Actuators (motors and gearboxes) account for roughly 45-50% of a humanoid robot's cost and a large share of its weight. This episode explains how injection-molded Stanyl (PA46) gearboxes — developed by Envalior with SENTImotion and Frencken Group as the SMFdrives concept — cut gearbox weight and cost by about half while meeting torque and durability requirements.
The capability of robot software has outpaced the hardware, and the actuator is the main cost and weight constraint. Machined-metal gearboxes are heavy and expensive to produce, which keeps overall robot cost high. The Envalior, SENTImotion and Frencken Group collaboration (the SMFdrives concept) addresses this by designing for the polymer rather than dropping plastic into a steel design. Stanyl (PA46) provides the stiffness, wear and friction behavior and thermal stability needed in hot, enclosed gearboxes, and supports high-precision injection molding for economical high-volume production. The resulting gearboxes weigh roughly 50% less and cost about 50% less than metal equivalents while meeting the mechanical requirements for safe, reliable operation; Envalior notes that switching the many gearboxes in a humanoid robot to plastic can reduce total robot weight by more than 20%. A lighter drivetrain reduces motor load, heat and battery demand, and form-factor compatibility supports adoption without redesigning the robot. Simulation-first development (CAE) avoids over-engineering, helping decouple complexity from cost and lower CO2 versus machining steel.