1. Industry Working Condition Pain Points: The Dual Dilemma of Space and Rigidity

In today's robot joint design, bearing selection has moved far beyond simple support functionality to become a fundamental variable defining overall machine performance. Next-generation intelligent equipment such as collaborative robots, humanoid robots and medical manipulators place nearly contradictory demands on joints—slender enough to free design space yet rigid enough to handle combined loads; large hollow passages for cables and tubes yet extremely high rotational accuracy and long life.

 

Traditional ball bearings carry loads through point contact. Under heavy loads or moments, local deformation occurs, leading to end-effector jitter. Domestic crossed roller bearings, despite having line-contact advantages, commonly suffer from insufficient roller crowning control, poor rolling consistency and weak cage strength, causing torque fluctuation, early micro-wear and precision drift under heavy loads. Imported products offer excellent performance but have long procurement cycles and high prices, making mass supporting cost-prohibitive.

 

Many automation engineers have experienced this: newly assembled robots have perfect accuracy, but after thousands of hours of operation, trajectory drift begins, eventually forcing speed reduction. The root cause often lies in early bearing micro-wear. On continuous production lines such as automotive body welding and power battery stacking where mid-process calibration is not allowed, this precision degradation directly threatens production capacity and product yield.

 

For applications requiring extreme space efficiency, ultra-high rigidity and long maintenance-free life, specialised thin-section crossed roller bearings with thin cross-sections, high rigidity, hollow design for cable routing and full-lifecycle precision stability are urgently needed.

 

2. Product Core Positioning: The Foundational Support for Robot Joints

Developed with Japanese precision bearing design and manufacturing experience, NMT thin-section crossed roller bearings feature orthogonally arranged cylindrical rollers as the core structure—rollers arranged at 90° perpendicularly in V-shaped raceways, expanding contact from points to lines, allowing stress to disperse evenly across raceway surfaces like flowing water. Even when a robotic arm extends at full speed and makes an emergency stop, the joint maintains geometric stability with no unwanted vibration transmitted to the end-effector.

 

Through strict control of roller crowning profiles and raceway surface integrity, NMT effectively reduces stress peaks in rolling contact areas. Even after millions of alternating load cycles, bearing rotational accuracy remains stable and clearances do not gradually increase. For continuous production lines such as automotive body welding and power battery stacking where mid-process calibration is not permitted, this full-lifecycle rigidity retention capability is the foundation of stable production capacity and product yield.

 

The ultra-thin cross-section design minimises inner and outer ring dimensions, providing reassuring support rigidity with minimal section height. The central hollow passage allows cables and tubes to pass straight through, eliminating the fatigue fracture risk from repeated bending. The overall machine appearance can thus be made more sleek and slender, and joint range of motion is no longer constrained by external cables.

 

NMT thin-section crossed roller bearings span vastly different engineering boundaries, from the vacuum environment of wafer handling robots to the high-impact scenarios of heavy-duty palletising robots. They do not pursue extreme single-parameter performance, but balance rigidity, precision, life and compactness into a holistic solution.

 

3. Structural Classification & Functional Advantages

(1) RB Series – Outer Ring Split Type

 

Outer ring split with integrated inner ring design, suitable for applications requiring high inner ring rotational accuracy. The split structure allows precise clearance adjustment, enabling high-accuracy rotational motion even under preload. Suitable for collaborative robot wrists, medical manipulators and other applications with extreme precision requirements.

 

(2) RE Series – Inner Ring Split Type

 

Inner ring split with integrated outer ring design, suitable for applications requiring high outer ring rotational accuracy. Main dimensions are the same as RB series, catering to different rotational accuracy requirements.

 

(3) RU Series – Integrated Inner and Outer Ring Type

 

Both inner and outer rings are integrated structures with pre-machined mounting holes, eliminating the need for fixing flanges and support housings. Installation has minimal impact on performance, providing stable rotational accuracy and torque, suitable for applications where both outer and inner rings rotate.

 

(4) RA Series – Ultra-Thin Compact Type

 

A new type derived from RB series design, with inner and outer ring thickness reduced to the极限. Most suitable for applications requiring lightweight and compact design, such as collaborative robots, humanoid robot wrists and ankles, precision alignment platforms and more.

 

General advantages summary: Orthogonally arranged cylindrical rollers with line-contact high rigidity; ultra-thin cross-section design providing reliable support with minimal height; central hollow for cable routing; strict control of roller crowning profiles and raceway surface integrity effectively reducing stress peaks; full-lifecycle precision retention capability; split structure allowing precise clearance adjustment.

