Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 60 of 707

An analysis of the process management of cleaning metal parts was carried out by the Institute of Electromechanical and Electronic Design of the Dresden University of Technology to help understand the current processes employed and the state of technology in the industry. Therefore, managers of cleaning processes were asked about the specific cleaning task of parts and the corre- sponding process management. Here, the focus was on the European auto- mobile industry and its categories: car body; powertrain and their elements; hydraulic parts; and bearings. The following information could be deduced from conversations with 73 professionals from different companies: • Although cleaning quality is tested regularly by the majority (74%), it is mostly evaluated only with subjective methods such as visual inspection or by checking the quality of the subsequent process • Only 23% of those questioned inspect the cleaned surface through a measurement • The cleaning agent manufacturer cooperates with the plant operator in 51% of the cases regarding desired parameters of the cleaning agent concentration. In 14% of the cases, the cleaning agent manufacturer determines this value on its own. Consequently, it can be said that the determination of the target state of a cleaning bath is predominantly based on the experience of the chemicals manufacturer • In 84% of the cases, the plant operator controls the cleaning agent concentration. He is, therefore, responsible for the optimization of the current process • 78% of those asked monitor the builder concentration, whereas 79% of them monitor using titration • Only 49% monitor the surfactant concentration, and 51% of them use the surface tension measurementfor this value • 33% of the respondents have an automatic dosing system for the cleaner. Only 56% consider their dosing optimal • 38% of those questioned think about further optimization possibilities in the process management through bath monitoring and bath regenerationactions The analysis shows that the cleaning process of metal parts has not been ful- ly mastered in comparison to other production processes (e.g., mechanical pro- cessing). This especially applies to a continuous control of input and output para- meters, as well as the process parameters, in order to ensure stable part quality. The level of development of the process management for parts cleaning is in con- flict with the process reliability requirements because 83% of the people inter- viewed state, in detail, consequential damages due to process instabilities. This fact indicates that 83% of the professionals polled knew about the consequences of a deficient cleaning process. 59

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