The effect of various surface treatments on piston pin scuffing resistance

A new test rig that was specially designed to evaluate the effect of various surface engineering methods on the tribological performance of piston pins is described. The test rig was used to study scuffing resistance provided by CrN and diamond-like carbon (DLC) coatings and by laser surface texturing in comparison with a base line standard pin. Scuffing inception could be obtained only with low viscosity base oil. In this case, all the treated pins performed better than the standard one, with the laser surface texturing offering the best performance. With formulated 20W50 engine oil, all the four types of piston pins performed satisfactorily until the load limit of the test rig, without scuffing.