Pistons for combustion engines usually are made of cast aluminum. But, increasing requirements for efficiency and performance can be met by steel pistons, and this option will probably gain popularity in the automotive industry in coming years. The pistons are forged and an expansive machining process is necessary to finish them.

In a usual, unidirectional forging process it is not possible to pre-forge important areas, such as the pin bores as they represent an undercut. With the help of a multidirectional forging operation it is possible to forge undercuts. FEA simulations already have shown the feasibility of such a process, which is distinguished by a pre-forging of the pin bores and an improved material usage.

Furthermore, the following machining operation will be easier due to simpler positioning of the part.

Currently, the forging tools are under development. Once they are finished they will be tested in an industrial environment on an eccentric press. The tools and parts will be analyzed concerning the quality of the parts, the die wear and the economic efficiency of this new process.

This research project (IGF project No. 18162N) of the research association for steel application FOSTA is funded by the AiF in the framework program of the industrial research community (IGF) by a resolution of the federal ministry of economic affairs and energy of the German parliament.

The authors are affiliated with the Institut für Integrierte Produktion Hannover GmbH in Hanover, Germany. Dipl.-Ing. J. Langner is the Project Engineer. Dr.-Ing. M. Stonis is the Division Manager, Process Technology. Prof. Dr.-Ing. B.-A. Behrens is a member of the management board, IPH. Visit www.iph-hannover.de for more information


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