Impurities adhering to the surface of components can cause problems in later stages of a production process – or even render the entire component useless. A new fluorescence scanner developed by the Fraunhofer Institute for Physical Measurement Techniques IPM allows specialists to achieve 100% inspection of metallic parts for residues of grease, machining chips and cleaning agents.
The smallest of details can have huge consequences. For instance, tiny particles of dirt clinging to the surface of components. The oil pan in vehicle engines is a typical example. If the process lubricant contains impurities that stick to the areas where the sealant will be applied, the seal will not be tight and the oil pan is likely to leak at this vulnerable point. Until now, it has not been technically possible to examine every single component for residual contaminants. The only solution was to test random samples, which is not only time-intensive but is also unreliable.
“The outstanding spatial resolution of this system enables us to identify even the slightest deposits or films of less than 10mg/m2,” explains Andreas Hofmann, Business Development Manager at Fraunhofer IPM.
The metallic component itself does not reflect beams of fluorescent light. But if traces of grease, remains of organic cleaning fluids, or fibres are detected on the surface, they reflect light in the visible fluorescence spectrum. A sensitive detector that captures these light frequencies ignores all other wavelengths, and is thus able to interpret the fluorescence signals as signs of contamination.
The laser beam scans the object at a rate of approximately 200 times per second. As a result, the quality controller receives an image showing precisely where any dirt particles or oil films have been detected.