ZERMEG II – Zero emission retrofitting method ... - Fabrik der Zukunft

7 Case studies7.1 A. Heuberger Eloxieranstalt GmbHThis company with its 24 employee is a typical Austrian SME. The number of employees haschanged from 15 to 24 in the last years. The production has increased from originally 20.000m²/year to 60.000 m²/year.The company anodises aluminium surfaces. In this process the aluminium surface isconverted to an oxide film. The generated dense and hard surface is perfectly connectedwith the ground material. It protects the anodised aluminium to a large extent fromcorrosion and abrasion. Almost all aluminium alloys can be anodised. The enterprise workson parts of most diverse origin. The spectrum covers profiles for fassades, windows andsolar panels, sheet metals, but to a large extent also small articles (parts for transmissionsand engines, exhaust systems, parts for bicycles, parts for mechanical engineering and partsfor the medical technology) are produced as well.The basic materials strongly affect the quality of the coatings, therefore surface treatmentmust be co-ordinated with the respective material. This covers also an intensive degreasingof the parts, which typically are received oily and greasy. By different procedures oxidecoatings can be manufactured, which meet decorative and certain functional requirements.During this work the average grease and oil film of the material, coming from the customers,was determined. It could be shown that polished parts are practically grease and oil-free,while mechanically treated parts and sheet metals showed an average oil rate ofapproximately 1 g/m² surface.After degreasing in a light alkaline bath the parts are pickled in caustic soda solution. Thus ametallic surface is produced. After pickling the parts are rinsed.This is a critical process, since the adhering pickling solutions must be completely andrelatively rapidly removed from the workpieces, in order to avoid uneven surfaces fromexcessive pickling. Since the pickling solution is very viscous, a relatively thick liquid filmsticks to the surface when the parts are taken out of the pickling tank.The drag out was subject to more exact investigations. It was shown that after the picklingthe drag out was several times higher than expected. After rinsing the aluminium parts theyare immersed in an electrolyte of sulphuric acid. By directly applying an electric current anoxide coating is produced. By selecting different electrolytes, current and bath parametersanodically produced oxide coatings can receive very different characteristics for a variety ofrequirements.17