Rolling bearing residual magnetic technology conditions

1 Scope of application
    1.1 This standard applies to all types of ordinary bearings in the range of 28 to 430 mm outside diameter.
    1.2 Bearing residual magnetism is a nonlinear non-uniform magnetic field, and its measured value is related to the measurement principle used, the sensing element and its measuring distance. Therefore, the residual magnetic value specified in this standard refers to the value measured under the conditions specified in 5.1. The residual magnetic value measured under other parameters is not applicable to this standard.
    2 Reference standard
        GB 3102.5-82 "Electrical and magnetic quantities and units"
        JB 3371-83 "Rules for Inspection of Rolling Bearings and Commodity Parts"
    3 definition and unit of measure
    3.1 Residual magnetism refers to the maximum residual magnetism that has been magnetized during the production process and has not been eliminated after demagnetization.
    3.2 Residual magnetism is expressed by the physical quantity of magnetic induction, and its unit is milliwatt (mT).
    4 Technical requirements
    5 Measurement methods
    5.1 Residual magnetic measurement Using the Hall effect principle, the measuring instrument must have a range of 1 mT and an accuracy of plus or minus 3%. The Hall component of the instrument is 4*2*0.2 cubic meters, and the distance between the plane of the Hall element and the measured surface is plus or minus 0.05mm.
    5.2 For radial ball bearings, the measuring parts are both end faces and chamfers. The maximum reading obtained is the residual value of the bearing when measuring.
    5.3 For cylindrical roller bearings, needle roller bearings, spiral roller bearings, tapered roller bearings and thrust roller bearings, the separable parts shall be separated and measured separately. In addition to the end faces and chamfers of the inner and outer rings (or seats, shaft rings), the exposed parts of the rolling elements should be measured. If the residual magnetic parts of the rolling elements are found at the junction with the cage, the rolling elements can be rotated appropriately. The portion was exposed and measured. For the measurement method of the inseparable type of this type of bearing, the provisions of 5.2.
    5.4 For spherical roller bearings, when measuring both end faces and chamfers, refer to the provisions of 5.2. When measuring the rolling elements, the radial planes of the inner and outer rings should be made 90 degrees apart from each other. The measurement method of the rolling elements is as specified in 5.3 for the measurement of rolling elements.
    5.5 For thrust ball bearings, the separable washers shall be measured after separation. The measuring parts shall be the seat, the end face of the shaft ring and the chamfer. For the measurement method of the inseparable type of this type of bearing, the provisions of 5.2.
    5.6 When measuring the residual magnetism of the bearing end face, the probe is perpendicular to the bearing end face position. When measuring the chamfer of the bearing and the residual magnetism of the rolling element, the probe can be tilted for proper recording, but the inclination angle is not more than 45 degrees.
    5.7 When the residual magnetism on the bearing ring or rolling element is close to the specified value, the bearing end face should be placed in a flat position, and then the treatment should be measured in the east-west direction to reduce the influence of the geomagnetic field.
    5.8 It is not allowed to measure on a magnetically conductive table and in an ambient magnetic field greater than the strength of the earth's magnetic field.
    5.9 The distribution of residual magnetism on the bearing is random. When measuring, the measuring position of the probe on the bearing cannot be preset. The probe should be moved in such a way that it can reach any part of the bearing. The measurement method of the fixed probe is not applicable to this standard.
    6 Inspection rules
    The residual magnetic inspection adopts the method of sampling acceptance. The number of samples is taken according to the provisions of JB3371, and the acceptable quality level AQL is 4, and the general inspection level is sampled.