Recent Developments in Biological, Structural and Functional Thin Films and Coatings: Lubricant-free Forming Processes
Sponsored by: TMS Functional Materials Division, TMS: Thin Films and Interfaces Committee
Program Organizers: Adele Carrado, University of Strasbourg; Heinz Palkowski, Clausthal University of Technology; Gerald Ferblantier, University of Strasbourg - IUT LP / ICube Laboratory - CNRS; Ramana Chintalapalle, University of Texas at El Paso; Nuggehalli Ravindra, New Jersey Institute of Technology; Nancy Michael, University of Texas at Arlington; Vikas Tomar, Purdue University
Monday 8:00 AM
February 24, 2020
Room: Oceanside
Location: Marriott Marquis Hotel
Session Chair: Heinz Palkowski, TU Clausthal
8:00 AM Keynote
Coated and Structured Tool Surfaces for Lubricant Free Forming Processes: Thomas Seefeld1; Adrian Ditsche1; 1BIAS - Bremer Institut für angewandte Strahltechnik GmbH
From economic and ecological points of view, the avoidance of lubricant usage in metal forming is desirable. The key challenge however is to influence the workpiece-tool interaction to be able to avoid friction and wear under dry metal forming conditions. This contribution will give an overview the various approaches taken within the Dry Metal Forming Priority Programme that was launched in Germany back in 2013 and review a selection of the outcome after 6 years of research that involved a total of 25 research partners within 13 research projects. Approaches include coatings like diamond and DLC or self-regenerating coatings, macro- and micro-structuring of tool and workpiece surfaces, as well as application of volatile lubricants and electric currents.As one example highlighted in more detail, an MMC deep drawing tool surface will be presented that is produced by laser melt injection of hard particles followed by subsequent laser ablation.
8:40 AM Invited
Deposition of Nanoscopic Smooth DLC tool Coatings for Dry Forming of Aluminum Sheets: Tim Abraham1; Ingmar Bialuch1; Günter Bräuer1; Felix Flegler2; Peter Groche2; 1Fraunhofer-Institute for Surface Engingeering and Thin Films; 2Darmstadt University of Technology, Institute for Production Engineering and Forming Machines
Diamond Like Carbon (DLC) coatings are well known for their tribological properties combining a high wear resistance with a low friction coefficient in contact with numerous materials. Recent investigations demonstrated the applicability of DLC as tool coatings for dry forming of aluminum sheets, which is a very challenging application field due to the high adhesion tendency of aluminum. However, an exceptionally low roughness of the coated forming tool is required to prevent a formation of aluminum adhesions and a rapid tool failure. To establish dry forming of aluminum in industrial production processes, efficient methods have to be developed to manufacture DLC coated forming tools with a reproducible high surface quality. This presentation illustrates two deposition processes, which are especially optimized for the deposition of nanoscopic smooth DLC tool coatings. The coating performance will be subsequently demonstrated in deep drawing tests of aluminum sheets.
9:10 AM Invited
Impact of Peak Material Volume of Polycrystalline CVD-diamond Coatings on Dry Friction against Aluminum: Markus Prieske1; Annika Bohlen1; Frank Vollertsen1; 1BIAS - Bremer Institut für angewandte Strahltechnik GmbH
For economic and environmental reasons, dry forming is of increasing interest due to the shortening of process chains, cost savings and reduction of environmental pollution. The aim of these investigations is to examine to what extent CVD-diamond coatings are suitable for the dry forming of aluminum alloy AlMg4.5Mn and to identify the surface topology requirements for a low friction coefficient and low wear. Nine different surface topologies of CVD-diamond coatings were tested in an oscillating ball-on-plate tribometer test against aluminum balls with a Hertzian contact stress of 760 MPa and 99,900 cycles. It could be concluded, that the peak material volume Vmp of the diamond coating is the most important factor to achieve a low abrasion of aluminum as well as a low friction coefficient against the aluminum. The Vmp should be smaller than 0.04 ml/m². Microcrystalline CVD-diamond with a post-treated surface has great potential for dry forming of aluminum.
