Numerical and Experimental Investigation on Hot Impression Die Forging: Flash Design Optimisation

In forging processes, several parameters have a great influence on the quality of the final product: complexity of the product geometry, lubricating conditions, temperature, preform shape. The main objective of a forging design process is to ensure an adequate material flow aimed to obtain a defect free component minimizing material losses, forging loads and tool wear. In this paper, the problem of optimising the flash geometry in hot forging is studied with particular reference to flash thickness and flash–land width. The main goals to be pursued concern the minimization of the flash volume (i.e. the surplus of material necessary to fill the die cavity), with the aim to reduce material losses, and also the reduction of the maximum load required to carry out the process. In this way, numerical investigations and design tools have been utilized to optimise the main process parameters. Furthermore, an experimental validation of the results has been carried out with the aim to verify the numerical predictions in terms of forming loads and complete die cavity filling. A numerical design procedure was developed able to enhance the process design performances with respect to the available empirical guidelines. With the proposed methodology an effective flash land geometry was determined able to guaranteed the fulfilment of product design specifications.