Correlation between contact load and surface roughness in plane strain extrusion

Effect of contact load and surface roughness on friction behavior in plane strain extrusion is one of the biggest phenomena in improving the sliding performance of cold forward extrusion. Wear resistance that commonly occurs on the plane requires an appropriate method to obtain the finest product surfaces. This paper highlighted is the correlation between contact load and surface roughness on the friction behavior and wear resistance of the sliding plane in the extrusion process. The analysis described in this paper involved the experiments to assess the contact load in the extrusion and the surface roughness. The experiments were set up by using pure aluminium A1100 as billet extruded between dies made of hot work tool steel (SKD11). Extrusion ratio of the process is three (3) and the billets were pressed by a hydraulic press machine. The contact load for each experiment was taken at a 20 mm length of the extrusion, and the average surface roughness of the aluminium was plotted on a graph. Three types of lubricants were used in this study: Refined Bleached Deodorized (RBD) palm stearin and two types of paraffinic mineral oil, 95 and 460. These two types of paraffinic mineral oil differed in viscosity. These three types of lubricants were run with four different quantities: 0.1 mg, 1 mg, 5 mg, and 20 mg. The results showed that an increased amount of lubricant reduced the surface roughness. The correlation between contact load and surface roughness showed significant differences for each lubricant while at 5 mg of RBD palm stearin and paraffinic mineral oil 460, the results showed the same contact load but different surface roughness. (C) 2013 The Authors. Published by Elsevier Ltd.