lubricous film on the part surface. Often referred to as the best lubricant for metal mating surfaces, PTFE modifies the mating surface after an initial break-in period.

Glass fibers are mainly added to resins to improve both short-term mechanical and thermal performance properties, particularly strength, creep resistance, hardness, and heat distortion. Wear resistance can also be improved with the addition of glass fibers, but the improvement is directly correlated to the efficiency of the glass sizing system which bonds the resins and fibers together. Glass reinforcement results in a marked improvement of the resins limiting PV by enhancing creep resistance, thermal conductivity, and heat distortion.