On the eve of mass production and commercialization of humanoid robots, the weight of the body is a challenge that many manufacturers must face. Humanoid robots are extremely sensitive to weight; for every 1 kg increase in self-weight, joint load and energy consumption grow geometrically, leading to issues such as reduced battery life. Moreover, an overly heavy chassis limits movement flexibility, hindering their adoption in scenarios like home services and industrial collaboration.

Therefore, the industry has been actively seeking solutions for robot lightweighting.

Take Tesla as an example: In December 2023, it released Optimus Gen2, a major highlight of which was achieving lightweighting without sacrificing performance compared to GEN1. The Gen2's weight was reduced by 10 kg to reach 63 kg. In November 2024, it released a demonstration of its next-generation dexterous hand catching and throwing balls, where Tesla engineers emphasized that reducing forearm weight would be one of the key focuses for subsequent work.

More recently, Elon Musk stated in an interview that the V3 design represents a significant improvement over V2. The core of the new generation design is further cost reduction and efficiency enhancement, leaning towards a lighter body, more compact structural design, and manufacturing technologies easier for mass production. A key focus corresponding to this is PEEK material.

From these points, it is clear that regardless of how Optimus evolves, lightweighting remains a direction they are continuously focusing on.

Lightweighting of Humanoid Robots Is an Inevitable Trend

** The Advantages of Lightweighting**

Just as weight loss brings benefits to humans, reducing the weight of humanoid robots naturally offers many advantages. The most obvious benefit is improved battery life. Currently, the amount of electricity a humanoid robot can carry is limited. Given that battery energy density and technological levels cannot yet undergo rapid iteration, using lightweight materials to reduce weight can enhance endurance. In many scenarios, endurance is a key factor affecting the practical deployment of robots. For instance, in tasks such as remote assistance or long-duration patrols, battery life directly impacts usability.

Furthermore, lightweighting reduces the motion inertia of humanoid robots. Compared with industrial robots, humanoid robots have significantly higher degrees of freedom in parts such as their hands and legs, demanding greater flexibility. A heavier robot body leads to greater motion inertia, which not only shortens the lifespan of components but also affects the efficiency and precision of movements.

In terms of performance, a lighter robot will perform better. A lightweight structure provides more weight margin for the design of other components, such as reserving additional space for key modules like sensors and actuators. This facilitates subsequent functional expansion and upgrades, thereby comprehensively improving the performance of humanoid robots.

Additionally, excessive weight poses significant safety risks to users. Lightweight humanoid robots cause less harm to humans in the event of a collision, which helps ensure personal safety.

The Pathways to Lightweighting

Currently, the pathways for lightweighting humanoid robots can generally be divided into structural lightweighting and material lightweighting.

Structural lightweighting achieves weight reduction by optimizing the shape, dimensions, and topology of the robot's structure. For example, it involves adopting integrated joints or directly eliminating unnecessary exterior structural components. This approach does not require changing materials and offers the advantages of low cost and ease of implementation. In the overall weight distribution of a robot, joint modules account for a large proportion, followed by structural components.

Lightweighting of materials is achieved by replacing traditional metals with high-strength, lightweight alternatives, thereby reducing weight while maintaining structural integrity. These lightweight materials are primarily high-end engineering plastics, carbon fiber composites, and magnesium-aluminum alloys. High-end engineering plastics include PEEK, PA, PPS, LCP, TPE, UHMW-PE, and others.

Replacing Steel with Plastic: PEEK Material Shows Clear Advantages

PEEK material, or polyether ether ketone, is a semi-crystalline thermoplastic with a melting point of 343°C and a crystallinity of 30%, classified as a special engineering plastic.

Compared with metal materials, PEEK's advantages are its light weight and high specific strength. Under the same weight, PEEK's specific strength far exceeds that of traditional metal materials, being approximately twenty-one times that of steel and eight times that of aluminum alloy. While meeting strength requirements, it can also significantly reduce material self-weight, and its insulation and chemical resistance are superior to those of ordinary metals.

