The Relationship between Constant Friction Factor and Coefficient of Friction in Metal Forming using Finite Element Analysis

Frictional shear stress is usually determined by utilizing the coefficient of friction or the constant friction factor models. The present study deals with finite element analysis of double cup extrusion process to determine the relationship between constant friction factor (m) and coefficient of friction (µ), since the metal flow in this process is very sensitive to frictional conditions. Therefore, the Finite Element-Code Deform 2D is used which is capable of utilizing both µ and m. According to this analysis a new equation between constant friction factor (m) and coefficient of friction (µ) is suggested. Moreover, in order to evaluate the suggested equation and to compare it with the pervious relationship, finite element analysis of barrel-compression test is carried out. Finite element results indicate that the new equation can accurately predict the relation between m and its equivalent μ value. The importance of converting these factors to each other is specially highlighted to introduce the frictional conditions in some professional and commercial finite element softwares.