The Influence of WEDM Parameters Setup on the Occurrence of Defects when Machining Hardox 400 Steel

Abstract

The unconventional WEDM technology is a highly used technology for producing precise and indented shaped parts of all at least electrically conductive materials. This wide use makes this technology applicable in almost all branches of industry, even in the automotive industry, where the abrasion resistant material under investigation Hardox 400 steel is widely used for the manufacture of truck bodies. The aim of this study was a comprehensive analysis of the machinability of this material using WEDM employing a 33-round experiment. Based on the change in machine parameters (gap voltage, pulse on time, pulse off time, discharge current, wire feed), the cutting speed, the topography of machined surfaces, chemical composition of the workpiece surface, the morphology and condition of the subsurface layer including TEM lamella production and a subsequent determination of individual elements distribution in the given area were analysed. It has been found that while the machining of this steel many defects occur in the subsurface layer of the material in the form of cracks with a depth of up to 22 µm and burned cavities. However, by appropriately adjusting the machine parameters, it was possible to completely remove these cracks.

The unconventional WEDM technology is a highly used technology for producing precise and indented shaped parts of all at least electrically conductive materials. This wide use makes this technology applicable in almost all branches of industry, even in the automotive industry, where the abrasion resistant material under investigation Hardox 400 steel is widely used for the manufacture of truck bodies. The aim of this study was a comprehensive analysis of the machinability of this material using WEDM employing a 33-round experiment. Based on the change in machine parameters (gap voltage, pulse on time, pulse off time, discharge current, wire feed), the cutting speed, the topography of machined surfaces, chemical composition of the workpiece surface, the morphology and condition of the subsurface layer including TEM lamella production and a subsequent determination of individual elements distribution in the given area were analysed. It has been found that while the machining of this steel many defects occur in the subsurface layer of the material in the form of cracks with a depth of up to 22 µm and burned cavities. However, by appropriately adjusting the machine parameters, it was possible to completely remove these cracks.