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Major impact on the life of the bearing installation aspects

Decision bearing length of life of many factors, but can be broadly divided into two types , one is internal ( bearing its own factor ) , the other is external TIMKEN bearings .
Bearing factors are mainly including structural design , quality manufacturing processes and materials , such as three factors .
Manufacture of bearings generally through forging , heat treatment, turning, grinding and assembly of multi- channel processing . However, the reasonableness of the processing technology , advanced, will also affect the stability of the bearing life . KOYO bearings which affect the quality of the finished heat treatment and grinding processes normally associated with bearing failure have a more direct relationship.
Bearing materials metallurgical quality of early bearing failure was the main factor . As metallurgical techniques ( such as bearing steel vacuum degassing, etc. ) progress, improve the quality of raw materials . Raw material quality factors in bearing failure analysis in the proportion has decreased significantly, but it is still bearing failure is one of the main factors . Appropriateness of the selection is still bearing failure analysis must be considered.
( A ) a fixed circle to take a small interference fit condition that matches the shape of the surface of both sides are very high precision and a smaller roughness , or cause installation difficulties removal more difficult , in addition, also need to consider the impact of the spindle thermal elongation .
( 2 ) using the pair of angular contact ball bearing spindle , mostly lighter loads , the amount of interference , such as too large, then the internal axial preload amount will be significantly larger , resulting in adverse effects . Using double row bearing shaft and the bearing spindle , which load is relatively large, so the interference with the relatively larger .
( 3 ) shaft and housing bore roundness and verticality of the shoulder block in accordance with the appropriate INA bearings precision requirements.
( 4 ) it is necessary to accurately calculate the rotation of the ferrule with the amount of interference , but also suitable for accurate calculation of the amount of the fixed ring .
Interference amount rotatable collar may also wish to obtain a smaller range . As long as the operating temperature and ensure the effect of thermal expansion , and the maximum speed of the centrifugal force , resulting in a tight fit so as not to creep or sliding surfaces . Fixed ring size according to the work load and bearing size, select small clearance fit or interference fit , too loose or too tight is not conducive to maintaining the original shape exactly .
( 5 ) under the conditions of bearings, such as in high-speed operation , and higher operating temperature , special attention should be rotating rings can not be too loose to prevent eccentric , as well as non- fixed ferrule with a gap to prevent ferrule deformation under load and excited vibrational
A dimensional accuracy tolerance
Diameter, outer diameter in the finished product inspection in tolerance possible, mainly due to :
1 before the process of product undetected .
(2) Check the ambient temperature changes assembly .
3 standard ferrule thermostat is not enough.
4 grinding using standard parts and finished products inspection failed .
SKF bearings diameter size is too large, should be judged as substandard products , the inner scrapped. Diameter size is too small, should be judged as substandard products , but you can rework grinding , making it qualified. Bearing diameter size is too large, can be re- grinding , making it qualified. But the outer diameter is too small, to be rejected bearing outer ring scrapped.
B. Rotate the accuracy tolerance
Generating rotational accuracy tolerance reasons:
1 ring in the grinding process , the channel center plane of the base end equal degree exceeded poor.
Two inner and outer surface of the channel is injured, there is dirt .
3 inner and outer rings datum injury .
4 large outside diameter variation channel .
5 installed last ball , makes the outer ring deformation, the surface of the ball card or injury .
6 may be mixed with the ball , the ball diameter is too large .
7 cage deformation.
8 groove shape deformation.
Kia Kea ultra poor and less scrap , even if there is due to a single ring on the inner or outer diameter of the channel thickness variation tolerance. But Sia and Sea -tolerance scrapped more . To reduce losses , often through the demolition of parts re- assembled , a certain improvement . Sd and SD -tolerance can only be scrapped .
C. Flexibility bad bearings
FAG Bearings flexibility is not good, its two main reasons:
1 riveting timely internal bearing into dirt.
2 riveting timely too much pressure , so that the cage deformation.
3 Die uneven force , the retainer pressure uneven deformation.
4 rivet diameter tolerance, length ultra- poor, so riveting timely same cage rivet deformation range, the retainer deformation.
5 cage ball size tolerance , so that turning the ball without sufficient radial clearance .
6 sets when combined radial clearance is too small.
7 individually mixed with big ball , you can not turn the other .
D. radial clearance tolerance
By radial clearance requirements together sets of radial clearance tolerance occurs for two main reasons :
1 ring size sorting values are not accurate, because of the selected accidental error , the measurement system error caused .
2 -channel ring radius of curvature tolerance.
3 measuring axial clearance , ball decile uneven location is incorrect , hands thrust inconsistent.
4 bearing cleanliness is not enough .
5 ferrule channel geometry deviation is too large .
6 cage center circle of tolerance is too large.
E. bearing corrosion
NSK Bearings corrosion for the appearance of inferior quality. Its cause is improper preservation bearing parts rust ; assembly process implementation of strict anti-rust process ; especially the rainy season the operator does not work with gloves ; assembly operations room air relative humidity is too large ; cleanliness so poor .
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