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Файл:Materials Processing Technology Part 2. Coursebook
.pdf
3) Since the complete dehydration of 95 per cent alcohol requires the use of
azeotropes and metallic magnesium, it ___________ be further concentrated by
distillation.
4) Some astronomical physicists have stated that he universe ____________
expand indefinitely.
5) Astronauts _____________ control the space shuttle manually if the computer
navigation system failed.
6) This system clearly shows that hormones _____________ exert their
physiological effects by altering the specificity of enzymes.
7) We _________________ halt the ‘greenhouse effect’ if we continue to burn
fossil fuels at the present rate.
_____8 Choose the correct modal auxiliary verb to be used with a passive or
active verb.
1) The diameter reduction can/ may be achieved if one die is limited, but several
dies in series may/can be used
to get the desired reduction.
2) Open die forgings can/may be worked into shapes which include discs, hubs,
blocks, and some custom shapes.
3) Depending on the size and complexity of the part, the hammer can/may be
dropped multiple times in quick succession.
4) The lubricant may/can allow for a higher production rate, which will also
depend on the material thickness and number of roll stations.
5) The shape and size of the roller die can / may be unique to that station, or
several identical roller dies may/can
be used in different positions.
6) To supply the current, it is necessary to use a transformer. The latter can /
must be switched on to strike the arc.
7) To join the workpieces the electrode holder should/may contain an electrode
rod. When the arc is struck the electrode can/ must brush against the workpiece
at 80º to its surface. The current must/ may be at least 60A and for thicker
workpieces it may/must be 250 A or more.
8) One should / may not leave the electrode too long in the same position because
it will become attached to the workpiece. The electrode must/ can be moved
across the joint continuously backwards in a straight line.
9) In order to protect yourself you must/ should always follow certain safety
rules.
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10) Arc welding processes may/should be manual, semi-automatic, or fully
automated.
11) The welding process should / may lead to drastic changes in the microstructure with accompanying effects on the mechanical properties.
12) You may/ must never stand in the way of the cutting laser beam.
13) A continuous or pulsed laser beam may/must be used depending upon the
application.
14) By increasing the beam current and the accelerating voltage, the beam power
can/should be increased to practically any desired value.
15) Flaw signal reflects from defect and enters piezoelectric transducer. This
may/can be observed on the electron-ray tube.
SPEAKING
____1 Choose one of the two topics to give a 5-10 minute presentation to the
members of your group:
a) Plasma applications.
To find information on the topic go to the website Wikipedia at
https://en.wikipedia.org/wiki/Plasma_%28physics%29.
b) Industrial plasmas.
To find information on the given topic go to the website Wikipedia at
https://en.wikipedia.org/wiki/Plasma_%28physics%29.
If necessary, you can use additional resources provided in the above
mentioned site.
42
Unit 4
ceramic matrix composites ruby piezo-ceramics glass ceramics
Quartz ferrite
diamonds technical ceramics alumina PCD sapphire CVD silicon
carbide
The time spent on ultrasonic machine depends on:
- the frequency of the vibrating tool,
- the size of grains of the abrasive slurry,
- the rigidity and the viscosity as well.
The grains used in the abrasive fluid are:
- boron carbide or
- silicon carbide.
The used abrasive can be carried away easily if the viscosity of the slurry
fluid is less.
Ultrasonic Machining
Ultrasonic machining, also known as Ultrasonic impact grinding, is an
operation that involves a vibrating tool fluctuating the ultrasonic frequencies in
order to remove the material from the work piece. Ultrasonic machining is an
abrasive process which can create any material into hard and brittle form with the
help of its vibrating tool and the indirect passage of abrasive particles towards the
work piece.
Ultrasonic Machining Process
The tool present in the machine for cutting the materials is made from a
soft material, such as soft steels and nickel, as compared to the work piece. When
the tool vibrates, the abrasive slurry (liquid) is added which contains abrasive
grains and particles. The abrasive slurry is added till the work piece interacts with
the grains. Due to the particles of liquid added, the work brittleness of the work
piece abrades the surface, meanwhile the tool deforms gradually.
This method is the best choice for working with hard materials, which
include:
Working Principle of Ultrasonic Machining:
The time spent on ultrasonic machine entirely depends on the frequency
of the vibrating tool. It also depends on the size of grains of the abrasive slurry,
43
the rigidity and the viscosity as well. The grains used in the abrasive fluid are
usually boron carbide or silicon carbide as they are more rigid than others. The
used abrasive can be carried away easily if the viscosity of the slurry fluid is less.
Ultrasonic machining is changing the manufacturing industries with its
superlative performance. The main reason why this machining process is used in
the manufacturing area is because it evolves less heat. All the operations done
with the ultrasonic machining method are cost effective and best in results.
Advantages of the process:
Machined all sorts of hard materials
Produces fine finished and structured results
Produces less heat
Various hole cut shapes due to vibratory motion of the tool
Disadvantages:
Requires a higher degree of integrity and skills
No certified record of radiography
Unnecessary large grain sizes causes defects
Additional repairs might be required due to spurious signs and
misunderstanding of the process
Ultrasonic machines are the future of machining which is used all over the
world for creating hard and brittle forms of materials for the industrial uses. A lot
of operations can be performed with the ultrasonic machine which can benefit
the industrialists in a variety of ways. The advanced technology creates solution
which helps in opening up the market opportunities and has made things easier.