9:40 AM Break
10:00 AM Invited
Dry Deep Drawing of Aluminium and the Role of Sheet Metal Roughness: Felix Flegler1; Peter Groche1; Tim Abraham2; Günter Bräuer2; 1TU Darmstadt Institute for Production Engineering and Forming Machines; 2Fraunhofer Institute of Surface Engineering and Thin Films IST
Dry forming processes are associated with major challenges, especially when it comes to aluminium as a material. The high tendency to adhesion to common tool materials makes it possible to eliminate lubricants only with major losses in process quality and robustness. Coatings based on amorphous hydrocarbons (a:C-H) can significantly reduce wear behavior. In previous investigations, a reduction of the sheet roughness based on the native mill-finish surface showed a significant improvement with regard to the friction and wear behaviour in the strip-drawing test. These tests are now transferred to a real work piece. First, the different zones of the deep drawing process are modelled in the strip-drawing test. While in the area of the drawing ring, the smooth sheet surface is virtually wear-free and characterized by a low coefficient of friction, in the blank holder area adhesions of aluminum are observed despite significantly lower tribological loads.
10:30 AM Invited
Advances in Dry Metal Forming using Volatile Lubricants Injected through Laser Drilled Microholes: Gerd Reichardt1; Manuel Henn2; Mathias Liewald1; Rudolf Weber2; Thomas Graf2; 1Institute for Metal Forming Technology; 2Institut fuer Strahlwerkzeuge
Conventional production of deep-drawn parts requires lubricants to prevent damage to components and tools. These lubricants must be applied before forming and washed off afterwards to enable subsequent processes. Furthermore, some of these lubricants can be harmful to humans and the environment. To counteract these disadvantages, a new tribo-system has been developed, using volatile media as lubricants. These media are injected directly into the friction zones via laser-drilled microholes integrated into the tool to reduce friction and prevent damage to contact surfaces. This article presents the latest findings from the field of ultrashort pulsed laser drilling, in which microholes with a depth of several millimetres and high aspect ratios are produced in hardened tool steel. Additionally, the latest advances in the characterisation of the novel tribo-system using stretch bending tests will be shown, as well as investigations on the influence of surface properties on friction conditions.
11:00 AM Invited
A Thermoelectrically Based approach to Reduce Adhesive Wear during Blanking: Markus Welm1; Philipp Tröber2; Hannes Alois Weiss1; Peter Demmel3; Roland Golle1; Wolfram Volk1; 1Technical University of Munich, Chair of Metal Forming and Casting; 2Technical University of Munich; 3MAN Truck and Bus AG
Almost every metal mass product go through a blanking process. Especially when processing aluminum, adhesive wear determines the cost efficiency. Many investigations on wear influencing factors were conducted so far, but one major determinant is almost unnoticed, the Seebeck effect. Due to this phenomenon, thermoelectricity occurs in every blanking tool. Recently published investigations show that the combination of tool and workpiece material has an influence on occurring thermoelectric currents and thus on adhesive wear development, whereby the current strength mainly depends on the material-specific Seebeck coefficient. This paper addresses the same phenomenon for a wider parameter spectrum. Blanking experiments with the aluminum EN AW 5083 were performed measuring both thermoelectric currents and the amount of adhesive wear. A variation of the tool material between the high-speed steel 1.3343, the stainless steel 1.4301 and the cemented carbide CF-H40S confirms the strong relation between Seebeck coefficients, thermoelectric currents and tool wear.
11:30 AM Keynote
Selective Oxidation of Tool Surfaces – An Approach to Reduce Friction and Wear in Dry Metal Forming: Hans Maier1; Bernd-Arno Behrens1; 1Leibniz Universität Hannover
The avoidance of lubricants in metal forming processes is attractive for both economic as well as ecological reasons. In the present study, oxide layers formed on steel tool surfaces were used as separation layers and their potential with respect to dry metal forming was evaluated. In the experiments, high strength sheet metal was drawn in a wear test bench over both conventional as well as powder metallurgical tool steels. Light and electron microscopy were used to shed light on the wear mechanisms and characterize the wear behavior. The α-Fe2O3 oxide layer formed on the tool steel surface provided for a low friction coefficient and acted as an effective layer that reduced wear of the tool. Substantial difference in wear behavior between the conventional and the powder metallurgical steel grade were observed. These could be attributed to the different microstructural constituents present at the tool surface.