A theoretically determined model for friction in metal working processes

Abstract A general theory for friction in metal working processes is developed based upon the slip-line theory as a model of analysis. The real area of contact α and the nominal friction stress τn are determined as functions of the nominal normal pressure q/2k and the friction factor m. The results show how the real area of contact increases and approaches the apparent, as the normal pressure increases. Furthermore it is found that Amonton's law is valid only until q/2k = 1.3 irrespective of the m- m value . Curves of τn/k as functions of q/2k and m show that τn/k approaches the friction factor m as q/2k tends to infinity. This means that Amonton's law in the case of small m-values (m