Application of Magnesium Alloys in Humanoid Robots

Magnesium Alloys in Humanoid Robots: Core Material Selection in the Lightweight Trend

As the humanoid robot industry accelerates toward commercialization, lightweighting has become a critical pathway to overcome core pain points such as short endurance, insufficient flexibility, and limited service life. With their low density, high specific strength, cost advantages, and continuously optimized manufacturing processes, magnesium alloys are emerging as an important choice for lightweight materials in humanoid robots, with their application potential continuously being released in key areas such as body shells, joint housings, and transmission components.

I. Core Driving Force for Magnesium Alloy Applications: The Critical Need for Humanoid Robot Lightweighting

Currently, humanoid robots commonly face issues such as short operating times (mostly only 2-4 hours), high joint load pressure, and insufficient movement flexibility. Lightweighting is the core solution to address these pain points. According to global robotics industry research data, mainstream humanoid robot products have shown a clear weight reduction trend:

• Tesla Optimus Gen2 reduced weight from 73kg to 63kg compared to Gen1 (13.7% reduction), achieved through carbon fiber composite materials and topology-optimized structures

• UBTECH Walker C reduced weight from Walker X (63kg) to 43kg through integrated servo modules and lightweight shell materials

• Unitree G1 (35kg) achieved a 25.5% weight reduction compared to H1 (47kg) by eliminating hydraulic systems and adopting self-developed high-torque density direct-drive motors

• Boston Dynamics Atlas latest version achieved approximately 15% weight reduction compared to previous generation through optimized material configuration and structural design

• Honda ASIMO subsequent versions achieved 20% weight reduction through material upgrades, significantly improving movement agility

Lightweighting not only reduces drive energy consumption to extend endurance but also decreases joint motor loads and reduces friction losses between components, thereby improving robot movement flexibility and service life.

Among various lightweight materials, magnesium alloys demonstrate particularly outstanding comprehensive advantages. From material performance parameters, magnesium alloys have a density of only 1.8g/cm³, which is 2/3 that of aluminum alloys (2.7g/cm³) and 1/4 that of ordinary steel (7.81-7.85g/cm³), achieving more significant weight reduction effects in the same volume. Meanwhile, magnesium alloys' specific strength (δ/ρ) reaches 191, superior to aluminum alloys (57) and neodymium iron boron, enabling weight reduction while ensuring structural strength to meet the performance requirements of load-bearing components such as humanoid robot bodies and joints.

Additionally, magnesium alloys possess excellent electromagnetic shielding properties (particularly good performance in mid-to-high frequency ranges) and damping characteristics (approximately 1.5 times that of aluminum), effectively protecting robot internal circuits from interference and reducing vibration and noise during movement, further adapting to the complex working environments of humanoid robots.

II. Key Support for Magnesium Alloy Applications: Cost Advantages and Process Breakthroughs

(I) Prominent Cost Economics: Magnesium-Aluminum Price Ratio Maintains Low Levels

In the past, magnesium alloys faced limited application promotion due to high raw material prices. However, in recent years, magnesium prices have continued to decline, making the cost advantages of magnesium alloys increasingly apparent. International metal market data shows that before 2021, the magnesium-aluminum price ratio was consistently above 1.5, providing insufficient motivation for magnesium material penetration. Since 2023, with weakening magnesium material prices, the magnesium-aluminum ratio has fallen to near 1.0, maintaining basically in the 0.9-1.0 range during 2024-2025, with price pressure gradually relieved. From theoretical cost calculations, when the magnesium-aluminum price ratio is 1.5, the raw material costs for processing the same component are approximately equal. Under current low price ratios, without considering processing cost differences, magnesium alloys' economic efficiency is significantly superior to aluminum alloys.

From the global supply perspective, capacity expansion by major magnesium-producing countries provides guarantees for price stability. Global magnesium alloy production reached record levels in 2024, with year-on-year growth exceeding 14%. According to the "Global Lightweight Materials Technology Roadmap 2.0," the global target for magnesium alloy usage per vehicle is 25kg in 2025 and 45kg in 2030, with a compound annual growth rate of 17.9%. This massive downstream demand will continuously drive magnesium alloy capacity release, providing sufficient material guarantee for humanoid robot applications.

