Ultrasonic Cleaning: 25, 40 or 80 kHz - Which to Choose?
Frequency drives both cleaning force and delicacy: 25 kHz removes heavy soil, 40 kHz is the all-rounder, and 80 kHz cleans fine, sensitive parts gently. This guide shows how to select frequency, tank size, power and cleaning medium based on part and level of contamination.
View ultrasonic cleanersWhich frequency fits which job?
Ultrasound cleans by cavitation: millions of tiny bubbles form and collapse against the part surface, blasting soil away. Frequency controls bubble size - low frequency makes large, high-energy bubbles for heavy soil, high frequency makes fine bubbles for sensitive and delicate parts.
At 25 kHz cavitation is most aggressive and reaches deep into blind holes and rough surfaces, but it can attack soft or polished finishes. 40 kHz is the universal standard for workshop, electronics and precision mechanics. 80 kHz and above work gently and reach tight gaps, circuit boards and optical parts without erosion damage.
How big does the tank need to be?
The tank must fully accommodate the largest part so it hangs free in the bath or sits in a basket without touching the tank floor. As a guideline, plan roughly 20‑30 % of extra volume above the workpiece so the fluid can circulate freely.
Beyond volume, power density is decisive. A proven figure is about 10‑20 W of ultrasonic power per litre of bath. Too little power cleans incompletely; too much can cause cavitation erosion on sensitive parts.
- The part must sit freely in the basket, not directly on the vibrating floor.
- Never overload the tank - parts must not shadow or touch each other.
- Always fill to the mark, otherwise cavitation suffers.
- For batch work, define basket or charge size in advance.
- 0.5‑3 l for small parts, 6‑30 l for workshop, above 30 l industrial.
Fluid, temperature and degassing - what matters?
Cleaning fluid and temperature drive success at least as much as frequency. A fluid matched to the soil and the right bath temperature speed up the process considerably.
- The most effective temperature is usually 50‑65 °C, where many cleaners work best.
- For flux and aluminium, respect the maker's temperature and pH limits.
- Never use plain tap water without additive - cleaning is clearly weaker.
- Rinse and dry after the bath so no residue is left behind.
How to keep tools and assemblies clean and serviceable long term.
Read the guideFrequently asked questions
Which frequency is right for electronics and circuit boards?
For circuit boards and sensitive electronics, 80 kHz is ideal because the fine cavitation cleans gently. 40 kHz also works but should be run with short times and a suitable neutral cleaner.
Can I clean everything with 25 kHz?
No. 25 kHz is very aggressive and ideal for coarse, robust parts such as engine components or castings. On polished, thin-walled or electronic parts it risks cavitation erosion, so 40 or 80 kHz is better.
How much power does my tank need?
As a guideline, use 10‑20 W of ultrasonic power per litre of bath volume. A 10-litre unit should therefore offer roughly 100‑200 W of ultrasonic power for fast, complete cleaning.
Why do I need to degas the bath?
Fresh water contains dissolved air that dampens the cavitation bubbles. Degassing for 5‑10 minutes without the workpiece drives out the air and restores full cleaning power.
Looking for the right ultrasonic cleaner?
We stock ultrasonic units from 0.5 to over 30 litres with 25, 40 and 80 kHz plus matching cleaning fluids - selected for your part and level of soil.
Right frequency
25, 40 and 80 kHz for coarse to delicate.
Right size
0.5 to over 30 litres for any charge.
Right fluid
Cleaners for oil, flux and oxide.
Expert advice
We help with frequency and power.