Fuel cell technology has been regarded as a niche sector for a long time. In the interim, demand has grown substantially, but higher throughput when welding metallic bipolar plates, which constitute the stack of a fuel cell, is required for efficient mass manufacturing.
Fast scanning systems and high-power lasers, both of which are now available, are required for high welding rates. The welding process, however, is the determining element in the speed that may be achieved. When a specific speed is surpassed, defects in weld seams such as “humping effects” and undercuts are common.
In a test configuration, Blackbird Robotersysteme used the Flexishaper Intelliscan 2D scan head. Scanlab and Holo/Or have released Flexishaper, a beam shaper that can be modified over the whole power spectrum. A process simulation was used to estimate the required beam shape. The beam shaper was created using a combined optical design that included diffractive optical elements (DOE) and a scanning system. The speed limit for error-free welding was changed from 45 m/min to up to 70 m/min as a result of the application testing.
Process demands are high
Welding thin sheet metal for bipolar plates puts the machining process under comparable stress as laser powder bed welding (LPBF). Both approaches necessitate a scanner image field of up to 500 × 500 mm2 and a processing speed of 1 m/s or less. Even with metal 3D printing, the scanning equipment or laser power does not limit the processing pace; rather, the process itself establishes the throughput constraints. As a consequence, the appealing laser welding outcomes are the first step toward enhancing LPBF operations.
The next step is to test the notion of laser welding on a bigger scale, as well as to explore many applications at the same time. Fibersys from Scanlabs is specially built to fulfill the requirements of both LPBF and welding operations. As a result, the development plan included the integration of DOEs into this scan system, which was specifically intended for usage in multi-head machines.
