1. Industry Working Condition Pain Points

In precision equipment such as industrial robot bases and wrists, crane slewing mechanisms, radar antenna turntables, medical equipment rotary platforms and CNC rotary tables, bearings are often required to simultaneously withstand axial loads, radial loads and tilting moments. Conventional solutions typically combine thrust bearings with radial bearings—thrust bearings for axial forces, radial bearings for radial forces, plus additional bearings to resist tilting moments. This multi-bearing stacking approach not only significantly increases axial dimensions and structural complexity, but the cumulative assembly errors of multiple bearings further degrade rotational accuracy, accelerating precision loss during long-term operation.

 

Domestic four-point contact ball bearings commonly suffer from large contact angle deviation, insufficient raceway waviness control and weak cage strength, leading to ball misalignment, cage fracture and torque fluctuation under heavy loads. Imported four-point contact ball bearings offer excellent performance but have long procurement cycles and high prices, making them unaffordable for small and medium manufacturers. Thin-section four-point contact ball bearings for industrial robots are largely dependent on imports. Although a few domestic manufacturers produce them, small batch sizes, limited variety, long delivery times and unstable quality severely constrain the normal development of the domestic robotics industry.

 

For applications requiring combined loads, compact space and long-term precision retention, professional four-point contact ball bearings with single-bearing multi-directional load capacity, compact structure and convenient installation are urgently needed.

 

2. Product Core Positioning

Developed with Japanese precision bearing design experience, NMT four-point contact ball bearings feature the Gothic arch raceway design as their core technology. A single bearing simultaneously withstands radial loads, bidirectional axial loads and tilting moments—equivalent to the functional integration of two back-to-back angular contact ball bearings, but with the width of only a single angular contact ball bearing.

 

Under no load or pure radial load, the balls form four-point contact with the inner and outer ring raceways; under pure axial load, contact transitions to two-point contact, combining the functions of both single-row and double-row angular contact ball bearings. This unique contact state transition characteristic enables the bearing to maintain optimal load-carrying performance when facing combined loads with frequently changing load directions.

 

The separable structure facilitates installation—the inner ring or outer ring is split, with two halves removable and installable separately. Compared to double-row bearings, four-point contact ball bearings offer smaller axial space, higher limiting speeds and smaller axial clearance. Typical specifications cover bore diameters from 16mm to over 650mm with speed ranges from 1500 to 17000 r/min.

 

NMT has specially optimised cage design, with pocket geometry and clearance precisely calculated to ensure flexible rolling element motion while effectively suppressing vibration and noise at high speeds. Through extreme control of bearing steel purity and microstructure, combined with precision heat treatment processes, NMT endows bearings with outstanding fatigue resistance.

 

3. Structural Classification & Functional Advantages

(1) Thin-Section Four-Point Contact Ball Bearing (Lightweight Compact Type)

 

Both inner and outer rings are integrated structures, with balls forming four-point contact with raceways and crown-type snap-in cages. Compared to standard bearings of the same bore diameter, weight is approximately 5% of standard bearings, with cross-sectional area approximately 20% of standard bearings. Cross-section dimensions remain constant regardless of bore diameter changes. Suitable for robot wrists, elbows and other joint positions.

 

(2) Heavy-Duty Four-Point Contact Ball Bearing (Reinforced Load-Carrying Type)

 

Both inner and outer rings feature integrated high-strength design, accommodating more balls for higher load capacity. Contact angles are typically 35° or 45°, with larger angles providing greater axial load capacity. Suitable for crane slewing mechanisms, large radar antenna turntables, heavy-duty industrial robot bases and other applications with higher load capacity requirements.

 

(3) Sealed Four-Point Contact Ball Bearing

 

With sealing ring configuration, providing dust-proof and oil-water ingress protection. NMT has optimised the sealing system with a composite structure—the outer lip blocks large particles while the inner labyrinth structure further intercepts fine dust, maintaining stable internal cleanliness even in metal-dust-filled environments such as welding workshops and foundries. Friction torque between seals and rings is controlled to extremely low levels, ensuring energy efficiency and motion sensitivity are not sacrificed due to added protection.

