| Nowadays, PEM (Proton Exchange Membrane) fuel cell is in widespread commercialization for its high efficiency, high power density, fast startup and high system robustness, as a way of converting and supplying energy. Bipolar plates (BPPs), as the most important component in PEM fuel cell, has micro-channel features on its surface, which can be fabricated by flexible forming process (FFP) on thin foils (100µm or less).;In this study, flexible forming process is used to form aluminum 1100 micro channels. This process only needs a female die, since polyurethane is used to act as a male die. Three micro-channel dies with 1mm, 0.8mm and 0.6mm channel widths and aluminum 1100 foils with 75µm, 50µm and 25µm thicknesses will be used for experimental study. These foils will be annealed at different temperatures to obtain different grain sizes such that a set of T/D ratios can be obtained; T/D ratio can be used as an indicator of the size effect in micro metal forming. In addition to channel widths, polyurethane type, foil thickness, T/D ratio and compressive forces will be used as other parameters for this study.;In this study, the depth of the micro-channels formed on the foils and the thickness of the channel wall are measured. Thinning ratio of the blanks in the forming process is calculated, based on the measurement of thickness. Thinning ratio η=(T0-T 1)/ T0, where T0 is the original thickness of the blanks, T1 is the thickness of the formed micro channels. Thinning ratio and depth of the micro-channels are used to evaluate the formability of Aluminum 1100 foils.;Through this study, it is found that compressive force will have a significant influence in forming micro channels; as micro channel width of the rigid die increases, better forming results will take place; hardness of polyurethane in the forming process acts negatively in the forming process; as T/D ratio of aluminum foils increases, the formability of the blanks in forming micro channels will decrease; also, it is found that under same conditions, thinner aluminum foils usually have better forming results. Finally, the optimum combination for forming aluminum micro-channels by using flexible forming process is suggested. |
