Definition
Ultrasonic cleaning machine is a device that uses ultrasonic waves to create a cavitation effect in a liquid medium to clean the surface of objects. It is widely used in laboratories, medical, electronics, machinery, and other industries to remove contaminants from the surface of samples or components, such as particles, grease, biofilms, etc. This equipment is usually composed of an ultrasonic generator, a transducer, a cleaning tank and a control system, and its working process does not rely on the strong reaction of chemical solvents, which is a physical cleaning method.
Principle
The core principle of ultrasonic cleaning is based on the cavitation phenomenon that occurs when ultrasonic waves propagate through liquids. When the ultrasonic generator generates a high-frequency electrical signal (typically in the frequency range of 20 kHz to 100 kHz), the transducer converts it into mechanical vibration and forms dense interphase sound waves in the liquid medium inside the cleaning tank. During the negative pressure half-period of sound waves, tiny bubbles (cavitation nuclei) are generated in the liquid; During the positive pressure half-cycle, these bubbles collapse rapidly, releasing strong local shock waves and high temperatures and pressures. This cavitation effect creates microjets and shear forces on the surface of objects, effectively stripping the attachment. The whole process can be described by the sound pressure formula:P = P0 sin(2πft), among themP0is the sound pressure amplitude,fis the frequency,tFor time.
Measurement method
The performance evaluation of ultrasonic cleaning machines often involves the measurement of multiple parameters. Cleaning efficiency can be quantified by weighing or optical methods, such as measuring the quality change or surface reflectance of the sample before and after cleaning. The cavitation strength can be assessed indirectly by observing the perforation pattern on the surface of the aluminum foil using the aluminum foil corrosion method. Frequency and power can be measured directly by a digital oscilloscope and power meter to ensure that the device output meets the set value. In addition, temperature and cleaning time monitoring helps standardize operating procedures, including ISO 17223:2014 guidelines for ultrasonic cleaning performance testing.
Influencing factors
The effect of ultrasonic cleaning is influenced by a variety of factors. Frequency selection is key: lower frequencies (e.g. 20-40 kHz) have larger cavitation bubbles and are suitable for removing heavy dirt; Higher frequencies (e.g., 80-100 kHz) cavitation are more delicate and suitable for cleaning of precision components. The properties of the liquid medium, such as viscosity, surface tension, and temperature, can affect cavitation thresholds and propagation efficiency. The geometry of the cleaning tank and the transducer layout can generate standing waves that result in uneven cleaning. The placement and material of the sample also need to be considered, such as brittle materials that should be exposed to high-intensity cavitation areas for a long time.
Application
In the field of laboratory testing, ultrasonic cleaning machines are used to pre-treat laboratoryware, such as glassware, chromatographic injection bottles, to ensure that no contaminants interfere with the analytical results. In the medical industry, it is used for the initial decontamination of surgical instruments. The electronics industry relies on it to remove flux residue from circuit boards. In industrial maintenance, it can be used to clean mechanical parts. In addition, in the field of environmental monitoring, cleaning of sampling equipment helps avoid cross-contamination. These applications are based on their non-invasive and consistent characteristics.
Selection
When selecting a model, it is necessary to comprehensively consider the cleaning needs and equipment parameters. First, clarify the material, size, and type of contamination of the cleaning object to determine the appropriate frequency and power range. For sensitive samples, models with temperature control and timing are available to reduce the risk of damage. The capacity of the cleaning tank should match the daily workload to avoid excessive consumption of liquid media. The safety features of the equipment, such as overload protection and insulation design, are useful in laboratory environments. It is recommended to refer to international standards such as IEC 60335-2-104 and give preference to equipment that provides verifiable performance data to ensure reliability in long-term use.