How to check the wear of MILL DC Motor brushes

1. Appearance inspection
Check the appearance of the brushes: Observe the appearance of the brushes visually to check for wear, breakage, shedding, etc. Under normal circumstances, the brushes should be smooth and uniform, with no obvious wear or damage on the surface.
Check the surface condition of the brushes: The brush surface should be smooth, crack-free, and free of burn marks. If the brush surface is rough, cracked, or has burn marks, it may indicate poor contact or current overload of the brush, which requires further inspection and treatment.
2. Dimension measurement
Measure the length of the brushes: Use a vernier caliper or a special measuring instrument to measure the length of the brushes. When the brushes are worn to less than 1/3 of their original length, they need to be replaced.
Measure the thickness of the brushes: Measure the thickness of the brushes to ensure that it is within the specified range. Under normal circumstances, the amount of wear of the brushes should meet the regulations, usually 3-6mm/1000 hours.
3. Pressure inspection
Check the pressure of the brushes: Use a spring scale or a special pressure detection instrument to measure the pressure applied by the brushes on the commutator. The pressure value should be within the range recommended by the motor manufacturer, usually 16-24kPa, and the pressure difference between the brushes should not exceed ±10%. Excessive or insufficient pressure will affect the normal operation of the brushes.
4. Contact surface inspection
Inspect the contact surface: The contact surface between the brush and the commutator should be smooth and in good contact. If the contact surface is unevenly worn or scratched, it may cause poor contact, sparks and arcs, and damage the commutator. Check whether the contact surface is smooth, and polish the contact surface or replace the brush as needed.
5. Commutator surface inspection
Inspect the commutator surface: The state of the commutator surface directly affects the operation of the brush. Check whether the commutator surface is smooth, and whether there are burn marks, scratches or uneven wear. If the commutator surface is uneven, sparks may be generated when the brush contacts it, causing further damage to the brush and commutator.
6. Spark inspection
Observe the spark: When the motor is running, observe whether there is spark between the brush and the commutator. Under normal circumstances, there should be only weak sparks. If the spark is large or lasts for a long time, it may indicate that the brush is in poor contact or there is a problem with the commutator surface, and the machine needs to be stopped for inspection immediately.
7. Resistance measurement
Measure brush resistance: Use a multimeter or other instrument to measure the resistance value of the brush. The normal brush resistance range is determined according to the specific model and specification, usually between a few ohms and tens of ohms. If the resistance value of the brush exceeds the specified range, it may cause the motor to work unstably or heat up.
8. Regular maintenance
Regular inspection: Perform at least three inspections and temperature measurements on the brushes per shift, especially 1 hour after taking over and when the unit load is high or the ambient temperature is high. Clean, maintain and replace the brushes once a week. Every time the machine is shut down, the carbon dust in the collector ring ventilation groove and ventilation hole should be removed to avoid affecting the heat dissipation and ventilation effects.