Case Study
Leinfelden-Echterdingen,
Reliable particle detection
Early short circuit prevention through precise inline particle analysis.
Like all other batteries, mini batteries for in-ear headphones or hearing aids are at risk: If the smallest particles creep in between the electrode bands during production, this can lead to short circuits during operation. An edevis testing system uses laser thermography to check the particle load and thus ensures that the processes in the customer's production are validated.
Project Description
Motivation
The customer was a battery manufacturer with a cell production facility in the battery sector. In this facility, unwanted particles can be generated, e.g., by cutting processes. In order to validate and optimize the cutting and cleaning processes, the electrode tapes in production had to be randomly checked for particle contamination.
Task
The task was to use random samples to obtain information about the optimal manufacturing and cleaning strategy (compressed air, brushes, etc.). The detection of metal and coating particles on anode and cathode strip material using laser thermography was therefore an important step in validating the processes. The detection was to be carried out by heating the electrode strip using a laser line and a high-resolution fast infrared camera. In this way, metal and coating particles in the electrode material had to be identified quickly and reliably.
coating particles
metal particles
Challenge
Implementation was no easy task, as particles larger than 15 micrometers had to be detected. This corresponds to just a single pixel in image processing. The required specifications were successfully achieved using the imaging technique. However, size was merely a question of technical configuration. More challenging was the requirement that particle detection had to take place continuously in real time, which placed increased demands on image processing performance and on algorithmic conversion methods that had to transform continuous films into still images.
Solution
The test bench was designed and built by the customer. It consisted of two rolls, which guide the electrode tape through the small test area, only 10 mm wide, similar to a cassette recorder. There, the electrode tape is heated by a laser line and the warm-up is recorded by a fast, high-resolution infrared camera. Coating particles heat up more than the background, while metal particles do not heat up as quickly and appear dark. By evaluating several lines, the test system analyses the heating and cooling behaviour and thus delivers a robust result.
Implementation
The customer implemented the test bench on its own and invited edevis to participate at the decisive stage of the process. The test concept was based on experience gained by edevis in a previous research project. The evaluation software was then developed jointly with the research partner and in consultation with the customer. The solution was implemented on the test bench, programmed at the edevis partner's premises, and finally put into operation at the customer's site.
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