Bearing material
Bearing ring and body of rolling is made from GCr12 or GCr15SiMn. when customers have any other requirment, can consulation using other material.

The hardness of bearing parts
When manufacturing bearing ring and dody of rolling with the material GCr15 or ZGCr15, the hardness of bearing ring and body of rollings is HRC60~64, the hardness of steel ball is HRC61~65; the hardness of wheel bearing ring is HRC58~62.

The surface of bearing and roughness of the bearing edge
The maximum of the surface roughness for bearing, shaft and housing with the end of the surface shall not exceed the values in table1.

表1 轴承配合表面和端面的表面粗糙度值

Clearance
The clearance means the bearing under the situation of non-load, when a ring fixed, the mobile contents another ring relate to the fixed ring by an extreme position to another extreme position. For ridial movment are known as ridial clearance for axial movement are called axial clearance.
Tipically, the original radial clearance is greater than the working clearance of the bearing. The bearing clearance is greatly affected the life, temperature and nosie of the bearing. It must consider as following when deciding the radial clearance of the bearing.
Interference with the installation, the expansion of the inner ring and the outer ring contraction leading to reduced the clearance.
In the operating temperature, the temperature difference between the inner ring, out ring and the thermal expansion of it's related parts led to changes of the clearance.
The clearance of ball bearing should close to zero in the operating temperature. For roller bearing, under the normal operating conditions should left a certain ridial clearance.

The tolerance of the rolling bearing
The tolerance and the precision of the rotation of the rolling bearing are shown in Table2-Table9, according with requirement of GB307.1-94, and equivalent to the standard ISO492-1981, ISO199-1979.
The definition of the centripetal bearing tolerance

Insider diameter
d--tolerance of insider diameter; ds--single inner diameter
d1--tolerance of outsider dimension; dmp--the average diameter in a single plane
△dmp--the average deviation of insider diameter in a single plane, △dmp=dmp-d（for tapered bore hole △dmp refer only to the samll end of the tapered hole theory)
△ds——the deviation of diameter of the single bore，△dmp=d1mp-d1；
Vdmp——The average variate in volume of insider diameter, the average discrepancy between the maximum and minimum of the insider diameter in a single plane.
Vdp--the variate in volume of insider diameter in a single ridial plane, the average discrepancy between the maximum and minimum of the insider diameter in a single axial plane.
d--outersider diameter; ds--single insider diameter
Dmp--the average of outsider diameter in a single plane; △Ds——single outsider diameter deviation，△Ds=Ds-D；
△Dmp——the average of outsider diameter deviation in a single plane，△Dmp=Dmp-D；
VDmp——the variate in volume of insider diameter in a single plane ，the discrepancy between the maximum and minimum of the outsider diameter in a radial plane，VDp=Dsmax-Dsmin；
VDmp--the average variate in volume of outersider diameter, the average discrepancy between maximum and minimum of the outsider diameter in a single plane.
B（C）——the metric width of insider ring(outsider ring)； Bs（Cs）——the singleness width of insider ring(outsider ring)；
△Bs——the deviation of the singleness width of inner ring，△Bs=Bs-B；Cs——the deviation of the singleness of outsider ring，Cs=Cs-C；
VBs——the variation of width of insider ring，the discrepancy between the maximum and minimum of the width of single outsider ring，VBs=Bsmax-Bsmin；
Vcs--the variation of the width of outsider ring, the discrepancy between maximum and minimum of the signlesness width of single outsider ring

T-bearing metric width
△Ts——deviation of measured bearing width，△Ts=Ts-T； rotation accuracy
Kia）——ridial runout of assembled bearing inner ring； Kea——ridial runout of assembled bearing outer ring；
Sd——beat of the base end face of the inner bore； Sd——The degree inclination of outer surface generation line relative to base edge；
Sia--The vibration of complete set inner ring edge relative to race way, Sea--The vibration of complete set outer ring edge relative to race way

