HERE YOU CAN LEARN ABOUT PATTERN

1. INDEX
Expt. No. Name of the Expt./ Assignment
01 Study of Casting Process
02 Study of Moulding Process
03 Study of Melting Furnace
04 Study of Special Casting Process
05 Study of Powder Metallurgy
06 Study of Joining Process – I
07 Study of Joining Process – II
08 Study of Plastics
09 Study of General Plastic Process.
10 JOB NO. 1
JOB NO. 2
JOB NO. 2

2. EXPERIMENT NO. : 1
AIM : Study of Casting Process.
Introduction :
Casting is the one of the oldest manufacturing process and even today is the
first step in manufacturing most products. In this process the material is first liquefied
by properly heating it in a suitable furnace. Then the liquid is poured into a previously
prepared mould cavity, where it is allowed to solidify subsequently, the product is
taken out of the mould cavity trimaned and cleaned to shape.
It is clear from the definition of process that a successful casting operation
needs a knowledge in the following areas :
i) Preparation of moulds and patterns (Use to make the mould)
ii) Melting and pouring of liquefied metal.
iii) Solidification and further cooling room temperature.
iv) Defects and inspection.
There are various of casting process depending among others on the material the
type of patterns and mould and pouring techniques before going into the details of there
process we shall discuss the basic common features among the various casting process in
the context of four area, we have just maintained.
The suitability of the casting operation for a given material depend upon :
i) The melting temp. of the job and the mould materials.
ii) The solubility and chemical reaction between the job and the mould
materials.
iii) The solubility of the atmosphere in the material at different temp. to be
encounted in the casting operation.
iv) The thermal properties such as conductivity and coefficient of linear
expansion of both the, mould and job material.
Importance :
Costing have several properties that clearly defines their sale modern
equipment used for mass production communications, power agriculture, construction
and in industry. Cast metal are required in various shaper and seizer and large
quantities of making machine and tool which in turn work to provide all the necessities
and comforts for life other metal shaping are of course necessarily to full fill a
tremendous range of needs. However certain advantage interested casting design and
metallurgical advantages and the casting processes itself make them superior over
other metals.
Pattern Making :
Patterns are required to make moulds. The mould is made by packing suitable
moulding material such as moulding sand around the pattern. When the pattern is with
drawn the imprint provides the mould cavity which is immediately filled with molten
metal to become casting.
A pattern may be defined as a full size model of the desired period. Casting
which when packed or embedded in a suitable moulding material produces a cavity
called mould. This mould whenfilled molten metal from the desired casting after
solidification of the molten metal. The pattern very closely confirm to the shape and
size of the desired casting except that it carries pattern allowances to compensate
metal shrinkage provides sufficient metal for mechanical surface and facilities
moulding. The process of making a pattern is known as pattern making.

3. Types of pattern :
The type pattern selected for particular casting depends upon the following
condition:
i) The shape and size of casting.
ii) The number of casting required
iii) The method of moulding employed.
The common type of pattern are discussed below :
i) Solid or single piece patterns :
A solid or single piece pattern as shown in fig. Has a compact form. It has no
joints parting or loose piece in its construct. It has usually one broad surface that
serves as a parting surface in the mould. This type of pattern is used for a limited
number of casting because most of moulding operations like parting surface
formation, calling of gating system withdrawal of pattern etc. is done by hand.
ii) Split Patterns :
The most of the patterns are not made in a single piece because of the
difficulties encounted in moulding them in order to eleminate this difficulty. Some
more patterns are made in two or more pieces. A pattern consisting of two pieces is
called a two piece split pattern as shown in figure. One half of the pattern rests in the
lower part of the moulding box, known as drag and the otherhalf in the upper part of
the moulding box known as cope. The line of separation of the parts is called casting
line or parting surface. Sometimes a pattern for complex casting is made in three
parts. Such a pattern is called as a multi-piece pattern. A three piece pattern requires a
moulding box with three parts the middle one being called as check.
Application :
The split patterns are commonly used for casting spindles cylinders steam
valve bodies water stop. Cocks and taps bearings small pulley and wheels.
iii) Match Plate Pattern :
The match plate patterns are used on machines for quantity production of
casting. A simple pattern or number of pattern may be mould on a match plate.
It consist of a flat metal or wooden plate to which patterns runners gates are
permanently fastened./ These plates are provided with holes on either end of fit in a
standard flask. When the match plate is lifted of the mould the pattern are withdrawn
and the gates and runners are completed in one operation.
IV) Loose piece pattern :
Some the pattern has to made with projection or over hanging parts. There
projection makes the removal of the pattern difficult. Therefore such projections are
made in loose piece and are fastened loosely to the main pattern by means of wooden
or wire dowel pins/ These pins taken out during the moulding operations. After
moulding the main pattern is withdrawn first and the loose piece is removed with the
help of lift.
V) Cope and drag Pattern :
When very large casting are to made the complete mould becomes to heavy to
be handled by a single operator. In order to this problem the cope and drag pattern is
used. It is nothing but two piece pattern split on convenient joint line one part is
moulded in a cope and the other part in a drag of the moulding box.

