The gearbox emits a piercing whistling sound at a specific speed.

[Janja]

The geared stepper motor (https://www.oyostepper.com/category-26- ... Motor.html) is running around 900 rpm when the entire gearbox suddenly emits a sharp whistling sound, and the housing visibly vibrates slightly.

Acceleration measurements show that the peak value is exactly twice the gear meshing frequency, indicating that a certain natural frequency of the gearbox has been excited. Increasing the gearbox wall thickness and adding damping pads have reduced the whistling sound, but it hasn't disappeared.

This speed range is precisely what our manufacturing process requires, and it cannot be avoided.

Is it possible to shift the frequency by changing the gear tooth ratio or modifying the gear tooth profile? The noise is so piercing that the workers are collectively requesting earplugs.

Any good suggestions or guidance would be greatly appreciated.