表2PO（G）级公差内圈

表3PO（G）级公差外圈

表4 p6(E)级公差内圈

表5 p6(E)级公差外圈

表6 p5(D)级公差内圈

表7 p5(D)级公差外圈

表8 p4(c)级公差内圈

表9 p4(c)级公差外圈

Match of rolling bearing
In order to prevent the skidding operation when the bearing inner ring, shaft, bearing outsider ring and bearing shell hole generated in the machine. In order to choose the right match, we must consider the type and size of load, bearing type and other perfomance requirement.

cylindircal bore bearing in choice of bearing mach, should consider following factors:

1.Load type
according to the load acting on the bearing related to rotation on the bearing ferrule, the load role in the ring can be divided into: fixed load, rotary load and swing load.
(1) Fixed load
Role in the ring synthesize radial load, is supported by the local area of raceway, and spread to the relative bearing shaft or local area, this load is call fixed load. The characterized of fixed radial load is static load synthesis by load vector and ferrule. We can choose the light match when the ferrule with a fixed load.

(2) Rotary load
Role in the ferrule synthesis of radial load vector rotate on the raceway along the circumferentia, sequential manner by the various parts of the racway to bearr this load is called rotary load,also known as cyclic loading. Rotary load characterized by a synthesis of ring radial load vector and the relative rotation.
Ferrul, shaft or housing hole which endure a revulation load should use interference match. If installation with space, ferrul with shaft or shaft with housing hould may occer the phenomenon of slipping, the contact face will wear and friction, and friction heat due to the rapid temperature ris, bearing will be damaged quickly. the amount of interference is not depend on the operation situation, to bearing under the load of operation, the ferrule hole in the shell co-axis or the surface is not a "crawing" as a principle.

(3) Swing load
Synthetic radial load vector role on the ferrule oscillation within a certain range in the raceway by the roller to bear a certain range, or the load acting on the bearing is impact load, vibration load, its direction or value changes frequently, this load called oscillation load, or variable direction load.
when bearing bear a swing load, especially bear a heavy load, the inner ring and outer ring should use a interference match. When the inner ring rotating, usually inner ring with a rotating load match.but when it bears a light load, can use a match loose than rotating load.

2.The size of load
The load of bearing ferrule is acting by the radial component will be compressed in the radial direction would causing the surface relaxation, in the case of load transfer back easy to produce skidding. Therefore, for heavy duty situations should normally be higher than in the more load and normal load occasions with the tight schedule. Load, the greater the amount of interference with the greater should be.
when radial load points"light", "normal" and "heavy" load, generally have the relationship listed in table 10.(Cr show the basic dynmic load of bearing)

表10 当量动负荷Pr与Cr的关系

3.Working temperature
When the bearing in operation, the ring temperature is usually higher than the temperature of the adjacent parts of the bearing, the inner ring may be loose due to expansion with the axis, the outer ring may be affected due to thermal expansion of the axial bearing swimming. Therefore, the choice must take into cosideration with the temperature difference and the direcion of the thermal conductivity.

4.Bearing rotation accuracy
When it's required of the rotation of the bearing accuracy and smooth operation, in order to eliminate the impact of elastic deformation and vibration, to avoid using clearance fit.

5.The design and material of shaft and bearing housing
If the shaft or bearing housing surface is irregular, will result in the inner ring and our ring of bearing not normal deformation, and asymmetry damaged force. For the open type bearing, the match of bearing outer ring and housing can not use interference match, but the outer ring should either run in the housing hole.When the bearing installed in the thin, ligh alloy bearing housing or the hollow shaft, in order to ensure adequate bearing surface, should use a match tighter than the it used in thick housing, cast iron or soild shaft.
Radial bearing with shaft tolerance zone, it is recommended to select from the table 11

表11安装向心轴承的轴公差带

Note:

1) Where a higher tolerance requirements on the occasion, application j5, k5 ... ... instead of j6, k5 ... ... and so on.

2）Angular contact ball bearings with little effect on the clearance can be used instead of k5 k6 and m6 and m5.

3）Bearing radial clearance should be used more than the basic set of roller bearings.