 

General advantages summary: Single bearing handles radial, bidirectional axial and tilting moment loads—one replacing multiple combinations; Gothic arch raceway design with contact states adapting to load changes; smaller axial space, higher limiting speed and smaller axial clearance compared to double-row bearings; separable structure for easy installation and maintenance; thin-section series with light weight and small cross-section for compact spaces; accommodates more balls for higher load capacity.

 

4. Two-Grade Material & Process Selection

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

 

Integral quenching and low-temperature stabilizing tempering achieve uniform overall hardness with excellent raceway and ball wear resistance. Suitable for conventional industrial robot joints, automation turntables, medical equipment and other stable combined-load conditions, with outstanding cost performance for complete machine supporting.

 

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

 

Inner rings, outer rings and balls undergo deep carburizing quenching for hard wear-resistant surfaces with a tough matrix core for impact resistance. Applied to heavy-duty robot bases, crane slewing mechanisms, large radar antenna turntables and other impact-type combined-load conditions, withstanding instantaneous peak loads to prevent raceway crushing and ball fracture, 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, achieving uniform raceway surface hardness with good core toughness—the "hard exterior, tough interior" material characteristic balancing wear resistance and impact resistance;

 

Gothic arch raceway ultra-precision grinding with precise control of groove curvature radius—the ingenious four-point contact geometry enables simultaneous, balanced load carrying from both axial directions and radial direction;

 

Multi-stage grinding and precision grading of balls, achieving excellent dimensional consistency with strictly controlled diameter variation within each bearing set;

 

Superfinishing and mirror-grade polishing of raceways, with surface roughness consistently controlled below Ra≤0.04μm for stable lubricating oil film formation;

 

Precision cage machining—new cage pocket geometry and clearance precisely calculated to ensure flexible rolling element motion while effectively suppressing vibration and noise at high speeds;

 

Precise assembly of separable structure in temperature-controlled dust-free workshops, with preload and clearance precisely controlled and contact angles set at 35° or 45°;

 

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 four-point contact ball bearings.

 

6. Seal Structure Matching for Working Conditions

Open Type : Maximum heat dissipation, suitable for high-speed spindles and high-temperature environments, convenient for regular grease replenishment;

 

Single/Double-Sided Non-Contact Seals : Dust-proof and light oil-mist resistant, suitable for robot wrists, elbows and other general conditions;

 

Contact Seals : Dust-proof, water-proof and oil-mist resistant, suitable for outdoor radar antenna turntables, welding workshops, foundries and other harsh environments.

 

7. Wide Application Fields

Industrial Robots: Bases, waists, elbows, wrists—with strong combined load capacity, high precision, low friction torque and smooth operation;

Cranes & Construction Machinery: Slewing mechanisms, boom supports, small and medium crane turntables—single bearing carrying radial, axial and tilting loads;

Radar Communications: Antenna turntables, missile launcher slewing devices—all-weather long-term stable operation;

Medical Equipment: CT scanner rotary platforms, linear accelerator slewing supports—low-vibration low-noise precision rotation;

CNC Machine Tools: CNC rotary tables, indexing plates, precision rotary worktables—high-rigidity precision indexing;

Port Machinery: Rotary conveyors, welding manipulators—long-term reliable service;

Automation Equipment: Industrial positioners, turntables, material handling equipment—24/7 continuous operation.

 

8. Brand Supply & Customisation Service

NMT maintains sufficient spot inventory of mainstream four-point contact ball bearing specifications for urgent equipment repair and mass complete machine supporting with short lead time. Customisation services include special contact angles (35° or 45°), special radial clearance, high/low temperature resistant materials, special grease, non-standard sizes, custom seal configurations 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 deformation and clearance under combined loads, extend precision retention cycles and cut the overall life cycle cost of equipment.