What is ultrasonic cleaning?

Ultrasonic waves are generated by transducers and generators that travel through elastic media such as liquids. Liquids are suitable for this type of cleaning because they can seep into underwater objects, and even complex and hard-to-reach parts can be cleaned on the surface.

The transducer generates high-frequency ultrasonic waves that cause a rapid change in pressure in the liquid, creating tiny bubbles that implode; this is called cavitation. The tiny bubbles stirred in the cleaning solution produce mechanical action to remove surface contaminants from the submerged article.

The heat generated during micro-current pulsations also helps to remove contaminants. A cleaning solution also helps to achieve better cleaning results. This cleaning method is very effective for machines and parts used in automobile manufacturing and workshops, electronic service stores, aerospace and ship parts manufacturing, railroads, assembly lines and other manufacturing industries.

Ultrasonic technology

Ultrasound

Sound transmits vibration through an elastic medium, which may be solid, liquid, or gas. Sound wave generation is the generation of sound waves in a conducting medium by a single or repeated motion, such as a vibrating motion. The movement of air through a radio speaker cone is a good example of the vibrational sound waves generated by mechanical motion.

Ultrasound, on the other hand, is the science of sound beyond the limits of human hearing. The frequency of a sound wave determines its timbre or pitch. Low frequencies produce low and high frequencies. The sound waves that travel through and agitate the cleaning solution cause cavitation, which erodes surface contaminants.

Cavitation

An important part of ultrasonic cleaning system is the generator of high frequency electrical signal. These signals are transmitted to the transducer and converted into sound waves. As the wave passes through the metal plate of the transducer through the cleaning solution, the wave creates a low-pressure region that produces cavitation.

Cavitation is caused by the rapid formation and rupture of steam bubbles in liquids. Energy jets are released during troughs and collapse at subsequent peaks or wavefronts, forming cavitation bubbles. The wavefront is an imaginary space representing the vibrating wave point.

The simultaneous collapse of the cavitating bubble leads to implosion, which causes the shock wave to radiate from the collapse site. The bursting and implosion of many bubbles in an activated liquid results in an effect usually associated with ultrasound. Mechanical cleaning by collapse is widely described as the scrubbing of parts to remove dirt and contaminants from their surfaces.

Frequency

In ultrasonic cleaning, different frequencies can remove all kinds of particles and dirt, and this technology is flexible in use and application. General cleaning frequency of 40kHz, can remove large chip, welding spatter, chip and laser oxide skin. The frequency is used in the hardware, plumbing, consumer goods, automotive and aircraft industries.

Low frequencies up to 25 khz will have larger and fewer bubbles, which are aggressive in particle removal but mild to the material. It can remove coarse dirt, carbon, sand, scale, soil and heavy road dirt. Low frequency is mainly used in off-road remanufacturing, casting, manufacturing and rough machining.

For finer pollutant removal, higher frequencies produce smaller cavitation bubbles that clean the material faster and more thoroughly. One example is when the frequency is set between 400 and 800 khz, which can remove dust, fingerprints, and process residues. This frequency level is used for disk drives, optics, and electronic devices.

Temperature

Temperature has an effect on the strength of the ultrasonic cleaning action and the effectiveness of the cleaning solution.

Temperature has more to do with the effectiveness of cleaning agents in use than with the effectiveness of ultrasonic cleaning systems. The ideal temperature varies with each ultrasonic cleaning tank and intended application. For basic applications, set the average machine temperature to between 55 ° C and 60 ° C.

High temperature improves the distribution of ultrasonic cleaning effect in the tank. It disperses tiny bubbles, reducing the concentration of cavitation energy.

Although the mechanical cleaning effect of ultrasonic cavitation will decrease at high temperature, the improvement of the effectiveness of the cleaning solution can overcome this decrease. Some cleaning solutions work best at high temperatures. By operating the ultrasonic cleaner at these high temperatures, the cleaning solution has the ability to improve the combination of loose contaminants and parts.

Each cleaning solution has an optimum temperature at which it works best. It is best to check the ideal temperature of the cleaning solution. When different cleaning solutions are used, an ultrasonic cleaning system with adjustable temperature settings is also recommended.

Cleaning solution

A cleaning solution is used as a cleaning agent and is as important as the frequency and power of ultrasonic waves. Most of the chemicals used fall into the weakly basic, alkaline, acidic and neutral categories. The liquid solution is provided in the form of a concentrated solution, so an appropriate liquid-to-water ratio is required to optimize the cleaning cycle. Manufacturers advise on dilution and cleaning temperatures.

A variety of cleaning solutions are formulated for different applications to protect material properties, save money and achieve optimum performance. One example is a weakly alkaline liquid solution, it comes in three types: 1) alkalescent General Purpose Cleanser 2) special cleanser containing Ammonia 3) special cleanser -- no Surfactant. The other is an alkaline liquid solution, there are two types: alkaline strong cleaning agent and non-silicate demulsification special cleaning agent. The third is a neutral cleanser, there are two types: a neutral cleanser for mild cleaning and a neutral general-purpose cleanser. Finally, the acidic liquid solution consists of three types: 1) special mild detergent 2) special powerful detergent 3) special demulsification detergent.

Many cleaning solutions on the market are formulated with non-toxic and biodegradable ingredients, making them environmentally friendly and easy to handle. Most solutions are water-based, so rust may be a problem, but you can solve it by adding a rust inhibitor.