4. VI) The Gated Pattern :-
The gated pattern is used for limited production of small casting. It eliminates
hand cutting of gates and thus makes the moulding easy. If the group of pattern is to
be placed in one mould the gate pattern has a further function of holding the pattern in
proper positions with respect to each other.
VII) Sweep Pattern : -
A sweep pattern is used for symmetrical moulding. It is not considered as true
pattern when compared with other. A sweep is template of wood or other material
which has counter corresponding to the shaped and size of casting. It is related about
a central spindle. Figure shows curved sweep which may be used from part of the
mould for a large cast iron kettle. The Principle advantage of this pattern is that it
eliminates expensive pattern consumption.
VIII) Skelton Pattern :-
When a few and large sized casting are required it is not available to use a
large solid pattern of that size . In such cases a Skelton pattern in the hallow form
consisting of a wooden frame and strips. The strips shown in figure are used to form
the outside and inside of the frame when it is filled with sand. In mounting the frame is
set on a level sand bed with the flange down and is filled with sand. The pattern is
formed by smoking off the outside with strikes. A half flask is placed over it and the
surface of the sand pattern is dusted with parting sand. The flask is then ran med up
and lifted away after which the surface of sand pattern is scraped away and stricks are
used to form the inside of core before the frame is removed.
IX) Shell Pattern :-
The shell pattern is used largely for drainage fitting and pipe work. This type of
pattern is usually made of metal and pasted along the centre line. The two sections
being accurately doweled together . the short bend are usually moulded and cast
impairs. The shell pattern is a hallow construction like a shell. The out side shape is
used as a pattern to make the mould while the inside the core box for making cores.
X) Segmental Pattern :-
These patterns are used for prepare moulds of large circular casting, Avoiding
the use of solid pattern of the exact size. In Principle they work like a sweep but the
difference is that a sweep is given a continuous revolving motion.
XI) Follow Board Pattern :-
A follow board is used for solid pattern having an irregular parting line. It may
be used either single or multiple gated patterns. The pattern requiring the follow
boards are usually some what difficult to make as split pattern. The board is gated out
so that the pattern rests in it upon the parting line and this board then act as a
moulding board for the first mould operation.
XII) Lagged –Up – Pattern :-
When a pattern or core box is so large or of such a form that it cannot be made
economically form a solid piece or when such a method would result in a pattern of the
little strength or excessive weight. It is necessary use a lagged or sand pattern.
XIII) Left and Right Hand Pattern :-
Some patterns are required to be in pairs and when their form is such that they
cannot be reversed and have the centres of hubs, boxes etc. opposite and in line then
they must be made right and left hand pattern is required on legs for wood turning
lathe.

