Ultrasonic Cleaning Problems and Solutions

Common Reasons Why Ultrasonic Cleaning Does Not Clean Thoroughly

1. Insufficient Ultrasonic Energy Output

• Aging or delamination of the transducer reduces conversion efficiency.
• Generator output power decreases due to module or capacitor aging.
• Loose or oxidized wiring causes unstable energy transmission.
◆ Symptoms: Fewer bubbles, lower sound level, and longer cleaning time.


2. Frequency Deviation or Poor Resonance

• The generator frequency deviates from the transducer’s resonant point.
• Abnormal circuit or aging control board.
◆ Symptoms: Cavitation is concentrated in one area, energy distribution is uneven, and some areas are not cleaned thoroughly.


3. Abnormal Liquid Conditions

• The cleaning solution is contaminated, or surface tension has changed.
• Incorrect liquid level, either too high or too low, affects sound pressure distribution.
• Excessive liquid temperature reduces cavitation efficiency.
◆ Symptoms: Bubbles are difficult to form, cavitation is inactive, and cleaning power is significantly reduced.


4. Improper Workpiece Placement

• Too many workpieces are loaded, or parts are stacked too closely, blocking ultrasonic waves.
• Workpieces contact the tank wall or bottom, causing energy concentration or reflection.
◆ Symptoms: Some areas are cleaned thoroughly, while other areas still have oil or dirt remaining.


5. Poor Environmental and Equipment Maintenance

• Oil sludge or scale accumulation at the tank bottom causes poor ultrasonic reflection.
• The transducer or tank bottom is not cleaned for a long time, affecting vibration efficiency.
◆ Symptoms: Overall cleaning performance gradually decreases and becomes inconsistent.

How to Measure Whether Ultrasonic Output Has Decreased?

1. Observe the Bubble Condition

• Normal: Bubbles are evenly distributed, with fine shimmering movement on the surface.
• Abnormal frequency: Bubbles gather on one side, and the liquid surface is unstable.
• Insufficient power: Bubbles are sparse or almost do not implode.


2. Observe the Current Output

• Use an ammeter to check the generator output current.
• If the current drops by 10–20% compared with normal operation, it indicates weaker output.
• If the current fluctuates unstably, the generator frequency may have deviated from the resonance point.


3. Judge by Sound

• During normal ultrasonic operation, the sound should be high-frequency and uniform.
• If the sound becomes low, dull, or suddenly becomes too quiet, it is usually caused by reduced transducer efficiency or abnormal power module output.

Tips to Prevent Power Attenuation

To maintain stable cleaning performance, daily prevention and maintenance are the most important:

• Clean the tank regularly to prevent oil contamination from blocking ultrasonic transmission.
• Maintain good grounding and heat dissipation conditions.
• Establish current flow records and compare the results regularly.

If ultrasonic cleaning does not clean thoroughly, it is often related to frequency deviation or power attenuation.
Through regular inspection, proper power matching, and stable output, ideal cleaning efficiency can be restored.
YONG JI Enterprise provides complete services including inspection and power re-matching to help customers maintain high-efficiency and long-life ultrasonic cleaning systems.