Super-Precision Cylindrical Roller Bearings

Super-precision cylindrical roller bearings use line contact between rollers and raceways to provide substantially higher radial stiffness than ball bearings of a comparable envelope. Their separable construction supports accurate mounting, while N, NN and NNU internal designs allow axial displacement between shaft and housing without using a loose ring fit.

Key Features and Customer Benefits

High radial stiffness helps stabilize spindle center position under cutting and process loads.

High radial load capacity supports compact, high-performance spindle designs.

Precision raceways and controlled roller geometry support low runout and consistent rotation.

Axial displacement capability allows the bearing to serve as a non-locating support and accommodate thermal shaft growth.

Tapered-bore designs permit radial clearance or preload to be adjusted by controlled axial drive-up.

Separable rings simplify mounting, inspection and dismounting of precision spindle assemblies.

Product Series Selection

Select the dimensional series according to speed, radial stiffness, load, available radial space and shaft diameter. The table is a series-level guide; exact dimensions, load ratings, speed limits, bore and cage must be confirmed for the selected size.

These bearings are intended primarily for radial loads. The flange arrangement guides the rollers and determines which ring can be separated. Because one ring has no integral flanges, the shaft can move axially relative to the housing within the bearing, making the design suitable for non-locating positions.

N, NN and NNU cylindrical roller bearings do not normally locate the shaft axially. Use an angular contact ball bearing set, thrust bearing or another suitable locating arrangement to carry axial load and define axial position.

Cylindrical-bore bearings rely on manufacturing tolerances, fits and selected clearance. Tapered-bore bearings allow the effective raceway diameter to be increased by driving the inner ring onto a tapered shaft seat or sleeve. This reduces radial internal clearance and can establish a defined operating clearance or radial preload.

Cylindrical bore: Fit and supplied clearance determine the mounted condition

Tapered bore: Controlled axial drive-up enables fine clearance or preload adjustment

Drive-up verification: Measure clearance reduction, axial position or a validated dimensional indicator

Operating condition: Include fit expansion, speed, centrifugal effects and temperature gradient

Avoid uncontrolled negative clearance

Excessive drive-up or preload can increase friction, heat and roller edge stress, and may cause seizure. The target mounted clearance or preload must be calculated and verified for the complete spindle.

Precision, Radial Stiffness and Runout

The performance of a precision spindle depends on bearing raceway accuracy, roller geometry, ring runout, shaft and housing accuracy, fits and mounting procedure. CHG can review SP-, UP- or application-defined precision requirements according to size and inspection agreement. Final tolerances must be stated on the approved drawing or technical specification.

Running accuracy

Radial and axial runout control supports stable spindle rotation

Radial stiffness

Line contact and multiple rollers limit elastic displacement

Ring marking

High point, orientation or matching marks can be supplied when agreed

Inspection

Dimensional, runout, clearance and material reports available by specification

Materials, Cages and Hybrid Designs

Bearing rings and steel rollers: High-quality bearing steel with controlled heat treatment and precision finishing

Hybrid rollers: Silicon-nitride ceramic rollers may be evaluated for selected high-speed designs

N 10 high-speed cage: Outer-ring-centred window-type engineered polymer/PEEK design according to size

Double-row cages: Machined brass or engineered polymer according to series, speed and temperature

Lubrication, Cooling and Minimum Load

Grease lubrication: Simple and clean; quantity, distribution and run-in must be controlled for high speed.

Oil-air lubrication: Supports high speed and directed lubricant delivery with limited churning.

Cooling: Housing and spindle cooling should control ring temperature differences and preload change.

Minimum load: Adequate radial load is required to reduce roller slip, smearing and cage instability.

Speed is a system limit

Permissible spindle speed depends on bearing size, clearance or preload, cage, lubrication, cooling, load, fits, balance and required life. Catalogue reference speed is not automatically the final spindle speed limit.

Application Areas

High-speed machining centers and motorized spindles

Grinding, milling, turning and boring spindles

Non-tool-end spindle supports requiring thermal displacement

Precision printing, coating and cylinder equipment

High-speed test rigs, dynamometers and precision rotating machinery

Large-shaft precision equipment requiring high radial stiffness

Selection Workflow

Define shaft diameter, available envelope and required dimensional series.

Provide radial load, load spectrum, speed, acceleration and duty cycle.

Select single-row or double-row design according to speed, capacity and stiffness.

Confirm the non-locating function, required axial displacement and separate locating bearing.

Choose cylindrical or tapered bore and establish the target mounted clearance or preload.

Select precision, cage, steel/hybrid rollers, lubrication and cooling.

Verify fits, shoulders, clamping, assembly measurement and run-in procedure.

Installation and Operating Guidelines

Keep bearings, tools and assembly areas extremely clean.

Measure shaft and housing roundness, cylindricity, coaxiality and shoulder squareness.

Support and align separable rings carefully; do not damage rollers or raceway edges.

For tapered bores, control drive-up using the approved clearance-reduction or dimensional method.

Apply mounting force only to the fitted ring and use approved heating or hydraulic tools.

Run in under controlled speed steps while monitoring temperature, vibration, noise and drive power.

Non-standard dimensions, ring geometry and lubrication features

Precision, radial clearance or preload and high-point marking

Steel or hybrid ceramic roller designs

Special cages, coatings, materials and operating-temperature solutions

Application calculation, drawing review, inspection and traceability documents

CHG Bearing provides application engineering and customized super-precision bearing development from Luoyang. We can review the complete spindle arrangement before quotation and support prototype validation through batch production.

Information Required for Quotation

Bearing designation or d × D × B dimensions and series

Spindle drawing, locating/non-locating positions and axial displacement

Maximum and continuous speed, acceleration and duty cycle

Radial load, load spectrum, shock and target life

Required precision, runout, stiffness and mounted clearance/preload

Lubrication, cooling, temperature and contamination conditions

Quantity, destination country, certificates and delivery date