READING Ultrasonic machining: components, performance, applications,
advantages and limitations
→ Read Study Skill
___1 Read the texts from Unit 4 of the Textbook.
___2 Survey the texts from Section 10.1 and underline the information
which answers the questions.
1) What is the basic principle of ultrasonic machining?
2) What are the components of the ultrasonic machining system?
44
3) What types of materials are used for a magnetostrictor, and what design
machining removes frequency abrasive voltage current grain
magnetic field brittle magnetostrictive cylinder ferromagnetic
oscillator mechanical transducer piezoelectric electrodes
oscillation vibrations slurry vibrating mill
characteristics should be applied to obtain its good efficiency?
4) What are the means for achieving the amplitude amplification?
5) What are the main drawbacks of magnetostrictive transducers compared to
piezoelectric transformers?
6) What are the components of the abrasive slurry?
7) What does the performance of ultrasonic machining depend on?
8) What do the rate of material removal and hence the machinability of ultrasonic
machining depend on?
9) What role plays the amplitude of the tool oscillation in the material removal
process?
10) What are the factors affecting the machining rate?
11) Which of the ultrasonic machining process variables has the greatest effect on
the material removal?
12) What are the factors affecting the machining rate?
13) What are the characteristics of drilling and coring process?
14) What are the advantages of micro-ultrasonic machining?
15) Which factors affect the advantages and limitations of ultrasonic machining?
VOCABULARY DEVELOPMENT
____1 Complete the following sentences with the words from the box.
Ultrasonic machining is a subtraction manufacturing process that
_________1) material from the surface of a part through high frequency, low
amplitude _________2) of a tool against the material surface in the presence of
fine abrasive particles. The fine _________3) grains are mixed with water to
form a __________4) that is distributed across the part and the tip of the tool.
Typical _______5) sizes of the abrasive material range from 100 to 1000, where
smaller grains produce smoother surface finishes.
Ultrasonic vibration machining is typically used on _________6) materials
as well as materials with a high hardness.
An ultrasonically __________7) consists of two major components, an
electroacoustic __________8) and a sonotrode attached to an electronic control
unit with a cable. An electronic __________9) in the control unit produces an
45
alternating current oscillating at a high _________10). The transducer converts
1. The magnetostrictor
k) the frequency of tool vibration, static
pressure, the size of the machined area,
and the abrasive and workpiece
material.
2. The magnetostrictor
g) the overcut (oversize) produced
during drilling of holes.
3. Materials having high
magnetostrictive alongation
j) are recommended to be used for a
magnetostrictor.
4. The main drawbacks of the
magnetostrictive transducer
f) vibrating a brittle tool as a graphite
or glass into the workpiece at an
ultrasonic frequency and relatively low
vibration amplitude.
5. The performance of ultrasonic
machining depends on
a) the manner in which the slurry is fed
to the cutting zone.
6. The rate of material removal depends
on
d) the machining rate in ultrasonic
machining.
7. Glass has a higher machinability
than
h) a metal of similar hardness.
8. The form accuracy of machined parts
suffers from
b) shallow cavities cut in hard and
brittle materials having a surface area
less than 1000 mm3.
9. Ultrasonic machining should be
applied for
l) the factors which cause oversize,
conicity, and out-of-roundness.
10. Ultrasonic polishing occurs by
e) are the high losses encountered, the
low efficiency, the consequent heat up,
and the need for cooling.
the oscillating current to a __________11) vibration.
Two types of transducers have been used in ultrasonic _________12) , either
piezoelectric or magnetostrictive.
The piezoelectric transducer consists of a piece of ________13) ceramic, such
as barium titanate, with two metal electrodes plated on its surface. The alternating
_________14) from the control unit applied to the __________15) causes the
piezoelectric element to bend back and forth slightly, causing it to vibrate.
The magnetostrictive transducer consists of a cylinder of __________16)
material such as steel inside a coil of wire. Magnetostriction is an effect which
causes a material to change shape slightly when a __________17) through it
changes. The alternating _________18) from the control unit, applied to the coil,
creates an alternating magnetic field in the ___________19) which makes it
change shape slightly with each _________20), causing it to vibrate.
_____ 2 Study the paragraphs 10.1.1 – 10.1.4 to find the characteristics and
applications which best describe the ultrasonic machining process.
46
11. The ultrasonic process accuracy is
measured through
c) has a high-frequency winding wound
on its core and a special polarizing
winding around an armature.
12. The surface finish is closely related
to
i) is energized at the ultrasonic
frequency and produces smallamplitude vibrations.
STUDY SKILL The prepositions at, on, and in
At, on, and in are the three most commonly used prepositions.
The Preposition at
The preposition at commonly refers to a position or a location that implies a
function.
It represents one dimension (i.e. a point or goal).
