Hairpin Welding in Electric Motors


The boom in e-mobility is generating an increasing demand for electric motors which are manufactured with solid copper pluggable shape windings (called hairpins) in the stator which generate a magnetic field that creates the motion. These copper wires need advanced production methods and strategies including ablation and welding before being ready to use, we discuss these processes below.

What is the need for hairpins?

Many electric vehicle manufacturers are moving to copper hairpin technology in place of copper winding in the production of vehicle stators. The hairpin is inserted into the stator and the hairpin/stator are welded together through the use of a laser beam.

Many hairpins are used, typically up to 220 are a common number to be present. Hairpin technology has the advantage of improving the vehicle performance substantially whilst also reducing the overall size of the stator too.

How are hairpins coated?

Copper hairpin wires are typically lacquered or coated with an organic layer (often polyamide-imide (PAI) or polyether ether ketone (PEEK)) to give them electrical isolation and may also have a thin layer of enamel and/or glue too. This layer needs to be removed from the welding zone prior to joining – this can be done by one of our ns pulsed fiber lasers. These wires can take many forms, from straight bar, would coil and small round wire < 3mm to square sections that can be up to 6mm in width. Traditionally this stripping was achieved mechanically, but this doesn’t scale up very well. This is a standard ablation task, which is just one of the many applications for which our range of fiber lasers can be used.

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Welding of hairpins - an e-mobility solution.


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