ULTRASOUNDS

Ultrasound washing

The ultrasounds are high-frequency sounds which cannot be heard by the human ear. When a high ultrasound energy is plunged in a cleansing solution, little bubbles implode with a very high force. The pulsing action of these bubbles is called cavitation. It removes all the contaminations on the object immersed in the cleansing solution. The cavitation works on all the areas of the piece even the more recessed ones, that is to say, on all the areas which can be reached by the cleansing solution. In this way, also the assembled parts can be completely cleaned without dismantling them.

How do the ultrasounds come up ?

Sound can be produced in two different ways: - mechanically, for example through the excitation of an column of air or by the vibration of a cord; - electrically, thanks to an oscilloscope, an amplifier or a loudspeaker In both the cases, the air around is put into an oscillating movement and the sound signal is transmitted to the receptor.

Can we hear the ultrasounds ?

As we know, man cannot perceive every single sound. Indeed he can only hear the sounds whose frequency is between 16 and 16.000 Hz. On the contrary, for ultrasounds we intend the sound produced by vibrations between 18.000 Hz and 500 Khz.

When have ultrasounds been discovered?

The ultrasounds were already known as a physic quantity on the second half of the 19th century. In any case, they could be produced only mechanically. In 1880 the brothers Curie discovered the features owned by some metals to transform the electric energy in mechanical vibrations. The piezoelectric was born. Such discoveries could not be used for the following 40 years. Only in the 1920's the ultrasounds found a practical usage. Indeed a device for the location through ultra-sounds was developed; this device will be used on the submarines. This instruments worked through principles which are still valid today: high-frequency oscillations produced electrically, transformation of ultrasounds through a piezoelectric effect and use of high-frequency vibrations to measure the distance of an obstacle through reflection. From 1945 on, further developments in the field of electric circuits of commutation and of oscillation converters, opened the way to the ultrasounds on an industrial level.