Shorten the bends, sharpen the performance

A typical hairpin wire design involves the build-up and connecting of 48 to 72 individual hairpin wires into several layers. In order to create the different phases of the electrical design, a continuous wire path has to be obtained, resulting in the need for the welding and formation of tight wire bends.

Achieving a tight bend is exactly where PEEK coating shines. Thanks to its single-step application process and high Insulation power, this type of coating can be made significantly thinner compared to PAI enamel coating. This subsequently facilitates the much-desired shortening and sharpening of the bends. In other words: less copper will be needed to achieve an effective winding pattern with the same energy output.

This, in turn, means a PEEK-coated magnet wire enables you to benefit from both weight and size savings, or to upgrade the performance of your motor to 800V and beyond.

Minimize the risk of defects during welding

While hairpin wire winding offers plenty of advantages, it comes with challenges as well. One of the biggest includes connecting the individual hairpins. This process refers to welding the rectangular shapes inside the stator, often achieved by laser welding. When selecting high-quality copper with minimal oxygen presence, issues during welding are heavily reduced. Another method to avoid extensive welding operations is to use continuous wave patterns. 

This immediately highlights the importance of a defect-free manufacturing process. Even if you only have a couple of welding points available, the winding wire in between still needs to be absolutely perfect. Otherwise, you risk turning your entire magnet wire into scrap.

Because of the fact that enamel insulation is applied step-by-step, there is a higher susceptibility to defects as each layer risks tearing, cracking, or blistering when bent into shape. 

In contrast to PAI enamel, PEEK coating exhibits a great level of flexibility. As a result, a PEEK-coated hairpin wire allows for sharper bends and compacter stator designs. Due to its thermoplastic nature, it can be applied in a single layer by means of extrusion and facilitates a trustworthy in-line inspection to detect any electrical defects as well as an accurate measurement of the coating centricity along its circumference.

Keep it cool in high-voltage environments

Every electric motor generates heat during operation. Hairpin winding technology offers enhanced heat dissipation, thus improving thermal management and reducing the risk of overheating. 

However, to get the most out of this benefit, you also need to maximize the lifespan of your insulation layer. PAI enamel coatings are known to become more brittle at thicknesses suitable for 800V applications. Moreover, they will be more easily affected by harsh environments, such as high temperatures or direct contact with dielectric fluids.

The thinner PEEK coating, by contrast, optimizes the heat dissipation even further and can handle maximum operating temperatures of more than 240°C. In addition to these excellent thermal characteristics, PEEK coating boasts stellar chemical resistance to the oils used in direct cooling processes. 

Drive the sustainable future of EVs

You may be surprised to learn that the type of coating used has a direct impact on the ecological footprint of your hairpin wire. This will become increasingly important as regulators push for stricter policies and consumers demand more transparency.

Whereas PAI enamel coatings are applied in a layer-by-layer process and use harmful solvents, PEEK coatings require a single-step extrusion process without any solvents. Additionally, at the end of the life cycle, a PEEK-coated wire could easily be recycled thanks to its thermoplastic characteristics.

Another significant benefit includes the reduction of copper needed to build the stator: as mentioned earlier, the flexibility and thickness of the coating enable shorter bends, leading to significant material savings, especially for those zones not contributing to the actual formation of the magnetic field. The reverse also applies: if the size of the e-motor stays the same, the thinner coating allows for more copper material in the stator, and thus a higher power density.

If you’re interested in learning more about the environmental impact of enamel coatings versus PEEK-coated hairpin wires, we highly recommend checking out this article on our blog.