Spindle Motor Troubleshooting

The spindle motor is a high speed, high precision mechanical and electrical precision component, we have a variety of failure phenomena in the maintenance of spindle motor process, ATO summarized in the maintenance of CNC spindle motor common failures and what are the solutions?

Large noise and vibration

Cause analysis: The spindle is damaged by improper assembly of bearings or other parts, low precision or poor retention of bearings, poor coaxiality of stator and rotor, the uneven air gap between stator and rotor, low manufacturing precision of spindle parts, or deformation after long-term use destroys the balance precision, too small preload or spring not installed in place or even broken, broken rotor cage bar or poor contact, poor rigidity and low precision of grinding wheel joint rod. 
Solution: screen better bearings, correct the coaxiality of the stator and rotor, check the accuracy of the main parts of the shell, rotor, rotor and large cover, increase the preload, reassemble the electric spindle, and choose the wheel joint with good rigidity and high precision to ensure the normal and stable work of the electric spindle.

Difficult to start

Cause analysis: The power plug is not plugged in, poor contact or not connected, the power supply is not enough or does not match with the electric spindle, the inverter start protection is not adjusted to the best value, the power supply is out of phase or poor contact, etc. will lead to the electric spindle starting difficulties. The preload added to the bearings in the electric spindle is too large and the parts touching each other will also lead to its starting difficulty, but in most cases, the reason for its starting difficulty is that the motor stator lead wire in the electric spindle is connected wrongly, the air gap between the stator and rotor is too small and the stator winding is damaged. 
Solution: First check the power supply voltage, current and power, and check the power supply condition. Re-adjust the inverter according to the electrical parameters of the electric spindle, then check the ground insulation of the stator winding and the balanced state of the three-phase winding, once the fault is found, immediately carry out maintenance. If the air gap between the stator and rotor is too small, repair and grind the outer diameter of the rotor to maintain the design value of the stator and rotor gap. If the parts are rubbing against each other, repair the outer diameter of the parts to ensure that there is sufficient clearance between them. Correcting the preload given value can also improve the starting condition of the motor spindle. Therefore, when an electric spindle has starting difficulties, a specific solution should be found for the equipment.

Speed reduction or unstable speed

Cause analysis: The power supply voltage is too low, and the electrical parameters do not match, the power is small, and the rotor cage bar is broken or has poor contact. 
Solution: First check whether the power supply output, frequency, voltage, power and electric spindle match. If the electric spindle power is small, choose a larger power electric spindle that meets the requirements of the working conditions, check the quality of the cage bar, and choose a larger capacity electric spindle.

Continuous bearing burnout

Cause analysis: Poor lubrication, too high speed, too small or too large preload, too large load-bearing.
Solution: Replace the grease or check the quality of the oil mist, and check the oil supply to the oil channel. Measure the rotational speed, adjust the inverter to ensure the normal operation of the electric spindle, and detect and adjust the preload to make it reach the best value.

Spindle heating

Cause analysis: The cooling water circuit is not smooth, the precision of the selected bearing is low, the fit is too tight, the bearing is back-mounted or not in place, the preload is too large, the power supply voltage is high, and the grinding tool feed is too large.
Solution: Check and unclog the waterway, screen the better bearings, measure their dimensions, re-match them, reduce the preload appropriately and reassemble them. Check the air gap and current value between the stator and rotor, check the supply voltage and control the grinding feed.

Too high stator winding temperature

Cause analysis: power supply is out of phase or voltage is too high, the rotor cage bar is broken, water leakage from the water jacket, the front end of the grease lubrication type electric spindle waterproof labyrinth sealing is not good.
Solution: Measure and adjust the voltage to meet the requirements of the electric spindle, check the quality of the cage bar to replace the rotor in time, check whether water leakage and change the front end of the electric spindle to a well-sealed structure.

ATO provides three kinds of high-precision electric spindle motors for CNC. Air-cooled spindle, water-cooled spindle, and automatic tool-changing electric spindle are available. If you encounter any problems, please contact our professional technicians in time.