Answers to Your Frequently Asked Questions About Ultrasonic Cleaners
Here are a series of questions frequently asked about ultrasonic cleaning. If you have a question that is not addressed here please contact us and we’ll provide an answer.
Q: Can I replace transducers on my cleaning tank?
A: Because this is a complex operation we recommend that repairing or replacing transducers be done by a qualified technician in a service center.
Q: Can cold cleaning solutions be used in an ultrasonic tank?
A: Yes but care must be taken to avoid condensation that can damage transducers.
Q: How do I remove rust stains?
A: Most rust films develop from ferrous products being cleaned. They can be avoided by regularly using a tank cleaning solution. But if they do occur, operate the tank with a mildly acidic cleaner at elevated temperature. Never use an abrasive cleaner on tank surfaces.
Q: How can I avoid or remove furring in an ultrasonic tank?
A: Furring can result when highly calciferous water contacts hot surfaces and usually occurs around the heating elements. It can be prevented by using ultrasound to circulate the bath during the heating cycle to minimize hot spots. Furring can be removed fairly easily and gently with standard citric or phosphoric decalcifiers. Never use an abrasive cleaner on tank surfaces.
Q: Can chlorides contained in tap water, in cleaning media or in deposits on items being cleaned damage the ultrasonic tank?
A: Yes under certain conditions. The potential for damage is increased when using cleaning media with pH values in the acid range. If tap water contains chlorides, we recommend using cleaning chemicals in the alkaline range. If the cleaning job requires an acid cleaner use distilled water instead of tap water.
Q: Can I put flammable media in an ultrasonic bath?
A: This is generally not allowed in an open bath. Instead you can treat a limited quantity of a flammable medium when it is placed in a separate, closed container (e.g. beaker with a lid) immersed in a tank containing water and a surfactant. Flammable solvents may be used in an explosion proof ultrasonic cleaner in an area suitably equipped for hazardous vapors.
Q: How do I choose the optimum ultrasonic cleaning frequency?
A: Here are some suggested frequencies.
- 25 kHz for the removal of coarse and tenacious adhesive contaminations and for pre-cleaning of robust surfaces such as stainless steel and cast iron
- 35-40 kHz is the standard frequency range for all simple cleaning jobs and for cleaning tasks in the laboratory and sanitary sector
- 45 kHz is used for fine cleaning and for the cleaning of sensitive surfaces such as light metal alloys
- 80-130 kHz is used for the finest cleaning jobs and for the cleaning of highly sensitive surfaces such as micro electronics, precision optics, and polished aluminum
Q: How do I know what ultrasonic cleaning solution to use?
A: Most ultrasonic cleaning solutions marketed today are biodegradable, are shipped as concentrates and are formulated as: acidic, neutral, or alkaline.
- Acidic solutions are used to remove rust and mineral deposits from ferrous metals, but not for light alloys susceptible to corrosion.
- A mildly alkaline ultrasonic cleaning solution is suitable for removing oil, grease, dust, soot and other organic compounds on glass, plastic, ceramic, rubber, iron and non-ferrous metals. Mildly alkaline detergents containing enzymes are used to remove blood and tissue from medical instruments.
- An ammonia-containing alkaline solution cleans laboratory appliances, work pieces and jewelry made of glass, ceramic and precious metals. It also brightens jewelry and non-ferrous metals.
- Strongly alkaline (caustic) solutions are used to strip burned on plastic residues from metal injection molds.
- Very delicate materials made of plastic, glass, metals and rubber call for a neutral solution to remove impurities such as dust, grease, pigments and other organic compounds.
- Nitric, sulfuric, formic, or hydrofluoric acid should only be used when a plastic tub is placed in the tank to protect the stainless steel. These solutions are not biodegradable and must be disposed of properly.
Q: What is cavitation erosion?
A: It is the erosion of the tank surface by cavitation associated with ultrasonic cleaning and can in the long run lead to tank failure. Tank life is prolonged with regular cleaning to remove settled particles that abrade the tank bottom when subjected to ultrasound, by not placing items being cleaned directly on the tank floor, and by operating the tank at the proper fill level.
Q: What is sweep?
A: Ultrasound at a fixed frequency creates fields of high and relatively low ultrasonic intensity, which can yield uneven cleaning results. Sweep is the term used to describe a continuous slight modulation of the ultrasonic frequency. This produces a more uniform distribution of the cavitation process and delivers better performance in the cleaning bath.
Q: What is oscillation?
A: Oscillation, also called agitation, is precisely controlling the up-and-down movement (± 2 cm) of cleaning baskets to maximize the efficacy of the cavitation process. Precision is critical because if movement is more severe it will in effect reduce or even eliminate the cavitation action.
Q: Why is degassing important?
A: A freshly filled ultrasonic tank contains air, as exemplified by bubbles observed when placing an item in water. Unless removed by degassing, the bubbles inhibit the cavitation process. Equipment should be operated in the degas mode when filled with fresh solutions and before starting the cleaning operation. If the unit has no degas mode, degassing can be accomplished by operating the ultrasonic power for about 15 minutes. The sound produced by the unit during operation changes discernibly when the liquid has been degassed.
Q: How can I reduce the noise level of an operating ultrasonic cleaning unit?
A: If your unit produces an uncomfortable noise we recommend using a cover over the tank or, if feasible, putting the equipment in an insulated box with an exhaust fan. Use ear protection devices when working near coverless units or turn the unit off when loading and unloading. Some models have the option of a hinged insulated lid to further reduce noise.
Q: Is it necessary to use DI water for cleaning with ultrasound?
A: Before you set up the cleaning process it’s important to define ‘clean’. DI water is used when a spot-free surface is required after cleaning. In most cases it is adequate to clean with a cleaning agent dissolved in tap water and rinse with DI water to remove residues. (Also, see answer above about water containing chlorides.)