Verfahren zur Bestimmung der Reinraumtauglichkeit von Werkstoffpaarungen

Task When manufacturing and finishing products sensitive to particulate contamination, maximum permitted contamination levels need to be taken into consideration and checked. Both adapted airflow guidance for the extraction of particles and filtration technology have already been successfully implemented to reduce particulate contamination in production areas. Up till now, in order to reduce the generation of particles due to frictional abrasion from materials in production systems, suitable material pairings have been selected based on previous experience and on their visual appearance. To improve the procedure for selecting materials suitable for use in cleanrooms, a method is required which is capable of determining the cleanroom suitability of material pairings. Such a method requires development, realization and verification. State of the art Existing methods for assessing material pairings subject to frictional stress usually consider the abrasion of the material surfaces involved. However, when determining materials for their cleanroom suitability, it is the generation of particulate products of abrasion into the clean environment which is important. To date, no international standardized assessment procedures for this exist. The current test equipment technology for determining wear serves as a basis for developing a test bench adapted to cleanroom technology requirement criteria. A method for assessing particulate emission from material pairings with regard to cleanliness needs to be developed which is based on established parameters. Solution approach Based on the fundamental functioning principle of a friction measuring instrument, a test bench has been developed for applying reproducible sets of stress and recording the particle emission behavior of material pairings. To fulfill the requirement profile of a cleanroom-suitable friction particle test bench, different variants were tried out and selected. Using the test bench developed, particles generated as a result of frictional stress on material pairings under clean conditions can be counted and sized time-resolved and without the occurrence of cross-contamination. Mathematical cumulation and regression methods were combined when developing the procedure for assessing particle emissions from material pairings. This permits the material pairings to be clearly classified with regard to their cleanroom suitability. Both the test bench and the assessment method developed have been verified with the aid of experimental tests to ensure that they fulfill the requirement criteria set. Application of the method Verification experiments have shown that the requirement criteria are fulfilled by the method developed for determining the cleanroom suitability of material pairings. The procedure enables the pairings to be clearly assessed and classified. The method has already been implemented in numerous industrial research projects and thus represents a sound basis for its industrial application for determining the cleanroom suitability of material pairings