Ultrasonic Cleaning Noise and Reduction Guide

Where Does Ultrasonic Cleaning Noise Come From? 4 Main Sources

1. Cavitation Noise — The Main Noise Source

When cavitation bubbles collapse, they generate a “sizzling” or “crackling” sound. The noise level is mainly related to:

1. Frequency
2. Power
3. Type of cleaning solution
4. Liquid level
5. Temperature

• Low frequency, such as 28 kHz: stronger cavitation impact and louder noise.
• High frequency, such as 80 kHz to 120 kHz: finer bubbles and lower noise.

2. Tank Resonance

Ultrasonic vibration is transmitted to:

• SUS304 / SUS316 tank plates
• Tank frame
• Outer panels

If the resonant frequency of certain metal parts is close to the transducer frequency, the following may occur:

• Metallic ringing noise
• Resonance humming
• Panel vibration noise

This type of noise is not a malfunction, but structural resonance.

3. Low-Frequency Vibration Transmitted Back to the Structure

When the transducer is attached to the bottom of the tank, the vibration does not only move toward the liquid side. It may also be transmitted back to:

• Back panel
• Machine frame
• Floor

These areas may generate low-frequency humming noise.

4. Generator Operating Noise

Inside the ultrasonic generator, there may be:

• Capacitor charging noise
• Coil and transformer magnetizing noise
• Cooling fan noise

These are normal operating sounds and do not affect performance.

What Kind of Noise May Indicate a Problem?

Sharp metallic impact noise
→ The transducer may be cracked, detached, or the metal may be fatigued.

Ultrasonic noise suddenly becomes quieter
→ Power may have decreased, frequency may have shifted, or the liquid level may be too high.

Vibration noise that fluctuates between loud and quiet
→ The generator load may be unstable.

Hammering metallic resonance noise
→ Possible resonance caused by aging or detachment of the adhesive layer.

What Factors Can Make the Noise Louder?

1. Liquid Level Too Low

• Cavitation becomes too concentrated, making the noise sharper.

2. Liquid Level Too High

• Energy distribution becomes abnormal, and resonance noise increases.

3. Insufficient Heating Temperature

• If the cleaning solution is too cold, the noise may become louder.

4. Tank Plate Too Thin

• Thin plates resonate more easily.

5. Different Types of Cleaning Solutions

• IPA and solvent-based liquids: cavitation is quieter than water.
• Alkaline water: cavitation is more intense.

What Methods Can Reduce Noise?

1. Use an External Noise Shield Cover

• Can reduce noise by 10–20 dB and is the most effective method.

2. Increase Tank and Outer Panel Thickness

• Thicker SUS plates reduce resonance and lower noise.

3. Add Vibration Isolation Pads or Damping Materials at the Bottom

• Helps reduce transducer back noise transmitted to the machine frame.

4. Adjust the Liquid Level

• Liquid level that is too low or too high may increase noise.
• Maintaining the original specified liquid level can reduce abnormal noise.

5. Heat to 40–60°C for Natural Noise Reduction

• When the liquid becomes slightly warmer, cavitation becomes more stable and the noise naturally decreases.

6. Use High-Frequency Equipment, 80 kHz and Above

• Smaller bubbles create finer cavitation and a softer sound.

7. Avoid Machine Resonance in Open Spaces

• Avoid placing the equipment near corners.
• Using anti-vibration feet can improve the condition.

Most ultrasonic cleaning noise comes from normal cavitation and structural resonance.
However, if sharp impact noise occurs, the noise suddenly becomes quieter, or the sound fluctuates between loud and quiet, it may indicate equipment abnormality.
By adjusting the liquid level, increasing the temperature, and adding sound insulation or vibration damping design, noise can be effectively reduced.
YONG JI Enterprise can provide sound insulation and vibration reduction recommendations according to equipment size and the on-site environment, ensuring both cleaning performance and stable operation.

© 2026. YONG JI 有限公司

永技企業有限公司

YONG JI Enterprise Co., Ltd.

243新北市泰山區中港西路137-10號

No. 137-10, Zhonggang W. Rd., Taishan Dist., New Taipei City 243079, Taiwan (R.O.C.)

TEL: +886-2-2297-1195

FAX: +886-2-2297-1053