Changzhou Zhihua Bearings Co., Ltd.
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Radial needle roller and cage assemblies have a steel cage that provides both inward and outward retention for the needle rollers.The designs provide maximum cage strength consistent with the inherent high load-ratings of needle roller bearings. Accurate guidance of the needle rollers by cage bars allows for operation at high speeds. Needle roller and cage assemblies have either one or tow rows of needle rollers.
Also,There are metric series needle roller and cage assemblies using molded,one-piece glass-reinforced engineered polymer cages(suffix TN). These operate well at temperatures up to 120°C(250°F) over extended periods. However, care should be exercised when these assemblies are lubricated with oils containing additives as service life may be reduced if the operating temperature exceeds 120°C(212°F) ,At such high temperatures,oil can deteriorate with time and it is suggested that oil change intervals are observed.
Needle rollers with high-carbon chrome steel as the material, after through-hardening, polishing and grinding to reach the required tolerance of diameter and roundness.
Types of Metric Radial N eedle Roller and Cage Assemblies
| TN | molded cage of reinforced engineered polymer
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| ZW | double-row
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| TNZW | molded cage of reinforced engineered polymer-double-row
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| H | hardned steel cage
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| F | machined cage
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| FH | machined cage,case hardened
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| FV | machined cage,hardened and tempered
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1,Dimension accuracy
Roller sorting group
Metric type needle roller and cage assemblies are supplied with rollers which their diameter are sorted into groups.Shown as table 1. This is in accordance with Grade G2 specified in ISO3096 standard.Roller sorting groups must be indicated on the package,Needle roller and cage assemblies from one batch normally contain rollers with group limits between 0.000 to 0.002mm(0.000 to -0.00008 in) and -0.005 to -0.007mm(-0.0002 to -0.0003 in).
| Group tolerance | Marking gage | |
| mm in. | mm in. | |
| 0.000 0.0000 | -0.002 -0.00008 | P0M2 |
| -0.001 -0.00004 | -0.003 -0.00012 | M1M3 |
| -0.002 -0.00008 | -0.004 -0.0002 | M2M4 |
| -0.003 -0.00012 | -0.005 -0.0002 | M3M5 |
| -0.004 -0.0002 | -0.006 -0.0002 | M4M6 |
| -0.005 -0.0002 | -0.007 -0.0003 | M5M7 |
| -0.006 -0.0002 | -0.008 -0.0003 | M6M8 |
| -0.007 -0.0003 | -0.009 -0.0004 | M7M9 |
| -0.008 -0.0003 | -0.010 -0.0004 | M8M10 |
| -0.009 -0.0004 | -0.011 -0.0004 | M9M11 |
2,Mounting Dimensions
Design of raceways
Radial needle roller and cage assemblies use the housing bore as the outer raceway and the shaft as the inner raceway. To ensure full bearing load rating and life, the housing bore and shaft raceways must have the correct geometric and metallurgical characteristics.The housing should be of sufficient cross section to maintain adequate roundness and running clearance under load. The only limit to precision of the radial clearance of a mounted assembly is the capability of the user to hold close tolerances on the inner and outer raceways. The suggested shaft tolerances listed in Table 2 are based on housing bore tolerance G6 and apply to metric series radial needle roller and cage assemblies with needle rollers of group limits between P0M2 and M5M7.
Suggested shaft tolerance for housing bores machined to G6
| Nominal shaft diameter in mm | ≤80 | ＞80 |
| Radial clearance | Shaft tolerance | |
| Smaller than normal | j5 | h5 |
| Normal | h5 | g5 |
| Larger than normal | g6 | f6 |
3,Axial guidance requirements
Radial needle roller and cage assembly must be axially guided by shoulders or other suitable means. The end guiding surfaces should be hardened to minimize wear and must provide sufficient axial clearance to prevent end-locking of the assembly. Length tolerance H11 is suggested.
If end guidance is provided by a housing shoulder at one end and by a shaft shoulder at the other end,the shaft must be axially positioned to prevent end-locking of needle roller and cage assembly.The housing and shaft shoulder heights should be 70 percent to 90 percent of the needle roller diameter to provide proper axial guidance.
4,Lubrication
Oil is the preferred lubricant for most applications.In critical applications involving high speeds,ample oil flow must be provided.Where assemblies are subjected to high centrifugal forces-such as in planetary gearing,or inertia forces,as in the small end of connecting rod-the contact pressure between the cage and the raceway guiding surface becomes critical.The allowable contact pressure depends on a combination of the induced force and the relative velocity between the cage and raceway and the rate of lubricant flow.
5,Special designs
Radial needle roller and cage assemblies made to special dimensions or configurations-such as those which are split to assemble around a one-piece crankshaft-can be made available on special order.Special coated or plated cages to enhance life,under conditions of marginal lubrication and high induced forces,also can be made available.