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Observation of the a-C:H run-in behaviour for dry forming applications of aluminium

: Abraham, T.; Bräuer, G.; Kretz, F.; Groche, P.

Volltext ()

Vollertsen, Frank (Hrsg.):
5th International Conference on New Forming Technology, ICNFT 2018 : Bremen, Germany, September 18-21, 2018
Les Ulis: EDP Sciences, 2018 (MATEC Web of Conferences 190)
Art. 14001, 9 S.
International Conference on New Forming Technology (ICNFT) <5, 2018, Bremen>
Konferenzbeitrag, Elektronische Publikation
Fraunhofer IST ()
metal forming; coating; tribology

Amorphous hydrogenated carbon coatings (a-C:H) are well known for their exceptional tribological properties and are established as tool coatings for numerous forming applications. However, utilized in dry forming processes of aluminium a premature failure of an a-C:H coated tool often occurs due to strong adhesive wear. In this paper the run-in behaviour of a-C:H is investigated and as a possible reason for the premature tool failure evaluated. Therefore, oscillating ball-on-disc tribometer tests and strip drawing tests, for a more realistic emulation of real forming processes, will be conducted. According to these tests, the run-in period of a-C:H coatings is characterized by a high friction value and adhesion tendency and thus is decisive for the tool performance. Based on a subsequent analysis of the coating wear, the predominating wear mechanisms during the run-in period are discussed. The intrinsic nanomater-scale a-C:H roughness is identified as a crucial factor determining the tribological properties of the run-in behaviour. By reducing the coating roughness prior to the forming process, the adhesion tendency and friction value can be reduced significantly. The results demonstrate the tribological performance of pre-treated a-C:H coatings for dry sheet metal forming of aluminium EN AW-5083.