Ultrasonic cleaning

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Ultrasonic cleaners, sometimes mistakenly called supersonic cleaners, are cleaning devices that use ultrasound (usually from 15-400 kHz) to clean delicate items.

They are often employed for cleaning of jewellery, lenses and other optical parts, coins, watches, dental and surgical instruments, fountain pens, industrial parts and electronic equipment. In everyday use such devices may be found in use in most jewellery workshops, watchmakers establishments, or in cellular phone repair workshops (where it could be used for cleaning a phone that has been exposed to enough moisture to hinder its operation).

In an ultrasonic cleaner, the object to be cleaned is placed in a chamber containing a suitable ultrasound conducting fluid (an aqueous or organic solvent, depending on the application). An ultrasound generating transducer is built into the chamber, or may be lowered into the fluid. It is electronically activated to produce ultrasonic waves in the fluid. The main mechanism of cleaning action is by energy released from the creation and collapse of microscopic cavitation bubbles, which break up and lift off dirt and contaminants from the surface to be cleaned.

Industrial ultrasonic cleaners are used in the automotive, sporting, printing, marine, medical, pharmaceutical, electroplating, engineering and weapons industries. Devices for home and hobby use are readily available, and may cost as little as US $60, as of November 2006.

[edit] Some suitable materials for ultrasonic cleaning:

(In approximate order of suitability)

• Stainless Steel
• Mild Steel
• Aluminium
• Copper
• Brass
• Other alloys
• Wood
• Plastics and Rubber
• Cloth

Ultrasonic transducers work by rapidly changing size when excited by an electrical signal. This creates a compression wave in the liquid of the tank. These compression waves actually ‘tear’ the liquid apart, leaving behind a ‘void’ or ‘partial vacuum bubble’. When these ‘bubbles’ (and there are many millions of them in an active ultrasonic tank) collapse, they collapse with enormous energy. You will remember from your high school physics that ‘nature abhors a vacuum’. When sufficient energy is built up in the ‘bubble’ or cavitation, the cavitation collapses violently. The energy released is breathtaking. A jet of plasma, which can reach temperatures measured in thousands of degrees, is ejected! This replaces your ‘elbow grease’. Different chemicals are used for different tasks, but milder chemicals than those traditionally used in many industries can be eliminated or greatly reduced with the introduction of ultrasonic technology into many and varied cleaning tasks. Ultrasonics are also used in many medical and dental techniques, industrial processes, as well as in industrial cleaning.

[edit] See also

• Acoustic cleaners
• Washing machine