What Are Our Concerns About Bearings（45）

Q16:What is NTN import bearing NTN thrust roller bearing import bearing failure？

A:The cause of imported bearing failure is often multi-factor, all the influencing factors of the design and manufacturing process will be related to the failure of imported bearings, and it is not easy to judge by analysis. In general, it can be considered and analyzed from two aspects: use factor and internal factor. For other knowledge about imported bearings, please refer to the introduction of the article “Imported bearings use Tips collection” in this site.

Use factor basically is to point to installation adjustment, use maintain, maintain repair to wait whether accord with technical requirement. Installation conditions are one of the primary factors in the use of imported bearings, often due to improper installation of bearings, resulting in changes in the state of force between the parts of the whole set of bearings, bearings in an abnormal state of operation and early failure. According to the technical requirements of installation, use, maintenance and maintenance of imported bearings, monitor and check the load, speed, working temperature, vibration, noise and lubrication conditions borne by the bearings in operation, find out the reason immediately and adjust it to make it return to normal. In addition, it is also important to analyze and inspect the quality of grease and the surrounding medium and atmosphere. How to judge the quality of imported bearings? Please see the introduction of “How to judge the quality of imported bearings”.

Immanent factor basically is to point to structural design, manufacturing technology and material quality

First of all, only when the structure design is reasonable and advanced can it have a long bearing life. The manufacture of bearings generally goes through forging, heat treatment, turning, grinding and assembly and other processing procedures. The rationality, advancement and stability of each processing technology will also affect the life of bearings. Among them, heat treatment and grinding process which affect the quality of finished bearing often have a more direct relationship with bearing failure. The research on the metamorphic layer of bearing working surface in recent years shows that the grinding process is closely related to the bearing surface quality.

Metallurgical quality of imported bearing materials used to be the main factor affecting the early failure of rolling bearings. With the progress of metallurgical technology (such as vacuum degassing of bearing steel), the quality of raw materials has been improved. The proportion of raw material quality factor in bearing failure analysis has decreased significantly, but it is still one of the main factors affecting bearing failure. Whether material selection is appropriate is still a factor that must be considered in bearing failure analysis.

The main task of imported bearing failure analysis is to find out the main factors causing bearing failure according to a large number of background materials, analysis data and failure forms, so as to put forward targeted improvement measures, prolong the service life of bearings, and avoid the occurrence of sudden early failure of bearings.

Q17:How can we make TIMKEN tapered roller bearing wet but not slippery?

A:TIMKEN tapered roller bearings can be installed by mechanical, heating or hydraulic methods according to their type and size. However, under no circumstances shall tapered roller bearing rings, cages, rolling bodies or seals be struck directly. During installation, the force applied to the TIMKEN bearing must not be transferred from one bearing ring to another through the rolling body, otherwise it may cause damage to the raceway.

• 1.the tank equipment of TIMKEN taper roller bearing should have two, one for use, one for standby, regular switch, standby tank cleaning, oil temperature precipitation, net oil water.
• 2. In the oil tank of TIMKEN tapered roller bearing, a degassing plate in the oil return area should be set to reduce refueling impact; Magnetic grid device – adsorbing iron impurity in oil return area; Floating oil suction port – oil suction at the appropriate position below the liquid level; Automatic drainage device or flood alarm device – precipitation separation of water discharged in time; Dynamic level control – alarm or interlock for sudden large amount of oil leakage.
• 3.TIMKEN tapered roller bearing oil supply filtration accuracy is high, generally requires the filtration accuracy of 10 ~ 20μm, in order to ensure the cleanliness of oil.
• 4.The oil supply pressure of TIMKEN tapered roller bearing should be kept constant, and the working pressure control device of the lubrication system should have high sensitivity and accuracy, so as to avoid the working pressure drop caused by pressure changes, resulting in insufficient oil supply of the local lubrication system, and the wear and sintering of the oil film TIMKEN bearing.
• 5.The tank volume of TIMKEN tapered roller bearings should be 35 ~ 40 times the displacement per minute of the oil pump, and some are even larger. In the case of high oil level operation, ensure that the oil in the tank for a long enough time to settle.
• 6.The pressure tank in the lubrication system of TIMKEN tapered roller bearings must operate normally, control reasonable oil filling flow value and tank level, and play a part in buffering system pressure fluctuation and emergency oil source supply.
• 7.the oil supply temperature of TIMKEN tapered roller bearing should be controlled between 40±2℃ to ensure the viscosity of the oil supply.
• 8.The filter of TIMKEN tapered roller bearing must exhaust the remaining air in the filter cylinder, and then switch the tapered roller bearing.

Q18:What is the classification standard of bearings?

A:The new standard should be

Double row angular contact ball bearings

1. Self-aligning ball bearing

2 self-aligning roller bearing and thrust self-aligning roller bearing

Tapered roller bearing

Double row deep groove ball bearings

Thrust ball bearing

6 deep groove ball bearings

7 Angle contact bearings

Thrust cylindrical roller bearing

N Cylindrical roller bearing and double row cylindrical roller bearing NN

U Outer spherical bearing

QJ four point contact ball bearing

In addition, there are front and rear bearing codes before and after the bearing code, as follows:

— Pre-code

The front code R is placed directly before the bearing basic code, and the rest codes are separated from the basic code by small dots.

GS. — Thrust cylindrical roller bearing ring. Example: GS. 81112.

K. — combination of rolling body and cage. Example: thrust cylindrical roller and cage assembly K.81108

R — Bearings without detachable inner or outer rings. Example: RNU207 — NU207 bearing without inner ring.

