Electrochemical Machining Multiple Slots of Bipolar Plates with Tool Vibration

Abstract

A bipolar plate is an important component of proton exchange membrane fuel cells (PEMFC). The fabrication of multiple slots is a key part in preparation of metallic bipolar plates. They can be produced by electrochemical machining (ECM). During the ECM process, high flow resistance occurs with the increase of slots length and depth, which will make metal hydroxide and other by-products accumulate in the outlet of electrolyte and limit the maximum feed rate of cathode. Therefore, a flow channels contraction cathode structure with variable cross-section has been proposed. It can make the flow velocity of electrolyte increase gradually in the inter-electrode gap and take away electrolysis products better. In order to remove electrolysis products further, tool vibration is applied. The flow channels contraction cathode has been determined with numerical simulations, and the comparison experimental results show that the way is effective in improving the feed rate and ensuring the uniformity of slots depth.

Study on the Control Method of Sidewall Taper in Electrolytic Broaching of Micro Multi-Grooves

“…The results showed that multiple independent machining areas could effectively improve the speed uniformity of each channel. Jiang et al [23] proposed a variable cross-section channel contraction cathode structure. The flow rate of the electrolyte in the electrode gap gradually increased to better remove the electrolytic products.…”