I. Humanoid Robots: The "New Blue Ocean" of the Bearing Industry

In 2026, humanoid robots are moving from laboratories to mass production. The accelerated advancement by global leading manufacturers has made this field the most explosive growth curve in the bearing industry.

 

How many sets of bearings does a humanoid robot require? The answer is 134 sets. From the shoulder joint to the dexterous hand, from the hip joint to the sole of the foot, every part that requires rotation or movement cannot do without the support of precise bearings. By 2030, the global market size for humanoid robot bearings is expected to reach 2.1 billion US dollars.

 

This is not just a scale expansion, but also a rigorous technical test. The operating conditions of humanoid robots are completely different from those of traditional industrial robots - more compact space, more complex motion patterns, higher frequency of start-stop impacts, and stricter weight control. Facing these challenges, NMT uses three core technologies - extreme thin walls, zero backlash, and anti-shock - to provide reliable rotational support solutions for each of the 134 precise joints of a humanoid robot.

 

II. Dextrous Hand: Precise Rotation in Micrometer-Scale Space

The dextrous hand of a humanoid robot is one of the most extreme scenarios for bearing application. In each finger joint, bearings must provide precise rotational support within a space with a diameter of only a few millimeters. Every time a finger grabs something, it requires bearings to maintain extremely low frictional torque and extremely high repeatability positioning accuracy.

 

NMT's dextrous hand-specific miniature deep groove ball bearings achieve the unity of low friction and high precision within a very small size. The ultra-precision grinding of the raceway controls the surface roughness to the nanometer level, combined with the multi-spectrum screening of high-precision steel balls, ensures that the bearings maintain stable torque characteristics during micro-motion rotation. In the opening and closing test of the dextrous hand, after millions of cycles, the frictional torque fluctuation range of NMT's miniature bearings remains within ±5% of the initial value - this means that each grab has a consistent feel and force.

 

III. Shoulder Joint and Hip Joint: Zero Backlash Support in Torque Transmission

The shoulder joint and hip joint of a humanoid robot are the power core of the entire machine. These joints not only have to bear the weight of the entire arm or leg, but also need to transmit tens of Newton-meters of torque during high-speed swinging. Any tiny backlash in the joint will be magnified as a positional deviation at the end due to the arm length or leg length.

 

NMT's cross roller bearings - with precisely arranged 90-degree interleaved precision cylindrical rollers simultaneously engaging the inner and outer rings - provide extremely high radial rigidity, axial rigidity, and anti-overturning ability within a very thin cross-section. The line contact structure between the rollers and the raceway enables the load to be uniformly distributed along the length of the rollers, completely eliminating edge stress concentration.

 

At the output end of the harmonic reducer, NMT's cross roller bearings achieve a zero-backlash precise pre-tightening state with a split outer ring and a monolithic inner ring design - fundamentally eliminating the joint deviation caused by backlash. When the humanoid robot's arm suddenly stops swinging, the zero-backlash characteristic of NMT bearings ensures that the end effector does not experience any random angular drift.

 

IV. Knee Joint and Ankle Joint: Toughness Test under Impact Load

The walking of a humanoid robot is essentially a series of controlled falls and supports. The knee joint and ankle joint must withstand several times the body weight of instantaneous impact loads at each step of landing. If the bearing's toughness is insufficient, the high-frequency impact will accumulate micro-cracks on the raceway surface, eventually leading to fatigue peeling.

 

NMT's thin-wall angular contact ball bearings adopt a gradient carburizing heat treatment process, forming extremely high hardness on the raceway surface while maintaining sufficient toughness in the core. This "outer hard and inner tough" material property enables the bearing to resist indentation on the raceway surface while absorbing impact energy without brittle fracture. In the walking test, the humanoid robot equipped with NMT thin-walled angular contact ball bearings maintained a repetitive positioning accuracy of no more than 0.01mm after continuous walking for 100,000 steps. This indicates that a humanoid robot can maintain a stable gait after leaving the factory and during its several-year service period without frequent calibration.

 

V. Wrist and Neck: Combined Load-bearing in Multi-Degree-of-Freedom Motion

The wrist and neck of the humanoid robot need to simultaneously achieve multiple degrees of freedom of motion. The bearings in these joints not only have to withstand radial and axial loads from different directions but also need to accommodate the stacking of multiple bearings in an extremely limited space.

