The effects of flash allowance and bar size on forming load and metal flow in closed die forging

Because of three-dimensional stress state and non-uniform material flow, the analysis of the closed die forging is complicated and, consequently, the design of forging dies, flash allowance and suitable bar sizes is quite difficult. In the present investigation, the effects of flash allowance and bar size on the die filling and required load were studied. To take the benefits of model material technique, such as better observation of the material flow and lower costs, the tests were carried out with Plasticine as the model material. With this regard, for two different axisymmetric parts, one with a vertical axis of symmetry and the other with a horizontal axis of symmetry, several forging tests were carried out using bars with various sizes and flash allowances. It was found that the die filling for the component with horizontal axis of symmetry was more sensitive to the sizes of the billet. For both the components, it was also observed that the greater the flash allowance, the larger was the forming load. Moreover, the forging load was influenced by the bar size. It was also found that, in some cases, it could be possible to consider flash allowances less than those suggested in the literature, to reduce the production costs.