As sales of electric vehicles increase, so does the production of electric motors. At the end of their useful life, these electric motors are shredded and then recycled. To date, it has not been possible to reuse the individual components and assemblies – there has been a lack of sustainable strategies for remanufacturing and reusing electric motors as part of a forward-looking circular economy. In the Reassert project, researchers at the Fraunhofer Institute for Manufacturing Engineering and Automation (IPA) are working alongside industry partners to pursue various concepts. These involve repairing, remanufacturing and reusing electric motors as well as new designs compatible with a circular economy.
The ongoing process of powertrain electrification is leading to increased use of electric motors, which contain valuable raw materials such as copper as well as rare earth metals like neodymium. China holds a quasi-monopoly over these metals, which cannot be recovered using current recycling methods. In addition, the materials used for the electric motors have a larger carbon footprint than combustion engines, underscoring how important it is to keep the motors in use for longer. “With sustainability in mind, innovative value retention strategies offer significant potential for emissions reduction”, says Julian Große Erdmann, a researcher at Fraunhofer IPA in Bayreuth. The Reassert project sees researchers collaborating with the project leaders at Schaeffler, the Karlsruhe Institute of Technology, Bright Testing GmbH, iFAKT GmbH and Riebesam GmbH & Co. KG to develop innovative methods for remanufacturing electric motors and reusing them in vehicles. The parties involved are focusing on the value retention strategies of reuse, repair, remanufacturing and mechanical material recycling. These are key to building a circular economy aimed at reducing natural resource consumption and minimising production waste. The project is funded by the German Federal Ministry for Economic Affairs and Climate Action.
At present, recycling raw materials is the predominant value retention strategy. Components, primarily copper and aluminium, are recovered through either manual or automated recycling methods. Electric traction motors are disassembled, shredded, sorted and melted down for this purpose. However, the recycled material often exhibits impurities and can no longer be used for motor applications, resulting in the destruction of individual components and assemblies. As a result, raw material recycling should only be chosen as a last resort for recycling and replaced by high-quality value retention strategies such as reuse, repair, remanufacturing and mechanical material recycling. “We want to establish a closed-loop system in which valuable resources are reused to make us more independent from raw material imports as well as minimising raw material extraction”, explains Große Erdmann. The project partners define reuse as reusing the entire motor for a new application and repair as the replacement of defective components and assemblies. Remanufacturing involves all the components being disassembled, cleaned, reconditioned and reused. “With these strategies, fewer raw materials like rare earths, copper and others are needed – at most only for spare parts”, the researcher elaborates. For mechanical material recycling, the project partners plan to disassemble the motor and sort the individual materials prior to shredding. The project partners are using motors from passenger cars to help them analyse which value retention strategies to use in a given application.
The project involves establishing a complete process, each step of which boasts its own demonstrator and test rig. This process consists of a number of stations – from inbound inspection for motor classification to disassembly, demagnetisation, cleaning, component diagnosis and remanufacturing, all the way through to reassembly and end-of-line testing to ensure that each motor works correctly. “For instance, during this process, a motor housing with minor signs of wear might be classified for reuse and, if necessary, reconditioned using machining processes to ensure functionality. Depending on the chosen value preservation strategy, different process steps and chains are involved, so the effort needed for reconditioning may vary”, explains the engineer. One of the possible challenges here is the disassembly and reuse of the magnetic materials from motors. “A rotor with permanent magnets is difficult to disassemble into its components, even in a manual disassembly process, due to the coating and bonding of the magnets. Here, the goal is to establish non-destructive disassembly methods.”
An AI-based decision-making tool developed as part of the project helps to select the optimum value retention strategy. This tool has access to the product and process data for the electric motors, which are saved in a digital twin.
The knowledge gathered in the project is intended to be used for the design of new electric motors. The goal is to develop a prototype motor specifically for the circular economy that can be easily disassembled and effortlessly matched up with one of the four above-mentioned value retention strategies.