On hot rolling mill production lines, red-hot steel slabs pass through mill stands at several meters per second, with work rolls subjecting slabs to tens of thousands of tons of rolling force to reduce them to thin sheets. In cold rolling mills, rolling forces are even greater, with bearings maintaining precise roll gap control under extremely high radial loads and high-speed operation. In aluminum foil and copper strip rolling mills, bearings carry sustained heavy loads and high-precision rotation under micron-level thickness tolerance requirements. In every metallurgical rolling mill and ultimate radial heavy-load equipment, four-row cylindrical roller bearings are the core precision components achieving ultimate radial load capacity and high-reliability operation.

 

Four-row cylindrical roller bearings are the highest-radial-load-capacity type in the cylindrical roller bearing family. Their core structure consists of four rows of rollers——four rows of rollers arranged in parallel between inner and outer rings, with roller quantity four times that of single-row bearings, achieving exponential increase in radial load capacity. Four-row cylindrical roller bearings feature line contact between rollers and raceways, with large contact area and extremely high load capacity, particularly suitable for rolling mill work rolls and backup rolls requiring ultimate radial loads. Four-row cylindrical roller bearings typically use full-complement roller configurations (without cages) or segmented cages to maximize roller quantity and load capacity.

 

Four-row cylindrical roller bearings are available in several configurations——FC type (four-row cylindrical roller bearing, outer ring without ribs, inner ring with ribs), FCD type (four-row cylindrical roller bearing, outer ring with ribs, inner ring without ribs), and FCDP type (four-row cylindrical roller bearing, outer ring with ribs, inner ring without ribs, with snap ring). These configurations accommodate different axial positioning and load direction requirements. Four-row cylindrical roller bearings are widely used in hot and cold rolling mill work rolls, backup rolls, levelers, continuous caster segments, heavy-duty gearboxes, ship propulsion shaft systems, large extruders and various ultimate radial heavy-load equipment.

 

NMT Four-Row Cylindrical Roller Bearing Technology Solutions

 

Japan NMT four-row cylindrical roller bearings are specialized product series developed specifically for the stringent requirements of metallurgical rolling mills and ultimate radial heavy-load equipment——ultimate radial load capacity, long life and high reliability.

 

Four-Row Ultimate-Capacity Structural Design——Four-row cylindrical roller bearing radial load capacity depends on roller quantity, diameter and length. NMT four-row cylindrical roller bearings feature four-row full-complement roller designs——four rows of rollers arranged in parallel between inner and outer rings, with roller quantity four times that of single-row bearings, achieving radial load capacity 3.5-4 times that of single-row bearings. Rollers undergo precision crowning——roller generating lines feature logarithmic curve crowning eliminating edge stress concentration at roller ends, ensuring uniform load distribution along the full roller length, significantly extending bearing life under ultimate heavy loads. Bearing ring wall thickness is specially calculated and thickened to resist deformation under tens of thousands of tons of rolling force, maintaining geometric accuracy. Validated through rigorous load capacity testing, NMT four-row cylindrical roller bearing dynamic and static load ratings are industry-leading, meeting the stringent requirements of continuous hot and cold rolling mill production.

 

FC/FCD/FCDP Multiple Configurations——NMT four-row cylindrical roller bearings offer multiple configurations for different axial positioning and load direction requirements. FC type (four-row cylindrical roller bearing, outer ring without ribs, inner ring with ribs)——Suitable for axial positioning applications with inner ring ribs providing axial guidance. FCD type (four-row cylindrical roller bearing, outer ring with ribs, inner ring without ribs)——Suitable for outer ring axial positioning applications. FCDP type (four-row cylindrical roller bearing, outer ring with ribs, inner ring without ribs, with snap ring)——Suitable for bidirectional axial positioning applications. NMT provides optimal configuration selection and design recommendations based on specific rolling mill structures, axial load directions and positioning requirements.

