Untersuchung der Span- und Gratbildung beim Mikrobohren

• Applicant: Professor Dr.-Ing. Jan C. Aurich
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 453335596

Micro-drilling is becoming more and more important due to the short process time, the excellent hole quality and the large number of machinable materials. At the same time, the continuous miniaturization of components requires a further reduction of hole diameters. However, the process is characterized by process-related burr formation at the drill entry and exit. Especially in the range of D < 300 micrometers, it is of high importance to achieve as good as possible chip formation and an associated low burr formation, since subsequent deburring is in many cases not at all possible. The relationship between tool geometry, process parameters and chip and burr formation with tools with a diameter of less than 300 µm has not been researched so far. This knowledge gap is to be closed in the project applied for in order to reduce burr formation and increase hole quality.Since the tool macro- and micro-geometry in combination with the process parameters and the drill entry and exit geometry of the workpiece have a decisive influence, a model for a single-edged micro-drill geometry is developed first, in which the tool angles and the cutting emicrometersdge radius can be continuously adjusted. Later on, this model is optimized with respect to the tool angles. This is followed by the production of single-edged tools with Ø 50, 100 and 300 micrometers at the laboratory of the proposer. These tools are used to manufacture micro holes at different entry and exit angles with defined process parameters and cutting edge radii in various materials. Afterwards, they are investigated with regard to chip and burr formation. In addition, 3D-FEM simulations are carried out to determine the temperature distributions and stresses that cannot be determined experimentally. Complementing the experimental results with the results of the FE simulations is the basis for a good understanding of chip and burr formation during micro drilling. Finally, in order to extend the knowledge, micro intersection holes are manufactured and investigated.Based on the overall findings, recommendations will be given on how to minimize the burr on micro intersection holes with D < 300 micrometers. In addition, it is possible to analyze the influence of the high rβ/h ratio, which cannot be reduced due to the process, on chip and burr formation. Based on these results it will be possible to define process parameters matched to the workpiece geometry with minimum burr formation as well as tools with adapted macro and micro geometry. In the future, miniaturized technical products can be manufactured economically and in good quality on the basis of the knowledge gained.

• DFG Programme: Research Grants