Humanoid Robot Core Components: Material Selection With Titanium Alloys

Different grades of titanium alloys vary in performance, machinability and application scenarios, and can precisely meet the requirements of the core components of humanoid robots, serving as a key to their lightweight design, high reliability and large-scale mass production. The core components of humanoid robots have significantly different material requirements, and pure titanium as well as α-type, β-type and α+β-type titanium alloys show clear compatibility with various components.

I. α+β titanium alloys

α+β titanium alloys combine strength, plasticity and high-temperature performance, and their properties can be regulated by heat treatment. They are the most widely used type in the core components of humanoid robots, represented by Gr5 and its derivative grades.

Gr5 (Ti6Al4V) has a tensile strength of 900–1100MPa with a balanced performance and cost, and is commonly used in heavy-duty joint components and load-bearing skeletons. Boston Dynamics' Atlas V11 adopts this alloy to manufacture spinal support frames, which greatly improves the stability of the robot body.

Gr5 ELI features better plasticity and biocompatibility, making it suitable for human-robot interaction components. The dexterous hand joints of UBTECH's Walker X use this grade and have passed 2 million cycle tests.

Ti6Al2Sn4Zr2Mo exhibits superior high-temperature performance, and is applicable to heat-generating components such as joint module housings, providing protection for electronic control parts.

II. β Titanium Alloys
β titanium alloys are mainly composed of β-stabilizing elements such as Mo, Nb, Ta and V with an addition amount of ≥10%. After heat treatment, their tensile strength reaches ≥1100MPa. They have excellent cold workability and biocompatibility, and are non-toxic, making them suitable for high-load and high-precision core components of humanoid robots.

Ti13Nb13Zr is free of vanadium and aluminum and has good biocompatibility. It is suitable for human-machine contact components of nursing and rehabilitation robots, which can reduce stress shielding and improve the safety and comfort of use.

Ti29Nb13Ta4.6Zr (TNZT) has an elastic modulus close to that of human bones, with excellent strength and corrosion resistance. It is mostly used in bionic joints and can reduce stress concentration, being suitable for medical assistive robots.

Ti15Mo has strong corrosion resistance, and is applicable to joint bearings and actuators of robots working in complex environments such as outdoor and chemical industries, which can prevent corrosion and ensure stable operation.

III. α Titanium Alloys
α titanium alloys are mainly composed of α-stabilizing elements such as Al, Sn and Zr, with a single α-phase structure at room temperature. They have good weldability and corrosion resistance, and their strength is higher than that of pure titanium, with a maximum high-temperature service temperature of 500℃. They are suitable for low-load and high-precision components of humanoid robots, especially for precision sensing assemblies.

Grade 9 (Ti-3Al-2.5V) has a balanced strength and plasticity as well as excellent machinability, and can be made into thin-walled parts with a thickness of less than 0.1mm with good electromagnetic shielding performance. It is commonly used in sensor housings and wire protective sleeves. Germany's Festo uses this material to package tactile sensors, reducing the thickness by 30% and achieving a resolution of 5μm, which greatly improves the sensing accuracy of bionic hands.

Grade 23 (Ti-6Al-4V ELI) has better plasticity and biocompatibility by reducing interstitial elements, making it suitable for flexible sensing components. The Shenyang Institute of Automation, Chinese Academy of Sciences, uses it as a substrate to make flexible pressure sensors applied to the fingertips of Xiaomi's CyberOne, enabling precise force control and delicate interactive movements.
IV. Commercially Pure Titanium

Commercially pure titanium contains no additional alloying elements, with excellent plasticity and corrosion resistance and moderate strength. It is suitable for auxiliary components with low strength requirements but high corrosion resistance needs, providing basic support for the core structure of robots.

Grade 2 has balanced comprehensive performance with controllable processing and cost. It is mostly used for connecting and sealing components such as joint sealing rings and connecting bolts, and can also be applied to controller housings to achieve lightweight design and anti-corrosion protection.

Grade 1 has good plasticity but low strength, and is suitable for thin-walled protective parts such as flexible sensor sheaths and wire protective sleeves. It is corrosion-resistant, not easy to damage, and has a longer service life.

Ruihang Group mainly produces the raw materials for your precision manufacturing. For more details,please reach us to the email: Sam.Rui@bjrh-titanium.com