UL 4 - Syllabus

< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
Introduction
Learning Objectives
On completion of this topic you will be able to understand
1. Application of ultrasonic waves in various fields e.g., engineering, medical, metallurgical,
physical, chemical, etc
2. SONAR
Ultrasonic waves have a wide range of applications in various fields e.g., engineering,
medical, metallurgical, physical, chemical, etc. Some of their uses are discussed in below
Ultrasonic Drilling and Cutting
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< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
Ultrasonic are used for making holes in very hard materials such as glass, diamond etc.,
When ultrasonic are passed through these materials it creates air bubbles. This air bubbles
collapses within short span of time, thereby a larger amount of pressure and temperature which are
used for cutting and drilling.
Ultrasonic Cleaning
Ultrasonic cleaning is an environmentally friendly alternative for the cleaning of
continuous materials, such as wire and cable, tape or tubes. The effect of the cavitations generated
by the ultrasonic power removes lubrication residues like oil or grease, soaps, stearates or dust.
In addition, the pollution particles are dispersed into the cleaning liquid. By that, a new adhesion to
the material to be cleaned is avoided and the particles are flushed away.
By the use of an innovative proprietary ultrasonic technology, very strong cavitations
fields are generated, so that very good cleaning results at high line speeds can be accomplished. As
the cleaning effect is based on the physical cleaning effects of the ultrasound, it can be used for
any ferrous and non-ferrous material, e.g. stainless steel, copper, aluminum, but also plastic or
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< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
glass. Most commonly ultrasonic cleaning machines are used for drawn wire, e.g. before cladding
or extrusion. By the concentration of the ultrasonic power to a low liquid volume, a very compact
design can be realized. This can be easily integrated into existing or new production lines, e.g.
directly after drawing or reel payoff.
Cavitation is an effect that is generated in liquids by intensive ultrasonic waves. The
resulting pressure waves create vacuum bubbles that implode subsequently. As a result of these
implosions, very high pressures and temperatures occur in combination with liquid jets of up to
1000km/h. At surfaces, these mechanical forces loosen impurities, so they can be flushed away
with the cleaning liquid. For an intensive cavitation - and by that for an intensive cleaning - high
amplitudes and a low ultrasonic frequency (approx. 20 kHz) are needed. Ultrasonic Cleaners are
used in various industries for a number of applications.
Some of the Ultrasonic Cleaning applications are:
1. Ultrasonic Cleaners in Scientific Labs
Lab Glassware, Test Tubes, Pipettes, Optical & Contact Lenses, Eyeglass Frames,
Scientific Instruments, Components
2.Ultrasonic Cleaners in Industrial Manufacturing
Switches, Relays & Motors, Gears, Precision Bearings, Metal & Plastic Parts, Assemblies
3. Ultrasonic Cleaners in Electronics Manufacturing
PC Boards, SMDs, Ceramic Substrates, Capacitors, Lapping Heads, Packaging Components,
Quartz Crystals, High-resolution Glass Plates
4. Ultrasonic Cleaners in Medical & Dental Labs
Cannulae, Syringe Parts, Surgical Instruments, Blood Oxygenators, Dental Instruments,
Burs, Dentures, Caps, Plates
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< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
5. Ultrasonic Cleaners in Jewelry Manufacturing
Watches, Clock Movements, Precious Metals & Gemstones, Intricate Settings, Chains,
Charms, Coins
Ultrasonic Welding Applications
INDUSTRY:
AUTOMOTIVE
(Stranded Cu lead to Ni plated brass terminal)
INDUSTRY: APPLIANCE
(Al disk to Al heating element)
Ultrasonic metal-welding is an advanced technical process for combining nonferrous
metals, stranded wire and many metal-alloys. It is a cold-phase friction welding technique; there is
no melting, no high-temperature buildup. The surfaces being joined are subjected to highfrequency mechanical oscillations while being rubbed together under pressure. The molecules of
the surfaces begin to swirl and intermingle with one another, creating a firm and lasting bond.
Improvements in quality and efficiency, reduced energy requirements and positive environmental
factors are the decisive advantages of this new technology.
SONAR
The word Sonar is an American term first used in World War II, it is an acronym for
SOund, NAvigation and Ranging. The British also call Sonar, ASDICS, which stands for AntiSubmarine Detection Investigation Committee. Later developments of Sonar included the echo
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< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
sounder, or depth detector, rapid-scanning Sonar, side-scan Sonar, and WPESS (withinpulseectronic-sector-scanning) Sonar.
