Sensor-based system monitors component cleanliness
STUTTGART, Germany – Manufacturers in a wide variety of industries have strict component cleanliness guidelines to follow, and a new camera-based measurement system called PuriCheck could help them live up to those guidelines.
As components emerge from processing, they often have multiple layers of impurities deposited on their surfaces, such as lubricant residues or filings. If these particles are not removed, they can affect the quality and functionality of the products in which the components are later used. To date, there has been no built-in method with which to monitor the purification process. The effectiveness of cleansing procedures must be checked through random sampling of individual components emerging from each batch. The process is laborious: Employees must manually wash away any residual impurities by hand in the laboratory, capture the particles rinsed away in a filter and then analyze the results under a microscope. This method is too time-consuming and labor-intensive to permit a statistically relevant testing frequency.
The PuriCheck sensor system can be connected to all standard component-cleaning systems. Photo courtesy of ©Fraunhofer IPA
The PuriCheck system, developed by researchers at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA, will make future cleanliness controls simpler and much more efficient. “This is a sensor system that can be connected to all standard cleaning systems, where it will monitor rinsing baths, for instance,” said Dr. Markus Rochowicz, group manager for contamination control at Fraunhofer IPA.
It consists of an analysis sieve with a variable mesh width, along with integrated camera technology and software for image analysis. The sieve is installed directly in the flow of the rinsing bath to trap any particles larger than the chosen mesh width. A built-in camera records the surface of the sieve at freely chosen measurement intervals and passes the images along to the software, which, in turn, analyzes the size and quantity of particles and generates the results in tabular form. The individual steps are now automatic, so they no longer need to be carried out by hand. This means that the sample size can be increased considerably.
Optical counters of particles in fluid have been on the market for some time – but until now, equipment that works well under laboratory conditions is still not up to the task in the rough-and-tumble production environment. “The systems currently available are very sensitive to air bubbles or oil drops in the water, and that can significantly falsify the measurement result,” Rochowicz said. With PuriCheck, air bubbles or oil drops can simply slip through the analytical sieve, which keeps them from erroneously being identified as particles.
The functional principle has already proved itself in multiple pilot applications. The researchers have brought Nägele Mechanik GmbH, a company with a long history of project experience involving particles, onboard as a step toward a marketable product.