30 Coil Technology
A licence to print... Coils Chris Callander finds out how a German company is transforming the production of motor coils, and explores what impact that may have on the motor repair sector.
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dditive Drives was born after two of its cofounders, Dr. Jacob Jung and Alex Helm, realised their expertise in the automotive sector and additive manufacturing, respectively, could be brought together to solve a challenge presented by the fast-growing demand for traction motors. It is well recognised that it is challenging to create working prototypes of motors for automotive applications. Setting up for prototyping or sampling motors often requires a lot of tooling, particularly when it comes to hairpin windings and large copper conductors. Plus, designs are restricted in terms of their geometry by conventional coil manufacturing. But Jacob and Alex recognised that if they could find a way to 3D print coils and, in doing so, benefit from optimised designs, they could overcome the limitations and speed up the production of prototypes, while in many cases doing so more cost-effectively than conventional methods. Officially launched in July 2020, Additive Drives, which is based in Dresden, Germany, primarily works with high-performance applications such as motors for racing and aviation applications, producing short- to medium-run production batches and fastturnaround prototypes. Coils are printed using selective laser melting, otherwise known as powder bed fusion. This additive manufacturing process uses high-power lasers to melt metal powders and fuse them together to form the desired solid mass. However, existing 3D printing machinery had to be adapted by the team at Additive Drives to make it suitable to work with the oxygen-free copper Quarter 1 2022
powder required to manufacture motor coils. MORE THAN SIMPLY PRINTING For Additive Drives, additive manufacturing is just the enabler that makes a range of benefits possible. As well as accelerated development times, additive coil production can deliver improvements in weight, volume, and performance. Alongside printing clients' coils to their design, Additive Drives also offers design optimisation, utilising the benefits available through 3D printing. Based on electromagnetic and
thermal simulation of a coil's CAD design, the Additive Drives team can save up to 40% of the copper mass, meaning only the remaining 60% needs to be printed. This makes it possible to identify areas where the copper cross-section can be reduced as it is not critical – such as in the connections – potentially reducing size, weight and cost. Equally, in areas where the analysis identifies hot spots, the copper crosssection can be increased to compensate – meaning greater performance and reliability. Creating the geometry through 3D printing allows coil geometries that are more complex than is
The design of bending radiuses can be optimised with insulation in mind.
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