Adaption of tribological behavior of a-C:H coatings for application in dry deep drawing

Abstract

Nowadays the sheet metal forming industry faces challenges regarding efficient usage of resources and sustainability. One strategy to increase the environmental friendliness is to abandon the application of lubricants. The direct contact between tool and workpiece leads to an intensive interaction which increases friction. Especially for deep drawing processes with long sliding distances, this causes distinctive wear. The tool sided application of carbon based coatings is a well-known approach to reduce friction and wear. Former studies have shown a beneficial behavior of hydrogenated amorphous carbon based coatings (a-C:H) to improve the tribological conditions in contact with steel sheets and aluminium alloys under dry conditions. Within this study the coating process and the resulting coating properties will be analyzed. Afterwards mechanical and laser based surface treatment processes prior and after the deposition process will be investigated to reduce the coating roughness. Different roughness values were achieved by varying the surface treatment processes. The laser based finishing enables a reduction of the Spk values by removing single roughness asperities. In order to identify the necessary process parameters for the laser treatment, an analytical model of the material removal was applied. The laser surface treatment achieved similar roughness characteristics compared to mechanical treatment. In this study the tribological behavior of a-C:H coated tools was analyzed under dry conditions within strip drawing tests. The tribological investigations revealed that for dry deep drawing of zinc coated DC04 a broader range of Spk values leads to acceptable tribological conditions whereas for AA5182 a smoother tool surface has to be ensured to prevent adhesion and utilize the full potential of a-C:H coatings.

Advances in friction of aluminium alloy deep drawing

“…And it can extend the service life of die while improving the forming quality of part. In the AADD process, due to excellent wear resistance and lubricating properties of carbon-based coating, it has received a great deal of attention from researchers [50,52,53,62,71,[155][156][157][158]. Hydrogenated amorphous carbon (a-C:H)-based coatings, also known as diamond-like (DLC) carbon coatings, are carbon-based coatings commonly used by AADD.…”

Design of Amorphous Carbon Coatings Using Gaussian Processes and Advanced Data Visualization

“…An example of a complex process is the coating of metal and plastic parts, as used for joint replacements, with amorphous carbon coatings [5]. In the field of machine elements [6,7], engine components [8,9] and tools [10,11], amorphous carbon coatings are commonly used. In contrast, amorphous carbon coatings are rarely used for load-bearing, tribologically stressed implants [12,13].…”