Why Does the A6 Servo Motor Emit a High-Pitched Whine Upon Power-On and How to Resolve It?

First, it's important to understand that the whining sound from a servo motor is essentially a high-frequency vibration. This vibration travels through the air and is perceived by our ears as a whine or squeal. The root causes primarily stem from the following aspects:

1. Mechanical Resonance (The Most Common Cause)

• Insufficient Connection Rigidity: The connection between the motor and the load (e.g., ball screw, belt, gear) lacks stiffness.
• Solution: Ensure that couplings, timing belts, gears, and other connecting components between the motor and load are securely fastened without any looseness or backlash. Replace or adjust connections that have play.
• Weak or Loose Mounting Base: The mounting baseplate for the motor and load has insufficient rigidity or is not firmly fixed.
• Solution: Ensure the mounting baseplate has adequate rigidity and that all mounting bolts are tightened to the specified torque. If necessary, add reinforcing ribs or use a thicker mounting plate.
• Low Natural Frequency of the Load Structure: The load itself has a low inherent design frequency.
• Solution: If the structure allows, try adding damping materials (e.g., rubber pads) or mass blocks to the motor or load to shift the natural frequency of the entire mechanical system away from the range that excites the whine.

2. Improper Servo Gain Tuning

• Excessive Rigidity (Gain Too High): To increase response speed, the speed loop gain or position loop gain is set too high. This causes the motor to "overreact," constantly making tiny corrections, leading to high-frequency oscillation and whining. This is a very frequent occurrence during commissioning.
• Insufficient Rigidity (Gain Too Low): While less likely to cause high-frequency whining, it can result in sluggish system response, overshoot during positioning, and other issues.

Solutions:

• Carefully check the setting of parameter C00.05.

• Try reducing the Speed Loop Gain (C01.01). This parameter has the most significant impact on noise. Decrease it in small increments (e.g., 10%-20%) and observe if the whine improves. If the response becomes too slow or following error appears after reduction, fine-tune the Speed Loop Integration Time Constant (C01.02) and Position Loop Gain (C01.00) accordingly to compensate.
• Use the Notch Filter: The A6 servo drive typically has a built-in Adaptive Notch Filter. This function automatically detects and suppresses specific resonant frequencies. It is highly recommended to enable this feature. It automatically identifies the system's resonance point and provides significant attenuation at that frequency, effectively eliminating the whine. For notch filter settings, please access the software as shown in the following operation guide:

In summary, when encountering an A6 servo whine:

1. First, inspect the mechanical installation for rigidity and tightness.
2. Then, access the A6 drive software, enable the Adaptive Notch Filter, and appropriately reduce the Speed Loop Gain (C01.01).
3. If the noise remains unacceptably loud, consider increasing the carrier frequency.

Updated on: 28/11/2025