EV-Tubes represent the most advanced slot insulation solution for stators with Hairpin, I-Pin and Wave Pin windings, specifically engineered for high-performance electric applications.

Designed on a custom basis and manufactured as multilayer spiral-wound tubes, EV-Tubes completely eliminate insulation overlaps in the slot closure area. The result is a significant improvement in thermal and electrical efficiency, increased motor compactness and an overall reduction in process costs.

The key advantages of EV-Tubes are directly linked to the absence of the overlap joint, which is typical of conventional slot insulation tapes. This construction ensures continuous and homogeneous insulation, eliminating geometric and functional discontinuities and delivering stable, repeatable performance over time.

Slot Fill Factor Optimization

Thanks to the controlled geometry achieved by eliminating overlap joints found in traditional insulation films, EV-Tubes maximize the copper fill factor within the stator slot.
The uniform insulation thickness enables the production of more compact, lighter and more efficient motors, with a direct positive impact on performance and driving range.

Superior Thermal Management

The absence of overlapping layers promotes improved heat transfer and eliminates thermal hotspots, reducing the risk of damage to rotor magnets and other critical components.
This ensures long-term performance stability and enhanced thermal reliability of the electric motor.

Hermetic Insulation and Partial Discharge (PD) Reduction

EV-Tubes provide a fully hermetic slot closure, ensuring high electrical insulation continuity.

Their superior mechanical resistance to micro-vibrations and insertion stresses significantly reduces the risk of partial discharges (PD), improving insulation integrity and overall motor reliability over the long term.

Partial discharges typically occur at the outer side areas of the stator or in the short section of insulation protruding from the slot. During hairpin bending, these areas are subject to high mechanical stress: micro-openings or tape discontinuities can trigger PD phenomena.

Thanks to the continuous hermetic closure provided by EV-Tubes, including at the slot ends, this risk is drastically reduced, ensuring uniform winding protection even under the most critical conditions.

Simplified Assembly – Automation Ready

EV-Tubes are supplied ready-to-use, eliminating low value-added manual operations such as cutting, folding and taping of traditional insulation.

This enables process standardization, consistent dimensional control and a significant reduction of operator-dependent variability.

The product can be easily inserted into stator slots and is fully compatible with automatic insertion systems, making it ideal for highly automated production lines.

In stators with a height exceeding 120 mm, traditional insulation insertion can become critical: insulation tapes tend to jam, deform or twist during sliding.

The use of EV-Tubes completely eliminates these issues, enabling smooth, controlled and repeatable insertion, even in deep slots, with clear benefits in terms of productivity, scrap reduction and process quality.

Manual Insertion without Automation Investment

For medium-to-low production volumes (e.g. buses, tractors, trucks, marine motors, etc.), EV-Tubes can also be inserted manually, without investing in automatic machinery costing hundreds of thousands of euros or dollars, and without additional maintenance or complex line setup.

Improved Resin Impregnation

The EV-Tube structure prevents resin infiltration or contamination during the hairpin bending phase, preserving the dielectric properties of the insulation system.

Reduced Scrap and Line Downtime

Eliminating the “telescoping effect” of traditional insulation tapes during the simultaneous insertion of multiple hairpins results in higher process stability, reduced scrap rates and minimized production downtime.

Sustainability and Cost Reduction

Smaller motors, longer battery life, reduced use of insulation materials and lower process and maintenance costs make EV-Tubes a technically and economically sustainable solution.

Ideal Applications

EV-Tubes are a validated and highly advantageous solution for production volumes of up to 100 e-motors per day, including:

• Electric buses and trucks
• Agricultural and industrial vehicles
• Electric marine applications
• Special medium-volume applications

In these scenarios, the benefits in terms of efficiency, manufacturing flexibility and cost reduction are substantial.

Certified Quality

The quality and reliability of Politubes’ manufacturing processes are ensured by the following certifications:

• IATF 16949:2016
• ISO 9001:2015 – TÜV Rheinland
• UL TEOU 2–8 No. E350605

Available Insulation Materials

EV-Tubes can be manufactured using a selection of high-performance insulation materials, chosen according to the electrical, thermal and mechanical requirements of the application:

• Nomex® aramid paper
• Kapton® polyimide
• Mylar® (DuPont™) polyester
• Ajedium® PEEK and PPSU (Syensqo™)

In Summary

EV-Tubes mean higher efficiency, superior quality and lower costs:
more compact motors, outstanding thermal and electrical performance, minimal waste and maximum production repeatability.