Abstract
The quality of a forming process highly depends on the pressure applied to the workpiece. Consequently, the demand for higher workpiece qualities results in a demand for tools that can withstand high compressive stresses. Moreover, the tendency of using materials like high-strength steels as workpiece material, urges the need for tool materials that can withstand high compressive stresses and are resistant to wear. A class of materials that offer a combination of hardness or wear resistance and ductility are cemented carbides. However, these properties hamper their machining with conventional cutting technologies. Due to its electro-thermal working principle, Electrical Discharge Machining (EDM) is able to machine materials independently from their mechanical properties. On the other hand, the removal process is accompanied by thermal stresses, which can cause residual stresses and micro cracks near the machined surface. Due to their pre-existing stresses from the sintering process, cemented carbides are especially susceptible for these kind of damages. It is therefore necessary to identify the impact of EDM on the material. Different machining strategies are tested with two different types of cemented carbides and examined regarding their fracture toughness. The crack surfaces resulting from the three point bending test are microscopically inspected regarding failure initiation. Additionally pin-on-disc tests are conducted to determine the influence of the EDM strategies on the tribological properties of the machined cemented carbides.
Highlights
Forming processes become increasingly important in manufacturing due to the superb properties of formed parts and their material utilization [1]
Mechanical and tribological parameters of two cemented carbides grades machined by different electrical discharge machining strategies were investigated
The white layer was mostly reduced through super finishing while the crack length declined already after finishing and only slight improvements were made through super finishing
Summary
Forming processes become increasingly important in manufacturing due to the superb properties of formed parts and their material utilization [1]. One trend is the implementation of lightweight design, which utilizes higher-strength workpiece materials that enable parts with thinner wall thicknesses. These trends aim for net-shape part production, which reduces subsequent machining steps and has to create a variety of different shapes and produce parts with higher accuracy and lower tolerances. Both examples result in higher tool loads that reduce their durability [2, 3]. Conventional machining of cemented carbides is hindered due to the properties that
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