Shape complexity factor for closed die forging

The present paper describes the application of a shape complexity factor - a criterion simplify the decision whether a pre-forming step is necessary or not, when a process of closed-die forging is under planning. Direct transformation of the billet into the final shape is possible only when the mass of the forging part is small. In order to produce flawless forging parts, there is a necessity of a proper set of preparatory and pre-forming steps. The forging sequence plays a decisive role for producing flawless forging parts. A shape complexity factor, allowing evaluating the necessity of pre-forming step is discussed. It is defined setting up on comparison of the work done in to the final impression with the work done for upsetting a simple equivalent body, obeying the volume constancy condition. Examples with different forgings have been carried out applying FEM analysis. Results prove that the new criterion is applicable and gives better results than the existing one.