As a new polymer material, PEEK is mainly used to replace metal materials. In the context of "replacing steel with plastic" and "lightweighting," PEEK can gradually replace the use of metal materials in mid-to-high-end applications due to its excellent properties.

Compared to other major engineering plastics, PEEK offers comprehensive performance and significant advantages, making it one of the most recognized high-performance thermoplastics. Specifically, PEEK exhibits superior heat resistance, with a glass transition temperature as high as 143°C and a melting point around 334°C. It can be used continuously at 250°C, with short-term usage temperatures even exceeding 300°C. Moreover, its tensile strength exceeds 100 MPa, while its flexural strength and modulus are outstanding. Possessing good toughness and impact resistance, PEEK combines rigidity and flexibility, ensuring it does not easily fracture under complex stress conditions.

In terms of corrosion resistance, PEEK exhibits good tolerance to most chemical reagents, including organic solvents and acids or bases. In highly corrosive chemical environments and complex industrial media, it can maintain its performance without being affected. Moreover, it retains high wear resistance at temperatures as high as 250 degrees Celsius. Its low friction coefficient and wear resistance enable it to effectively reduce wear and extend service life when used in manufacturing moving parts such as bearings and gears. Additionally, PEEK possesses excellent processability, including ease of injection molding, extrusion, and machining.

In humanoid robots, PEEK is primarily used in main components such as limb skeletons and joints, robotic arms, gears and chains, bearings and bolts, sensor and actuator housings, decorative parts, battery casings, and insulating components. This application is driven by its weight reduction and cost optimization benefits. For the skeleton structure, PEEK can reduce weight by 40% compared to metal materials while maintaining sufficient strength and rigidity to meet the robot's load-bearing and flexibility requirements.

For humanoid robots, material selection often determines performance limits. In terms of mechanical strength and other properties, PEEK aligns well with the performance needs of humanoid robots, making it the preferred material for lightweighting.

Previously, Optimus Gen2 achieved a 10 kg weight reduction without compromising performance, largely due to lightweight PEEK materials. Gen3 will continue this approach, with Tesla planning to significantly increase the proportion of PEEK usage to cover more components such as motors, bearings, and casings.

As Mass Production Accelerates, PEEK Materials Rise to the Forefront

Regarding robot mass production, Tesla CEO Elon Musk stated at the July earnings conference that the third-generation prototype of the humanoid robot Optimus will be launched by the end of this year. Mass production of Optimus is estimated to begin in 2026, with a target of producing 1 million units annually within five years.

In July, domestic robots saw a series of order announcements. First, Zhiyuan Robot and Unitree Robotics won the bid for the "China Mobile (Hangzhou) Humanoid Biped Robot Contract Manufacturing Service Procurement Project," with a total procurement budget of 124 million yuan (tax included). Subsequently, UBTECH Robotics won the bid for a robot equipment procurement project from Miayi (Shanghai) Automotive Technology Co., Ltd., valued at 90.5115 million yuan. This stands as the largest procurement order currently secured by a humanoid robot company globally.

Earlier reports from Morgan Stanley predicted that the global "humanoid robot market" will exceed $5 trillion in value by 2050. Morgan Stanley also noted that several major commercial robot orders have recently emerged in China, a fact that supports their viewpoint.

It is widely believed in the market that, given the strong demand for lightweight materials in humanoid robots, PEEK materials are poised for rapid development due to their advantages in weight reduction and physical properties. According to forecasts from Frost & Sullivan, assuming the main terminal applications of PEEK materials in China remain unchanged, the domestic demand for PEEK materials will rise from 2,334 tons in 2022 to 5,079 tons in 2027, corresponding to a compound annual growth rate of approximately 16.8%.

With the acceleration of humanoid robot mass production and lightweighting becoming an inevitable trend, the prosperous era for PEEK materials may just be beginning.