Effect of EDM dimple geometry on friction reduction under boundary and mixed lubrication

The purpose of this work is to study the effect of electrical discharge machined (EDM) dimple geometry on friction reduction under boundary and mixed lubrication. Three different types of dimple geometry were designed with equal area density of 10.4% and EDM on test surfaces of aluminium alloy 7075 square pins. The specimens were tested against a rotating high speed steel counter-disc using a pin on disc apparatus under mixed lubrication condition. Tribo-tests were conducted at increasing sliding speed with varying nominal contact pressures. The friction coefficient of the EDM dimpled specimens are found 11-24% lower than that of the non-textured specimens. It is also found that the round dimple geometry gives the lowest friction and wear among others.