Cyan Tec Systems recently played a key role in battery stack production for a large automotive manufacturer.
Following the assembly of EV battery stacks – a number of battery cells compressed together on a standard platform – the terminals were laser cleaned before the battery was fitted with busbars and a pair of harnesses to complete the assembly. The battery stack was presented in an optimal position for laser cleaning, where a servo-driven gantry system placed the laser head in front of each of the terminals, triggering the cleaning process.
Once cleaned, the battery stack was fitted with busbars – various versions depending on the type of battery – which mechanically link the terminals together. The busbars, located in a carrier system, were fitted loosely prior to welding, and therefore relied on dedicated clamping tools (also designed and manufactured by Cyan Tec) to apply the required force to the terminal/busbar/harness area. This process is critical to laser welding as any gaps between the two materials will produce an unsatisfactory weld.
A gantry system was again used to move the laser head in front of the accurately positioned battery stack. An intelligent vision camera checked that the battery terminals and busbars were in the correct position prior to the initiation of laser welding. When the vision system confirmed a satisfactory scan, a penetration weld was performed on each busbar and terminal within the stack. The laser welding was repeated for both sides of the stack before the product was removed from the laser station.
Once the busbars were welded in place, a harness was fitted to either side of the battery stack, used for diagnostics once the stack is integrated into a vehicle. The harness welding used the same principle where a gantry system was used to position the vision system in front of the battery stack and upon verification, the laser was initiated to perform a spot weld on each tab on the harness.
All three of the laser processes described above were performed using a fibre laser, with dedicated optics to suit the application. Ranging from 1 kW up to close to 4 kW, the laser output power varies for each process.
Contact: Tony Jones