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Examination of sharpness protection effect of super hard amorphous carbon coating on knifes of hardened steel

Prüfung des Schärfebewahrungseffekts einer superharten amorphen Kohlenstoffschicht auf Messern aus gehärtetem Stahl
: Zind, S.; Dültgen, P.; Stucky, T.

Univ. Hannover, Institut für Fertigungstechnik und Werkzeugmaschinen:
THE Coatings in Manufacturing Engineering 2007 : October 25-26, 2007, Hannover
Garbsen: PZH Gesellschaft, 2007 (Berichte aus dem IFW 10/2007)
ISBN: 978-3-939026-64-8
International Conference THE Coatings in Manufacturing Engineering <6, 2007, Hannover>
Conference Paper
Fraunhofer IWS ()
amorpher Werkstoff; diamantähnlicher Kohlenstoff; gehärteter Stahl; Härte; Messer; Schärfe

The increase of cutting performance of knifes attempt to enhance the abrasion resistance of the edge, for example with coatings. Nowadays there are sporadic applications using hardened steel knifes for non-shape cutting, which use a coating of Titanium, Chromium or Titanium aluminium nitride. Thereby are friction minimizing and abrasion protection more important than cutting performance enhancement. The paper describes the results of studies with coated knives which use a super hard Diamond Like Carbon coating (DLC). The trials show that the amorphous carbon coating improves the cutting output of hardened knives. The research shows that the cutting performance of technical knives can be enhanced through coatings. The amorphous hydrogen-free carbon coating obviously improves the cutting output of hardened stainless steel knives. Coated machine-guided paper knives show a double cutting performance compared to uncoated knifes. Furthermore the tests have not been performed to the end so the difference in practice might be higher than the test results in laboratory. By the coated samples the aimed sharpness protecting effect occurs. The protection of one edge side leads to wear on the uncoated side thus minimize the widing of the edge breadth. Therefore the sharpness of th coated knife stays on longer. To achieve such good results it was very important to produce a very adhesive coating. For that reason the pre-treatment of the sample before coating has been adjusted for this special base material. The micro edged geometry and the coating properties have to be adapted for each application. An integrated view which takes all those parameters into consideration fails. Even though the results show that coatings can improve the cutting performance of hardened knives, further research is needed to understand the adhesion problems of the coatings at the small edge. The behaviour of the coated side is different to the free surfaces because of its unequal properties. The influence of the roughness and the sharping method is not scientifically defined. The effect to the coated side adhesion is not quite clear and subject of further research.
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