Numerical modeling of wear on forming dies in high-volume metallic bipolar plate production for fuel cells

Fuel cell electric vehicles (FCEVs) have been receiving attention as a key technology to reduce the green-house gas (GHG) emission by replacing internal combustion engines in the mobility sector. As a crucial component of the proton exchange membrane fuel cell (PEMFC), Bipolar plates (BPPs) provide a multitude of important functions such as distributing media, providing structural rigidity, heat dissipation and electrical pathway. To provide 100 to 150kW of electric power for mobile applications, around 300 to 400 BPPs are required in a single stack. Therefore, increasing production rate and reducing the manufacturing costs of BPPs is crucial to an exponentially increasing market volume and support the large-scale deployment of FCEVs.
The metal forming process has great impact on production rate and therefore inherits a high potential to realize economic viability thanks to its scalable production characteristics. However, millions of repetitive sheet metal forming operations leads to wear on the forming tool, which refers to the deterioration of tool geometry over time. Furthermore, due to the high precision requirement, the tool wear has great significance in micro scale forming, which is used to manufacture BPPs. In addition to that, the determination of tool wear is a highly interdependent and multicriterial phenomenon, for example regarding the material model and surface boundary condition. An excessive tool wear can lead to inaccurate forming results, stress concentration, and potential fracture on the metallic BPP. Therefore, consideration and assessment of tool wear is important especially for the high-volume production scenario.
In this study, a tool wear simulation model was developed in ABAQUS simulation software to alternate time consuming and resource intensive experiments. To predict the wear depth on forming tools in the sheet metal forming, where contact sliding and abrasive wear are prevalent, an Archard wear model was used as a governing equation. Predicted wear depth calculated from the governing equation was then updated on each mesh node by the geometry update scheme. The developed simulation model aims to provide insights into the wear patterns, anticipate the lifespan of tools, and enable proactive maintenance strategies. Furthermore, by considering factors such as geometry, material properties of tool and sheet metal and contact conditions, the simulation model aids in making informed decisions about tool selection and process optimization, contributing to improved efficiency and cost-effectiveness in high-volume bipolar plate production.