Seoul – October 5, 2026 -- SeAH Besteel has commercialized a proprietary special steel for robot reducers, the mechanical joints that convert high-speed motor output into precise robotic motion, breaking a reliance on a concentrated group of foreign suppliers for this core material.

Ultra-clean refining pushes gear backlash toward zero

The steel is engineered for the flexspline, the component that transmits motor power within a reducer. SeAH Besteel applied a vacuum degassing system during refining to eliminate non-metallic inclusions that cause micro-cracks, producing an ultra-clean steel intended to maximize fatigue life under continuous robotic movement.

Alloy design controls thermal deformation during heat treatment

Through proprietary alloy design, the company addressed microscopic shape deformation caused by thermal stress during heat treatment, a defect that previously compromised the dimensional precision required for robotic gear machining. The material is designed to resist shape change under varying temperatures and physical impact while maintaining machinability during precision processing.

SPG became the first customer in February, with full-scale production now underway

SeAH Besteel began supplying the material to SPG, a Korean precision reducer manufacturer, in February before transitioning to full-scale mass production. The company reports expanding market share across industrial applications since the initial shipment.

Company targets humanoid robot applications next

SeAH Besteel is broadening its special steel portfolio to include grades tailored for humanoid robots, building on the flexspline material's commercial rollout. A company representative said mass production through proprietary technology marks a milestone in a reducer-materials market historically dependent on a small group of foreign suppliers, calling sovereign capacity in core robotic materials critical to the robotics ecosystem's growth.