Precision at scale: Inside Mercedes-Benz's axial flux motor production in Berlin-Marienfelde
Mercedes-Benz has started large-scale production of its axial flux electric motor in Berlin-Marienfelde, using advanced manufacturing processes, AI-driven quality control and precision assembly techniques to bring high-performance EV technology to automotive-scale production.
As Mercedes-Benz’ oldest production site the Berlin-Marienfelde plant has been a key part of the company's global powertrain production network for the last 120 years. Now, with around 1,800 employees and a three-digit million-euro investment in its transformation, the plant is taking the lead in the manufacture of a compact, high-performance electric motor that pushes the boundaries of what industrial production can achieve.
This year the plant has started large-scale series production of electric axial flux motors, establishing the site as a centre of excellence for high-performance electric drives.
The motor makes its production vehicle world debut in the new Mercedes-AMG GT 4-Door Coupe, and the performance figure are impressive, acceleration from 0 to 100 km/h in 2.1 seconds and a top speed of 300 km/h. But for AMS the big story is not the technology’s performance, it’s the complexity of its manufacture.
High performance, compact electric motor technology
Unlike conventional radial flux motors – in which electromagnetic flux runs perpendicular to the axis of rotation – the axial flux motor routes its electromagnetic flux parallel to that axis. The core components are arranged in a disc-shaped layout: two rotors sandwich the stator from left and right. This architecture delivers high power and torque density in a dramatically smaller package.
In the new Mercedes-AMG GT 4-Door Coupe, the axial flux motor at the front axle is just under nine centimetres wide, while the two motors at the rear axle each measure around eight centimetres. All three are integrated per axle into High Performance Electric Drive Units (HP.EDU), combined with a compact input planetary gearbox within a single housing.
The OEM says this technology builds on the foundational work of British electric motor specialist YASA, which became a wholly owned subsidiary of Mercedes-Benz AG in 2021. Since then, the car maker has developed both the motor and the production processes required to manufacture it at automotive scale.
New processes and patents for axial flux production
Mercedes highlights the manufacturing challenges that have previously made volume production difficult. Looking at some numbers associated with production operations; 98 process steps are required to manufacture the axial flux motor. Of those, 65 are being used for the first time at Mercedes-Benz and 35 of those processes are genuinely novel in industrial terms. The company also notes that technologies developed to make them work have resulted in more than 30 patent applications.
At the Berlin-Marienfelde plant production operations for the motors covers approximately 30,000 sq. m across three halls and seven production lines. The manufacturing operations combine highly automated manufacturing processes, laser technology, intelligent control systems, AI-based quality control and the skills of highly qualified employees.
Copper coils and the problem of precision bending
One of the central manufacturing challenges involves the copper coils that are a key part of the motor's stator. The design requires rectangular copper wire to be used rather than conventional round wire, to achieve the high-power density. Rectangular wire allows more copper to be packed into the same installation space, an important feature of the compact motor architecture.
The challenge in production is bending. The wire must be shaped at high speed into tight radii without forming creases, damaging the insulation layer or reducing the wire's cross-section. Any of those outcomes would compromise motor performance or reliability. Mercedes says that it has developed a special process in cooperation with partners that combines maximum precision with the throughput rates required for large-scale industrial production.
Laser welding in confined spaces
Once the coils are formed, the geometry of the axial flux motor creates a further challenge as they must be interconnected within the. Each coil end must be connected to its corresponding interconnection wire within a very confined installation space. The proximity of plastic structures makes conventional welding methods unsuitable; excess thermal energy would cause damage.
The solution is highly precise laser connection of the copper wires. Laser welding enables minimal energy input precisely at the welding point, while keeping process times short. The result is a thermally controlled joining method suited to the tight tolerances and sensitive surroundings in the interior of this motor.
Polymer welding with AI-supported quality control
The assembly of plastic components in the drivetrain presents a separate set of challenges. Mercedes explains that simultaneous laser transmission welding of plastic parts requires the highest level of geometric accuracy, combined with minimally invasive energy input to avoid damage to surrounding areas.
In this process AI-supported optical real-time quality control plays a key role. During the conditioning of components before joining, AI-based image processing identifies the precise position of each part, applies virtual protection zones over sensitive areas and ensures the laser acts only on the intended surfaces. Once joined, components are verified immediately – documenting the quality of each weld in real time to support process reliability. The resulting joints are both oil-pressure-tight and capable of withstanding high mechanical loads.
Assembling under magnetic force
Mercedes says the final assembly stage – known internally as the "wedding" – is perhaps the most technically dramatic step in the production sequence. During this process, the stator must be positioned between two rotor discs fitted with permanent magnets and permanently joined. The challenge is the magnetic force involved: up to 9 kN, equivalent to approximately 900 kilograms, acting on the components during assembly.
While managing that force, the stator must simultaneously be held within the magnetic centre plane to a tolerance of less than 0.1 millimetres. An innovative control algorithm manages this in the final 0.5 seconds of the process, using high-frequency control impulses to correct the stator's position in real time. As Mercedes describes it, what matters here is not force alone, but intelligent control, sensitive sensor technology and precise process management.
A platform for the future
The axial flux motor production launch is major part of the broader transformation of Berlin-Marienfelde. Since 2022, the plant has housed the Mercedes-Benz Digital Factory Campus – a real production environment in which digital applications and manufacturing processes are developed, tested and scaled under series-production conditions, using the company's MO360 digital production ecosystem.
With the industrialisation of the axial flux motor, Berlin-Marienfelde brings together high-performance electric drive systems, digital production and intelligent automation under one roof.
