Investigate the effect of rubber layers thickness on forming of bipolar plate's microchannels in rubber pad forming process

In this study the effect of rubber thickness on forming quality of metallic bipolar plates microchannel’s was investigated in rubber pad forming process. ABAQUS/Standard finite element software was used to simulate the process, where the accuracy of the simulation results was evaluated by using experimental results. To perform experimental procedures a die with parallel flow field was used to form SS316 bipolar plate with 0.1 mm thickness. For this purpose the effect of punch load and rubber thickness on channel depth, filling percentage, thickness distribution and thinning percentage of the formed parts were investigated. In this regard, rubber layers thickness of 1 mm to 7.5 mm thickness were tested. First, the effect of punch load and rubber thickness on the microchannels depth of bipolar plates was investigated. The results demonstrate that with increasing punch load and thickness of the rubber layer, leads to increasing the channel depth and filling percentage. Amount of force in forming of four microchannels will decrease from 82.25 kN to 55.15 kN by increasing in thickness of rubber layer from 1.5 to 5.5 mm, that show 31% decrease in forming force to achieve 0.75 mm channel depth; while more increase in rubber layers thickness has no significant effect on forming force. Moreover optimum thickness of rubber layer will decrease from 5.5 mm to 3 mm by decreasing the number of microchannels from 4 to 1. According to the result, increasing the rubber thickness would achieve greater channel depth at equal punch force, which also leads to increase in thinning percentage. Furthermore, increase in the thickness of rubber layer leads to more uniformity of the samples thickness distribution at outer corner radius. Thinning percentage difference at outer corner radius decreases from 3% by using rubber thickness of 1.5 mm to 0.4% by using rubber thickness of 5.5 mm, which indicates considerable improvement in uniformity of thickness distribution.