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Beschichtungen zur Verminderung der Umweltbelastung bei Umformprozessen. Teilvorhaben: Entwicklung und Charakterisierung geeigneter Schichtsysteme

: Taube, K.

Braunschweig, 1997
Reportnr.: BMBF 13 N 6194
Fraunhofer IST ()
aluminium; Beschichtung; Blechumformung; carbon based coating; clinching; coating; deep drawing; diamantähnlicher Kohlenstoff; diamond like carbon; Edelstahl; forming tool; friction; Fügen; galling; hardness; Härte; Kaltaufschweißung; Kohlenstoff-Schichten; lubrication; PACVD; PECVD; PVD; Reibung; Schmiermittelreduktion; Schmiermittelvermeidung; sheet metal forming; stainless steel; stamping; Stanzen; Tiefziehen; Titan; titanium; Tribologie; tribology; Umformwerkzeug; Verschleiß; wear

Coatings for avoidance of cold welding on forming tools are an interesting possibility to achieve production methods environmentally less harmful, to reduce costs by reduction of the consumption of lubricating agents and to increase productivity by fall away of washing processes between working steps. The aim of this project financed by the OSTec-programme of the BMBF was the evaluation of various carbon based coatings (pure amorphous carbon or diamond like carbon, known as a-C:H or DLC, metal containing amorphous carbon, known as Me-C:H) for sheet metal forming. Industrially established hard coatings are successfully applied in order to increase tool life time. But they failed to reduce necessary amounts of lubricating agents at materials difficult to form like aluminium, stainless steel or titanium. The coating systems investigated were deposited in DC, RF or pulsed DC excited PECVD and reactive PVD processes at tool temperatures below 200 deg C. In order to coat large tools of formi ng technology the further development and up-scaling of these processes (reactive DC magnetron sputtering of Me-C:H, pulsed DC PECVD of a-C:H) was one of the working items of the project. Various carbon based coating systems were deposited on laboratory samples as well as on testing and production tools, characterized with respect to their mechanical and tribological properties and investigated with respect to their performance in various forming processes. Pure carbon films could proof their potential for lubrication free working in a hard modification for working of stainless steel and titanium (deep drawing, bending, stamping) as well as in a softer modification for aluminium forming (bending, folding, stamping). At aluminium forming processes with a high forming degree a significant reduction of the amount of lubrication was possible (e. g. with deep drawing well below 1 g/m2). The absolute dry forming of aluminium requires further development of coating systems.