Investigations on optimization of the cutting edge of twist drills for the machining of the high temperature resistant nickel-based alloy Inconel 718

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The applied project is the continuation of the last DFG project. Within this framework, extensive investigations were carried out to analyse the loads occurring during the drilling of Inconel 718. Especially the thermomechanical loads on the tool cutting edge and the contact zone between tool and workpiece were investigated in order to gain insights into the drilling process. Based on the obtained results, drilling tools were developed, manufactured and used which have a geometrically simple retraction on the flank face. This modification led to significant increases in tool life, especially when parameter sets were applied that feature an increased productivity. Therefore, the aim of this project is to further develop the basic concept of a retraction on the flank face by yielding geometric structures onto it which serve to channel the cooling lubricant flow and effectively guide it towards the cutting edge.By means of detailed simulative and experimental analyses, the cooling lubricant flow as well as the resulting mechanical and thermal interactions at the cutting edge are first investigated in order to evaluate the effects of the already developed flank face retraction. On this basis, a targeted design of complex flank face structures is carried out taking into account the feedback from a Computational Fluid Dynamics (CFD) simulation. The tools developed in this way are then manufactured either by laser or grinding and evaluated in experimental tests. In addition to basic tool life tests, analyses of the resulting thermal loads and investigations of the influence on the cooling lubricant flow are carried out in order to verify the simulatively determined advantages of the complex flank face structures.