The electric vehicle (EV) market is experiencing explosive growth, projected to surpass traditional internal combustion engine vehicle sales within the next two decades. This shift has intensified demand for advanced electric motor technology, emphasizing efficiency, cost-effectiveness, and sustainable solutions. In this evolving landscape, stator and rotor potting are gaining attention, offering high performance and durability essential for modern EVs. At Demak, a company specialized in potting solutions for motors, the expertise in this field bridges mechanical and chemical engineering, enabling the company to deliver integrated potting solutions that are both efficient and environmentally friendly. «Demak offers a complete engineering process, starting from a recommendation of the best resin to a proposal of the most suitable equipment» explains Pietro Colombotto, Business Development Manager for North America.
Demak’s core approach: integrated potting solutions
Demak core value lies in its ability to provide a full-service approach from initial analysis to final execution. This begins with in-depth collaboration with clients to assess motor design and determine the optimal resin selection. The company experts conduct in-house testing within a specialized potting lab, evaluating application tack-time, cycle times, and resin suitability. This process allows to design and engineer custom machinery and tooling, ensuring the clients receive a turnkey solution encompassing resin, machinery, and process guidance tailored to their specific needs.
Key Demak resin properties and performance testing
«Demak’s resin formulations leverage our mechanical expertise to deliver low-viscosity materials that facilitate deep impregnation during vacuum potting applications. Our resin systems, particularly epoxy-based ones, provide excellent resistance to chemical exposure, humidity, and thermal cycling. Thermal shock testing, both in-house and collaboratively with clients, ensures high performance under extreme operating conditions—a critical requirement for stator and rotor potting due to the intense thermal stresses involved» explains Colombotto.
Sustainability in potting processes
«Our potting technology offers a sustainable manufacturing edge, as the 100% solidified resin eliminates harmful emissions typically associated with solvent-based alternatives» explains Colombotto. Besides acting as robust electrical insulators, potting resins enhance heat dissipation, reduce vibration and noise, and add protective layers against environmental stressors, all while meeting flame-retardant standards. These attributes ensure quieter, more reliable, and durable motor performances.
Stator potting: enhanced performance over traditional insulation
Historically, stator insulation relies on trickling and dipping technologies. However, the increasing demand for motor performance has underscored the benefits of potting, particularly due to its higher filling factor and superior protection against environmental agents and thermal stresses. «Unlike trickling or dipping, potting minimizes overheating, thus reducing insulation degradation and improving motor reliability» says Andrea Turolla, R&D Manager, Demak Polymers Srl. Potting also significantly reduces vibrations and noise, further enhancing motor stability and performance.
From the left: Andrea Turolla, R&D Manager, Demak Polymers Srl; Pietro Maria Colombotto, Demak Business Development Manager – North America and Key Account
Advanced resin systems for stator potting
Modern encapsulation materials are engineered to achieve high electrical insulation and low permittivity values under high temperatures, ensuring optimal performance and extended durability. «Our resins feature high thermal conductivity, crucial for effective heat dissipation, while maintaining mechanical stability to withstand vibrations and high operating temperatures. This makes them ideal for high-performance automotive applications» says Turolla.
Resin selection for thermal conductivity and glass transition temperature
Demak resin portfolio spans materials with varied thermal conductivity and glass transition (Tg) values. Glass transition temperature is the temperature at which a material transitions from a rigid to a more rubber-like state. High Tg materials maintain their rigidity and mechanical stability even at elevated temperatures, essential for potting rotors that operate under heat condition. In rotor potting, a high elastic module at high Tg is crucial because it ensures that the material maintains its structural integrity and performance at elevated operating temperatures, preventing deformation or loss of mechanical strength of the windings at < 15,000 rpm
These are some of the solutions Demak can offer for rotor potting:
- XE 661 Resin: Offers moderate thermal conductivity and Tg, suitable for industrial motors;
- XE 663 Resin Family: Our bestseller for traction applications, providing thermal conductivity of approximately 1.7–1.8 W/m·K with adequate Tg, ideal for static applications in the stator.
- XE 202W Resin: A high-performance option with over 2 W/m·K thermal conductivity, designed for high-stress applications requiring a higher Tg.
Increased thermal conductivity often means higher filler content, leading to increased viscosity and processing complexity. «It is not possible to find a resin that fits all and thank to our knowledge we can find the solution which best fit the Client´s needs. This variability necessitates a tailored approach, leveraging our extensive experience to recommend the best resin for each application» explains Turolla.
Rotor potting: a new trend for sustainable and efficient electric motors
While stator potting is an established and known technology, Rotor potting is an emerging trend in the design and manufacturing of electric motors, and it is gaining traction, especially in Europe, due to its alignment with environmental sustainability objectives. This process enhances motor performance and extends longevity while significantly reducing the environmental impact, making it highly relevant in today’s industrial landscape.
«The primary appeal of rotor potting lies in its potential to eliminate the need for permanent magnets, which are traditionally used in rotor manufacturing» explains Colombotto. Permanent magnets require rare earth elements, the extraction and refinement of which often result in significant environmental degradation. By eliminating permanent magnets, rotor potting reduces both the environmental impact and the geopolitical dependency on these resources.
Technological benefits of rotor potting
Potting resins have high thermal conductivity and a high glass transition temperature, which prevents the rotor from overheating during operation. This is critical in maintaining motor efficiency and durability. Further, full encapsulation of the rotor prevents vibrations, significantly reducing noise during operation and creating a quieter working environment. The potting materials proposed by Demak have exceptional mechanical resistance, allowing them to withstand the high RPMs and demanding conditions in which electric motors operate. In rotor applications, the material must maintain both high mechanical strength and electrical insulation at elevated temperatures. Potting resins such as the XE201 TG and XE201 HTG demonstrate high glass transition temperatures, meaning they retain rigidity under high temperatures, which is essential for rotors running at over 15,000 RPM.
Theory and practice
Demak stands out in the rotor potting market due to its dual expertise in both mechanical and chemical engineering. By combining advanced resin chemistry with highly specialized potting equipment, Demak provides a full-service solution, ensuring that materials perform as well in practice as they do on technical data sheets. Their technology also includes patented solutions tailored to customers’ specific needs, supporting everything from small-scale lab testing to fully automated, high-volume production. Colombotto explains «It is very easy to have good results on paper but these results must also fit the reality. In our potting lab at Demak we have the possibility to test many resins and many tools for potting because the resin is important as the right potting machine». Demak offers also potting machines, both semi- and fully automated. Automated potting systems can enhance production quality by ensuring consistent resin application, improving the reliability of electric motors. DEMAK’s automated solutions are scalable, ranging from compact set up for R&D to fully automated production lines for mass manufacturing, reducing human error and enhancing traceability.
Demak’s two souls
What differentiates Demak from its competitors? Colombotto states: « We are proud to say that our unique strength lies in our dual expertise: both mechanical and chemical. While many materials can look impressive on paper—showing high thermal conductivity, excellent glass transition, and other strong technical specs—in real-life applications, neither chemistry alone nor machinery alone is enough to achieve top-tier results. This is where our core expertise truly shines. Our deep knowledge of the entire process, combined with years of hands-on experience, especially in the electric motor industry, allows us to bring out the best in these materials. Our know-how is recognized and valued by our customers because we can bridge the gap between theoretical performance and practical application. By combining our technical backgrounds with our ability to share insights directly with clients, we ensure they achieve the optimal results in real-world settings. This blend of expertise and practical support is what truly sets us apart from others in the field».