European and American Magnesium Alloy Industry Development Dynamics:

• Germany leads globally in magnesium alloy precision processing technology, with magnesium alloy application experience from automotive manufacturers like Volkswagen and BMW providing technical reference for the robotics field

• United States companies like Tesla and Ford extensively use magnesium alloy components in electric vehicles, with related technologies gradually transferring to the robotics field

• Japan companies like Toyota and Honda have achieved major breakthroughs in magnesium alloy surface treatment and corrosion resistance technologies, laying the foundation for long-term robot use

(II) Process Bottleneck Breakthroughs: Semi-Solid Forming Technology Addresses Performance Shortcomings

The main application pain points of magnesium alloys in the past were poor corrosion resistance, easy oxidation, and low processing safety. The maturity of semi-solid magnesium alloy die-casting processes has effectively solved these problems. International research institutions point out that magnesium alloy products produced by traditional liquid die-casting processes have problems such as easy combustion, numerous gas entrapment defects, and unstable mechanical properties. Semi-solid injection molding technology (Thixomolding) heats and shears metal particles to a semi-solid state before injecting them into molds for forming, offering three core advantages:

1. Higher Safety: Forming under sealed conditions without using high-risk magnesium furnaces, avoiding liquid magnesium combustion risks

2. Superior Product Quality: Laminar filling reduces pore formation, improves casting density, while finer crystal structures achieve tensile strengths of 150-250MPa, approaching aluminum alloys (200-450MPa) to meet load-bearing requirements

3. Environmental Friendliness and Low Energy Consumption: No need for SF6 protective gas, forming temperatures 100-150°C lower than traditional die-casting, 50% energy consumption reduction

International Equipment Technology Breakthroughs:

• German Arburg Company developed Allrounder series magnesium alloy injection molding equipment, widely used in European automotive industry with high technological maturity

• Japanese JSW Company magnesium alloy die-casting equipment demonstrates outstanding precision and stability, adopted by multiple robot manufacturers

• Italian Idra Group large-tonnage magnesium alloy die-casting equipment can handle complex robot structural components with maximum clamping forces exceeding 40,000kN

• Swiss Bühler Company leads in magnesium alloy surface treatment equipment technology, solving magnesium alloy corrosion resistance issues

These high-tonnage, high-precision equipment can cover production needs for different-sized components from humanoid robot joint housings (small-to-medium) to body structural parts (medium-to-large), further expanding magnesium alloy application scenarios.

III. Application Scenarios of Magnesium Alloys in Humanoid Robots and International Cases

Combining magnesium alloys' performance characteristics with process maturity, their applications in humanoid robots mainly concentrate in the following core components, with international robot application cases providing reference:

(I) Body Shells and Structural Components

Magnesium alloys' low density and excellent die-casting performance (suitable for complex thin-walled parts) enable production of surface-refined shell components while reducing overall machine weight. International cases show that magnesium alloy industrial robot prototypes jointly released by multiple European robot manufacturers in 2024 achieved approximately 33% weight reduction in similar components and 11% overall machine weight reduction by replacing aluminum alloys with magnesium alloys in structural components, significantly reducing drive energy consumption.

If this technology were transferred to humanoid robots, taking Tesla's Optimus Gen2 (63kg) as an example, adopting magnesium alloys for body shells and other structural components could achieve an additional 6-8kg weight reduction, further improving endurance capabilities.

International Application Cases:

• Hyundai Motor Company (Korea) has begun testing magnesium alloy shell components in its robot projects

• KUKA (Germany) adopted magnesium alloy arm segments in new-generation collaborative robots, achieving significant weight reduction

• SoftBank (Japan) Pepper robot subsequent versions consider using magnesium alloys to optimize weight distribution

(II) Joint Housings and Transmission Components

Joints are the core of humanoid robot movement, requiring extremely high material strength, damping, and heat dissipation properties. Magnesium alloys' damping properties are approximately 1.5 times that of aluminum, reducing vibration and noise during joint movement. Meanwhile, their thermal conductivity reaches 54-61W/mK. Although lower than aluminum alloys (100W/mK), combined with heat dissipation path optimization from lightweighting, they can effectively reduce motor operating temperatures.

Research indicates that magnesium alloys have excellent machinability (small cutting forces, high processing efficiency), enabling rapid processing of high-precision joint housings to match humanoid robots' motion precision requirements.