5. Example : Hangers for over head shaftings, Legs for bench, legs of paddle type
sewing machine, brackets for luggage racks in the railway carriages etc.
PATTERN MATERIALS :-
The common materials of which the pattern are made are follows :
1. Wood
2. Metals
3. Plaster
4. Plastics
5. Waxes
Factors affecting the selection of pattern material :
1. No. of casting to be made.
2. Method of moulding to be used, i.e. hand moulding or machine moulding
3. Type of casting method to be used
4. Degree of accuracy in dimensions and the quality of surface finish required on the
castings.
5. Design of casting.
PATTERN ALLOWANCES :-
A pattern is always made larger than the required size of the casting for several
reasons such as shrinkage, machining, distortion and rapping etc.
The following allowances are provided on a pattern:
1. Shrinkage allowance :
Most of the metal used in casting work contract during cooling from pouring
temp. to room temp. This contraction takes place in three forms. Viz. Liquid
contraction, Solid contraction, Solidifying contraction.
The first two are compensated by gates and risers and the last one by
providing adequate allowances in the pattern. The amount of contraction varies with
different metals and therefore their corresponding allowances also differ. The
prominent factors which influences the metal contraction are the following.
i. Pouring temp. of the molten metal.
ii. Design and dimension of casting.
iii. Moulding method.
iv. Type mould material.
v. Mould resistance to shrinkage of metal.
vi. The metal of which the casting is to be made
The contraction of metal is always volumetric but the contraction allowances
are always expressed as linear measures.
Machining Allowance :-
A casting may required machining all over or on certain specified portion,
depending upon the assembly conditions and the operation it has to perform. Such
portions are marked duly in working drawings. The corresponding portions or surfaces
on the pattern are given adequate allowances, in addition to the shrinkage allowance,
by increasing the metal thickness there to compensate for the loss of metal due to
machining on these surfaces. The amount of this allowances depends upon the metal
of casting used, size, shape of casting and the degree of finish require on the
machined portion. Ferrous metals need more allowance.

6. Draft Allowance :-
All patterns are given slight taper on all vertical surfaces, i.e. the surfaces
parallel to the direction of their withdrawal from the mould. This taper is known as draft
or draft allowances. It can be expressed either in degree or in terms of linear
measures.
Rapping or Shake allowance :-
When pattern is to be withdrawn from the mould, it is first rapped or chucken
by striking over it from side to side, so that it surface may be free from the adjoining
sand wall of the mould. As a result of this the size of mould cavity increases a little and
negative allowances is to be provided in the pattern to compensate the same.
Distortion Allowance :-
The tendency of distortion is not common in all the casting. Only casting which
have an irregular shape and some such design that the contraction is not uniform
through out will distort on cooling on account of the setting up of thermal stresses in
them. Such an effect can be easily seen in some dome shaped or U shaped casting, to
eliminate this defect on opposite distortion is provided in the pattern so that the effect
is neutralized and the correct casting is obtained.
Pattern Colour Code :-
There is no universally accepted standard for the representation of different
type of surfaces by different colurs. The practice varies with different countries and
sometimes with different manufactures in the same country. The following practice will
serve as useful guide both for pattern and core boxes.
1. Red : Surfaces to be machined.
2. Black : Surfaces to be un machined.
3. Yellow : Core prints
4. Red strips on yellow base – seats for loose pieces.
5. Black strips on yellow base – stop offs.
6. Clear or no colour – parting surfaces.

7. EXPERIMENT NO. : 2
AIM : Study of moulding processes.
Types of moulds :
Methods of sand mould may be classified according to type of sand use for
preparing the mould the moisture content of the sample.
1. Green Sand Mould :
Green sand moulds are prepared with natural moulding sand or with mixtures
of silica sand, bonding clay and water. To make the green sand mould the sand must
be properly tempered before it can be used. If the sand is to dry additional water is
added, if too wet dry sand is added until it has the proper temper. To check the sand
for proper temper a handful is grasped in the fist. The pressure is released and sand
is broken in two section. The section of sand should retain their shapes and edges of
the break should be sharp.
The surface of the mould which comes in contact with molten metal forms the
most important part in green sand mould.
2. Dry Sand Mould :-
The moulding process involved in making dry sand moulds are similar to those
employed in green sand moulding except that the different sand mixture is used and all
parts of the mould are dried in a oven before being reassembled for casting.
The sand used for dry sand moulds depends upon added binding material such
as floor, resin, molasses or clay. The materials are thoroughly mixed and tempered
with a thin clay water.
Metal flask must be used for dry sand mould to with stand the heat in the oven.
Before drying the inside surfaces of a dry sand mould are coated with wet blacking , a
mixture of carbon black and water with a small addition of a gum.
Dry sand moulds are often used for large work such as engine cylinders,
engine blocks, rolls for rolling mills etc.
3. Skin dried mould :-
This is a process that dries the mixture from the surface layer of the rammed
sand to depth of about 25 mm or more by using gas torch. It has the advantage of
both green sand and dry sand moulding to a certain extent. Since the time required
for drying is less than in the case of dry sand. The method is less expensive. Skin dry
is particularly adopted to very large moulds all to work which required accurate details.
Loam mould :
Loam is clay and sand mixed with water to form a thin plastic mixture from
which moulds are made. The Loam must be sufficiently adhesive, so that it can cling to
vertical surfaces. Loam moulds always require serial provisions, to secure adequate
ventilation.
Moulding sand composition :-
Main constituents of moulding sand are :
1. Silica sand
2. Binder

