In the starting holes
Channel structures are often used in cooling systems for components that are under high thermal stress, for example in turbines, combustion chambers or other high-temperature manufacturing plants in which necessary heat removal is maintained by a flow of gases or liquids.
State of the art
The channels are often created in the shell components by wire erosion or wire cutting. This requires that so-called starting-hole channels are provided into which the cutting wire is inserted. They have to completely penetrate the element in a straight line, so that there is no short-circuiting between the cutting wire and the workpiece. Deep hole or erosion drilling methods have established themselves in the manufacturing of such penetrations. The snag here is that from a drilling depth of around the 150-fold diameter, the drilling axis starts to drift away from the ideal axis and gradually “loses its way”.
Scientists at the KIT Institute for Neutron Physics and Reactor Technology (INR) have now developed a multiphase method that enables the manufacture of very fine starting-hole channels for comparatively long metal components. First, grooves are milled into the surfaces of the metal parts. These processed surfaces are then precisely fitted onto each other, first of all along the separating lines running on the outside of the elements and with the aid of electron ray welding, and then on the contact surfaces between these lines, using hot isostatic presses (HIP) under high gas pressure, and close to the melting point of the material. Thus, grove by grove, a closed structure of starting-hole channels develops. Once the areas along the edges have been removed, the ends of the starting-hole channels are exposed, and with wire erosion, individual channel geometries, oblongs or circles can be created. Here, it is possible to achieve any ratio between the ligament and the channel, and in addition, it can vary flexibly within a metal component. The shell elements can be further processed with reforming and welding methods.
With the technology described above, length-to-diameter ratios beyond 400 have been demonstrated, and corresponding sets of parameters have been developed at the Institute.
Options for companies
KIT is looking for partners for the advancement and practical application of this technology.
Your contact person for this offer
Dr.-Ing. Philipp Scherer,
Karlsruhe Institute of Technology (KIT)
Innovation Manager Mobility, Innovation and Relations Management (IRM)
Phone: +49 721 608-28460