Position of time, place, or measure:
1. The rocket was launched at 5:30 am.
2. The neutron is at the centre of the atom.
3. Sulfur melts at a temperature of 113º C. (at + a measurement noun is a
common
structure).
Other uses:
at the age of
at the beginning
at the bottom
at the end
at the level
at a node
at a point
at a stage
at the surface
at the terminal
at the top
Location that implies function:
1. The professor is at the lab today. (The professor may be inside or outside
the actual
lab. This sentence indicates that the professor is doing the things one
normally does in a lab).
2. The assistant is at the post office. (i.e., the assistant is doing what one
normally does at a post office, such as buying stamps, mailing a letter, or
picking up a package).
_____3 The link below will help you use Quizlet to enrich your vocabulary
on the topic
Ultrasonic vibration machining:
https://quizlet.com/400031660/ultrasonic-vibration-machining-flashcards/?new
47
Other uses:
at the airport
at the bank
at court
at the garage
at home
at the hospital
at school
at the store
at work
The Preposition on
The preposition on commonly refers to a line or a surface. It represents one
dimension
(a line) or two dimensions (i.e. a surface or a plane).
Line:
1. Building on a fault line is not advised.
2. 32º F is 0º on the Centigrade scale.
Other uses:
on the average
on the edge
on the gauge
on a line
on a side
Surface:
1. Check the reading on the barometer.
2. Oxides on the surface prevent the metal from corroding.
Other uses:
on the affected
area
on the face (of)
on a plane
on a side
The Preposition in
The preposition in commonly refers to containment or mode. It represents
three dimensions (i.e. a cube or containment in three-dimensional space).
Containment:
1. The sample is in the test tube.
2. Ozone occurs in the upper atmosphere (a limited area).
3. The program failed because of bugs in the system.
Other uses:
in the body
in this case
in the circuit
in a liquid
in a manometer
in the ocean
in a plane
in this problem
in a position
in a range
in a situation
in a tank
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Mode (measure, direction, action):
1. The box is two feet in length.
2. The lava flowed in a westward direction.
3. The blood is constantly in motion.
4. The error occurred in collecting the data.
STUDY SKILL The prepositions of time (1)
The preposition at denotes a specific time,
on indicates a day or date, and
in indicates a month, season, year, century, etc.
There are prepositions of time that indicate 1) range, 2) starting point, 3)
endpoint or limit, and 4) time period.
Range: from, to, through, between, and until
The range prepositions indicate a range of time which begins with the
object of from and ends with the object of to, through, or until; or which
is described by between and and:
The comet was visible from March to May.
The comet was visible from March until May.
______1 Add at, on, or in to the blanks.
1. The pressure ____ the bottom of the deepest part of the Pacific Ocean is
16,380 pounds per square inch.
2. The planets _____ the solar system lie for the most part ____ a plane.
3. Some researchers claim to be ____ the verge of discovering the cause of some
forms of the disease.
4. The depth of the ocean is 2.5 miles ____ the average.
5. Large-scale cooling towers are usually constructed ___ the site.
6. Enzymes bind the substrates ___ very specific locations.
7. A force acting ____ a body produces an acceleration ____ the direction of the
force.
8. The reading ____ a barometer indicates atmospheric pressure.
9. Hydrogen boils ____ a temperature of -252.87º C.
10. The specimen was mounted ____ a glass slide for microscopic analysis.
11. A human embryo is considered to be full term ____ forty weeks.
12. Craters ____ the surface of the moon were probably caused by falling
meteorites.
49
The comet was visible between March and May.
The comet was visible from March through May.
(To, until, and between suggest “up to the beginning of
May,” whereas
through means ‘up to the end of May.”
Until indicates that at the described time, the opposite action
took place.
Until can be used with a negative verb and indicates not a
range but a
starting point :
The comet was not visible until May. (first not visible, then visible)
Starting Point: since and for
Both since and for indicate the time at which something begins.
Since indicates the name of a time (e.g. Saturday, 1997, 3:00 p.m., his
childhood).
For indicates the period between the ‘name of the time’ and the reference
time (e.g. four days, 10 years, several hours, his entire life):
The antibiotic penicillin has been available since 1938.
The hydrogen fuel supply of the sun will last for another 5 billion years.
______2 Fill the blanks with from, to, through or between …and.
1. The Age of Mammals extends _____ 60 million years ago ____ the present.
2. The planet was visible ____ May _____ the whole month of June.
3. The reaction continued ____ all the aluminum was consumed.
4. The cyclotron is open to the public _____ 10 a.m. _____ 4 p.m. on weekdays.
5. The El Nino current, a massive ocean-atmosphere disturbance, had its greatest
impact ____ springn1982 ____ July 1983.
6. The greatest snowfall ever recorded, 193 cm in 24 hours, occurred in Colorado
_____ April 14 ______ April 15, 1921.
7. The experiment will begin in March and continue ______ the Arctic summer
_____ the first snowfall.
8. The average life span of a cat is _____ 10 _____ 12 years.
9. The sun’s output gradually declined ______ February 1980 _____August
1981, then began to rise again.
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