ANALYSIS: E-MOBILITY
Rising to the challenge of large-scale e-mobility production
Pravin Sievi, of Scansonic, introduces processing optics that facilitate reproducible and highly reliable hairpin welding in the production of electric motors
Electric cars are no longer an exotic sight, with the required charging infrastructure also steadily growing. All large-scale manufacturers have now added a number of electrified models to their portfolios. In Norway – a trendsetter in e-mobility – almost two-thirds of the newly registered passenger vehicles in the past year have been electric. In three years, no new combustion engines will be permitted in the country. The transition to e-mobility
presents challenges not only for battery technology and the charging infrastructure, but also for the adaptation of production technologies. In addition to the frequently
discussed topic of battery technology, which is the decisive factor for vehicle range, the production of drive motors is
“The keyhole can briefly close and the vapour pressure can cause the ejection of molten material”
16 LASER SYSTEMS EUROPE SUMMER 2022
also presenting manufacturers with a number of challenges. Most importantly, these motors must be suitable for economical large-scale production. Laser- based hairpin welding is therefore becoming increasingly common in the production of traction motors.
Hairpins: A key technology The stator accounts for the largest proportion of production costs in an electric motor. Not only is the copper used in the part quite expensive, but the winding of the coils is also a relatively complex process. When producing traction motors for electric vehicles, most manufacturers use an alternative to coil winding, in which the coils consist of individual copper pins bent in the shape of a hairpin. These hairpin coils are inserted into the stator’s laminations during assembly and then laser welded. The result is a coil, similar to those produced by traditional winding, which generates the necessary magnetic field. This method permits a compact motor design and is highly efficient. An automated and safe
process is particularly important for large-scale production. Depending upon the motor design, several hundred hairpins must be welded with one another. A single defective weld can render the entire stator unusable. The stators are
As a material, copper places high demands on the control of the welding process – pore formation and spattering must be avoided through optimised parameter selection
Laser-based hairpin welding is becoming increasingly common in the production of traction motors
therefore produced using laser welding technology, which is already successfully employed in a wide variety of areas within the automotive industry. This method permits short cycle times, can be easily automated and is very flexible. The hairpins can be welded with a targeted
and focused application of energy, without damage to the insulation layers. Unlike electron- beam welding, which also enables a targeted application of energy, no vacuum is required. The greatest challenge is the material, since copper requires innovative solutions to
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