Sensitivity study of frictional behavior by dimensional analysis in cold forging

In metal forming operations, material flow and quality of the product depend on the conditions at the billet/tools interface friction, lubrication, and surface finish. Of these parameters, friction is the most difficult to characterize and its influence is often difficult to predict because of its dependency on a variety of factors. Recently, through a number of investigations conducted, a linear relationship among shear friction factor, dimensionless load and tip distance was obtained. The aim of the present study is to see whether the linear relationship obtained in the previous works was fortuitous or genuine by applying a dimensional analysis introducing processing parameters such as contact pressure, ram velocity, viscosity of the lubricant, load, surface roughness and shear friction factor. From the dimensional analysis based on Buckingham pi theorem and the data obtained from the tip test experiment, the present theoretical work derives dimensionless parameters and analysis of variance determines any correlation between the dimensionless parameters obtained. This work reconfirms the theoretical background of the previous experimental findings in the literature.