Error analysis and correction in the slab method for determining forming forces

The accuracy of the traditional slab method, a well established method to calculate forming forces for simple metal forming operations, is investigated for the upset forging of a cylindrical billet. Axisymmetric finite elements modelling is used to confirm the mathematical slab result and simulate the real forging operation, in which the effects of billet barrelling are considered. The predicted pressure distribution and forming forces are used to compare the methods for a number of forming conditions. The effects of friction and deformation level on the errors in the slab method results are rationalised. A correction equation is proposed to bring results for the slab method closer to those found when considering barrelling. The research was carried out by a group of fi nal-year mechanical engineering students under the guidance of an academic lecturer and a PhD student.