 

Precision Raceway and Roller Machining Technology——Four-row cylindrical roller bearing operational precision and life directly depend on raceway and roller machining precision. NMT employs fully closed-loop controlled ultra-precision grinding systems for precision form grinding of raceways. Raceway roundness, cylindricity and surface roughness are strictly controlled to ensure uniform line contact between four rows of rollers and raceways at any position. Raceway surfaces undergo superfinishing with surface roughness controlled to extremely low levels (Ra≤0.08μm), achieving mirror-like surface finishes that fundamentally reduce friction and temperature rise during operation. Diameter deviation of four rows of rollers is controlled to minimal ranges, with grading precision of each row strictly controlled to ensure uniform load distribution across all four rows without localized overloading.

 

Segmented Cage and Full-Complement Roller Design——Four-row cylindrical roller bearings offer segmented cage and full-complement roller configurations based on operating conditions. Full-complement roller design——Without cages, maximizing roller quantity for highest ultimate radial load capacity, suitable for low-speed heavy-load and impact applications. Segmented cage design——Cages divided into four segments individually guiding four rows of rollers, providing stable roller guidance while maintaining load capacity, suitable for medium-to-high-speed and heavy-load applications. Cage materials utilize high-strength brass or steel stampings with precision machining and dynamic balancing correction, maintaining accurate roller guidance under heavy loads to prevent collision and misalignment. NMT provides optimal cage configuration recommendations based on specific speed, load and temperature conditions.

 

Separability Design——The separability of inner rings, outer rings and roller/cage assemblies is a key advantage for large rolling mill applications. NMT four-row cylindrical roller bearing inner rings (with roller and cage assemblies) and outer rings can be installed separately——this characteristic greatly simplifies assembly processes during rolling mill major maintenance, enabling bearing replacement without removing mill housings. Separability also facilitates bearing cleaning and inspection, allowing condition assessment and component replacement during periodic maintenance without complete bearing disassembly.

 

Impact and Fatigue Resistance Enhanced Design——Rolling mills generate severe impact loads during steel billet biting, tail-out and roll changes. NMT four-row cylindrical roller bearing roller and raceway materials undergo specialized heat treatment processes, achieving extremely high surface hardness (HRC60-64) while maintaining core toughness to effectively resist indentation and spalling under impact loads. Bearing ring wall thickness is specially calculated and thickened to resist deformation under impact loads, maintaining geometric accuracy. Roller end face-to-rib contact areas are lubrication-optimized for adequate lubrication and heat dissipation under impact conditions. Validated through rigorous impact fatigue testing, NMT four-row cylindrical roller bearings show no indentation or spalling on raceways or roller surfaces under simulated hot and cold rolling mill impact cycles, maintaining stable rotational accuracy.

 

High-Efficiency Lubrication and Seal Design——Four-row cylindrical roller bearings operate long-term under ultimate heavy loads and harsh environments, imposing very high requirements on grease/oil extreme-pressure performance and retention. NMT four-row cylindrical roller bearings use oil lubrication——high-viscosity extreme-pressure lubricating oil is delivered through rolling mill circulating lubrication systems to bearing interiors, forming stable lubricating films under ultimate radial loads to effectively separate roller and raceway contact surfaces. Inner or outer rings feature oil holes and grooves ensuring uniform oil distribution to all four rows of roller contact areas. Seals employ high-performance labyrinth seals or contact seals, effectively blocking external cooling water, iron oxide scale and dust ingress. Seal geometry is optimized to maintain sealing effectiveness while keeping friction torque within reasonable limits.

 

Wide-Temperature-Range and Heat-Resistant Design——Rolling mill bearings experience large temperature variations from cold startup to hot operation. NMT four-row cylindrical roller bearings utilize thermally stabilized materials maintaining dimensional stability from -30°C to 150°C. Bearing clearance is precisely calculated with temperature compensation (with C3, C4 and other clearance grade options), maintaining proper internal gaps across the full temperature range to prevent binding from thermal expansion or vibration from excessive clearance. Ring and roller thermal expansion coefficients are matched to maintain stable fit conditions during temperature changes.

