1. Industry Working Condition Pain Points

In equipment such as main drive spindles, large reducers, hot rolling production lines, mining crushers and large fan spindles, the main shaft bears extremely strong unidirectional radial pressure, making transmission shafts highly susceptible to bending deformation under load. Ordinary deep groove ball bearings adopt point-contact structures, causing concentrated contact stress under heavy loads, resulting in roller crushing and large-area raceway pitting and spalling. Tapered roller bearings, while capable of handling combined loads, suffer from high friction loss and severe temperature rise under pure radial conditions.

 

Cylindrical roller bearings, with their line-contact structure and superior radial load capacity, have become the ideal choice for pure radial heavy-load applications. They are widely used in large and medium-sized motors, rolling stock, machine tool spindles, reducers, rolling mills, vibrating screens, and lifting and transportation machinery. However, domestic general-purpose cylindrical roller bearings commonly suffer from insufficient roller crowning control, lack of raceway waviness management and weak cage strength. Under heavy loads, roller ends are prone to premature failure due to edge stress; cages experience abnormal wear during frequent starts and stops; roller deflection wear and high-temperature oil leakage are regular failures. Imported cylindrical roller bearings have long procurement cycles and high prices, bringing high cost pressure for mass replacement in production lines.

 

For pure radial heavy loads, high-speed continuous operation and spindle rigidity requirements against deformation, professional cylindrical roller bearings with high rigidity, strong radial load capacity, modular structure and multi-scenario adaptability are urgently needed.

 

2. Product Core Positioning

Developed with Japanese heavy-duty bearing design experience, NMT cylindrical roller bearings focus on pure radial force conditions, with the line contact between cylindrical rollers and raceways as the core technology. The line-contact structure greatly raises the upper limit of radial load capacity, with overall rigidity far exceeding ball bearings.

 

NMT adopts asymmetric logarithmic curve profile modification on roller contours—contact stress decreases uniformly from the centre toward both ends, presenting a smooth arched distribution along the entire contact line. Even under eccentric loads or overturning moments, stress distribution inside the bearing remains uniform without localised overload causing early pitting. By optimising the length-to-diameter ratio and quantity configuration of rollers, NMT achieves a more uniform stress transmission path within limited space.

 

The modular separable design enables independent assembly and disassembly of inner and outer rings, facilitating maintenance, grease replenishment and separate replacement of damaged parts to cut maintenance costs. Multiple structural types support one-way axial positioning, two-way axial positioning and free axial sliding to match differentiated assembly requirements. N and NU type bearings allow axial movement without constraining axial displacement of the shaft or housing.

 

NMT also offers a full complement roller design option, eliminating cages to accommodate more rolling elements within the same external dimensions and significantly improving radial load capacity. To solve the friction problem between full complement rollers, NMT introduces tiny spherical protrusions on roller end faces, converting line contact to point contact, combined with special extreme-pressure grease to form a tough isolating oil film between rollers. For high-speed lightweight applications, NMT also offers a hollow roller structure option, significantly reducing individual roller mass while maintaining radial rigidity.

 

3. Structural Classification & Functional Advantages

(1) NU Type – Outer Ring Without Ribs (Floating Type)

 

The outer ring has no fixed ribs on both sides, allowing the inner ring and roller assembly to slide axially freely. Mainly applied to motor floating ends and long spindle thermal elongation compensation to offset additional axial stress caused by thermal expansion of high-speed spindles and prevent bearing seizure and shaft bending. NU type bearings do not carry axial loads and allow bidirectional axial displacement between shaft and housing.

 

(2) NJ Type – Outer Ring With Single Rib (One-Way Positioning)

 

The outer ring features a single integrated rib for one-way axial limitation. Suitable for reducer gear shafts and crusher main shafts to bear auxiliary axial force and restrict unilateral shaft displacement.

 

(3) NUP Type – Two-Way Positioning Combined Bearing

 

The outer ring has ribs on both sides, with the inner ring featuring a fixed single rib on one side and a separable flat rib ring on the other. The NJ bearing combined with a snap ring forms a fully fixed two-way axial structure for complete spindle locking. Used for gearbox input ends and rolling mill fixed supports.

 

(4) N Type – Inner Ring Without Ribs

 

The inner ring has no ribs while the outer ring provides overall limitation, convenient for interference assembly of large spindles and separate hot disassembly of the inner ring to greatly improve overhaul efficiency.

