Fraunhofer Institute for Production Systems and Design Technology
Fraunhofer Institute for Production Systems and Design Technology

Keeping Electric Motors in the Loop

As part of ReTraNetz-BB, concepts are being developed to apply circular economy to electric motors in electric vehicles.

With the electrification of mobility, an increasing number of electric motors are entering circulation. When an electric car reaches its end of life, this currently also means the end for the electric motor, even though the motor itself may be far from worn out. For this reason, electric motors should be designed so that, after their first life cycle, they can be efficiently refurbished for a second phase of use. While the circular economy advocates this approach for every conceivable product, it is particularly relevant for electric motors because they contain many valuable raw materials.

Treasures inside the housing

A typical electric motor consists of several basic components, with two main modules at its core: the stator and the rotor. The stator contains windings, which are usually made of copper and connected to an AC power supply. They generate a rotating magnetic field that drives the rotor – thus creating motion. Synchronous motors, in particular, use permanent magnets embedded in the steel rotor to maintain a constant magnetic field.

In addition to the stator and rotor, an electric motor includes other important components. These include the shaft for power transmission to the drivetrain, bearings for safe shaft operation, and the housing, which provides protection and ensures heat dissipation. And what all these parts have in common is that they are made of valuable metals.

The materials used in modern electric motors are primarily cast iron, steel, aluminum, and copper. Permanent magnet synchronous motors additionally use magnets containing a variety of rare earth metals – including hard ferrites, alnico, samarium-cobalt, and neodymiumiron-boron. These are associated with significant uncertainties in the global supply chain. If fewer of these 
materials are required, the vehicle manufacturers’ dependence on suppliers declines.

Valuable during operation and after the vehicle's end of life: electric motors for electric cars

A second life for electric motors

Among the established R-strategies, those aiming at using the entire product a second time are particularly suitable for electric motors: reuse, repair, remanufacturing, and refurbishment including retrofitting. Recycling approaches that break the product down into its components and aim to reuse the raw materials are less appealing. In practice, this means that electric motors are not simply disposed of at the end of their first 
service life, but are instead reused, remanufactured, 
repaired, retrofitted, or recycled.

However, not all components of an electric motor are equally suitable for reuse. The housing is robust and suffers minimal wear, so its potential for reuse or repurposing is very high. The shaft and rotor (excluding the magnets) also have a good chance of a second life thanks to their long service life. Although the permanent magnets are extremely valuable, they can lose performance through demagnetization. The stator poses a greater challenge due to its complex composition and because inspection is correspondingly time-consuming. Bearings are typical wear parts and are usually replaced.


Design for circularity

To make electric motors suitable for circular use, they must therefore be designed and manufactured in such a way that they can be easily disassembled, repaired, and remanufactured. This can be achieved by using standardized components and materials, as well as by applying modular designs and remanufacturing technologies. Some parts may find a second use not in 
vehicles but in other applications – such as drives for pumps, compressors, or fans in industrial facilities. Those parts that cannot be remanufactured should be designed so that the materials they contain can be separated by type. In this way, materials such as copper, aluminum, and rare earth elements can be recycled. 

Aside from the fact that appropriate design concepts for electric motors are just starting to be developed, there is currently a lack of sufficient technologies and instance-specific product data to support complex recycling decisions and the subsequent activities. Resource-efficient machining processes for refurbishment also need to be developed. The Berlin-Brandenburg Regional Transformation Network for the Automotive and Supplier Industry (ReTraNetz-BB) is playing a pioneering role in this regard. The network supports manufacturing companies in transforming toward CO2‑neutral mobility, digitalization, and sustainable production.

In the ReTraNetz-BB real-world laboratory at Fraunhofer IPK, technologies for a digitally supported circular economy – using e-mobility as an example – are being examined, and a corresponding infrastructure is being established for further testing and transfer to industry. There, Fraunhofer IPK offers direct access to technologies for evaluating circular economy decisions, implementing various circular strategies, and analyzing the environmental impacts of different circular economy strategies. The focus is on reusing, remanufacturing, repairing, and retrofitting electric motors and their components. In this way, the electric motor becomes a fully sustainable technology. 

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