 

4. Two-Grade Material & Process Selection

Grade 1: Through-Hardened Bearing Steel (General Version)

 

Integral quenching and low-temperature stabilizing tempering achieve uniform raceway hardness and excellent roller wear resistance. Suitable for general industrial robot joints, automation turntables, precision testing equipment and other conventional conditions, with outstanding cost performance for mass production supporting.

 

Grade 2: Carburized Bearing Steel (Heavy-Duty Reinforced Version)

 

Inner rings, outer rings and rollers undergo deep carburizing quenching for hard wear-resistant surfaces with a tough core for impact resistance. Applied to heavy-duty palletising robots, large six-axis robots, humanoid robot hips and other high-load applications, withstanding instantaneous peak loads with significantly extended service life under extreme conditions.

 

5. Japanese Precision Manufacturing Process

Vacuum degassing refining of high-purity special steel forging, controlling non-metallic inclusions to extremely low levels and eliminating fatigue crack initiation points;

 

Precision forging + gradient heat treatment, ensuring thin-section rings maintain stable geometric shapes after quenching, preventing warpage from residual stress release;

 

Staged stabilisation treatment precisely coordinated with ultra-precision grinding—equal-section thin-section bearing rings are prone to residual stress release and distortion after grinding; NMT employs staged stabilisation treatment precisely coordinated with ultra-precision grinding to bring raceway roundness and roughness to demanding levels;

 

Precise roller crowning profile control—strictly controlling roller crowning curves and raceway surface integrity to effectively reduce stress peaks in rolling contact areas;

 

Flexible pocket cage design—NMT's unique process for rolling consistency in crossed roller bearings uses flexible pocket structures enabling smooth re-establishment of contact during direction changes rather than sudden impact, effectively suppressing torque fluctuations;

 

Group matching of rollers with micron-level dimensional tolerance control for uniform load distribution;

 

Superfinishing and mirror-grade polishing of raceways with stable surface roughness control for stable lubricating oil film formation;

 

Assembly in temperature-controlled dust-free workshops with precise preload and clearance control;

 

100% full inspection including torque, vibration, rotational accuracy and run-in tests, with complete data archived.

 

All dimensions comply with international standards for direct interchange with mainstream crossed roller bearings.

 

6. Precision Grades & Customisation Options

P5 Grade: General precision grade, suitable for most industrial robot joints and automation turntables;

 

P4 Grade: High precision grade, suitable for precision testing equipment, optical instruments and medical imaging equipment;

 

P2 Grade: Ultra-high precision grade, suitable for semiconductor equipment, aerospace-grade precision rotation mechanisms.

 

Customisation options: special clearance configurations, high/low temperature resistant materials, special grease adaptation, non-standard sizes, integrated locating taper design and more.

 

7. Wide Application Fields

Industrial Robots: Bases, shoulders, elbows, wrists, finger joints—high-rigidity compact support;

Collaborative & Humanoid Robots: Wrists, ankles, hips—dual requirements of thin-section and rigidity;

Medical Equipment: Surgical robot bases, CT scanner slip ring systems, rehabilitation equipment rotary platforms;

Semiconductor Equipment: Wafer handling robots, vacuum transfer chambers, IC manufacturing equipment rotary platforms;

Precision Testing Equipment: Precision test turntables, optical telescopes, large radar antennas;

Laser Processing Equipment: Laser cutting machine turntables, LiDAR scanning mechanisms;

Aerospace: Satellite antenna azimuth drives, missile launcher slewing devices;

General Machinery: DD motors, robotic rotating sections, precision alignment platforms.

 

8. Brand Supply & Customisation Service

NMT maintains sufficient spot inventory of mainstream thin-section crossed roller bearing specifications for urgent equipment repair and mass complete machine supporting with short lead time. Customisation services include P4/P2 high precision grades, special clearance, high/low temperature resistant materials, special grease, non-standard sizes, integrated locating taper design and more. Professional engineers provide targeted selection schemes based on equipment load spectrum, installation space, accuracy requirements and speed range to optimise bearing configuration and structural selection, improve overall machine rigidity, control end-effector jitter, extend precision retention cycles and cut the overall life cycle cost of equipment. Once bearing quality crosses a certain invisible threshold, the overall machine performance in vibration suppression, temperature rise control and long-term stability rises to an entirely new level—this is the most practical answer NMT has delivered to the industrial manufacturing sector after years of deep cultivation in rolling contact technology.