On geometrical accuracy in precise metal forming

There are five main factors which influence the accuracy of the formed parts: raw piece, forming procedure, tool, forming machine and tribology. The material flow and behavior, the contact stresses, and the forming load during the forming processes are analyzed with the finite element method. This will allow the study of the mutual effect between tool and formed part, and from that the shape accuracy. The applied finite element method based on Markov's variational principle for rigid plastic material, includes the consideration of friction on the interface between tool and formed part. The friction affects the material flow and the material behavior due to the temperature rise on the interface. Numerical results are shown for forging processes.