RA Series Crossed Roller Bearings

RA-series cross-roller bearings are available in several structural configurations, including integral inner rings, split outer rings, and thin‑walled designs. During installation, it is essential to observe the correct sequence of parts and ensure thorough cleaning. Factors that affect bearing installation accuracy include the measurement method, measuring instruments, and applied loads. The inner and outer rings of this bearing are manufactured with very thin wall thicknesses, resulting in a compact footprint and high load-carrying capacity, making it well suited for applications requiring high precision and rigidity.

RA-series cross roller bearings are available in several structural configurations, including an integral inner ring, a split outer ring, and thin‑walled designs. During installation, it is essential to observe the correct sequence of parts and ensure thorough cleaning. Factors that affect bearing installation accuracy include the measurement method, measuring instruments, and applied loads. The inner and outer rings of this bearing are manufactured with very thin wall thicknesses, resulting in a compact footprint and high load‑carrying capacity, making it well suited for applications requiring high precision and rigidity.

I. Installation Precautions for RA Series Crossed Roller Bearings

1. Part Sequencing and Cleaning

Before beginning installation, inventory and document the components in accordance with the assembly sequence. Note that certain assemblies, such as bearing housings, must be thoroughly cleaned in advance. Additionally, remove any burrs from all parts to ensure high‑precision bearing operation.

2. Fixed Flange

First, place the flange onto the RA-series cross-roller bearing and gently rock the mounting flange to align it with the bolt holes. Next, insert the mounting bolts into the holes, taking care to ensure that any misalignment of the bolt holes—when the bolts are turned by hand—does not impede their insertion. During installation, also note that full tightening of the mounting bolts must be achieved through repeated tightening. When tightening the split inner or outer ring, you can correct any misalignment between the rings and the housing by slightly rotating the entire outer or inner ring.

II. Factors Affecting the Installation Accuracy of RA-Series Crossed Roller Bearings

1. Measurement Method

Whether the RA series crossed roller bearings can fully leverage their advantages hinges primarily on installation accuracy, and the correctness of the installation method significantly influences that accuracy. Accordingly, based on the bearing’s specific characteristics, one can select the most suitable approach—common methods include the steel ball spacing method, the comprehensive inspection method, and the preloading method.

2. Measuring tools

The accuracy of the measuring tools also affects the installation precision of bearings. If the measuring instruments are faulty or inaccurate, subsequent operations will be significantly compromised. During installation, the clarity of the drawings and the expertise of the personnel both have a substantial impact on the service life of RA-series crossed roller bearings. In practice, we can strive to use measurement tools that do not deform the bearing, thereby maintaining installation accuracy.

3. Load

Bearing precision must account for load effects; it is important to recognize that the inner and outer rings of RA-series crossed roller bearings experience different static and rotational loads. Furthermore, bearings subjected to heavy loads should be made from appropriate materials—typically, only high‑precision bearings can withstand high rotational speeds. Dimensional accuracy of the spindle and bearing housing must also be carefully controlled, with particular attention paid to avoiding excessive interference fits.

Application Scope of RA Crossed Roller Bearings

This series features a compact design with the inner and outer ring thicknesses reduced to the absolute minimum. It is ideally suited for applications requiring lightweight, space‑efficient solutions, such as the rotary joints of robots and manipulators.

Product Specifications

 

RA Series Crossed Roller Bearing Model Parameters
Model number	Main dimensions							Basic quota load		Weight
	Inner diameter	Outer diameter	Diameter	Width	Oil hole		rmin	Radial (kN)
	d	D	dp	B, B1	a	b		C	Co	Kilogram
RA 5008	50	66	57	8	2	0.8	0.5	5.1	7.19	0.08
RA 6008	60	76	67	8	2	0.8	0.5	5.68	8.68	0.09
RA 7008	70	86	77	8	2	0.8	0.5	5.98	9.8	0.1
RA 8008	80	96	87	8	2	0.8	0.5	6.37	11.3	0.11
RA 9008	90	106	97	8	2	0.8	0.5	6.76	12.4	0.12
RA10008	100	116	107	8	2	0.8	0.5	7.15	13.9	0.14
RA11008	110	126	117	8	2	0.8	0.5	7.45	15	0.15
RA12008	120	136	127	8	2	0.8	0.5	7.84	16.5	0.17
RA13008	130	146	137	8	2	0.8	0.5	7.94	17.6	0.18
RA14008	140	156	147	8	2	0.8	0.5	8.33	19.1	0.19
RA15008	150	166	157	8	2	0.8	0.5	8.82	20.6	0.2
RA16013	160	186	172	13	2.5	1.6	0.8	23.3	44.9	0.59
RA17013	170	196	182	13	2.5	1.6	0.8	23.5	46.5	0.64
RA18013	180	206	192	13	2.5	1.6	0.8	24.5	49.8	0.68
RA19013	190	216	202	13	2.5	1.6	0.8	24.9	51.5	0.69
RA20013	200	226	212	13	2.5	1.6	0.8	25.8	54.7	0.71