8. 3. Addictive
4. Water
1. Silica Sand :-
Which do not passes the clay content and need addition of suitable binders to
make them usable for foundry work. When added with other constituent like binders
and addictives then it is known as Synthetic sand.
2. Binders :-
The purpose of adding a binder to moulding sand is to impart a sufficient
strength and cohesiveness so as to enable it to retain its shape after the mould has
been rammed and the pattern withdrawn. The common binders are :
i) Organic Binders : a) Dextrin b) Molasses c) Linseed oil d) Cereal Binders
e) Pitch f) Resins
ii) Inorganic Binders : In inorganic group common binders are clay, sodium silicate and
Portland cement.
3. Additives :-
Additives are those which are added to the moulding sand to improve upon
some of its existing properties or to impart certain new properties to it. They are :
i) Coal Dust
ii) Sea Coal
iii) Cereals or corn flour
iv) Silica flour
v) Wood flour
vi) Pitch
vii) Dextrin and molasses
viii) Fuel oil
4. Water :
For getting required strength and bond suitable quantity of water is added to
the sand along with clay. This quantity of water varies from 2 to 8 percent according to
different requirements. The water content present in the sand mass is partly is mixed
form called pore water and partly in free state know as free water.
Properties of moulding sand :-
Proper moulding sand must have following six properties :
i) Porosity :
ii) Flowability
iii) Collapsability
iv) Adhesiveness
v) Cohesiveness or strength
vi) Refractoriness
Moulding Machines :-
Moulding machines performs two important functions. It packs the sand and
draws the pattern. Moulding machines are therefore classified according to

9. a) The method of computing moulding sand
b) The method of removing the pattern
In the machine moulding there are basically methods used for ramming the sand into
the moulding flask. They are :
i) Jolting
ii) Squeezing
iii) Sand – slinging
Core Making :
Core making consist of following operations :
i) Core sand preparations
ii) Core moulding
iii) Baking
iv) Core finishing
Types of core :-
i) Horizontal cores :
The common type of core, usually cylindrical inform and is laid horizontally at parting
line . The ends of core rest in the seats provided by the core prints on patterns.
ii) Vertical core :
Placed in vertical position both in cope and drag in two halves. Top and bottom of the
core are usually provided with taper.
iii) Balance Core :
When the casting have opening only at one side and only one core print is available
on the pattern, a balanced core is suitable.
iv) Hanging and cover core :
If the core hangs from the cope and does not have any support at the bottom of the
drag it is referred as a hanging core on the other hand if it has its support on drags, it is
called cover core.
Core Properties :
i) A strong enough to retain its shape without deforming
ii) Cores must be permeable to allow the core gases to escape easily.
iii) Core should be highly refractory in nature to withstand high temp. of the molten
metal.
iv) Must be sufficiently low in residual gases forming material to prevent excess
from entering the metal.
v) Must be stable with minimum contraction and expansion to make true form of
casting should be collapsible.

10. EXPERIMENT NO. : 3
AIM : Study of melting furnaces.
Types of furnaces :
The main types of furnaces used in foundries for melting of various varieties
ferrous and non-ferrous metals and alloys are as below.
Crucible Furnace :
These are the simplest of the all furnace used in foundries. They are used in
most of the small foundries where melting is not continuous and large variety of metals is
to be melted in small quantities. In these furnace the entire melting of the metal takes
place inside a melting pot called crucible. Which is made of clay and graphite. This
furnaces is classified in two groups as below :
a) Coke Fire Furnaces: These furnaces are generally installed in a formed pit and are used
for melting small quantities of ferrous metals. (Pig Iron) For producing iron casting and
also for non-ferrous metals, and alloys. They are provided with refractory lining inside and
chimney at top. Coke is used as a fuel. Both natural as well as artificial draft can be used.
Broken pieces of metal are placed in crucible.
b) Oil and Gas Fired Furnace : This furnace utilize oil or gas as a fuel. The mixture usually
enters tangentially and encircles the crucible while burning. The furnace essentially consist
of Steel shell, provided with refractory lining inside and proper passage for entry of fuel
mixture. The crucible is seated on a pad form at the bottom. A cover is provided at the top
to prevent heat losses.
Metal Pot Furnaces :
The alloy of aluminum, mg, antimony, zinc, lead, cadmium & tin can be melted in a
metal pot which is usually made of cast iron or steel. The metal container is preferred for
melting those alloys which have relatively low melting point.
The metal pot is supported by its rim in stationary furnace which is fired by gas or oil
fuel. The product of combustion are discharged through a flow and do not come in contact
with the metal.
Direct Arc Furnace :
It consist of a steel shell having a spherical bottom as shown in fig. The complete furnace is
mounted on a rollers, so that it can be tilted for pouring the melt in to the ladle. Three vertical
electrodes are suspended through the top through which three phase current is led into the
furnace. These electrodes can be raised up or lowered as desired.

