The short answer
Ultrasonic cleaning needs a chemical that lowers surface tension so cavitation can work — water alone has no cleaning properties. Run most aqueous ultrasonic baths at 5% concentration and 50–65 °C. Never use flammables, and avoid acids or bleach, which damage stainless tanks.
- Optimum temperature
- 50–65 °C
- Typical concentration
- 5% aqueous solution
- ALB on aluminium
- 5–9% at 28–40 kHz
- Never use
- Flammables, low flash point liquids
- Avoid
- Acids and bleach — damage stainless tanks
An ultrasonic cleaner is a metal tank with piezo transducers bonded to its base or sides. High-frequency electrical energy becomes sound energy, which forms and collapses millions of microscopic bubbles in the liquid. That collapse — cavitation — releases enough energy at the part surface to lift contamination out of bores, blind holes and crevices that no jet can reach.
Choosing the chemistry
Ultrasonic solutions are compounded from detergents, wetting agents and reactive components. Selection is driven by the substrate first, then the soil.
| Parts | Grade | Notes |
|---|---|---|
| Multi-metal, general machining soils | POWER CLEAN XL | 1–15%, 60–70 °C, rust inhibited |
| Aluminium, brass, copper, bronze, nickel | POWER CLEAN NF-14 | Neutral pH, 3–15%, 40–55 °C, no white rust |
| ADC10/ADC12 and 6000-series aluminium | POWER CLEAN LF-59 | 2–10%, ambient–65 °C, pH 9.3–10.3 |
| Aluminium needing brightening | POWER CLEAN ALB | 5–9%, room temp, 28–40 kHz, 3–8 min |
| Carbon deposits, engine parts | POWER CLEAN CR21 | 5–25%, 62–70 °C |
| Rust and oxidation removal | PC Rust Remover 27 | 1:3 light, 1:2 heavy rust |
Temperature and time
Heat almost always helps: most detergent solutions are formulated to work best warm, and higher temperature lowers soil viscosity. The best results usually fall within 50–65 °C. Beyond that you gain little and start paying for evaporation.
Cycle time is the easiest variable to change and the one most often misapplied. Visible soil removal should begin almost immediately once the ultrasonics start. If a cycle needs to be long, the problem is usually concentration, temperature or the wrong chemistry — not insufficient time. Approximate the cycle from experience, then validate it with your actual soiled parts.
What must never go in the tank
- Flammables and low flash point solvents — cavitation converts energy into heat and creates hazardous conditions. This is a safety rule, not a preference.
- Acids and bleach in the main tank — they damage stainless steel tanks and can create hazardous by-products. Where unavoidable, use indirect cleaning in a glass beaker suspended in the bath.
- Uninhibited high-alkaline cleaner on aluminium — it will etch and darken the part.
Checking your machine is actually working
Cavitation degrades as transducers age, and a weak tank looks identical to a healthy one. The aluminium foil test is the standard quick check: suspend a sheet of household foil in the tank and run a short cycle. Even, fine perforation across the sheet means cavitation is distributed properly; untouched areas mean dead zones.
Bath maintenance
- 1Replenish when cleaning action noticeably drops or the solution is visibly spent — a fresh batch every session is not required.
- 2Skim floating oil and filter particulate; both extend bath life substantially.
- 3Monitor concentration by titration or refractometer rather than by eye.
- 4Rinse after cleaning to remove chemical residue, using tap, distilled or DM water depending on how critical the part is.
- 5Dry thoroughly — parts left damp will corrode regardless of how well they were cleaned.
Send us a part and tell us your tank size and frequency — we will specify the chemistry, concentration and cycle, and prove it on your components first.
Get an ultrasonic recommendationFrequently asked questions
What chemical should I use in an ultrasonic cleaner?
An aqueous cleaner formulated for your substrate. POWER CLEAN XL suits multi-metal machining soils, NF-14 is neutral-pH for aluminium, brass and copper, and LF-59 handles ADC10/ADC12 die-castings. Never use flammable solvents in an ultrasonic tank.
What temperature should an ultrasonic cleaner run at?
Usually 50–65 °C. Heat enhances and speeds up cleaning and most detergent solutions are designed to work best at elevated temperature, but the optimum for your parts is best found by testing.
Can I put acid or bleach in an ultrasonic cleaner?
Generally no. Acids and bleach damage stainless steel tanks and can create hazardous conditions. If an acidic process is unavoidable, use indirect cleaning — the part and acid in a glass beaker suspended in the water-filled tank.
Why is water alone not enough in an ultrasonic bath?
Water has no cleaning properties of its own. Soils are bonded to the part, and the chemical's job is to break that bond; the cavitation assists it. Detergents and wetting agents also lower surface tension, which increases cavitation intensity.
How do I know if my ultrasonic cleaner is still cavitating?
Run the aluminium foil test: suspend a sheet of foil in the tank and run a short cycle. Even, fine perforation means cavitation is working across the tank; untouched areas indicate dead zones or failing transducers.
How often should ultrasonic cleaning solution be changed?
When cleaning action visibly drops or the solution is dirty or spent. Skimming oil and filtering particulate extends bath life considerably, so a well-maintained bath lasts far longer than an unmanaged one.
