Tribological Behaviour of PVD Coatings for Sheet Metal Forming Tools: Laboratory and Industrial Evaluation

Abstract

In the last decades, Physical Vapour Deposition (PVD) and Chemical Vapour Deposition (CVD) processes have been significantly improved and optimized for the applications on dies for sheet metal forming processes. However, due to the different contact conditions at dies-blank interfaces, and the wide range of applied contact pressures, the selection of the correct coating may be still affected by trials-and-error approaches. Although many methods to evaluate the tribological performances of such coatings can be found in scientific literature, they often suffer of limitations in reproducing the interface conditions typical of industrial processes. The objective of the present research work is to investigate the tribological behaviour of two coatings deposited by PVD magnetron sputtering technique. Both investigations in laboratory and industrial conditions were performed: the former to evaluate their tribological characteristics, the latter to test the performances of coatings in production lines. The results, in terms of wear resistance, outline the comparison of the new technology with the performances of traditional dies.

Effect of Elevated Temperature on Tribological Properties of PVD Layers

“…Thickness of the deposited layers was determined by Calotest and reached 2.6 µm for TiAlNmulti layer and 1.8 µm for nACo layer. The method is described in detail in [18,19]. The roughness of the layers was tested by profilometer Hommel Tester T 1000 and achieved Ra = 0.09 µm for TiAlNmulti and Ra = 0.07 µm for nACo.…”

Novel Experimental Set-Up to Investigate the Wear of Coatings for Sheet Metal Forming Tools

“…A literature review on PVD and CVD coatings reveals that many efforts have been produced in studying and analyzing the performances of new coatings by different approaches and techniques. Some Authors compared the behaviour of different coatings using laboratory approaches, such as pin-on-disk tests [4,5,6,7], while others focused on direct observations made on production dies or developed specific on-field tests to reproduce accurately the same conditions of the industrial process, such as in [8,9,10]. Both the above-mentioned methodologies may provide useful information concerning the coatings performances, but the former are sometimes far from the industrial conditions and the latter result too much related to the specific process conditions.…”