Grant for One-of-a-Kind Machine Tool Measuring Technique
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Whether parts for aircraft engines or high-precision components for medical technology: To give metal pieces their final shape, they are often machined – that is, formed with a hard tool that abrades material, for example through milling, turning or drilling. During this process, extreme conditions prevail at the point of contact between the tool and the workpiece: high temperatures that can even equal the metal’s melting point, intense pressure like otherwise only created by deep rock strata and chemical reactions that occur in under a millionth of a second.
The interaction of these effects influences how quickly a tool wears out and the quality of the machined surface – and thus also the costs and environmental balance of numerous technical products. The problem? It has not yet been possible to analyze the process accurately at the high speeds long common in the industry – effectively the most important thing. Modern manufacturing reaches cutting speeds of up to 800 meters per minute, meaning that the metal flies past the tool at almost 50 kilometers per hour. However, scientific studies on the mechanisms at work during the machining process have so far mostly stopped at a quarter of this speed. The outcome is that optimization at higher speeds has largely been achieved through trial and error.
Four perspectives in one machine
This is the starting point for the project that Dr. Jörg Debus from the Department of Physics is implementing with Professor Dirk Biermann and Dr. Jannis Saelzer from the Department of Mechanical Engineering. Together, they are developing a special machine that combines high throughput with multidimensional measurement. To achieve the highest possible speeds, the tool and the workpiece are mounted on two slides that move in opposing directions, which has the effect of adding their speeds together. This simultaneously reduces the vibrations that can affect the sensitive measuring equipment. By applying four spectroscopic methods at the same time, it is possible to measure several properties – chemical composition, 3D structure, depth temperature and surface tension – and in this way observe in real time how reactions take place and protective layers form. The shape of the tool, workpiece and metal chips can be determined with nanometer precision. What’s more, this technique makes it possible, for the first time, to measure the tool’s internal temperature. Combining these optical and spectroscopic measuring techniques in a single machine operating at maximum speed represents pioneering interdisciplinary work and a unique selling point for Dortmund at both the national and international level.
The benefits of this one-of-a-kind machine extend beyond basic research, as the insights gained will facilitate more sustainable production: Higher speeds mean shorter machining times and thus lower energy consumption and CO2 emissions per component. Once the processes so far hidden are understood for the first time, it will be possible to design tools more expediently, detect wear at an earlier stage and control processes more reliably.
Integral part of research in Dortmund
The project ties in with key priorities at TU Dortmund University: The DAEDALUS Research Center headed by Dr. Jörg Debus, for example, bundles activities in the field of optical spectroscopy and is working on the refinement of various measuring techniques that use light to deliver information about materials. As such, DAEDALUS is an important pillar for the focal area “Materials Science” that TU Dortmund University and Ruhr University Bochum are further developing within the Ruhr Innovation Lab alliance. The aim here, above all, is to harness the potential of AI to identify novel materials that can be produced, characterized and upgraded in rapid iteration. The new machine, which is to be built and tested over the next two years, will be a valuable addition to these areas of expertise.
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