Applications of Ultrasonics

APPLICATIONS OF ULTRASONICS

1) Ultrasonic drilling and cutting:

Ultrasonics are used for making holes in very hard materials such as glass, diamond etc., When ultrasonics are passed through these materials it creates air bubbles. This air bubbles collapses within a short span of time, thereby releasing a large amount of pressure and temperature which are used for cutting and drilling.

2) Ultrasonic welding and soldering:

Some materials cannot be welded at high temperature. In such cases the welding can be done at room temperature using ultrasonics and is called as cold welding. It is also used for soldering aluminium foil condensers, aluminium wires etc., without any flux.

3) Ultrasonic cleaning and drying:

Ultrasonics can also be employed in cleaning motors, aeroplanes, electronic assemblies etc., Here the cleaning tank is partially filled with detergent solutions. The article to be cleaned is placed in this tank. The ultrasonics are imparted to the solution, which accelerates the molecules in the liquid to move with high kinetic energy. This particles strikes the dirt particles and clean it. Further it can also be dried using acoustic drier.

4) Coagulation:

They are used in coagulation (changing from liquid phase to a semi solid phase) and crystallisation, hence can be used in the manufacturing of paints, polishes etc.

5) In industries:

ultrasonics are used to remove air bubbles in the liquid metals and convert them into fused metals. Low frequency ultrasonics are used in sorting paper fibers from the paper pulp. They are also used to increase the sensitivity of colour in photographs by dispersion of dye in the emulsion.

6) Sound Signalling:

High frequency ultrasonics can be sent out in the form of beams, which spreads in all directions as spherical wavefronts and passes the signals from one place to another. Thus the signals can be used as an identification for landing the ships. In military field the method of sound signalling can used to identify our warships.

7) Depth sounding:

Echo sounding is the principle used to find the depth of the sea. A beam of ultrasonics is directed towards the bottom of the sea and the reflected signal is received as shown in Fig. 5.10.

The time interval between the transmitted and received signal is noted and let it be 't'. If 'v' is the velocity of the ultrasonics, then

Velocity = Distance travelled / Time taken

From Fig.5.12, we can write

 v  = [PR+ RQ]  / t = 2RO (approx) / t

RO = Depth of sea = vt / 2

The depth of the sea can be directly calibrated using the instrument called as Fathometer (or) Echometer.

NOTE: Using the same principle, ultrasonics are also used in sound navigation purpose (SONAR).