WS — Thrust cylindrical roller bearing ring. Example: the WS. 81112.

Q19:What are the identification methods for roller bearings?

• A:(1) The identification of centripetal ball bearings in normal technical state, the inner and outer raceway of the centripetal ball bearings should be free from peeling and serious wear marks, and a bright arc groove; All ball bearings should be kept round, without spots, cracks and spalling; The cage is not loose, broken or worn. When using one hand to hold the inner ring, the other hand quickly push the outer ring rotation, the rotation is required to be stable, only hear the slight sound of ball rolling on the raceway, no vibration; The normal centripetal ball bearing, the clearance between the inner and outer rings and the rolling body is 0.005-0.010mm. When the inner and outer rings are sloshing along the radial direction, there should be no clearance. The used bearing can shake the inner ring along the axis a few times by hand. When the outer ring and the ball have obvious sound, it indicates that the matching gap exceeds 0.03mm, and should not be continued to use.
• (2) Identification of tapered roller bearings After the use of bearings, should check whether the rolling body and inner raceway peeling, cage is too loose, inner ring before and after the edge is complete, the outer ring raceway is cracked. After the inner ring and roller assembly is loaded into the outer ring, the roller shall fall into the middle of the raceway, and the forward movement shall not exceed 1.5mm. One of them is not qualified, that is, cannot be used. 
• (3) The identification of self-aligning roller bearings and short cylindrical roller bearings the outer ring of this kind of bearing is separable. In normal state, the inner and outer ring raceway and roller should not be broken, pitting and deep wear marks; The cage shall have no deformation and be able to close the roller on the inner ring; The fit clearance between inner and outer raceway and roller should not exceed 0.06mm. 
• (4) When the thrust ball bearing is identified in the normal state, the two raceway should have no peeling injury and serious wear, and the ball should have no crushing and pitting; The cage shall be free of deformation, free from contact with the two raceway washers, and the ball bearings firmly packed together.

Q20:What are the models of cross roller bearings?

• A:INA cross roller bearings SX series models are as follows:
• SX011814 SX011818 SX011820 SX011824 SX011828 SX011832 SX011836 SX011840 SX011848 SX011860 SX011868 SX011860 SX0118/500
• INA cross roller bearing XSU series models are as follows:
• XSU080168 XSU080188 XSU080218 XSU080258 XSU080318 XSU080398
• XSU140414 XSU140544 XSU140644 XSU140744 XSU140844 XSU140944
• THK cross roller bearing RA series models are as follows:
• RA10008 RA11008 RA12008 RA13008 RA14008 RA15008 RA16013 RA17013 RA18013 RA19013 RA20013
• THK cross roller bearings RE series models are as follows:
• RE7013 RE8016 RE9016 RE10016 RE10020 RE11012 RE11015 RE11020 RE12016 RE12025 RE13015 RE13025 RE14016 RE14025 RE15013 RE15025 RE15030 RE16025 RE17020 RE18025 RE19025 RE20025 RE20030 RE20035 RE22025 RE24025 RE25025 RE25030 RE25040 RE30025RE30035 RE30040 RE35020
• RE35025 RE40035 RE40040 RE45025 RE50025 RE50040 RE50050 RE60040
• THK cross roller bearing RB series models are as follows:
• RB7013 RB8016 RB9016 RB10016 RB10020 RB11012 RB11015 RB11020 RB12016 RB12025 RB13015 RB13025 RB14016 RB14025 RB15013 RB15025 RB15030 RB16025 RB17020 RB18025 RB19025 RB20025 RB20030 RB20035 RB22025 RB24025 RB25025 RB25030 RB25040 RB30025RB30035 RB30040 RB35020 RB40035 RB40040 RB45025 RB50025 RB50040 RB50050 RB60040 RB70045 RB80070 RB90070 RB1000110 RB1250110
• THK cross roller bearing RU series models are as follows:
• RU124G RU148G RU178G RU228 RU297 RU445 RU228X RU297X RU445X RU228G RU297G RU445G
• IKO cross roller bearings CRB series models are as follows:
• CRB8016 CRB9016 CRB10016 CRB10020 CRB11012 CRB11015 CRB11020 CRB12016 CRB12025 CRB13015 CRB13025 CRB14016 CRB14025 CRB15013 CRB15025 CRB15030 CRB16025 CRB17020 CRB18025 CRB19025 CRB20025 CRB20030 CRB20035 CRB22025 CRB24025 CRB25025CRB25030 CRB25040 CRB30025 CRB30035 CRB30040 CRB35020 CRB40035 CRB40040 CRB40070 CRB45025 CRB50025 CRB50040 CRB50050 CRB50070 CRB60040 CRB60070 CRB600120 CRB70045 CRB70070 CRB700150 CRB80070 CRB800100
• IKO cross roller bearings CRBC series models are as follows:
• CRBC8016 CRBC9016 CRBC10020 CRBC11020 CRBC11020 CRBC12025 CRBC13025 CRBC14025 CRBC15025 CRBC15030 CRBC20025 CRBC20030 CRBC20035 CRBC25025 CRBC25030 CRBC25040 CRBC30025 CRBC30035 CRBC30040 CRBC40035 CRBC40040 CRBC40070 CRBC50040 CRBC50050 CRBC50070 CRBC60040 CRBC60070 CRBC600120 CRBC70045 CRBC70070 CRBC700150 CRBC80070 CRBC800100
• IKO cross roller bearings CRBH series models are as follows:
• CRBH10020A CRBH11020A CRBH12025A CRBH13025A CRBH14025A CRBH15025A CRBH20025A CRBH25025A