Rotary platforms of construction machinery, automated indexing turntables, industrial robot joints, radar rotary mechanisms and small rotary support devices need to bear radial loads, bidirectional axial loads and continuously changing overturning moments during operation. Restricted by overall layout, many rotary mechanisms have limited axial installation space and cannot accommodate two sets of independent angular contact ball bearings. If ordinary single-row bearings are used in combination, complicated assembly will generate accumulated assembly errors, leading to uneven rotary clearance, operation stagnation and excessive end runout, which directly damage positioning accuracy and running stability.

Conventional double-row bearings have bulky dimensions and cannot meet lightweight compact design requirements. Traditional angular contact bearings only sustain unidirectional axial force. Paired installation is required to realize bidirectional bearing capacity, which increases component quantity and manufacturing costs while extending axial dimensions. Most outdoor construction machinery and open-air automated equipment are exposed to rain, dust and drastic temperature fluctuations all year round. Simple sealing structures fail to block moisture and dust, resulting in grease deterioration, rolling element rust and wear, abnormal noise and rotation blockage within short service cycles. Bearing damage will lock rotary mechanisms and cause complete shutdown. Maintenance for outdoor equipment consumes massive time and generates heavy economic losses.

Furthermore, precise rotary equipment has strict standards for rotation flexibility and clearance control. Excessive clearance triggers shaking and positioning deviation, while excessive preload raises friction, accelerates heat generation and shortens service life. The market demands precision four-point contact ball bearings that can bear composite loads with single unit, feature compact structure and stable rotary accuracy, simplifying transmission structure within limited installation space while balancing load capacity, rotary precision and environmental adaptability.

NMT Precision Four-Point Contact Ball Bearings adopt unique Gothic arch raceway structure. Steel balls inside a single bearing form four contact points. One single bearing can support radial loads, bidirectional axial loads and overturning moments simultaneously, replacing two angular contact ball bearings installed in back-to-back arrangement. The design greatly simplifies rotary mechanism layout, reduces axial space occupation, facilitates lightweight compact equipment design, cuts component quantity and shortens assembly procedures and production costs.

Inner and outer rings are forged from high-purity vacuum degassed bearing alloy steel. Stabilization heat treatment eliminates residual internal stress generated during forging and machining and restrains deformation under long-term cyclic loads. Multi-pass CNC precision grinding and superfinishing are applied on raceways to achieve accurate curved contour and high surface finish. Steel balls move along smooth tracks with evenly distributed contact stress to prevent raceway fatigue pitting caused by local stress concentration. Rolling steel balls are sorted to micron-level uniformity to guarantee smooth rotation, lower rotary friction and reduce operating temperature rise.

Multiple internal clearance options are available. Zero-clearance and standard slight-clearance schemes can be selected flexibly according to working conditions to satisfy differentiated demands of precision positioning and low-speed heavy-duty rotation. A variety of sealing configurations including metal shields, contact rubber seals and non-contact seals are provided to adapt to indoor dust-free workshops, dusty outdoor environments and humid open-air sites. Seals prevent dust, moisture and contaminants from entering bearing chambers, protect internal lubricants, slow rusting and abrasive wear and greatly extend maintenance intervals. High-strength wear-resistant cages separate steel balls to avoid collision friction and further reduce operating noise.

All products follow international standard dimensions with complete specifications covering miniature models for robot joints and medium-sized models for construction machinery. Direct replacement of imported bearings can be realized without large modification of bearing housings, facilitating maintenance and upgrading of new and existing equipment. The bearings adapt to multiple motion modes including intermittent indexing rotation, continuous low-speed rotation and periodic forward-reverse rotation and are widely used on various precision rotary equipment.

Core Product Advantages

Gothic arch four-point contact raceway enables single bearing to withstand radial, bidirectional axial and overturning composite loads, eliminating paired bearing assembly and simplifying mechanical design;

Compact axial structure saves substantial installation space compared with double bearing combinations to support miniaturized lightweight equipment design;

High-precision superfinished raceways distribute stress evenly, suppress stress concentration, mitigate raceway fatigue pitting and maintain long-term rotary precision;

Rich clearance options support zero-clearance assembly to control rotary shaking and meet high-precision positioning demands of precision turntables;

Optional diversified sealing structures deliver excellent dustproof and waterproof performance to adapt to complex working environments of outdoor construction machinery;

High-performance wear-resistant cages isolate steel balls to reduce collision friction for lower noise and smoother rotary movement;

Capable of bearing alternating forward-reverse loads, suitable for frequent reversing intermittent operation with good impact resistance against load fluctuation;

Standard dimensions and strong universality support direct replacement of imported bearings and reduce equipment renovation and spare part procurement costs.

Typical Application Scenarios

Joints of industrial collaborative robots and manipulator rotary units; CNC indexing turntables and automated welding rotary fixtures; rotary supports for small construction machinery; rotary platforms for optical inspection equipment; rotary mechanisms of monitoring pan-tilts and radars; rotary stations and rotating fixtures of packaging automation equipment.

Quality Assurance

Raw materials of NMT Precision Four-Point Contact Ball Bearings are premium refined bearing steel. Incoming inspection covers chemical composition, hardness sampling test, metallurgical structure analysis and non-metallic inclusion detection to eliminate material defects from the source. Blanks of inner and outer rings adopt composite precision cold and hot forging technology to form dense uniform texture free of pores and shrinkage cavities. Stress relief annealing is conducted after rough machining, followed by deep quenching and low-temperature stabilization treatment to minimize dimensional variation during long-term operation.

Progressive multi-step grinding including rough grinding, finish grinding and superfinishing optimizes raceway curved profiles with strict control over dimensional tolerance, roundness and surface roughness. Steel balls are sorted precisely for unified dimensional accuracy. Cages are manufactured by precision stamping or machining with tight tolerance control. All components go through thorough cleaning and dust removal before assembly in dust-free workshops, filled with long-service-life lubricating grease. After assembly, finished products undergo rotary torque testing, clearance inspection, end runout detection, cyclic endurance simulation and sealing performance testing. All nonconforming products are eliminated to guarantee consistent quality of delivered goods. NMT supplies stable and reliable precision rotary bearing solutions for automation equipment, intelligent equipment and construction machinery manufacturers.

Product Range

Open four-point contact ball bearings, single/double sealed four-point contact ball bearings, zero-clearance precision four-point contact ball bearings. Model selection depends on rotary speed, load type, positioning precision requirements and field environmental conditions.

Brand Strength

NMT has long been engaged in R&D and manufacturing of precision motion support bearings. Targeting industrial pain points of rotary turntables, robot joints and construction machinery rotary mechanisms such as limited installation space, composite loads, frequent forward-reverse rotation and harsh outdoor environments, NMT continuously optimizes product design. The brand solves existing drawbacks of paired angular contact bearings including complicated structure, large space occupation, hard-to-control assembly error and high cost of bidirectional load solutions by upgrading raceway curved design, heat treatment technology and sealing structures. The bearings effectively reduce failures such as rotary shaking, positioning deviation, excessive temperature rise and premature rust wear. NMT helps equipment manufacturers simplify structural design, cut overall production costs, reduce shutdown maintenance frequency of terminal equipment and lower later operation expenses to support stable long-term operation of automation equipment and construction machinery.