Electrical strip – a core material
Both steel and cast products continue to be essential for the engine and powertrain as the switch is made to electric cars. “Electromobility is not possible without steel,” says Andreas J. Goss, CEO of Thyssenkrupp Steel. The company considers itself to be the market and technology leader for electrical strip, the core material for all electric motors. Motor torque depends to a large extent on the quality of the magnetically soft steel product. The iron-silicon alloy determines the efficiency level, which is supposed to be as high as possible, and the energy loss due to remagnetisation, which is supposed to be as low as possible. Only a few manufacturers anywhere in the world supply this expensive special material; the competitors that do so include Arcelor Mittal and the Austrian company Voestalpine.
Research and development work in the electrical strip area has not been completed by a long way yet. Vacuumschmelze from Hanau in Germany recently demonstrated just how much potential the electrical strip technology has. Equipped with material from Vacuumschmelze, the world record-holding electric racing car “Grimsel” accelerated from zero to one hundred kilometres per hour in only 1.513 seconds. No car in the world that is produced in series can get anywhere near acceleration of this kind, not even the 1,000-horsepower “Project One” model manufactured by the Daimler subsidiary AMG. This “Hypercar” with Formula 1 technology, which was presented at IAA 2017, took 2.5 seconds to reach 100km/h. The four electric motors in the “Grimsel” have sheet metal packages made from a special material that would be prohibitively expensive for series production. Yet Vacuumschmelze is thinking of launching a modified electric motor material for premium vehicles on the market.
Electromobility is creating additional market opportunities for foundries
Plenty of castings from foundries such as Georg Fischer (GF) or Nemak are also common in electric cars. From 2019 onwards, for example, the GF Automotive Division based at the Mettmann location in Germany will be producing battery housings made of aluminium with an integrated cooling system for a French car manufacturer. Competitor Nemak also confirms that additional growth is being generated by the change in drive concepts and the introduction of new structural electromobility components like battery housings.
Electric drive systems for cars require a large number of new components. Besides housings for batteries, these are, first and foremost, housings for electric motors and power electronics, which are designed preferably as castings due to their complexity, as Christian Heiselbetz, R&D Director Global at Nemak Europe, reports.
Combustion engines made from die-cast aluminium have been standard for a long time now. Electromobility is creating additional market opportunities for foundries. Cast motor parts are premium key components in both partly electrified and battery electric vehicles. Since 2013, Nemak has been supplying the die-cast electric motor housings for the BMW models i3 and i8. Particularly for complex parts and when the integration of functions is needed, casting technology is able to show its strength and meet varied challenges – be it with low-pressure casting and such casting processes as lost foam, sand and investment casting. If complex cooling circuits are necessary then low-pressure casting permits the use of sand cores or the inclusion of tubes in order to be able to carry out optimised cooling, as Heiselbetz emphasises.
Franz-Josef Wöstmann, foundry expert and departmental manager at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, thinks there is a promising future market for foundries not only in lightweight structures or housings for electric motors, batteries and power electronics. He considers rotors with aluminium or copper and even hybrids to be an issue. The foundry expert stresses that coils can be cast and new magnetic casting materials could become a market.
New drive concepts with formed steel and die-casting
Another component that will still be needed for the drive technology of electric vehicles is the transmission, and thus highly complex die-cast aluminium components as well as equally complex steel components manufactured via forming technology. This is confirmed by Astrid Wilhelm-Wagner, Marketing Manager at Voit, an automotive supplier from Saarland in Germany that has its own foundry. The company intends to strengthen the production of conventional transmission parts (primarily for the supplier ZF) and expand the electromobility business at the same time.
“The established manufacturing segment for conventional powertrains is already being substituted in the hybridisation of existing drive concepts up to and including completely integrated electric drive modules,” says Wilhelm-Wagner. In her opinion, some existing components will be eliminated entirely in future, while other components such as control units for power electronics will be integrated directly into the transmission. Wilhelm-Wagner is sure that the product range will be extending more and more in the coming years. The expert lists such components as internal transmission parts, housing structures for electromobility applications, housing structures for power electronics, electric motor housings, energy recovery components and fuel cell stacks.
This article was first published on www.etmm-online.com.