Foundries and diecasters can never be sure where the next process or material challenge will come from, particularly in an automotive industry hooked on the appeal of new consumer products and process technologies – an atmosphere ripe for product and supplier displacement. The subject here is disc brakes, an important product category for high-value automotive castings.
The Trumpf Group’s Laser and System Technology unit has taken a high-tech approach to elevating the value of brake discs by promising to reduce the degradation that occurs with normal use, and more specifically to reduce the particulate matter that results from disc brakes wearing down. The new approach is laser deposition, and the results are being evaluated in series production with some automotive manufacturers and suppliers.
"As a technologically leading laser system manufacturer, we have been working closely with the automotive industry for years and know the market very well,” according to Richard Bannmüller, president and CEO of TRUMPF Laser- and System Technology. “High-speed laser metal deposition is cost-effective, can be used in series production and thus offers the potential to become the new standard in brake disc manufacturing."
Energy efficiency. Laser cladding works through a complex interaction between laser and metal powder, making it possible to create pore- and crack-free layers. The key to the process is the powder and energy input. Instead of applying the metal powder to the component and then melting it there by laser light, in high-speed laser buildup welding the metal powder enters the laser beam just above the component. The light heats the powder to melting temperature even as it is being delivered to the component surface. This makes it possible for brake manufacturers to apply the coating much faster and to use the energy employed much more efficiently to form the layer.
The new process has already received several awards, Trumpf noted, including the Berthold Leibinger Innovation Award.
Health concern. Even very low concentrations of particulate matter are said to carry health risks. Trumpf cites data that about half of the particulate emissions related to motor vehicle operation are due to wear on brakes, tires, clutches and the road surface, and about half that amount is brake dust. Brake discs coated by high-speed laser metal deposition emit far less particulate matter than conventional brake discs.
The laser-deposition process not only ensures less fine dust is produced from the brakes while in service, but also less wear, and the market potential for that is huge. German automakers produce around 3.4 million cars/year, and for the roughly 49 million cars already on the market in Germany drivers have had to replace their brake discs several times, often after just 50,000 km, depending on driving style and wear. Laser deposition could mean these replacements could be necessary much less frequently.
EVs, inevitably. High-speed laser build-up welding also offers corrosion protection, which is particularly important for the brake discs of electric vehicles. These work primarily with recuperation, i.e. energy recovery, when braking, so the disc brake is rarely used to come to a stop. As a result, the brake discs accumulate flash rust more quickly, which leads to performance losses during braking and, in extreme cases, can necessitate premature replacement.
"Our laser systems are already in use at numerous manufacturers of electric cars, helping to produce the battery, the e-motor, or high-performance electronics. With high-speed laser metal deposition for brake discs, we offer another manufacturing technology for future mobility," Bannmüller said, referring to lasers as a “decisive tool” for making e-cars possible in series production.