Abstract
Oil starvation at sliding elements causes seizure, resulting in a combined increase of friction and temperature at the sliding interface. Therefore, steady preservation of oil films at the interface even under severe operation conditions is important to prevent the occurrence of seizure. Surface texturing, which is the process of creating specific roughness and geometries on a surface to improve tribological properties, is a well-known technique to preserve oil on the sliding surface. However, active supply of oil to the sliding surface is difficult in case of conventional surface texturing. Therefore, we proposed an inner micro-structure termed a “Spiral path structure” that makes it possible to supply lubricant to poor lubricated area utilizing rotary motion of the tribo-element. The Spiral path structure, which has micro spiral paths underneath the sliding surface, supplies oil from an oil reservoir up to the sliding surface by utilizing rotary motion of the tribo-element. Technically, it is difficult to fabricate test samples having an inner curved micro-structure by conventional methods such as cutting and casting. Metal 3D printer was hence utilized to make such complexly textured structures.
In this study, test samples having the spiral path structure were fabricated by metal 3D printer. Oil supplying effect and frictional properties were investigated. As a result, the tribo-surface having spiral path structure showed lower friction coefficient in a wide speed region, compared to conventional dimple textured surface.