11. High Frequency Electric Furnace :
This furnace consist of crucible surrounded by water cooled coil of copper tubing. This
coil also conducts, the high frequency current and acts as a primary winding. The metal
charge in crucible serves as a secondary winding. Thus the furnaces works on the principle of
a transformer. As the high frequency current is passed into the primary winding , EDDY
current are produced in the metal charge through induction. Thus the charge rapidly melted
and agitated. The furnace is usually of tilting type.
Cupola Furnace :
For melting of C.I. in foundry the cupola furnace is used.
Construction : It has construction in the form of hallow vertical cylinder made of strong M.S.
plates riveted or welded at seams. Welded joints are more common in modern practice. Such
cupola are further strengthen by providing the brick retaining rings at suitable height. The
bottom door of the shell can be in one piece hinged to a supporting leg, or in two pieces : each
piece hinged separately two opposite legs. Bottom door is supported by prop during
operation.
A wind chamber or wind belt as it is more commonly known, encircle the cupola shell
at a place little the bottom of the shell. These belt is connected to the furnace blower by
means of blast pipe. The amount of air required is forced in to the chamber by the blower.
Which enters the furnace through opening called tyres. Charging door is located as suitable
height. The top of the cupola is provided with a mesh screen and a sparked arrester. It is cone
shape construction.
Operation Of Cupola :
The different steps involved in cupola operation are :
1. Preparation of cupola :
First operation in-preparing cupola is to clean out slag and refused on the lining. The
bottom door are raised and held in this position by metal props. The bottom sand is induced
through the charging door.
2. Firing the cupola :
In firing cupola, a fire of kindling wood is ignited on the sand bottom. This should be
done 2.5 to 3 hours before the molten metal is required. The coke is added to level slightly
above the tyres and air blast is turned on at a blower than normal blowing rate to ignite the
cone. As soon as red spots begin to show over the top of the fuel bed, additional coke is
introduced into the cupola to reach a height of 700 to 800 mm. Above the upper row of
tuyers.
3. Charging the cupola :
As soon the coke bed is built up to the correct height and ignited normally uniformly
throught alternate tuyers of pig iron, Coke & flux are changed from the charging door until the
cupola is full. Suitable scrap is also added with the pig iron to control the chemical
composition of pig iron produced the weight of metal charge should be form 100 to 15% of the
hourly output of cupola. The Object of adding flux is to remove impurities in the iron.
4. Soking of Iron :
After the cupola is fully charged upto the charging door the charge should soak in the
heat for about 45 minutes.
5. Air Blast :
At the end of the soking period, full blast is turned on. Before turning of the blast, the
tuyre open & the tapping hole are kept closed. After the blast has been on for few minutes say
above 10 min., molten metal stress accumulating in the hearth.
6. Slagging & Tapping :
The first tapping can be made40 to 50 minutes after full air blast is turned on. During
this period, sufficient metal is collected in hearth above the sand bed. When slag accumulates

