Preform design is critical for multi-stage forging processes to ensure the production of defects-free parts. Moreover due to the geometry and material flow complexities in forging processes, finding the optimal preform shapes could be difficult and time consuming. This paper proposes an efficient preform design methodology based on geometrical resemblance which requires a few FEA simulation iterations to obtain a good preform shape. The premise of this methodology is such that the initial and subsequent simulations are carried out by constructing a slightly larger part which geometrically resembles the desired part. Initial FEA simulation of the larger part is performed with reasonably guessed preform shape which may allow the occurrence of forming defects or flash formation. Then a series of intermediate resembling parts between the largest part and the desired part are constructed. The undeformed shape corresponding to the intermediate part could be obtained by backward tracing of material flow from the simulation results of the larger part. This undeformed shape is then taken as the preform shape of the intermediate part. The procedure is repeated until the intermediate part is geometrically close to the desired part, which leads to the preform shape. In order to verify this preform design methodology, several case studies on forging and extrusion processes have been carried out. The methodology has been proven to be computationally efficient since it requires fewer numbers of iterations.

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