Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 59 of 707

cleaning agent, and energy. Here the main focus is on Figure 2: State variables of a cleaning bath. maintaining the concentrations of the cleaning agent compo- nents (surfactant and builder), which are defined as optimal by the manager of the cleaning processes. The degree of con- sumption for both cleaning agent components, surfactant, and builder, is different and an ade- quate dosage for each compo- nent is required.1 The concen- tration of the cleaning agent components change constantly due to various reasons. For exam- ple, carry-over effects by the flow of parts, removal of cleaner com- ponents because of bath rege-ner- ation (e.g., ultra-filtration), or diluting processes over the cas- cade. Figure 3: Measuring the free surfactant concentration with bubble pressure tensiometers. Figure 4: Continuous measurement of the surface tension in a cleaning bath. An optimal match of all influ- encing parameters is the basis for economical and ecological process management. The required cleaning quality is only guaranteed if the process, the plant, and the cleaning chemi- cals are adapted to the part being cleaned and its contamination. This happens with the coopera- tion of the person in charge of the cleaning process working in concert with the cleaning agent manufacturer and plant manu- facturer, before putting a new plant into operation or prior to changing plants or processes. Desired process parameters, as well as the cleaning agent con- centration and its acceptable lim- it values, are determined on the basis of individual experiences, test runs, or optimization runs in a laboratory and/or produc- tion plants in order to reach the required cleaning quality. Currently, many cleaning agent components get strongly overdosed in order to ensure the cleaning power in baths. 58

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