12. in well, the slag hole is opened and the slag is run off, preferably into a bogie for easy
removal.
7. Closing the cupola :
When the operation is over, the blast is shut off and top under the bottom door is
knocked down so that the bottom plates swing open. This enables cupola remains to drop on
to the floor on into a bucket. They are then quenched and removed from underneath the
cupola.
Cleaning Of Casting :
After proper solidification of casting the moulds are broken to obtain the casting. This
operation is called shake out operation. In manual operation mould dropped from height &
thus breaking the same to separate casting from it. Alternatively the sand may be broken by
striking against it through suitable means. The mechanical shake out consist of transferring
the mould to shake out machine in which the mould is dropped on to a vibrating screen which
provides a jarring action on the same & separate the casting & flask from the sand. Casting
and flask remain on screen either in a pit or on a moving but conveyor below the screen. The
sand is conveyed to the reconditioning plant and the casting removed from screen. The
casting so obtained is not a fully finished article asit. Carries risers, runners, gates, chills and
nails etc. attached to it. Also a lot of sand remains adhering to its surface in the form of core
etc. Such a through cleaning & finishing of casting is necessary before it can be brought to a
usable form. The various operation which are normally required to be performed after shake
ot are :
1. Removal of core dry sand cores.
2. Removal of gates and rises.
3. Removal of unwanted metal projections, fins, nails etc.
4. Removal of unwanted adhering sand of oxide, scale etc.
5. Repair of casting wherever possible.
6. Heat treatment of casting.
Inspection & Quality Control :
Inspection is an act of checking the acceptability of casting. After the asting have been
cleaned, they are inspected to check it they will performed. Specified function during service.
It broadly covers a large no. of methods & techniques used to check the quality of casting.
These method explained to chapter of this text, may be classified into fire categories.
1. Visual Inspection
2. Dimensional inspection
3. Mechanical testing
4. Flow direction by non destructive method.
5. Metallurgical inspection.
Defects In Casting :
Sand casting particularly, are subjected to contain details which in a well designed
casting are controllable by proper foundry. Technique but are not wholly preventable casting
defects are as follows.
1. Shifts : This an external defects in a casting causes due to core misplacement or
mismatching of top and bottom parts of the casting usually at a parting line.
2. Warpage : Warpage is unintentional & undersible deformation in a casting that occurs
during or after solidification. Due to different rates of solidification in different sections of
casting, stresses are setup in adjoining walls.

13. 3. Fin : A thin projection of method not intended as a part of the casting is called the fin. Fins
are occurs usually at parting of the mould.
4. Swell : A swell is an enlargement of mould carity by metal pressure, resulting in localized or
over all enlargement of the casting. This is called by improper or defective ramming of mould.
5. Blow holes : Blow holes are smooth, round holes appearing in the form of a cluster of a
large number of small holes are caused by excessive moisture in the sand or when
permeability of sand is low, sand grains are to fine, sand is rammed too ward or when venting
is unsufficient.
EXPERIMENT NO. : 4
AIM : Study of Special Casting Process.
Introduction :-
A large number developments have taken place in this field and various new moulding
& casting methods have been evolved to serve certain specific purpose. These new methods
have helped in one way or other in increasing production rate, effecting grater economy,
improving quality of casting, eliminating or minimizing the need of further machining, providing
better surfaces finish & may other such aspects. These methods are termed were as ‘special
casting methods’ for the reason that economic consideration prohibit their common use in
every foundry.
Investment Casting :
Precision investment casting or the lost wax process, though known since long, come
in practical during world war – II. The process is consist of preparing wax, plastic or frozen
mercury by pouring the same into a metal mould or die.
Steps involved in making investment casting
i) Die making
ii) Making wax pattern
iii) Assembling the wax pattern
iv) Investing
v) Removal of wax patterns
vi) Pouring & casting
vii) Cleaning & inspection
Centrifugal Casting :
This is process where the mould is rapidly about its central axis at metal is poured
into it, because of centrifugal force a continuous pressure will be acting on the metal as it
solidifies. The slag oxide & others inclusions being lighter get separated from the metal and
segregates forward the centre. The three main centrifugal casting are as follows :
i) True Centrifugal Castings
ii) Semi Centrifugal Castings
iii) Centrifusing
i) True Centrifugal Casting :

