32 allow for better thermal contact with the stator core or direct oil cooling, preventing the motor from derating during high-speed driving. Because the parts are rigid, they can be inserted by high-speed robots, making them ideal for mass-market EVs. However, there are drawbacks. At high frequencies, current tends to flow on the ‘skin’ of the conductor and because hairpins are thick, this creates massive losses and heat at high speeds. Furthermore, once the tooling is set for a specific pin shape, changing the motor design can be expensive. X-pin The X-pin winding is an emerging tech where pins are crossed or braided to cancel out internal eddy currents. These designs are specifically engineered to reduce proximity effect losses, where the magnetic field of one pin reduces the current in the next. However, this is expensive. Currently, the machinery required to bend and weave these complex shapes is far more expensive than that used on standard hairpin lines. In a standard hairpin, the ends are twisted parallel to each other. In X-pin designs, the geometry is altered so that the ends cross over each other in an ‘X’ pattern before welding. This allows for a more robust mechanical joint and provides more surface area for a laser to create a consistent melt pool. Technically, this reduces the heat-affected zone during welding, protecting the nearby slot insulation from thermal degradation. It is often used in smaller, high-torque-density motors where space for welding tools is extremely limited. Compared with a traditional hairpin, the X-pin has a lower end height, which can further reduce the size of the motor, which is conducive to the layout of the vehicle’s axial space and improves power density. Moreover, the manufacturing process is simpler than that for wave winding. However, production line investment is based on the current hairpin production and investment in wire upgrading is relatively low. The difference between the wire forming process and traditional hairpin forming is not significant, and it is important to focus on the forming accuracy because the X-pin does not have a cutting flat process, and the consistency of the pin angle after forming is high. Because the length of paint (insulation) removal is only about 5 mm, mechanical paint removal will cause the cross-section to not fully fit and the laser welding will leak. Therefore, only laser paint removal can be used. So, the X-pin has higher precision requirements than the standard hairpin, and the equipment requires high wire feeding precision, which is difficult to implement. Coating A hairpin uses an impregnation paint + coating process to ensure insulation performance and strength. The X-pin can also use the impregnation paint + coating process, but the welding area and pull-out force of the X-pin are lower than those of the hairpin, so it is recommended to use a higher-strength end potting process for insulation treatment. This process can improve the insulation performance and strength of the motor, and also improve its reliability. X-pin motors have higher power density than hairpin motors, and the production process is relatively simple, which improves the efficiency of the motor. At the same time, owing to the reduction of production processes, the complexity of X-pin motor manufacturing equipment has increased, and X-pin motor equipment requires higher precision control and stricter process requirements. With demand for continuous development of new energy motor technology and the continuous optimisation of production lines, X-pin motors are seen as a key new trend for more efficient EV motors in the future. X-pin motor automation equipment can provide semi-automatic and fully automatic winding and assembly according to customer process requirements. Compared to a hairpin, the X-pin saves more than 20 mm of copper loss and can remove paint from both sides. The biggest change point of the X-pin relative to the hairpin’s torsion head is the cancellation of the straight line segment, which makes it impossible to achieve the barrel twisting method. The lack of trimming technology means the end is not a flat surface. A new twisting process is needed to ensure the consistency of the cutting surface after twisting, and the control of twisting rebound requires extremely high equipment accuracy and algorithm compensation. The X-pin is also soldered differently. Hairpins use hot melt welding where a solder ball is formed at the end. The heataffected area is large, generally around 8–10 mm², the welding area is 110% of the cross-sectional area and the pull-out force is generally around 800–1000 N. In contrast, the X-pin uses lowtemperature welding. The solder ball is no longer formed at the end and needs to penetrate downward. The heatTech focus | Hairpin & advanced windings July/August 2026 | E-Mobility Engineering Options for hairpins (Image: Wafios)
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