Machine vision accelerates battery production

High speed, precision, and reliability: These are the determining factors for battery production. To meet the rapidly growing demand for batteries, companies are developing increasingly efficient production processes. Laserax has developed a new system in which the laser welding of battery cells is significantly accelerated using the standard machine vision software MVTec HALCON.

With the “Battery Welding Machine”, Laserax from Quebec, Canada, has developed a system that significantly accelerates the automated robot-based welding of the current collector and busbar to the battery module. The company, founded in 2010, has developed an efficient welding solution for a critical production step in battery manufacturing. Thanks to the μm-precise robot guidance provided by the integrated machine vision software MVTec HALCON , battery modules can now be produced significantly faster and with less waste. The solution is suitable for the production of batteries for the automotive industry, automated guided vehicles (AGV) in logistics, e-bikes, and power tools. “We are in close contact with our customers from the battery industry. We have realized that they are specifically looking for a solution to weld the current collector and the busbar to the battery module. Although there were already other methods for connecting, these could not offer the necessary speed and quality. That’s why we developed our own system for this process, based on laser welding,” says Keven Tremblay, Product Line Manager at Laserax.

The result is the so-called ‘Battery Welding Machine’, in which four SCARA robots successively clamp the contacts of battery modules and connect them using a laser welding process at a very high speed and with little waste. This new process is made possible by Laserax's ingenious engineering and machine vision. The utilized machine vision software MVTec HALCON can localize the cells of the battery module with micron precision, enabling the robots to perform the clamping and laser welding work with absolute precision.

The challenge for the system: high speed, precision, and 100 percent objective

There are three main challenges in the complex processes of battery production: First, the processes must be very fast. Second, quality must not suffer as a result, so that the battery achieves the desired performance and longevity. Third, the traceability of components and production steps is very important.

Until now, established methods such as ultrasonic bonding or welding methods such as spot or resistance welding were used to connect the current collectors and busbars to the battery module. Laser welding has numerous advantages over these methods: among other things, it is highly accurate, even when connecting the smallest components, and produces minimal distortion as the heat input is low. “We knew that the entire system, including the laser welding and the fast, adaptable clamping had to be considered as a single system. We rely on the machine vision software MVTec HALCON for precise and fast operation,” says Keven Tremblay.

Four robots optimize welding of the current collector to the module

At the beginning of the workflow, a module is delivered to the system and fed into the “Battery Welding Machine” through an opening on the side. There are four robots that carry out the busbar clamping and one gantry-mounted laser head with larger field of view to perform the laser welding. Two cameras are mounted on the side of the laser scan head to allow 3D stereoscopic vision. In the first step, the two cameras take high-resolution images of the battery module on a 400 x 400 mm area from above. The machine vision software HALCON then calculates the X-Y-Z positions of all the cells by merging the images from the two cameras. The coordinates determined in this way are transmitted to the clamping robots and the laser system. The precise position of each spot to be welded on the battery cells is found and determined with very high accuracy. This is not as easy as it seems, as Keven Tremblay explains: “The workspace of 400 x 400 mm is quite large. Determining the individual positions in the μm range is technologically extremely challenging.”

The robots clamp the current collectors onto the battery cells, while the laser welds the clamped components one after the other. The machine works with four robots to maximize the operating time of the laser. Weld quality monitoring is performed during the welding process using a specially designed sensor.

Laser welding based on machine vision: more energy for battery production

“The ‘Battery Welding Machine’ is now being used by our customers. The feedback we have received has been consistently positive. Above all, our customers appreciate the fact that they can now produce much faster and maintain quality and versatility. This means that our solution has hit the nail on the head,” says Keven Tremblay at Laserax.

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