Crossed Roller Bearing Selection, Installation & Common Troubleshooting Solutions

Crossed Roller Bearing Selection, Installation & Common Troubleshooting Solutions

Crossed roller bearings are core precision components for automated machinery, CNC rotary tables, robot joints, indexing tables and inspection equipment. They feature small size, high rigidity, high precision, and can bear radial load, axial load and overturning moment simultaneously. Most precision failures, abnormal noise, stuck rotation and short service life are caused by incorrect selection, irregular installation and improper preload control.

1. Correct Selection Guide for Crossed Roller Bearings

1. Select structure according to application

- XU/XSU / RU Series: Light & thin structure, widely used in robot joints, small rotary tables and automation jigs.

- YRT Series: Heavy-load & high-rigidity type, ideal for CNC rotary tables and machining centers.

- CRBT/ CRBF/RAU Series: Mainly for limited installation space ，e.g Humanoid robots joints etc.

2. Match precision grade with equipment requirements

Bearing precision directly determines equipment positioning accuracy:

- P5 Grade: Standard automatic equipment and low-speed turntables.

- P4 Grade: CNC rotary tables, testing machines and industrial robots (mainstream high-precision demand).

- P2 Ultra-precision Grade: High-end scientific research and precision inspection instruments.

3. Confirm size by load and speed

Crossed roller bearings withstand combined loads. Always calculate peak load, continuous load and overturning moment. Avoid overloading small-size bearings, which causes raceway damage, early wear and backlash increase.

2. Standard Installation Steps

1. Clean mounting surfaces (the most important step)

Remove all burrs, metal chips and dirt from housing and shaft shoulders. Even tiny particles of 0.01mm will cause unparallel surfaces, runout error and permanent precision loss.

2. No direct hammering during installation

Never hammer the bearing ring directly. It will cause raceway deformation, roller indentation and rotation jitter. Use thermal installation or uniform pressing tools.

3. Tighten bolts diagonally

The precision of crossed roller bearings relies on uniform preload. Tighten mounting bolts diagonally in several steps. Uneven force causes bearing distortion, warping surface and unstable rotating torque.

4. Post-installation inspection

Check end runout, rotating smoothness, no stuck points, no abnormal noise and proper preload after installation.

3. Common Failures & Solutions

1. Rotation noise & stuck rotation

Causes: Dirty mounting surface, uneven bolt torque, raceway indentation, excessive preload.

Solutions: Re-clean surfaces, tighten bolts diagonally, reset preload, replace qualified bearings.

2. Positioning deviation & increased backlash

Causes: Low precision grade, long-term overload, preload relaxation, installation deformation.

Solutions: Upgrade to P4 precision bearings, recalculate load, reset preload, improve installation tools.

3. Overheating & excessive torque

Causes: Too tight preload, insufficient lubrication, misalignment, excessive interference fit.

Solutions: Adjust preload clearance, refill special grease, correct concentricity.

4. Short service life & fast wear

Causes: Dust intrusion, overspeed operation, overload usage, unqualified tolerance.

Solutions: Improve sealing, match correct working conditions, adopt factory precision ground bearings.

4. Conclusion

The precision and service life of crossed roller bearings mainly depend on correct selection and standardized installation. Proper application and maintenance ensure long-term high-precision operation of CNC turntables and robot equipment, reducing failure rate and after-sales cost effectively.