Polyamide 6 Recycled Polyamide 6 in Circuit Breakers

Related Vendors

Siemens AG

FAULHABER Drive Systems

Siemens has used chemically recycled polyamide 6 in a safety-relevant housing of an RCD circuit breaker for the first time. Material-specific characteristics, recycling technology, and industrial validation must be considered in this process.

The requirements for housing materials for residual current circuit breakers are clearly defined—they include thermal and mechanical durability, flame resistance without halogen-based additives, reliable electrical insulation, and dimensional stability under temperature influence. In the case of the Sentron 5SV3, an FI switch of type A or AC, additional requirements such as high switching cycle durability (over 10,000 cycles according to IEC 61008-1) and permanent marking capability come into play. Siemens has broken new ground by using Technyl-4-Earth in exactly this application—for the first time, a compound with 50 percent recycled content has been used in a UL-certified safety-critical plastic housing at a serial scale.

Lower CO2 Footprint With Full Functionality

The material, developed in collaboration with Domo, is based on chemically recycled polyamide 6, which is recovered from industrial textile waste and fibers. The unique aspect lies in the processing method: the PA6 is depolymerized into caprolactam, purified, and then repolymerized. This produces a PA6 with the technical properties of a primary polyamide—but with significantly lower environmental impact. According to Domo, the material's carbon footprint is reduced by approximately 20 percent (cradle-to-gate) compared to the fossil-based reference, while maintaining the same functionality.

Gallery

The compound used, Technyl-4-Earth C52G1 V25 CR GY 2747, combines a halogen-free flame retardant system with a 25 percent glass fiber reinforcement. The formulation was adjusted to ensure that neither demolding nor dimensional stability causes issues under serial production conditions—a crucial point, as the components are manufactured in existing injection molding tools. Siemens confirmed in internal tests that the mechanical, thermal, and electrical properties meet the requirements. Additionally, both laser markability and the desired color stability in the specific gray tone RAL 7035, which is frequently used in the electrical market, were achieved. The UL certification for use in flame-retardant applications is available and also valid for variants with chemically recycled content, as confirmed by Domo.

Processing takes place in Siemens' own manufacturing facilities, including the Regensburg site. Only green electricity is used there—a criterion necessary to meet the internal Siemens Eco-Tech label. This label evaluates new products across three dimensions:

• sustainable material selection
• optimal use and
• circularity

The use of Technyl-4-Earth in the 5SV3 Type A/AC not only formally meets these requirements but has also been validated by TÜV Rheinland as part of the Siemens governance model.

Eco-Design As Part of Product Development

At Siemens, during the conceptual phase, the so-called eco-design process is used to examine how a product can be improved from an environmental perspective—whether through alternative materials, more resource-efficient designs, or more efficient use. The evaluation is carried out according to an internal framework that takes into account the manufacturing phase, the operating phase, and disposal.

Special attention is placed on material usage. Therefore, in the early phase of the project, the housing material was analyzed for its environmental impact—including through a life cycle assessment (LCA) that Siemens conducts for all relevant product lines. Combined with an EPD (Environmental Product Declaration), this creates a high degree of transparency for customers and regulatory authorities.

The project clearly demonstrated that using a recycled polyamide does not automatically result in performance losses. The material enabled a double-digit percentage reduction in CO₂ emissions without compromising safety-critical properties.

Joint path to series production

The close cooperation between Domo and Siemens' manufacturing and development teams was crucial in enabling critical material issues such as dimensional stability, aging behavior, and flame resistance to be assessed and adjusted at an early stage. Despite its high recycled content, Technyl-4-Earth, unlike traditional mechanical recyclates, meets the flame retardant properties required for UL certification.

Overall, the project demonstrates that recycling technologies can now also be implemented in safety-critical applications—provided material selection is coordinated early and the requirements are clearly defined. The 5SV3 switch not only meets technical standards but also shows that a robust sustainability approach in industrial production is feasible without compromising material quality.

By using Technyl-4-Earth, Siemens sends a clear signal to the industry: chemically recycled engineering plastics are no longer a research topic but an industrially scalable reality—even in highly regulated application fields. The key to this success lies in the combination of recyclable material technology, transparent life cycle assessment, and industrial partnerships on equal footing.

Domo is already planning to further expand its sustainable material portfolio and provide both PA6 and PA66 compounds based on various recycling technologies for applications requiring flame retardancy.

Future-Proof Authentication with Universal RFID Readers

Universal RFID Readers: One Solution for All Credentials