Assembling Electric Vehicle Motors

The shift from the internal combustion engine to batteries and electric motors is, in automotive terms, monumental. But, there is no denying that it’s a challenge that manufacturers and suppliers are tackling head on.

Faced with new regulations to help reduce global carbon emissions, original equipment manufacturers (OEMs) had no choice but to shift focus away from diesel and gasoline to batteries. Almost every OEM has now gone public about their plans for electric vehicles. That paradigm shift has piqued the interest of both traditional motor manufacturers and a handful of startups developing new technology.

Whether it’s an electric car, truck or tractor, traction motors are vital to making wheels spin. That’s why many automakers, such as BMW, Ford, General Motors and Volkswagen plan to assemble motors in-house.

For instance, Ford is spending $150 million to refurbish its 53-year-old Van Dyke Transmission Plant in Sterling Heights, MI, to mass-produce e-motors. General Motors is also taking a vertically integrated approach with its modular Ultium Drive power train family, which consists of three interchangeable motors.

“As with other propulsion systems that are complex, capital intensive and contain a great deal of intellectual property, we’re always better off making them ourselves,” says Adam Kwiatkowski, executive chief engineer for global electrical propulsion at GM.

“Most of the Ultium Drive components, including castings, gears and assemblies, will be built with globally sourced parts at [our] existing global propulsion facilities on shared, flexible assembly lines,” explains Kwiatkowski. “[This will allow us] to more quickly ramp up EV production, achieve economies of scale and adjust [our] production mix to match market demand.”

“Taking over the role of the internal combustion engine in car engineering, e-motors are a fundamental building block of electric cars, together with the battery and power electronics,” adds Henrik Green, chief technology officer at Volvo Cars, which has committed to assembling electric motors at its power train plant in Skövde, Sweden.

“Bringing the development of electric motors in-house will allow [our] engineers to further optimize the entire electric driveline,” explains Green. “This approach will [enable us] to make further gains in terms of energy efficiency and overall performance.”

While there are many different types of e-motor designs, every device has four basic components: a rotor, stator, body assembly and battery control module. And, there are fewer parts overall than with an internal combustion engine (ICE). An e-motor typically has only about 20 moving parts vs. 200 or more in an ICE.

Automated Assembly
As OEMs and suppliers ramp up EV production, more robots will be used to assemble smaller parts and subassemblies, in addition to the entire motor itself. One area that is an ideal candidate for automation is rotor assembly, where close tolerances present numerous challenges.

Rotor and stator assembly applications use robots to pick, wind and shape coils or windings. Robots can also be used for making connections, pressing the rotor shaft, welding and gluing, plus bolting the body together.

“Accurate, automated injection of glue into magnet housings is essential to ensure retention of the magnets, even at very high rotational speeds of 15,000 rpm or more,” says Patrick Matthews, global power train group manager at ABB Robotics. “Test and inspection also is a continuous activity throughout e-motor production, with robots constantly monitoring quality and correct assembly within very tight tolerances.”

Suppliers such as ABB have seen an uptick in business due to the automotive industry’s recent shift to electrification. In particular, they’re producing more automated systems for assembling electric motors. According to Matthews, two themes in the electric motor market are constant change and ongoing product improvements.

“For everyone involved in electric vehicles, the whole race is about producing cars faster and at higher quality,” says Matthews. “To do that, you need to really scale up development, and that is what we see as both a challenge and a new horizon. Through the years, OEMs have found it easy to build at low volumes, but the challenge comes when you need to build thousands of components in a month.”

ABB engineers are developing robotic assembly cells that can help manufacturers achieve those high-volume levels.

“We want to help them get to volumes of 500 to 1,000 units, and then scale up further,” explains Matthews, adding that maintaining high levels of quality is vital. “Electric motors are no longer a niche product; they are going mainstream and they need to be [assembled] right.”

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