As humanoid robots move closer to mass production, thermal management is emerging as a critical bottleneck. Component efficiency, cramped joint architectures, and limited heat-dissipation space are all making system design harder and shaping the next wave of humanoid robot development.
The gearbox edge
Precision gearbox maker Khgears said at a recent earnings briefing that it has already been approached by a Chinese humanoid robot customer. The company expects to send samples of a new low-tooth-difference gearbox for testing in the third quarter of 2026. Compared with harmonic reducers, whose operating efficiency is below 80%, the new gearbox can reach nearly 95%, the company said.
Heat where it hurts most
Operating efficiency levels directly affect overall thermal performance. Khgears CFO George Chang said harmonic reducers are less efficient, causing them to lose more energy as heat. In humanoid robot joint modules, where space is already tight, that makes overheating is a major challenge.
The marathon moment
When Honor won this year's Beijing humanoid robot half marathon in China, the market quickly began debating a cooling in humanoid robots. Unlike other robots that rely on physical cooling, Honor crossed the finish line using a liquid-cooling system adapted from consumer electronics. Industry analysts said a humanoid robot's power consumption can reach 5–8kW, while conventional air cooling can support only about 30 minutes of high-intensity operation. Liquid cooling can extend endurance by three to five times.
A squeeze on every front
Supply-chain players in China said humanoid robot joint modules are difficult to cool for several reasons. Structurally, the joints must balance light weight and compactness, leaving internal gaps of typically less than 2mm; in some dexterous-hand components, cooling space is smaller than 5cm³, making heat difficult to disperse quickly. Some joint housings are also made of materials with poor thermal conductivity, and sealed designs prevent heat from escaping effectively. Under long-duration, high-load operation, heat tends to accumulate.
Cooling is not limited to the joints. Batteries and computing stacks in the torso are also heat sources. Industry players said unresolved cooling issues will directly trigger an "avalanche-like" decline in a humanoid robot's operating efficiency — directly cutting into how much torque a joint can deliver. After long periods of operation, if overheating triggers a protection mechanism, maximum output torque could fall by 40% or more.
When robots hit the wall
The Beijing humanoid robot half marathon offered a clear example. In the 1–3km portion of the race, robots generally demonstrated strong gait and movement with high pacing. But as the race progressed into the middle and later stages — especially after 15km — the effects of accumulated heat began to show, and the robots started to slow down.
Beyond AI and precision
As humanoid robots move into testing and batch production, cooling has evolved from a component-level issue into a system-level bottleneck. Industry players said the key to future competition will not only be AI capability or joint precision, but also the ability to solve power-density and thermal-management challenges within a miniaturized architecture.
Article translated by Charlene Chen and edited by Jerry Chen
