Investigation of Die Clearance in Rubber Pad Forming of Metallic Bipolar Plates

In this research, rubber pad forming process of metallic bipolar plates made of stainlesssteel 316L with a thickness of 0.1 mm has been studied. In addition, a rubber pad made of polyurethanewith the hardness number of shore A 85 and a thickness of 25mm is used in order to apply pressure tothe plate to form the sheets. In order to study the effect of die clearance on depth filling, two die sets withdifferent clearances were made. The results showed that when clearance is applied between punch dieand matrix, the amount of uniformity becomes more in the depth of stuffed channel. But, the rubber padis destroyed after some forming operation and plastic deformation occurs in it. Also, in the die set withthe lower clearance, the amount of rubber pad life has been increased and the amount of flow channeldepth gets greater. In the research results, it was determined that when the channel depth is small and arubber pad is used with a higher hardness, the die set with a clearance has more favorable results due touniformity in the flow channels’ depth. However, by increasing the depth of bipolar plate channels, usingdie sets with lower clearance are better due to the increasing the rubber pad life.