Chinese engineers have created “supersized” cast parts that have the potential to cut production costs and assembly times in lightweight electric vehicles (EVs) significantly.
Much like Tesla’s “gigacasting” technology, the process involves casting two roughly 2.2-square-metre magnesium alloy parts from a single mould – the car’s chassis and the battery box housing cover.
Magnesium alloys are roughly 70 per cent lighter than steel and 40 per cent lighter than the traditional aluminium alloys used in the automotive industry, according to Jiang Bin, a professor associated with Chongqing University’s National Engineering Research Centre for Magnesium Alloys (CCMg).
Weight reduction in EVs is a constant goal because it goes a long way to alleviating what industry experts call “range anxiety” or the fear of an EV battery running flat while travelling, said Jiang to state media. In a recent survey by the social media giant, LinkedIn, up to 30 per cent of EV operators in 2022 reported they still experienced range anxiety during their day-to-day commute.
The single mould, two-piece casting process was developed by CCMg and local fabrication firms, Chongqing Millison Technologies Incorporated and the Chongqing Boao Magnesium Aluminium Manufacturing Company.
Engineers created the oversize parts by injecting molten magnesium alloy into the mould at immense pressure, before allowing the superheated mass to cool, according to the South China Morning Post.
Gigacasting, as the method is known, results in components with smoother edges and surfaces, fewer blemishes and increased stability.
Creating a motor vehicle that requires very little welding also saves crucial extra weight. The ability to pour the mould into a single casting also simplifies the production line significantly, as fewer specialised machines are required to fabricate the vehicle’s parts.
Gigacasting has improved Tesla’s production capacity at its Berlin and Shanghai factories greatly, according to a Reuters article, with the Model Y’s rear underbody reduced the number of welding contact areas from 700 to 50 and the production cycle from between 60 to 120 minutes, to three to five minutes.
These improvements mean the Model T’s rear body weighs 30 per cent less and is 40 per cent cheaper to manufacture.
China is uniquely positioned to take advantage of magnesium alloy gigacasting. The country commands up to 70 per cent of the world’s magnesium reserves and has several decades of expertise in both the element and the mining thereof.
Despite magnesium’s marginally higher material cost relative to aluminium, its qualities and ability to lend itself to mega and gigacasting made it better-suited for the automotive industry going forward, according to CCMg’s Jiang Bin.
Major industry players, including Volvo, Toyota, Mercedes, Nio and Xpeng, have all expressed interest in implementing the practice into their production, as stated in a July 2023 report by the South China Morning Post.
https://interestingengineering.com/innovation/chinese-giant-magnesium-parts-for-cheaper-lighter-cars
