Effect of roughness geometry on friction during micro V-die bending by using finite element method

Abstract

Interfacial conditions such as friction and roughness tend to be the dominant process characteristics when simulating sheet metal forming processes. Therefore, accurately modeling the tool workpiece interface is essential. Additionally, the accuracy of conventional methods of modeling the interface is insufficient for microforming. This work presents a novel approach for describing friction by modeling the geometric roughness of the tool surface instead of using the conventional friction coefficient or factor in dry contact. This finite element-based model was validated in terms of loads and metal flow in two cases of micro V-die bending processes. One process modeled a conventional flat tool surface with a friction coefficient. Another process modeled a rough tool surface described as roughness geometry with zero friction. In addition to elucidating how the roughness geometry of a tool surface affects friction during microforming, this work provides fundamental information about the interfacial conditions of the contact surface as well as improved accuracy and flexibility compared to conventional friction models. Another important application of the friction calculation results in this study is in microforming applications.