 

General advantages summary: Radial load capacity more than 2.5 times that of deep groove ball bearings of the same size due to line contact; superfinished roller end faces reduce rib friction and heat generation; sliding friction between roller end faces and cages is converted to controllable boundary lubrication; combined with high-strength copper alloy matrix and solid lubricant fillers, cages show almost no significant wear; two cage options—solid brass for heavy impact loads and stamped steel for high-speed lightweight operation; asymmetric logarithmic profile eliminating edge stress concentration; separable design for easy installation and maintenance.

 

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 consistent raceway and roller wear resistance. Ideal for continuous stable radial load conditions such as industrial motors, fans, medium and small reducers and conveyor rollers, with outstanding cost performance for complete machine 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 impact-absorbing core. Raceway surfaces form a high-hardness fatigue-resistant layer while the core maintains toughness. Applied to crushers, shield machines, hot rolling mills and heavy-duty gearboxes with shock radial loads to withstand instantaneous peak loads and prevent rib cracking and roller fracture. Steel that has undergone special thermal stabilisation treatment has its retained austenite content controlled to extremely low levels, ensuring bearing inner and outer diameters do not undergo significant change even under repeated thermal cycling, avoiding abnormal noise or vibration caused by loose fits.

 

5. Japanese Precision Manufacturing Process

Vacuum arc remelted bearing steel billet forging to eliminate internal inclusions and porosity, improving material compactness;

 

Isothermal annealing after forging to eliminate forging internal stress;

 

Integral/carburizing quenching and multiple high-low temperature tempering for stable dimensional accuracy and avoidance of aging deformation during long-term operation;

 

Superfinishing of cylindrical roller outer diameters and mirror polishing of end faces to reduce rib friction coefficient;

 

Asymmetric logarithmic profile modification—contact stress decreasing uniformly from centre to both ends, eliminating edge stress concentration;

 

Multi-point measurement online closed-loop grinding process, compressing raceway roundness error to sub-micron levels;

 

Raceway waviness harmonic analysis—deliberately weakening specific order waves prone to causing resonance;

 

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

 

Aging treatment after grinding to eliminate machining residual stress;

 

Assembly in temperature-controlled dust-free workshops, with four full inspections before delivery: load test, temperature rise test, clearance test and noise test.

 

All dimensions comply with national N, NU, NJ and NUP series standards for direct interchange with mainstream cylindrical roller bearings without modification of spindle or housing installation dimensions.

 

6. Seal Structure Matching for Working Conditions

Open Type : Maximum heat dissipation for high-speed spindles, high-temperature rolling mills and high-power motors, convenient for regular grease replenishment;

 

Single/Double-Sided Steel Dust Covers : Block dust and iron filings, suitable for indoor reducers, fans, pumps and other moderate cleanliness applications;

 

Rubber Contact Seals : Dustproof and oil-water resistant, suitable for open-air fans, mine auxiliary equipment and outdoor transmission mechanisms.

 

7. Wide Application Fields

Power Equipment: High-voltage industrial motors, variable-frequency spindle motors, large centrifugal fans, air compressor spindles;

Transmission Equipment: Hardened tooth gear reducers, planetary reducers, gearboxes, winch reduction mechanisms;

Metallurgical Equipment: Hot rolling rolls, cold rolling backup rolls, continuous casting machine roller tables, straightener spindles;

Mining & Construction Machinery: Cone crushers, jaw crusher spindles, shield machine main bearings, loader drive shafts;

Industrial Robots: Robot reducer internal supports, injection moulding machine take-out robots, high-speed parallel robots, welding robot wrist joints;

General Machinery: Large conveyor drums, paper machine rollers, vertical cement mill spindles, large water pumps.

 

8. Brand Supply & Customisation Service

NMT maintains sufficient spot inventory of full-series cylindrical roller bearings for urgent equipment repair and mass complete machine supporting with short lead time. Customisation services include special radial clearance, high-temperature modified bearings, low-temperature cold-resistant bearings, reinforced rib heavy-duty customisation, hollow roller lightweight customisation, full complement high-capacity customisation, and special lubrication-adapted bearings. Professional engineers provide targeted selection schemes based on spindle weight, rotating speed, radial load, operating temperature and assembly form to optimise bearing configuration, reduce spindle deformation, overheating and wear failures, extend equipment maintenance intervals and cut the overall life cycle cost of equipment.