Ultrasonic Cleaning Troubleshooting Guide

1. Incorrect Frequency Selection for the Workpiece or Contamination

Different frequencies correspond to different cleaning characteristics:

• Low frequency (28 kHz): Strong cavitation, suitable for heavy oil contamination.
• Medium frequency (40–80 kHz): Balanced cleaning performance.
• High frequency: Suitable for precision parts and fine holes.

If the frequency is selected incorrectly, extending the cleaning time still cannot improve the result.

Further Reading: How to Choose Ultrasonic Cleaning Frequency?

2. Insufficient or Uneven Power Density

Common problems:
• Insufficient power → contamination cannot be removed effectively.
• Large tank, but no power increase.
• Energy is concentrated only in certain areas, resulting in uneven cleaning.

The key point is not power itself, but “power density (W/L).”

Further Reading: How to Choose Ultrasonic Cleaning Power?

3. Incorrect or Degraded Cleaning Solution

• Water-based cleaning solution is not suitable for oil contamination.
• Cleaning solution has not been replaced for a long time.
• Surface tension is too high.

The cleaning solution directly affects cavitation performance and degreasing ability.

Further Reading: How to Choose Ultrasonic Cleaning Liquid?

4. Improper Temperature Setting

• Too low → oil contamination is not easy to break down.
• Too high → cavitation becomes weaker instead.

The optimal temperature range is usually 40–60°C.

Further Reading: Ultrasonic Cleaning Temperature Guide
Further Reading: Why Can’t Ultrasonic Cleaning Temperature Keep Increasing?

5. No Degassing or Incomplete Degassing

Dissolved gases in the water may:

• Absorb energy
• Block cavitation
• Cause uneven cleaning

After adding fresh water or after the machine has been stopped for a long time, degassing must be performed before cleaning.

Further Reading: Degassing Principle

6. Insufficient Flow Field and Circulation

Even if the contamination is removed, if:

• Contaminants are not carried away
• Contaminants circulate inside the tank
• Contaminants reattach to the workpiece

The cleaning result will appear as if it is “never fully clean.”

Further Reading: Flow Field Design

7. Incorrect Workpiece Placement

Common mistakes:

• Workpieces are stacked.
• Cavitation areas are blocked.
• Workpieces are placed in energy dead zones.

Ultrasonic cleaning is based on “direct exposure to cavitation.” Placement is very important.

Further Reading: Ultrasonic Cleaning Fixture and Basket Design

8. Incorrect Adjustment Method

When cleaning is incomplete, the most common mistake is:

Wrong methods:

• Extending the cleaning time
• Increasing the power
• Heating the solution

The correct approach should be:

• Check the frequency
• Check the power density
• Check the liquid and flow field
• Then adjust the cleaning time

Poor ultrasonic cleaning performance is usually not an equipment problem. It is often caused by an imbalance among frequency, power density, cleaning solution, temperature, flow field, and workpiece placement.
Simply extending the cleaning time or increasing the power usually cannot truly solve the problem.
Only by judging and adjusting based on actual process conditions can a stable and efficient ultrasonic cleaning process be established.
YONG JI Enterprise can assist with testing and verification based on different workpieces and process requirements, ensuring that ultrasonic cleaning equipment achieves the best cleaning performance.

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永技企業有限公司

YONG JI Enterprise Co., Ltd.

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