The humanoid robotics revolution is fast approaching. Across the globe, test models are already working side-by-side with humans in factories, while AI companies race to develop advanced foundation models that enable robots to perceive and interact with the world as naturally as people do. But while much attention is focused on the artificial intelligence driving these machines, their physical forms—the “bodies” that make movement possible—are just as critical.
At the core of these robotic bodies are mechanical components like motors, gears, bearings, and screws. Among them, screws play a vital role by converting the rotational energy of motors into the linear motion humanoids need to walk, lift, or perform delicate tasks. Traditionally, ball screws—which use a circulating track of small balls between a threaded shaft and nut—have been the standard. But that’s starting to change.
A new mechanical hero is emerging: planetary roller screws. These next-generation components are quickly becoming essential to humanoid robot design thanks to their ability to handle heavier loads, last longer, and deliver smoother motion—all crucial qualities for robots expected to operate for years in challenging environments.
“Over time, planetary roller screws should represent the majority of screws used in humanoids,” researchers at Morgan Stanley predicted in a February 2025 report.
Planetary roller screws operate on a similar principle to ball screws but use threaded rollers instead of balls, enabling far greater contact surface and load-bearing capacity. That makes them ideal for humanoid robots, which face repetitive stress and complex movement patterns. Tesla’s Optimus robot, for example, uses four planetary roller screws in its calves. Other major players—including Figure AI, Agility Robotics, 1X, and nearly all of China’s humanoid robot manufacturers—are also incorporating them into their designs.
According to Jack Li, R&D and product manager at Chinese manufacturer Nanjing Process Equipment, the market for planetary roller screws is already worth $1.8 billion, and it’s expected to grow at over 30% annually over the next five years.
Actuators—devices that convert energy into movement—are central to robot function. As robotics expert Jonathan Aitken of the University of Sheffield explains, “They’re highly accurate… you get good precision in conversion from angle to linear distance travelled.” Traditionally, linear actuators struggled with high loads, while rotational ones handled them better. Planetary roller screws combine the strengths of both.
However, cost remains a significant hurdle. Producing planetary roller screws requires specialist knowledge and precision equipment that only a few companies globally possess. “Each bot needs 40 or more,” says Scott Walter, chief technical advisor at Visual Components and a leading figure in robot design. “The bulk of the cost of a humanoid will be in the actuators.”
Estimates from J.P. Morgan suggest that reducers and roller screws make up about 33% of the typical humanoid’s bill of materials. Each screw can cost between $1,350 and $2,700, making them one of the most expensive single components in a humanoid robot.
To reduce dependency on imports, especially amid growing geopolitical tensions, Chinese companies are heavily investing in domestic screw manufacturing. In October 2024, Shanghai Beite Technology—once an auto parts manufacturer—announced a 1.85 billion yuan ($260 million) facility dedicated to producing planetary roller screws.
China’s existing infrastructure, partly thanks to its drone industry, gave it a head start. “They already had a large installed base of small actuator manufacturers,” says Walter. “Not exactly the same requirements, but close enough to support early humanoid prototypes.”
This leaves the West at a crossroads. With increasing tariffs and an escalating trade war, relying on Chinese components is becoming riskier. Yet few Western companies have the tools or experience to build planetary roller screws at scale.
“The dirty little secret is even if actuators are assembled stateside, the important components are still coming from China,” Walter warns. “Planetary roller screws are precision equipment. For humanoids, they need to be small and efficient.”
There’s another problem: the designs aren’t finalized, and no one knows how big the market will be. “The supply chain does not yet exist because the designs are not yet locked,” Walter explains. “Nor is there a consensus on the size of this supply chain.”
Still, with growing investments, expanding factory deployments, and rapid AI development, the need for a robust hardware backbone is becoming more urgent. If even a fraction of the predictions about humanoid adoption prove true, then planetary roller screws could become one of the most critical—and competitive—technologies of the robotics era.
By Impact Lab
