Professor of Materials and Surface Technology at Chemnitz University of Technology, Interview: Robert Piterek
Prof. Lampke, you are the spokesperson for the new DFG research group "Functional surfaces through adiabatic high-speed processes". What research is it about?
The focus is on high-speed shearing (HGSS) used in sheet metal part production, whereby we want to investigate the cut surfaces of the workpieces in more detail. Our own preliminary work shows that, depending on the sheet metal material and process parameters, adiabatic shear bands can form in which the material separation then takes place. In this way, cut surfaces with exceptional properties can be produced, which ideally can be used as functional surfaces without further post-processing. In our research group, we are pooling the knowledge of the 6 participating research institutes in order to develop a model based on materials science and process technology that describes shear band formation as comprehensively as possible, i.e. for different materials and in a wide range of process parameters. In addition to high-strength and ultra-high-strength steels, we are also investigating an aluminum alloy and the low-melting-point materials tin and zinc. The funding amounts to 3.7 million euros for an initial period of 4 years.
The adiabatic shear bands produced in the HGSS are intended to provide various advantages for the surface. How can this be?
The formation of adiabatic shear bands influences the quality of the cut surface in terms of its geometry and performance properties, e.g. hardness, fatigue strength and resistance to wear and corrosion. Adiabatic shear bands are localized, highly sheared material areas that form at high deformation rates, although the exact conditions under which these effects occur have not yet been systematically researched. However, it is known that the extremely fine-grained structure characteristic of shear bands leads to a significant local increase in hardness, which presumably also increases abrasion resistance. In addition, there are indications that the shear bands known as white etching bands are less susceptible to certain corrosive media. We want to investigate this.
You want to specifically adjust the properties of the cut surface. How do you intend to achieve this?
As soon as we understand the relationships between the process parameters, the resulting microstructure and the resulting properties, it will be possible to set a defined microstructure in the cut surface by specifically adjusting the cutting speed, cutting gap and cutting energy, which will lead to a property profile that meets the requirements. To this end, there is to be close cooperation and feedback between the sub-projects of the research group that focus on production technology and materials science.
Does surface functionalization without coating ultimately save time and energy?
That is true. Conventionally cut components often have to be reworked. The cutting process is often followed by so-called re-cutting in order to produce a burr-free, right-angled cut surface. Thermal or thermochemical surface coating processes are then frequently used to increase wear resistance. For improved corrosion protection, coatings are applied by electroplating, for example. Our vision is to ideally dispense with post-processing steps because the cut surface already has the required property profile directly after the process. This shortening of the process chain has great economic and ecological potential.
ABOUT THE PERSON
Prof. Thomas Lampke
first studied mechanical engineering in Bremen and then materials science, majoring in surface technology, at Chemnitz University of Technology. After completing his doctorate in 2001, he qualified as a professor in 2008 and has been Professor of Materials and Surface Technology in the Faculty of Mechanical Engineering at Chemnitz University of Technology since December of the same year.
More on the topic at: www.tu-chemnitz.de/tu/pressestelle/aktuell/11363
