Development and Industrialization of a Laser-Based Hard Material Coating System for Brake Discs
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Abstract
Fine dust emissions caused by road transportation are being investigated and discussed in detail by governments and vehicle manufacturers. Brake abrasion contributes to a significant extent to this ambient air pollution. There are different approaches to minimize this brake disc abrasion, one of the most promising is the coating of the friction surface with wear resistant layers, i.e. with metal matrix composite (MMC). One coating technology, the extreme high-speed laser material deposition, has proven to be extremely effective, especially in combination with appropriately adapted brake pads. In detailed investigations with various brake disc manufacturers, HPL Technologies in Aachen, Germany, examined influences on the quality such as reliable corrosion and wear resistance. In order to enable a pore-free bonding layer, the surface must be accurately prepared, and the overlaying wear resistance layer needs to be accurately bonded on the buffer layer, meanwhile keeping the carbide structures and providing a homogeneous surface finally. Due to the melting metallurgical application process, thermal effects on the brake disc have to be taken into account. Targeted adjustments must be made regarding e.g. spot size, feed speed and working distance, and the sensitivity of the workpiece with regard to so-called ""shielding"" must be taken into account in the process technology. The investigations and co-ordinations are carried out under the leadership of HPL Technologies in Aachen, with intensive support and co-operation of the Fraunhofer Institute for Laser Technology (ILT), the Chair for Digital Additive Production (DAP) of the Aachen University and the machine tool manufacturer Buderus Schleiftechnik (Asslar, Germany) on behalf of leading brake disc manufacturers. The results show the consistent development of the entire value chain with targeted tolerance sensitivity analyses and specifications and show the technical feasibility and economic production potential, for the reliable series production.