Technical Development Dynamics:

• MIT Laboratory developed magnesium alloy joint housings that have passed 100,000 cycle tests

• Stanford Robotics Laboratory robotic arm joints made with magnesium alloys achieved 40% noise reduction

• CMU humanoid robot projects show magnesium alloy transmission components significantly improved movement smoothness

(III) Internal Brackets and Motor Housings

Magnesium alloys' electromagnetic shielding properties (particularly good performance in mid-to-high frequency ranges) protect robot internal circuits from external interference, while their lightweight characteristics reduce motor loads and improve response speeds. International test data shows that robot prototypes using magnesium alloy motor housings and internal brackets achieved not only 10% energy consumption reduction but also 5% cycle time improvement with faster response and smoother operation.

This advantage is particularly important in humanoid robots, helping maintain stable operation of precision control systems in complex environments.

IV. Global Technology Development Trends for Magnesium Alloy Robot Applications

(I) Emerging Technology Breakthroughs

Surface Treatment Technology Advances:

• New magnesium alloy surface coating technologies developed by Swiss and German companies improve corrosion resistance by 300%

• Plasma Electrolytic Oxidation (PEO) technology developed in Japan provides excellent surface protection for magnesium alloys

Alloy Composition Optimization:

• Rare earth magnesium alloys developed by US national laboratories achieve 50% strength improvement, more suitable for high-load applications

• New magnesium-lithium alloys funded by EU Horizon projects further reduce density to 1.4g/cm³

(II) Manufacturing Process Innovation

3D Printing Technology:

• German SLM Solutions Company's magnesium alloy 3D printing technology can manufacture complex robot components

• US Desktop Metal Company developed magnesium alloy printing materials suitable for small-batch customized production

Smart Manufacturing Integration:

• Industry 4.0 technology applications in magnesium alloy processing achieve real-time quality monitoring

• AI-assisted magnesium alloy forming process optimization improves production efficiency and product consistency

V. Market Prospects and Development Opportunities

(I) Global Market Demand Forecast

According to International Federation of Robotics (IFR) predictions, the global humanoid robot market will grow at a 45% compound annual growth rate from 2025-2030, with lightweight materials market scale reaching $15 billion. Magnesium alloys, as one of the core lightweight materials, are expected to capture 20-30% market share.

(II) Regional Development Characteristics

North American Market:

• Companies represented by Tesla and Boston Dynamics drive technological innovation

• Government support for advanced manufacturing development provides policy guarantees for magnesium alloy applications

European Market:

• Countries like Germany and Switzerland lead in precision processing technology

• EU green development plans promote environmental material applications

Asia-Pacific Market:

• Japanese and Korean companies have deep accumulation in materials science and robotics technology

• Massive manufacturing bases provide support for large-scale applications

VI. Risk Warnings

Despite the broad application prospects for magnesium alloys in humanoid robots, the following potential risks still require attention:

1. Humanoid Robot Mass Production Below Expectations

The lightweight materials market space for humanoid robots is highly correlated with humanoid robot mass production scale. If production progress by mainstream manufacturers like Tesla and Boston Dynamics slows, it will directly impact magnesium alloy component order releases, leading to demand below expectations.

2. Technology Route Change Risks

Current lightweight materials present a multi-technology route competitive landscape. If carbon fiber composites (such as low-cost carbon fiber), titanium alloys, or new engineering plastics (such as PEEK, PEI) achieve technological breakthroughs and cost reductions, they may substitute magnesium alloy applications, affecting penetration rate improvement pace.

3. Raw Material Price Volatility Risks

Although current magnesium-aluminum price ratios maintain low levels, magnesium prices are significantly affected by supply-demand relationships, energy costs, and geopolitical factors. If magnesium prices rise significantly in the future, it will weaken magnesium alloys' cost advantages, constraining their large-scale applications in humanoid robots.

4. Technical Standardization Challenges

Differences in magnesium alloy technical standards and safety regulations across global regions may affect international product applications and supply chain integration.

5. Environmental Regulation Risks

As global environmental requirements become increasingly strict, environmental impacts and recycling issues in magnesium alloy production processes may face stricter regulation, increasing compliance costs.

This article is compiled based on public materials and industry research, aimed at providing reference for magnesium alloy applications in the humanoid robotics field. Investment involves risks; decisions should be made cautiously.

aikerly