Sonar is a system that uses transmitted and reflected underwater sound waves to detect and
locate submerged objects or measure the distances underwater. It has been used for submarine and
mine detection, depth detection, commercial fishing, diving safety and communication at sea. The
Sonar device will send out a subsurface sound wave and then listens for returning echoes, the
sound data is relayed to the human operators by a loudspeaker or by being displayed on a monitor.
As early as 1822, Daniel Colloden used an underwater bell to calculate the speed of sound
underwater in Lake Geneva, Switzerland. This early research led to the invention of dedicated
sonar devices by other inventors. Lewis Nixon invented the very first Sonar type listening device
in 1906, as a way of detecting icebergs. Interest in Sonar was increased during World War I when
there was a need to be able to detect submarines.
In 1915, Paul Langévin invented the first sonar type device for detecting submarines called
an "echo location to detect submarines" using the piezoelectric properties of the quartz. He was too
late to help very much with the war effort; however, Langévin's work heavily influenced future
sonar designs.
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< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
The first Sonar devices were passive listening devices - no signals were sent out. By 1918,
both Britain and the U.S had built active systems, in active Sonar signals are both sent out and then
received back. Acoustic communication systems are Sonar devices where there is both a sound
wave projector and receiver on both sides of the signal path. The invention of the acoustic
transducer and efficient acoustic projectors made more advanced forms of Sonar possible. There
are two major kinds of sonar, active and passive.
Active sonar creates a pulse of sound, often called a "ping", and then listens for reflections
of the pulse. The pulse may be at constant frequency or a chirp of changing frequency. If a chirp,
the receiver correlates the frequency of the reflections to the known chirp. The resultant processing
gain allows the receiver to derive the same information as if a much shorter pulse of the same total
power were emitted. In general, long-distance active sonars use lower frequencies. The lowest
have a bass "BAH-WONG" sound. To measure the distance to an object, one measures the time
from emission of a pulse to reception.
Passive sonars listen without transmitting. They are usually military (although a few are
scientific). Passive sonar systems usually have large sonic databases. A computer system
frequently uses these databases to identify classes of ships, actions (i.e. the speed of a ship, or the
type of weapon released), and even particular ships.
Basic concept of SONAR
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< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
Sonar is based on the echo-sounding technique of ultrasound. When an ultrasonic wave is
transmitted through water, it is reflected by the objects in the water and will produce an echo
signal. By noting the time interval between the generation of the ultrasonic pulse and the reception
of the echo signal (t), the depth of the object can be easily calculated. Since the ultrasonic velocity
“v’ in sea water is known, the depth of sea is calculated as follows
Depth of sea (distance between surface and bottom of the sea) = vt/2
The same procedure is also used to find the distance of submarine or iceberg from the
surface of the sea and the distance between two ships in the sea.
Check your understanding
1. What are the applications of ultrasonic in industry?
2. What is meant by cavitation?
3. What is SONAR
4. What are the applications of SONAR?
Check the correct answers on page 8.
Summary
On completion of this topic you have learned
1. Ultrasonic waves have a wide range of applications in various fields e.g., engineering,
medical, metallurgical, physical, chemical, etc.
2. SONAR is an acronym for “Sound Navigation and Ranging”. The principle of SONAR is
based on the echo sounding technique of ultrasonic. It is the acoustical technique for
locating the objects like submarine or iceberg in sea, by transmitting a high frequency
sound pulse and receiving it after reflection from that object.
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< Engineering Physics-I >
< Ultrasonics – Applications of Ultrasonics >
Suggested Reading
1. “Engineering Physics” by Dr.P.K.Palanisamy, Scitech Publications (India) pvt, Ltd, Chennai
2. “Engineering Physics” by Dr.G.SenthilKumar, VRB Publishers Pvt Ltd, Chennai.
Answers to CYU.
1. Ultrasonics are used in cutting, drilling, welding, soldering etc
2.
Cavitation is the processes of creation and collapse of bubbles, due to the principle of
negative local pressure created inside the bubble.
3. SONAR is an acronym for “Sound Navigation and Ranging”.
4. SONAR is used to (i) find the depth of sea (ii) guide the submarine or ships in seas,
and (iii) locate the shoal of fish
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