34 September/October 2025 | E-Mobility Engineering controlled manner, aluminium means that vehicle occupants will be better protected from intrusion. Automotive grades of aluminium alloys are also less prone to corrosion because of the self-healing, protective barrier that forms in milliseconds when they are cracked, dented or deformed. Unlike automotive steel grades, which are inherently susceptible to rust and rely on protective systems for durability, aluminium does not need a protective coating, even in severe environments. Steel is recyclable but needs higher processing temperatures of 1400 C, whereas aluminium melts at less than half that temperature (650 C). Typically, vehicles are manufactured with 600 kg or less of aluminium for every metric ton of steel; therefore, the energy savings associated with aluminium are noteworthy. 3D printing Carbon reinforced plastic (CRP) has also been used for the battery housing of an electric motorcycle using a multi-phase approach combining 3D printing, CNC machining and casting to optimise the thermal management, safety and reliability. The process combined CNC machining and sand casting with a CRP material to create a prototype via 3D printing. This was then used to create the aluminium casing for production. The unit had to perform under acceleration and fast charging, while remaining electrically safe, thermally stable, mechanically strong and ready for EMC testing. It also had to be brought into series production on a tight schedule. The development began with a full-scale prototype produced by selective laser sintering using a glass fibre-reinforced polyamide. The high temperature resistance and electrical insulation allowed direct r&d and testing on a working component. The 3D build volume of 550 x 550 x 450 mm allows the entire prototype to be printed in one piece, including the central septum. This is an aluminium plate that directs airflow to prevent battery overheating during acceleration or fast charging. The second step was rapid casting of the battery housing in aluminium, followed by CNC machining. The structure – made of two shells – had to maintain dimensional accuracy, resist distortion and be safe in case of motorcycle impact. For production, the process evolved into traditional sand casting, using the same aluminium alloy. The refinements made during the prototyping phase meant that no rework or delays occurred. Thermoplastics Thermoplastics present a very interesting option for battery enclosures owing to their unique combination of mechanical, thermal and environmental advantages. One of the benefits is the lightweight nature paired with a strength-toweight ratio greater than that of other approaches. By overcoming traditional cost and processing barriers, the latest thermoplastic casings offer manufacturers a scalable alternative to metal and thermoset materials. Tech focus | Battery pack materials An aluminium enclosure (Image courtesy of Novelis) A CRP prototype battery enclosure for an electric motorcycle (Image courtesy of Windform/CS Energica)
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