70 January/February 2024 | E-Mobility Engineering “There is always a trade-off between data quality and time investment, says an expert from our multi-technology inspection provider. “To achieve high resolution CT images, cycle time can be a barrier for some inline inspection requirements. X-ray based imaging also can struggle with inspections of samples with multiple materials of different density. Batteries are sometimes difficult to image due to the mixed materials inherent in their design.” Radiation safety is always a concern, she adds, so X-ray inspections are conducted within an enclosed cabinet. This provides safe working conditions but also can limit the size of samples that can be imaged. For example, cells are easily imaged, but large modules can be problematic, and while complete EV packs can be imaged, they require the extremely expensive solutions based on linear accelerators. Cameras, including infrared thermographic sensors, always need a line of sight to the item being inspected, and all optical systems depend on lighting. Most optical systems today use visible light sensors, including red-greenblue (RGB) cameras, according to the expert from a camera-based inspection system provider, but this is changing. “We see more applications moving to other sensors such as NIR (near infrared) or ultraviolet (UV) in different wavelengths,” he says. He adds that the company has developed what he terms a multispectral camera/light that provides illumination in and detection of RGB and near infrared (NIR) light at the same time, initially for inspection of printed circuit boards (PCB). “NIR has a longer wavelength and it penetrates into silicon or other materials. Visually, you cannot see the defect because of the paint, but the NIR can penetrate that paint and detect the defect underneath.” Evolving inspection ecosystem The integration of these technologies into the processes of battery manufacture varies among manufacturers, and is currently limited. However, another expert reports a discernible uptick in interest and is discussing the implementation of an “ecosystem” for management and archiving of inspection data. This is a software suite designed to facilitate a streamlined and organised integration of inspection technologies into the broader battery manufacturing processes. They remark: “the evolving interest in integration indicates a growing recognition of the importance of seamless incorporation of inspection technologies into the manufacturing workflow.” Physical integration of optical inspection systems, for example, involves the installation of cameras and lighting systems on or near the production machinery, so the systems have to be very flexible and customisable, according to our optical inspection systems expert. He says most current systems are general in nature rather than specific to battery inspection. He adds that a one-size-fits-all inspection system would be ideal, but is very difficult to achieve. “Different applications have different requirements for speeds, resolutions and lighting, based on the material under inspection.” Many of the 3D inline CT provider’s solutions are used in labs or as close as possible to the production line, and current applications are fully integrated into the line, typically located after hot pressing or canning stages in the manufacturing process. The company is working with customers to integrate CT technology as early as possible into the production line. “This signifies a shift towards more proactive and pre-emptive inspection methodologies,” this expert says. Essential to this process is the provision of interfaces to different customers’ manufacturing execution systems (MES). “This facilitates the exchange of information and enables fast interactions at scale, allowing for immediate adjustments and responses based on inspection results,” he adds. With cross-platform software and data storage solutions, the instrument status and resulting data can be shared, processed, traced, and archived. Finding root causes Information generated by inspection technologies plays a pivotal role in addressing and rectifying issues within the manufacturing process. “When defects are identified, this information often serves as a key indicator of the root cause, or significantly contributes to the root cause analysis,” says one expert. “Subsequently, the manufacturing process or materials can be adjusted based on the insights gleaned from the inspection results. This iterative approach to problem-solving Focus | Battery inspection Machine vision cameras such as this Teledyne FLIR Blackfly CS commonly use the GigE interface standard that enables high-speed transfer of video and control data over Ethernet (Image courtesy of Teledyne FLIR)
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