When one of Italy’s most exclusive automakers decided to create an electric version of its premium sportscar, the engineering team knew it would need a high-performance electric battery capable of matching the power, speed and performance of its traditional counterpart. They turned to a Tier One technology provider to design and deploy the battery manufacturing lines, who in turn commissioned Comau to create a non-invasive quality control system. Comau’s innovative solution would combine thermal imaging and artificial intelligence to automatically test both electrical and mechanical properties during the module assembly process, helping verify the integrity of the high-voltage battery while minimizing module waste.
Comau was asked to design a technology solution that could be seamlessly integrated into a semi-automatic battery manufacturing process without impacting the cycle time or manufacturing layout. Unlike traditional end-of-line battery testing, in which each battery undergoes a series of charge and discharge cycles, the solution would need to verify the battery quality at a module level before closing and welding the entire pack. With each battery featuring 13 high-performance modules, the system would need to both verify the battery at a module level, and, in the case of failure, accurately identify which module or modules were not compliant with the customer’s specified tolerances.
Comau engineers first verified the number of individual cells in each of the battery’s 13 modules. These cells are structurally held together and electrically connected by numerous welded joints, for which the team quickly identified poor joint quality as a potential point of failure. Given that non-conforming joints can lead to an instable battery and possible safety risks, the team set out to design a system that could analyze both the mechanical and electrical resistance of the welded joints in a fast and efficient way.
Leveraging an infrared camera and neural network intelligence, the team built a hybrid thermography solution able to perform non-invasive melting pool inspection at a joint level to detect surface defects and automatically perform the quality control verification. The solution is based on the in-line acquisition of thermal images that are immediately pre-processed, cropped and analyzed via a previously-acquired knowledge-base. After receiving a trigger from the laser welding robot, the system automatically records the cooling phase and performs features-based analysis to assess the qualitative health of every single joint.
The non-destructive testing system was also designed to work within the existing manufacturing process, helping optimize workflow and protect cycle times. And because the thermal cameras analyze both visual and resistance defects before the final assembly process, any non-conformance can be fixed at a module level with no need to scrap the entire battery. Finally, the Comau-designed solution is fully integrated with the traceability system, allow it to collect all the process and quality information in a unique data management system and make them available in a simple, efficient and intuitive way.
Upon delivering the in-line solution to the technology provider tasked with building a 360° battery manufacturing process, both Comau and its customer immediately began putting the system to the test. The first result was achieved by the ease at which the innovative testing paradigm was seamlessly integrated within the assembly line.
The second result of Comau’s automated, non-destructive system can be seen in the improved accuracy of aesthetic defect detection, which often exceeds that of visual inspection.
Furthermore, as the high electrical resistance of a poor joint can create high energy loss and heat generation, it can also increase the joint temperature. This in turn can provoke potential safety issues in addition to reducing the battery efficiency. By automatically assessing the surface defects and the electrical resistance of each joint before final assembly, the Comau-designed solution is helping the final customer save time and costs.
Finally, real-time results of the process can be collected and used for analysis and re-training. And since the system is interconnected with the comprehensive data infrastructure, the customer can track eventual quality issues and make adjustments to the manufacturing process as needed.
For more information: www.comau.com