Standardization of test particles by trial-based approximation of the damaging potential of manufacturing swarfs

Particulate residues originating from manufacturing and assembly processes can cause severe incidents in automobile powertrains or safety-relevant modules. Robustness validation and tribological studies require synthetic test contamination to imitate the particulate residues. A collaborative research project was started to evaluate whether such particles could be produced with high reproducibility and if they would reveal sufficient damage potential. To enable future mass production micro powder injection molding (MicroPIM) was chosen as manufacturing process with the lowest tolerances and best reproducibility. For this purpose micro suitable feedstocks containing 42CrMo4 steel powders had to be developed. Additionally, micro mold inserts incorporating free-formed surfaces had been used for the first time. The damage potential of the test particles was evaluated based on trials using journal bearing and shift valve test rigs. Furthermore, test particles and particulate debris from assembly processes were analyzed by light microscopy and micro computer tomography in order to check the fit of characteristics.