4）Who have a higher tolerance level or speed of a requirement, should be used h7, IT5 form tolerances for the shaft journal.

表12安装向心轴承的外壳孔的公差带

Note:

1) It shall have a higher tolerance requirements of the occasion, should use the standard tolerance P6, N6, M6, K6, J6, respectively instead of P7, N7, M7, K7, J7 and H7, and should also use a whole-housing.

2) should be selected for the light alloy shell than steel or cast iron housing with the seat other than tight.

表13配合表面的粗糙度

Rolling bearing pre-load
Bearing internal clearance before installation(original space) is different with the bearing clearance reach operation temperature after the installation(called the working space). The original space is bigger than the working space. With different applications, many request requests to run a negative clearance, the imposition of load, this pre-bearing load is to ensure co-ordination under the con co-ordination under the conditions used to prevent the load slipping the load slipping and causing damage.
Major role: to improve bearing stiffness, reduce operating noise, compensate clearance increaing wear and tear in operation, improve accuracy of the guide shaft, for extended bearing life.
pre-stress is often the main target (dynamic load rating Cr) coefficients, the best preloading load needs to calculate the preload force first, constandly revised by the trial confirms after the conventional value determined by different methods of implementation of the regulation.

The installation and disassemble of the rolling bearing
Bearing installation method should be decided by the type and size of bearing before the installation: mechanical method, hydraulic method, heating method. The inner ring, outsider ring, cage and body of rolling should not bear the direct impact with either of these methods, in strict accordace with the bearing installation and remove prodedures for installation and removal personnel should under strict training and examiation, and are quipped with specialized equipment and tool.Pre-installation does not allow the bearing axis as the gauge to test the surface with the housing hole with the dimensional accuracy and processing in order to avoid injury with the surface and magnetic bearing.
Bearing installation, making the bearing and the shaft in the same line, if the bearing position skew, not only makes the assembly difficult, shaft surface is also easy to produce and make curved indentation, and sometimes even make bearing inner ring splitting.
Before the preparation of bearing installation completed, generally do not open the package of the bearing, to avoide the assembly time last too long, resulting in rust and dirty instusion.
With the bearing size increases, the required installed capacity will increased significantly. Inner ring and bearing housing should be heat first, but the heating temperature should not exceed 120°, otherwise the bearing material will undergo structure changes. Sealed bearing can not be pre heated to prevent the oil spill.
Bearing removal is based on the anti-order of the installation. Must have proper removal method, and to take a series of protective measures, without damage to its component parts bearing and maintain the integrity of the original bearing the state for analysis and research.

The lubrication and maintenance of the rolling bearing
To assure the rolling bearing run reliably, they must offer adequate lubrication to avoid the direct metal contact among the rolling roller, rolling path and cage, which may cause the abrasion of the bearing’s surface. So in a variety of applications of bearings, select a appropriate bearing lubrication agents and Lubrication is extremely important, and so does right maintenance.
To assure the rolling bearing run reliably, they must offer adequate lubrication to avoid the direct metal contact among the rolling roller, rolling path and cage, which may cause the abrasion of the bearing’s surface. So in a variety of applications of bearings, select a appropriate bearing lubrication agents and Lubrication is extremely important, and so does right maintenance.
Bearing applications under operating conditions (temperature, speed) and to ensure reliable lubrication, Bearings run in the lowest operating temperature with minimal dose of lubrication under reliable lubrication with operating conditions (temperature, speed) . But when the lubricant need to seal and heat at the same time, the dose should increase; excess lubricant will rise operating temperature especially at high speed. Bearing under low-speed (or very low speed) operation need antisepsis, and bearing box should be filled with lubricant.
Under open applications, due to mechanical effects, aging and pollution increases, the lubricant in bearing device will gradually lose its lubricating properties. Therefore lubricant should be constantly added and updated.
When replacing or adding lubricant, new grease should be encased between the rollers before removing the old one and the environment must be definitely clean. No impurity gets into bearing or bearing box.