Product cleanliness (purity) testing is a very important element in the quality assessment of many components used in the automotive industry (and beyond). Such tests are carried out in a clean room of ISO 6 cleanliness class (according to ISO 14644) and the basic factors determining the purity of the test object are: mass of insoluble impurities, mass of soluble impurities, amount of insoluble impurities of a certain size and type of contamination. In the case of insoluble impurities, it is possible to divide them according to their nature: metallic, non-metallic and fibres, as well as by chemical composition. In order to determine these properties, an appropriate method of extracting pollutants is selected: shaking, pressure washing, ultrasonic techniques, washing on functional test benches reflecting the working parameters of the test object. The choice of the method depends on the characteristics of the test object and on the specified properties: internal/external/overall purity.
Separated pollutants are analyzed by the following methods:
- weight – the mass of contamination
- microscopic – the quantity and size of the contaminants
- scanning electron microscopy – the composition of the impurities
- infrared spectroscopy – the composition of the impurities