Optimizing moulds and stamping processes for bipolar plates used in fuel cells

 Optimizing tools for stamping processes, finding the right process parameters and ramp-up forming production of sheet metals is a big topic in manufacturing industry, especially for those segments heavily handling sheet metals. This experiment is specifically looking into bipolar plates for fuel cells, an emerging market contributing to renewable greener energy supply, e.g. for Fuel Cell Electric Vehicles (FCEV). However, to gain market share, fuel cell production costs need to decrease.

 

Challenge
The process at Borit currently implemented does not involve simulation software for the forming process. Borit starts with creating the geometry of the bipolar plates in CAD. The corresponding tool geometry is also created using CAD software. The tool is then manufactured based on the CAD design. The mould is tested ‘on press’ and the design is iteratively altered until the plates have the intended nominal shape. This iterative process can take up to 6 to 8 weeks for just one plate depending on the plate complexity.
The manufacturing challenges are related to the quality of the resulting bipolar plates, e.g. not fully formed plate features and/or local rupture of the plate material. The simulation challenges are related to the accuracy of the model. A high fidelity simulation tool that can cut down the number of iterations needs to be found that responds in reasonable time using affordable compute resources. In addition, a simulation model needs to be defined that captures the plate behaviour with high enough resolution representing features like small radii and narrow channels.

Benefits
The experiment result is expected to close the loop between the Design Engineering Process and Manufacturing Life Cycle by the development of surrogate models based on high-fidelity simulation with approximately 30 percent of time reduction for the trial-and-error process (2 to 3 weeks faster than the current 6 to 8 weeks) and significant improvements to the manufacturing quality. Moreover, it is expected to reduce the scrap rate from 5 to 2 percent; potentially € 10,000 per year of avoided scrap. With the introduction of simulation and optimization tools more complex and challenging designs can be handled thus motivating Borit to come up with innovative shapes for their bipolar plates that further improve product performance.

Faster engineering based on better simulations will allow the end user Borit to reduce the design time (value 10 k€/iteration). Based on the product complexity, up to 8 iterations can are required for a new product. Reducing this by 25 percent, adds up to € 70,000 to € 100,000 per year for five new products, to reduce the amount of non-productive (test-)time on the press (100 €/h). Virtual testing can reduce the test hours on press (8 hours/test) also by 25 percent - a total reduction of 7 to 10 days can be achieved which equals € 6,000 to €8,000 per year, to reduce the number of tools to be produced (value up to € 20,000 per tool). For five new products (average complexity) Borit expects a reduction of 5 to 7 test tools and to reduce time to market (value for the fuel cell manufacturer). Moreover, quality-improved forming capabilities and increased customer satisfaction will attract additional customers. This may create additional revenue of several hundreds of thousands of € per year. The reduction in design time and total time to market will allow the existing employees to handle more projects per year.

Organizations involved
BORIT - Belgium
NOESIS - Belgium
Arctur - Slovenia