Wear mechanisms and surface engineering of forming tools

Abstract

The manufacturing of parts is faced with ever-increasing demands for higher strength (hardness) and toughness of the work material, as well as higher productivity and environmental concerns. At the same time, the quality requirements are high and will continue to grow in the future. This leads to restrictions in terms of the type and use of lubricants and especially to increased requirements relating to the wear and fatigue resistance of tools. The main focus on improving the wear resistance and tribological properties of forming tools has mainly been on developing tool steels with an improved fracture toughness and then modifying the lubricants for better retention and permeability at the tool/work-piece contact area. Nevertheless, the wear resistance of forming tools can also be successfully improved by surface-engineering techniques. In recent years, hard coatings in particular have shown enormous potential for improving the tribological properties of contact surfaces. This paper reviews the wear mechanisms encountered in forming processes, as well as various surface-engineering techniques designed to improve the wear resistance and the anti-sticking properties of forming tools. The possible benefits and restrictions of different surface-engineering techniques are presented for the example of sheet-metal forming, fine blanking and forging.