Feasibility of Forming U-Shaped Microchannels by Flexible-Die Forming Process

Metallic bipolar plates can be mentioned as one of the main components of the fuel cell. Various methods such as hydroforming process, electromagnetism, stamping, and rubber forming are used to produce these plates. In this study, the effect of rubber layer on the production of the metallic bipolar plate by the rubber forming method was investigated. The forming die with a convex pattern and parallel helical grooves was used to fabricate bipolar plates made of SS316 with a thickness of 0.1 mm. First, the effect of forming force on channel depth in both transverse and longitudinal directions was studied. Experimental results indicated that there is a direct relationship between the depth of the channel and the applied force, and the maximum depth of the channel occurs in the transverse direction. In addition, the effect of hardness of rubber on the channel depth of bipolar plates was investigated. The results showed that the maximum depth of the channel decreases with increasing hardness of the rubber. On the other hand, with a large decrease in the hardness of the rubber layer, it would be difficult to provide the pressure for applying the plastic deformation on the sheet metal. Then, the depth of the middle and side channels in the longitudinal direction was measured in order to evaluate the dimensional accuracy of the channels. The experimental results showed that the depth of the channels is uniform in this direction, which indicates the acceptable dimensional accuracy for the fabricated samples.