Fuel Cell ASAP: Two Iterations of an Automated Stack Assembly Process and Ramifications for Fuel Cell Design-for-Manufacture Considerations

Abstract

Polymer-electrode membrane (PEM) fuel cell technology, a low-emissions power source receiving much attention for its efficiency, will need to progress from low-volume production to high-volume within the course of the next decade. To successfully achieve this transition, significant research progress has already been made towards developing a fully-functional fuel cell automatic stack assembly robotic station. Lessons can be drawn from this research with regards to design-for-manufacture (DFM) and design-for-assembly (DFA) considerations of fuel cells; however, more work still remains to be done. This document outlines both iterations of the robotic fuel cell assembly stations, other work to date, DFM and DFA lessons learned, and the anticipated future progression of automatic fuel cell stack assembly stations. A literature search reveals numerous patents pertaining to equipment and processes for fuel cell assembly as well as a great number of patents pertaining to fuel cell stack features to aid in manufacture or assembly. However, most of this is focused upon proper compression of the membrane material, with little thought given to overall assembly and throughput. Journal articles have begun to consider real-world manufacturing considerations pertinent to production scale-up, but much remains to be done. Therefore, there is a need for more contributions to stack manufacture and assembly. Work already completed (by the authors and their lab) towards the manufacturing workcell specifically includes the design and construction of two individual robotic fuel cell assembly stations, including custom-built end effectors and parts feeders. The second station incorporated numerous improvements, including overlapping work envelopes, elimination of a shuttle cart, software synchronization, fewer axes, and a better end effector. Consequentially, the second workcell achieved a four-fold improvement in cycle time over the previous iteration. Future improvements will focus in part upon improving the reliability of the overall system. Close study of the manufacturing workcell indicated that stack component design features are key for production and scale-up of fuel cell stack manufacturing processes. Critical features are discussed in this article, as well as their ramifications for the overall stack design. As the stack assembly workcell continues to improve, research will focus upon the ramifications and interplay of tolerances, stack failure modes, sealing, reliability, and the potential for component redesign specifically to optimize fuel cell manufacturing throughput.