In this study, we propose a method of determining the coefficient of friction between a tool flank and a sheared surface in shearing. In this method, the vertical force and horizontal force need to be measured after completion of the separation process, after which the coefficient of friction is defined as the ratio of vertical force to horizontal force. In this study, the influences of punch speed, kinematic viscosity of lubricating oil and clearance on the coefficient of friction were investigated. Using the proposed method, a coefficient of friction of about 0.35 was obtained when ordinary lubricating oil was used. The coefficient of friction between the tool face and the material surface was also determined from sliding friction tests. The results of Finite Element Method taking into account the coefficients of friction obtained by the method showed good agreement with experimental results for the piercing of small holes.
2006 by The Japan Society of Mechanical Engineers