Development of a novel process for manufacturing of fuel cell bipolar plates: INTERNAL pressure assisted embossing of micro-channels with in-die mechanical joining

A novel process for manufacturing of fuel cell bipolar plates was developed and described in this paper. This process combines the hydroforming of double thin sheet metal blanks with in-die mechanical joining to enable integrated forming of micro-channels on both surfaces (as anode and cathode) and at the middle (as cooling channels) in a single operation, thus, reducing post process operations, variation in dimensional tolerances, and cost while promises to increase the producibility, product quality, and performance of the fuel cell by ensuring consistent contact resistance characteristics. This paper discussed two experimental investigations that were performed to characterize and evaluate the feasibility of the proposed manufacturing process. The first investigation involved hydroforming of micro-channels with the channels geometry of 0.5 mm in both width and height on thin sheets of stainless steel 304 with a thickness of 0.051 mm. The second investigation focused mainly on the mechanical joining process of thin sheet metal blanks. The effects of different process variables on the bond quality and the mechanisms of the bond formation were studied. The experimental results presented in this paper demonstrated that the proposed manufacturing technique is feasible for making of the fuel cell bipolar plates.