 

NMT thin-walled deep groove ball bearings and four-point contact ball bearings provide bidirectional axial load-bearing capacity within a very thin cross-section. The single set of four-point contact ball bearings can replace the traditional two sets of angular contact ball bearings, simplifying the structural design of the joint while saving axial space.

 

In the composite motion test of the wrist, the NMT four-point contact ball bearings maintained stable rotational accuracy when simultaneously bearing radial loads, axial thrust, and overturning moments. This means that the wrist of the humanoid robot will not experience position errors due to the deformation of the bearings under the combined loads during precise operations.

 

VI. Harmonic Drive: Precision Maintenance in Flexible Deformation

The harmonic drive is one of the most precise transmission components in humanoid robot joints. Its working principle relies on the periodic elastic deformation of flexible bearings - driven by the wave generator, the flexible bearings undergo elliptical deformation along the cam profile, driving the soft wheel to mesh with the rigid wheel.

 

This working principle imposes extremely strict requirements on the flexible bearings: in each cycle of tens to hundreds of times per second, the bearings must maintain extremely high rotational accuracy and extremely low friction torque. Any slight loss in accuracy or increase in friction will be amplified by the transmission ratio of the harmonic drive, manifesting as positioning errors of the end effector.

 

NMT harmonic drive-specific flexible bearings use high-purity bearing steel and special heat treatment processes to maintain the fatigue strength and dimensional stability of the material during repeated elastic deformation. The ultra-precision ground raceway surface and precisely controlled ball size ensure that the flexible bearings maintain stable rotational accuracy during deformation.

 

VII. Core Models of NMT Humanoid Robot Bearings

Cross Roller Bearings (CRB Series)

 

Used for the output end of the harmonic drive and the main bearings of the RV drive. 90° staggered roller arrangement, providing high rigidity, high overturning resistance, and zero backlash precision preload within a very thin cross-section.

 

Thin-Walled Angular Contact Ball Bearings (ACB Series)

 

Used for parts such as the knee joint, ankle joint, and shoulder joint that bear combined loads and impact loads. Gradient carburizing heat treatment gives the raceway high hardness and the core high toughness.

 

Thin-Walled Deep Groove Ball Bearings (DGB Series)

 

Used for parts such as the wrist and neck that require multi-degree-of-freedom motion and compact space. The thin cross-section design provides reliable radial and axial load-bearing within a limited space.

 

Four-Point Contact Ball Bearings (QCB Series)

 

Used for parts such as the wrist and neck that require bidirectional axial load-bearing. A single set of bearings replaces two sets of angular contact ball bearings, significantly saving axial space.

 

Flexible Bearings (FB Series)

 

Used for the inner part of the harmonic drive soft wheel. Special heat treatment and ultra-precision grinding processes maintain accuracy and lifespan during repeated elastic deformation.

 

Micro Deep Groove Ball Bearings (M-DGB Series)

 

Used for dexterous finger joints. Provide low friction and high-precision rotational support within a few millimeters of space.

 

VIII. From 134 Bearings to Stable Gait: The Systematic Value of NMT

The 134 sets of bearings of a humanoid robot are not isolated parts. They are highly coordinated systems - the cross-roller bearings of the shoulder joint provide zero backlash for large torque transmission, the thin-walled angular contact bearings of the knee joint bear the impact of each step landing, and the micro bearings of the dexterous hand ensure the precise feel of each grasp.

 

NMT's understanding of humanoid robots goes beyond the traditional model of "providing bearings", extending to the system engineering dimension of "participating in joint design". At the output end of the harmonic reducer, the zero-backlash characteristic of NMT's cross-roller bearings matches the precision of the reducer; under the impact load of the knee joint, the gradient carburizing heat treatment of NMT's thin-walled angular contact bearings cooperates with the robot's gait algorithm; in the limited space of the dexterous hand, the low-friction characteristic of NMT's micro bearings corresponds to the sensitivity of the force control sensor.

 

From each swing of the shoulder joint, to each step landing of the knee joint, from each rotation of the wrist to each grasp of the fingers - the NMT specialized bearings for humanoid robots provide consistent, reliable and lasting rotational support for 134 precise joints.