Investigation of micro-pits formation on billet surfaces in plane strain extrusion

Abstract

Extrusion is a process of pushing a material through a die to yield a desired cross-section product. The application of surface texture has become well known for enhancing tribological performance. In this research, the effect of micro-pits embedded on a work piece lubricated with vegetable oil using plain strain extrusion were studied and compared with those seen with mineral-based oil lubricant. The experiments were conducted at room temperature (around 27ºC). A taper die with a 60 die half-angle, with micro-pits array, was prepared. Test lubricants used were paraffinic mineral oil (PMO) VG460 and VG95 and refined, bleached and deodorized (RBD) palm stearin. The results were analysed to determine the extrusion load and the billet’s surface roughness and plastic deformation. RBD palm stearin was recorded as having the highest extrusion load (83.15 kN).