Development of surface textures using micro-milling operation for improved tribological characteristics of aluminium alloy

The present work focuses on improving the tribological performance of aluminium alloy (Al 4032, piston material) using micro-texturing. Conventional high-speed micromachining setups with ball nose end mill cutters of three diameters (0.15, 0.20 and 0.40 mm) are used to fabricate semi-hemispherical micro-dimple geometries on Al alloy plate surfaces. These micro-dimple geometries were created in a 45° staggered configuration with 0.167 depth/diameter ratio for texture preparation of each diameter. The effects of micro-textured geometries, low surface roughness and tribological process parameters on coefficient of friction (COF) are estimated by tribology tests performed in reciprocating pin-on-plate configuration under in vitro conditions of a piston-ring-liner interface. Findings of this investigation demonstrate that conventional micromachining processes are effective techniques for creating textured surfaces on aluminium alloys and similar materials used for pistons. Among different surface configurations, micro-textured surfaces with low surface roughness and 240 μm diameter produced the lowest COF in most tested conditions due to the larger volume to store the lubricant and comparatively higher pitch distance for generating significant load-carrying capacity.