Component Cleaning doesn’t have to be Caustic

Successful, effective and environmentally friendly cleaning of components can be achieved using an aqueous based system such as an ultrasonic bath.

Environmental issues have been in the spotlight for many years but they continue to grow in importance as we persist in causing harm to the atmosphere and o-zone layer. Although solvent emissions only account for a small percentage of waste that companies produce, these emissions can be almost completely cut out by using an ultrasonic cleaning system. So how does it work, why is it better than a solvent based system and how can it be incorporated?

Although it has been used in industry for over 20 years ultrasonic cleaning is now becoming the method of choice to replace solvent based systems. Ultrasonic cleaning is an aqueous based system that uses no solvents and produces far less hazardous waste than other alternatives which are available.

The process of ultrasonics uses high frequency sound waves in a liquid to create millions of microscopic bubbles. The sound waves are created by passing electrical current through a number of piezo electric transducers. As the current is passed through these transducers they become excited and vibrate, creating ultrasonic energy. This is then transferred into the tank creating bubbles. These bubbles are forced to expand by the sound waves until they reach a point where they cannot support their own density, causing them to implode: the phenomenon called cavitation. The following implosion creates huge pressures within the liquid as the surrounding fluid rushes in to fill the gap left by the bubble. This released energy creates a scrubbing action within the fluid, which has the ability to remove even the most tenacious substances off the surface of the any hard substrate or complex shaped item. Although extremes of pressure and temperature occur during the implosion the cleaning action is an extremely gentle process and has the facility to clean even small, delicate items without causing damage. It means that any area in contact with the fluid can be cleaned. This even applies to difficult to reach and unsighted areas such as boxed joints, hinges and internal channels. Ultrasonic cleaning will basically clean any surface the liquid comes into contact with once submerged within the tank.

In order to maximise the ultrasonic process a detergent is also required. These work in much the same way as a household detergent by aiding in the loosening of surface contaminants. The detergent also intensifies the ultrasonic power. No detergents used within an ultrasonic system are solvent based meaning they produce no harmful waste and are completely bio-degradable. The tank will not emit any harmful emissions and the cleaning solution can be drained away without any special treatments being required. Ultrasonic detergents are also far cheaper than their solvent counterparts, meaning businesses should see a reduction in running costs almost instantaneously.

One of the great benefits of ultrasonic cleaning is its versatility. It can be incorporated into existing processes with great ease and for relatively minimal outlay. If cleaning tanks already exist they can be made ultrasonic by the simple introduction of a series of submersible transducers and generators. In laymen's terms, a submersible transducer is a sealed box which is immersed into the cleaning tank. Within this box are a number of piezo electric transducers. These transducers are powered by an external generator. The submersible transducer will emit sound waves into the fluid causing cavitation to occur.

Now that the digital age is upon us technology is moving forward at a great rate of knots. This technology is now being incorporated into ultrasonic cleaning systems. Unlike before where systems required step by step operation, technology now means that it can be a fully automated procedure. Advancements have meant systems can now incorporate a wash tank, rinse tank and a drying system into one fully automated unit, in some cases requiring no operator to load to unload the items.

Benefits from using ultrasonic cleaning over other methods include a reduction in running costs due to the cycle times required to clean items to the same level as alternative methods. Cycles are typically around ten minutes meaning throughput can be increased while overall quality is also improved. Coupled with this is the extended life of the detergents which can outlast solvents meaning consumption will drop leading to a reduction in costs.

As featured in Factory Equipment, Jan 2006 issue