Powder Injection Molding Of Free-Formed Micro Test Specimen

Although micro powder injection molding (MicroPIM) represents a strong technological task it becomes even more difficult in case of free-formed geometries. A challenging example are micro-sized test particles. Such artificial specimen are required for modelling and simulation of wear effects caused by manufacturing debris/swarfs occuring in e.g. journal bearings or combustion engines. The free-formed geometry was derived from a real manufacturing swarf previously characterized by micro computer tomography (µCT). Micro mold insert design incorporating the free-formed surfaces was comprehensively simulated and realized by milling and discharge machining. Novel for MicroPIM, specially tailored feedstocks containing 42CrMo4 steel powders were applied. The related molding, debinding, and sintering procedures had to be developed too. The damage potential of the test particles was evaluated based on designed experiments using a journal bearing and a shift valve test rig. Thereby, it could be ascertained that the artificial swarfs will allow for development of standardized wear test procedures.