 

Precision Measurement and Matching Technology——Four-row cylindrical roller bearing assembly precision directly affects rolling mill roll gap control accuracy. NMT four-row cylindrical roller bearing inner rings, outer rings and roller assemblies undergo precision measurement and matching, with diameter deviation of four roller rows within each bearing controlled to minimal ranges. Bearing radial clearance is precisely controlled and graded, allowing users to select optimal clearance grades for specific rolling mill operating conditions. NMT provides detailed installation guides and clearance measurement methods for optimal on-site assembly and roll gap control accuracy.

 

Why Choose NMT Four-Row Cylindrical Roller Bearings?

 

Compared to conventional bearings and industry-standard four-row cylindrical roller bearings, NMT four-row cylindrical roller bearings offer distinct advantages:

 

Four-row full-complement roller design with roller quantity four times single-row for ultimate radial load capacity

 

Precision logarithmic curve roller crowning eliminating edge stress concentration

 

Ultra-precision form-ground and superfinished raceways with Ra≤0.08μm

 

FC/FCD/FCDP multiple configurations for different axial positioning requirements

 

Full-complement roller/segmented cage dual configurations for low-speed heavy-load and medium-to-high-speed conditions

 

Separable inner/outer ring/roller assembly for convenient large rolling mill assembly and maintenance

 

Specialized heat treatment for surface HRC60-64 with tough core

 

Thickened ring walls for deformation resistance under tens of thousands of tons of rolling force

 

Oil hole and groove design for uniform oil distribution to four rows of rollers

 

Labyrinth/contact seals dual options for dust, water and iron oxide scale protection

 

Thermally stabilized materials + wide clearance (C3/C4) for -30°C to 150°C stability

 

Precision measurement and matching for uniform load distribution across four roller rows

 

Passed ultimate load, impact, fatigue and temperature rise testing

 

These performance advantages establish NMT four-row cylindrical roller bearings as the core precision components for hot rolling mills, cold rolling mills, levelers, continuous casters and various ultimate radial heavy-load equipment.

 

Application Scenarios

 

Hot rolling mill work roll and backup roll bearings

 

Cold rolling mill work roll and backup roll bearings

 

Aluminum foil and copper strip rolling mill bearings

 

Levelers and skin pass mill bearings

 

Continuous caster segment bearings

 

Heavy-duty gearboxes and reducers bearings

 

Ship propulsion shaft system bearings

 

Large extruders and presses bearings

 

Precision Manufacturing

 

Produced strictly according to ISO precision standards and four-row cylindrical roller bearing manufacturing specifications, with zero-defect quality execution, NMT four-row cylindrical roller bearings utilize high-purity bearing steel, processed through vacuum degassing treatment, precision heat treatment, ultra-precision raceway form grinding and superfinishing, precision roller crowning and four-row grading screening, ring rib precision machining, segmented cage precision forming, precision assembly and matching, precision oil hole/groove machining, rotational accuracy inspection, clearance grade precision control, ultimate load testing, impact testing, fatigue life testing and temperature rise testing. Every product is processed through fully automatic grinding and superfinishing in temperature-controlled clean workshops, with critical dimensional tolerances and four-row roller grading precision strictly controlled—ensuring ultimate radial load capacity, long life and high reliability.

 

Product Range

 

FC type four-row cylindrical roller bearings (inner ring with ribs)

 

FCD type four-row cylindrical roller bearings (outer ring with ribs)

 

FCDP type four-row cylindrical roller bearings (with snap ring)

 

Full-complement four-row cylindrical roller bearings

 

Segmented cage four-row cylindrical roller bearings

 

C3/C4 large-clearance four-row cylindrical roller bearings

 

Custom non-standard four-row cylindrical roller bearings

 

Global Industrial Service

 

Japan NMT supplies high-quality four-row cylindrical roller bearings to global metallurgical equipment manufacturers, steel mills, aluminum and copper processing companies and heavy industrial users. With ultimate radial-capacity precision engineering and long-term stable reliable performance, NMT continuously empowers continuous high-efficiency production and equipment reliability of global metallurgical and heavy-load industries.