requirements. Subsequent process When choosing cleaning techniques, cleaning agents and cleaning processes, the subsequent processes, i.e. the further processing of the cleaned parts, is of special interest. The classification follows basically the metal work theory: Machining Cutting Joining Coating Heat treatment Assembling Measuring, testing Repairing, maintenance In time, empirical values were established, how efficient the cleaning has to be, to assure the processes for the particular guarantee period and beyond. Choosing the cleaning method often starts from here. Challenges and trends The details above illustrate how extremely complex this specific field is. Already small changes in the requirements can cause completely different processes. Thus, it defies scientific, technical determination. It becomes more and more important to receive the required cleanliness as cost-effective as possible and with continuously minimized health and environmental risks, because cleaning has become of central importance for the supply chain in manufacturing. Applying companies usually rely on their suppliers, who—because of a big experience base—suggest adequate equipment and processes, which are then adapted to the detailed requirements in tests stations at the supplier’s premises. However, they are limited to their scope of technology. To put practitioners in a position to consider all relevant possibilities meeting their requirements, some institutes have developed different tools: SAGE: Unfortunately, no longer in operation, the comprehensive expert system for parts cleaning and degreasing provided a graded list with relatively general processes of solvent and process alternatives. Developed by the Surface Cleaning Program at the Research Triangle Institute, Raleigh, North Carolina, USA, in cooperation with the U.S. EPA (used to be available under: http://clean.rti.org/). Cleantool: A ‘Best Practice’ database in seven languages with comprehensive and specific processes, directly recorded in companies. It contains furthermore an integrated evaluation tool, which covers the areas of technology, quality, health and safety at work, environmental protection and costs. Also included is a comprehensive glossary (seven languages, link see below). Bauteilreinigung: A selection system for component cleaning developed by the University of Dortmund, assisting the users to analyze their cleaning tasks regarding the suitable cleaning processes and cleaning agents (German only, link see below). TURI, Toxic Use Reduction Institute: A department of the University of Lowell, Massachusetts (USA). TURI's laboratory has been conducting evaluations on alternative cleaning products since 1993. A majority of these products were designed for metal surface cleaning. The results are available on-line through the Institute’s laboratory database (English only link, see below). See also