How to judge the degree of wear of Flying Shear Motor brushes?

1. Direct observation method
Length measurement: This is the most intuitive method. The brush length can be measured regularly (for example, every week or every two weeks, depending on the frequency of use of the Flying Shear Motor). Use a tool such as a caliper to remove the brush from the brush holder (if it is convenient to operate), or measure its visible length as accurately as possible when the brush is installed. When the brush is worn to 1/3 - 1/2 of its original length, it is generally necessary to consider replacement. For example, a brush with an initial length of 30mm, when the length is worn to about 10 - 15mm, the degree of wear is more serious.
Contact surface observation: Check the contact surface between the brush and the commutator. The normal brush contact surface should be flat and fit well with the commutator. If there are obvious pits, gaps or unevenness on the contact surface of the brush, this will affect the conduction of current, increase the contact resistance between the brush and the commutator, and generate sparks. At this time, even if there is still room for the brush length, the brush may need to be replaced because this irregular contact surface will accelerate the wear of the brush and may have caused damage to the commutator.
2. Operation status monitoring method
Spark situation judgment: During the operation of the Flying Shear Motor, observe the sparks generated between the brush and the commutator. Under normal circumstances, only weak and almost invisible sparks will be generated between the brush and the commutator. If there are obvious sparks and the spark level exceeds level 1.5 (according to the brush spark level standard, sparks above level 1.5 will damage the brush and commutator), this may be caused by brush wear, improper brush pressure, or uneven commutator surface. After excluding other factors, if the spark problem still exists, it is necessary to check the degree of wear of the brush and may need to replace the brush.
Temperature change monitoring: Use an infrared thermometer to measure the temperature of the brush. The temperature of a normally working brush should be within a reasonable range and generally not exceed 80-100℃ (the specific value varies depending on factors such as the motor working conditions). If the brush temperature is too high, in addition to considering factors such as motor overload and poor ventilation, the wear of the brush itself or poor contact may also be one of the reasons. When the brush temperature continues to be too high and cannot be reduced by other means, it is necessary to check whether the brush needs to be replaced.
3. Electrical parameter detection method
Contact resistance measurement: When the motor is stopped, a micro-ohmmeter or milliohmmeter can be used to measure the contact resistance between the brush and the commutator. Under normal circumstances, the contact resistance should be within a low range, and the specific value depends on the model of the motor and the specifications of the brush. As the brush wears, the contact resistance will gradually increase. When the contact resistance exceeds a certain limit (usually 2-3 times the initial contact resistance), it means that the brush is severely worn and needs to be replaced.
Current distribution check: By installing a Hall current sensor on the brush (if the motor has a corresponding monitoring device), the current distribution between the brushes can be checked. Under normal circumstances, the current distribution should be relatively uniform. If the current of one brush is significantly lower than that of the other brushes, it may be that the brush is excessively worn, resulting in poor contact, so that the current cannot pass normally. In this case, it is also necessary to check the degree of wear of the brush and consider replacing it.