Linear joint module assembly of the robot. [Photo/Shuanglin Group for Tide News]

Ningbo-based Shuanglin Group is transforming the humanoid robot industry with a mass-produced joint component priced at just 499 yuan ($71).

In January, Shuanglin announced the mass production of its self-developed planetary roller screw, a core joint for humanoid robots. Industry insiders estimate that similar components on the international market sell for over 5,000 yuan, making Shuanglin's product less than one-tenth the global price.

"The planetary roller screw functions like a tendon," said Shuanglin Chairman Wu Jianbin. "It determines whether a robot's arms lift steadily and its steps are precise. The underlying technology is familiar, but the application is entirely new."

Shuanglin's expertise comes from decades of experience in precision automotive components. The company dominates China's automotive seat drive market and has a strong global presence in electric vehicle parts. Techniques originally used to grind seat screw threads — with a tolerance of 0.003 millimeters — have been adapted to humanoid robot joints. This level of precision allowed the company to develop the new component in just three months.

The joint is already in use in XPeng's IRON humanoid robot, where more than 20 joints rely on Shuanglin's parts. From February 2024 to April 2025, the company's stock surged 1,366 percent, signaling strong investor confidence.

Ningbo's robotics ecosystem is rapidly expanding. Over 30 local listed companies focus on intelligent robotics components, from servo motors to controllers.