Crossed Roller Bearing

CRBH has inseparable (one-piece) inner and outer rings for highest rigidity and supports both inner and outer ring rotation. RB has a separable (split) outer ring with an integral inner ring, optimized for inner ring rotation applications and easier roller installation. RU has integrated inner and outer rings with pre-machined bolt holes on both rings for direct flange mounting without separate housings. SX is an ultra-thin type with a split inner ring and integral outer ring. It has the thinnest cross-section in the range, suited for applications with severe space constraints. All four types use the same 90° alternating roller arrangement and carry combined radial, axial, and moment loads.

Angular contact ball bearings use point contact and must be paired in back-to-back (DB) or face-to-face (DF) arrangements to handle bidirectional axial and moment loads, doubling the axial envelope and requiring careful preload management. A single cross roller bearing uses line contact with rollers alternating at 90°, carrying radial, axial, and moment loads simultaneously in one row with a thinner cross-section. This gives cross roller bearings roughly 3 to 4 times the moment stiffness at the same bore diameter. The tradeoff is speed: angular contact ball bearings achieve higher limiting speeds. In practice, most robot joints operate below 300 rpm, well within cross roller bearing limits, so the stiffness and compactness advantages outweigh the speed difference.

BOM manufactures cross roller bearings in P6, P5, P4, and P2 precision grades. P6 is suitable for general industrial rotary tables and indexing mechanisms. P5 is the most common grade for industrial robot joints, where it balances cost and positioning accuracy. P4 is used in semiconductor wafer-handling robots, optical inspection stages, and other applications requiring sub-micron positioning repeatability. P2 is the highest grade, reserved for metrology instruments and ultra-precision positioning systems. Higher precision grades have tighter tolerances on radial and axial runout, dimensional accuracy, and rotational accuracy. Contact BOM's engineering team for grade-specific tolerance tables.

An integrated assembly combines the cross roller bearing with mating components (output flange, hollow shaft, or rotary plate) into a single precision-machined unit. This eliminates the clearances and dimensional stack-up errors introduced by bolting separate parts together, producing a more compact rotary module with higher combined accuracy and higher moment load capacity. Integrated assemblies are particularly valuable in robot joint actuators where every micron of positional error matters.

Yes. BOM manufactures cross roller bearings with non-standard bore, OD, and section width, as well as custom preload settings, sealed versions, alternative materials, specialized coatings, and integrated assemblies combining the bearing with application-specific flanges and housings. BOM's capability extends to complete bearing architecture redesign for applications where no catalog product meets the requirement. Contact our engineering team with your load requirements, speed, and application specifics.