Effect of Friction conditions on Material Flow in FE Analysis of Al Piston Forging Process

Abstract

In the hot forging process of aluminum piston using water-soluble lubricants, the lubricant layer is often peeled off due to excessive deformation of the material during forming, which may result in direct contact between the material and the die, thereby partially increasing the friction. The constant friction in the Finite element (FE) analysis of this process sometimes results in a completely different result from the actual material flow. Therefore, this study was designed to investigate the friction condition to accurately predict the material flow in the FE analysis. The FE analysis was performed for various material temperatures and friction parameters and the proper friction condition was also derived to remove forging defects. Finally, the forging test was carried out for the initial specimens produced by three different methods to verify the analytical results and eliminate the forging defects. The results showed that the friction depends on the effective strain in the FE analysis and the critical value to increase friction is approximately 1.5-1.8. In addition, among the three different specimens, the shot peened specimen can remove the forging defect by increasing the amount and uniformity of the lubricant on its surface.