Session: 18-05: Advanced Manufacturing and Design II

Submission Number: 178056

Laser Welding Process and Fixture for Bipolar Plates in Fuel Cells for Electric Aircraft 

The aviation industry is committed to decarbonizing its operations to meet policy targets, such as the Paris Agreement and the EU Green Deal. In particular, Flightpath 2050's ambitious climate protection goals demand disruptive and revolutionary propulsion concepts. The use of proton exchange membrane fuel cells (PEMFCs) is a promising approach, enabling zero local emissions, especially for short‑ to medium‑range aircraft. The fuel cell functions as an energy converter, powering electric propulsion, which requires higher gravimetric power density and compliance with the stringent aviation safety and quality standards.

This paper focuses on the laser welding of bipolar plates (BPPs), a critical component of the PEMFC stack, made from titanium grade 1 and stainless steel 316L. The emphasis is on achieving reproducible weld seams with low heat input and minimal distortion. Parametric trials were conducted to determine the impact of process parameters (e.g. laser power, feed rate, and laser spot size) on seam geometry and porosity. The quality of the seams is evaluated through a combination of visual inspection and metallographic analysis. Visual inspection entailed the analysis of welds for surface defects, cracks, and surface profile. Metallographic cross-sections are used to characterize the heat-affected zone (HAZ), weld width, penetration depth, and defects.

Based on these results, the approach was applied to a representative BPP geometry. Particular attention is paid to fixturing and clamping. The clamping system was examined to minimize gaps and guarantee precise path control along complex contours while minimizing workpiece distortion and adhering to aviation-grade quality assurance standards.

The results of this paper provide guidelines on process parameter settings and clamping system design for BPP welding suited to bipolar plates in fuel cells for electric aircraft.

Presenting Author: Rainer Horstkotte Fraunhofer-Institute for Production Technology IPT

Presenting Author Biography: Research Assistant

Authors:

Patrick Sperling Fraunhofer-Institute for Production Technology IPT
Stefan Gräfe Fraunhofer-Institute for Production Technology IPT
Apoorva Nagarkar Fraunhofer-Institute for Production Technology IPT
Rainer Horstkotte Fraunhofer-Institute for Production Technology IPT
Florian Huesing Fraunhofer-Institute for Production Technology IPT
Sascha Gierlings Fraunhofer-Institute for Production Technology IPT
Christian Brecher Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University
Thomas Bergs Manufacturing Technology Institute (MTI) of RWTH Aachen University