Some comments on cold forming process stability analysis

The paper deals with accuracy problems in different forming processes. In cold forging, the outcoming part is exactly defined with tolerances and mechanical properties. On the incoming side, where the material is defined, the definition of geometry and mechanical properties fluctuations is not so clear, because they depend also of the chosen technology, available machinery, etc. In the contribution, the authors present some industry examples and underline the problems connected with the stability of these processes. It is very important nowadays to balance between production costs and accuracy demands that are given by the customer. In order to produce as cheaply as possible, it is necessary to control the production in every single detail. There is the need to have a clear picture of main influencing parameters that affect the end-product geometry. The connection between the fluctuating tensile strength on the geometrical accuracy in the cold flat forging of wire as well as its influence on the curvature after roller straightening has been studied. The results obtained are presented in a diagram and can be very useful to a production engineer in making quick decisions about the raw material tolerances needed for appropriate quality.