Fabrication of PEMFC metallic bipolar plates with micro-channel arrays using stamping and hydroforming processes

Stack cost is one of the major barriers for commercialization of fuel cells into the market. In this study, investigations were conducted on the formability and dimensional capability of metallic bipolar plates using both stamping and hydroforming processes considering. Several thin metal sheet alloys (SS304, SS316L, SS430, Ni270, Ti grade 1 and 2 with initial sheet thickness of 0.051 mm) were used in the experiments. Stamping and hydroforming tests were performed using the same die that had 0.75 x 0.75mm micro-channel arrays. The test results showed the feasibility and process capability of both methods in producing micro-channel arrays. However, hydroforming was found to provide better dimensional accuracy on bipolar plate micro-channels when compared to the stamping process. In addition, the effect of the stamping speed (0.1 and 1mm/s) and the hydroforming pressure rate (0.1, 1, and 10MPa/s) was found to be insignificant on the formability of the micro-channels, especially at a higher force or pressure levels. Finally, SS304 and SS316L were shown to possess better formability when compared to the other alloys. SS430 and Ti grade 2 demonstrated the worst formability among all.