RA Series Crossed Roller Bearings
Structure: Ultra-thin-wall, inner ring rotation, integrated inner/outer ring design, with two outer rings and one inner ring.

Interchangeability: The RA series crossed roller bearings can replace the THK RA and RA-C series, as well as the IKO CRBS series.

Features of RA Bearings

Crossed roller arrangement

• Cylindrical rollers are arranged orthogonally at 90° and separated by spacers, enabling the bearing to simultaneously handle radial loads, axial loads, and overturning moments. The overall load capacity far exceeds that of standard ball bearings.

• Line contact design: The line contact between the rollers and raceways provides 3 to 5 times greater rigidity than angular contact ball bearings, offering superior resistance to deformation.

Ultra-thin-wall lightweight design

• The inner and outer rings feature a one-piece structure (no split), with thickness approaching the design limit (e.g., a width of only 8–13 mm), significantly reducing mechanism weight and making it ideal for space-constrained applications such as robotic joints.

• Compared to conventional bearings, the cross-sectional area is reduced by 43% and mass is reduced by 38% (when comparing models with the same inner diameter).

High precision and low friction

• Rotational accuracy reaches P4/P2/USP grades, with repeatable positioning error ≤ ±0.001 mm, suitable for micron-level motion control.

• The spacer design minimizes friction between rollers, reducing rotational torque and supporting smooth, high-speed operation.

Pre-lubricated and long service life

• Pre-filled at the factory with high-performance grease (e.g., lithium-based grease); select models feature non-contact seals (RS type) for dust and contamination protection, supporting long-term maintenance-free operation.

• Material: High-carbon chromium bearing steel (GCr15) for the rings; cage made of TN engineering plastic for wear and corrosion resistance.

Typical Applications of RA Bearings

1. Industrial Robots

• Joint rotating sections (e.g., six-axis robot wrists, SCARA robotic arms) leverage their high rigidity and moment resistance, with a service life of over 50,000 hours.

2. Precision Machine Tools and Machining Centers

• CNC rotary tables and indexing plates: Ensure micron-level positioning accuracy during cutting (axial runout ≤ 0.005 mm).

3. Semiconductor and Optical Equipment

• Wafer stages and probe station rotation mechanisms in lithography machines: Require nanometer-level motion stability and cleanroom compatibility.

4. Medical Imaging Equipment

• CT scanner rotating gantries and MRI scanners: Meet requirements for quiet operation and no magnetic interference (stainless steel material available as an option).

5. Renewable Energy and Automation

• Solar tracking system slewing shafts and precision rotary tables for automated production lines: Adaptable to outdoor environments and high-frequency motion.