14. This is normally used for the making of hallow pipes, tubes, hallow bushes etc. which are
axis metric with concentric holes. Since the mutual is always pushed outward because of
the centrifugal force, no core needs to be used for the making of concentric hole. The axis of
rotation can be either horizontal, vertical or any angle in between. Very long pipes are
normally cast with horizontal axis where as short pieces in vertical axis. A normal centrifugal
machine used for making cast iron pipe in sand moulds as shown in fig. First moulding flask
is properly rammed with sand to confirm to the outer contour of the pipe to be made. Any
end details, such as the pipe to be made or flanged ends are obtained with the help of dry
sand cores located in the ends. Then the flask is dynamically balanced so as to reduce the
occurrence of undesirable vibrations during the casting processes. The finished flask is
mounted in between the rollers and the mould is rotated slowly. Now the molten metal in
requisite quantity is poured in to the mould through movable pouring basine. The amount of
metal poured determines the thickness of the pipe to be cast. After the pouring is complete,
the mould is rotated as its operational speed till it solidifies, to form requisite tubing. Then
the mould is replaced by a new mould machine and process continued. Water jackets are
provided around the mould for cooling.
Semi Centrifugal Casting :
Semi Centrifugal casting is used for jobs which are use for made complicated than
those possible in true centrifugal casting, but are axisymmetric in nature. It is no necessary
that these should have a central hole. Which is to obtained with the help of a core. Which is to
be obtained the moulds mode made of sand or metal are related above a vertical axis and the
metal enters the mould through the central pouring basin as shown in fig. For larger
production rules, The mould can be stocked one over the other, all feeding from the same
central pouring basin. The rotating speed used in this process are not as high as in case of
centrifugal casting.
Centrifusing :
In order to obtain to higher metal pressure during solidification, when casting shape
are not axisymmetrical the centrifusing process is use. This is suitable for only small jobs of
any shapes. A number of such small jobs are joined together by means of radial runners with
a central spray on a removing table as shown in fig. The jobs are uniformly placed on table
around the periphery. So that their masses are properly balanced. The process is similar to
semi-centrifugal casting.
A comparison of the various casting processes discussed above are presented.
Shell Moulding :-
It is process in which the sand mix with a heated metallic pattern plate, so that a thin
strong shell of mould is formed around the pattern. Then the shell is removed from the pattern
and the cope of drag are removed together & kept in a flask with necessary back up material
& the molten metal is poured into the mould.
Find and dry sand is used in shell moulding the grain size of the sand choosen is is depend
on it is essentially a thermosetting resin which get wardened irreversibly by heat. The resins
most widely used, are the phenol formaldehyde resins, combined, with sand they have high
strength & resistance to heat.
Addetives may sometimes be added into the sand mixture to improve the surface finish &
avoid thermal cracking during pouring . Some of the additives used are coal dust, pulverized
clay, magnese dixide calcium carbonate.
The first step in preparing shell mould is the sand mixture in such away that each of
the sand grain is thoroughly coated with resin. To achieve this, first the sand, hexa & additives
which all are very dry are mixed inside a Muller for a period of 1 min. Then the liquid resin is
added and mixing is continued for another 3 min. To this cold or warm air is introduced into

15. the Muller & mixing is continued till all liquid from the mixture and casting and coating of grains
is achieved for desired degree.
Since the sand resin mixture is to be use d at about 0 degree temperature preparing
pattern is grey. C.I. Mainly because of its easy availability & excellent stability of temp.
involved in the process. But some times additional rise ring provision is required as the cooling
in shell mould slow.
CO2 Moulding :-
The process is basically hardening process for mould and cores. The sand mixture
used in this process is pure dry silica sand, free form clay and sodium silicate liquid base
binder, the mould is prepared with a mixture of sodium silicate and sand & then treated with
carbon dioxide for two or three minutes such that a dry compressive strength over1-4 mPa is
arrived at. The carbon dioxide is expect to form a weak acid which hydrolyses the sodium
silicate resulting in amorphous silica which forms the bond. Because of high strength of band
core need not to better dimensional accuracy is achieved. But it is a little expensive process.
The shake out properties of CO2 are poor compared in normal moulding. Mould and
covers get deferioted from water pick up gf they kept stored for longer periods.
The core sand should be completely free from clay moisture and any other impurities,
otherwise the binder consumption will increase.
The gassing of CO2 into the mould of core is done of number of ways depending essentially
on the size of the core of the mould. For smaller gastight hood is connected to CO2 source is
placed directly in core box. For very large mould which may be connected to a manifold
getting the CO2 supply. The press should be maintained around 0.14 to0.28 mpa depending
largely on the thickness of section to be gassed.
There are four main types of die casting machines:-
1. Hot chamber die casting machine
2. Cold chamber die casting machine
3. Air blown or Goose-neck type machine
4. vacuum die casting machine.
Hot Chamber Die-Casting Machine :
The main part of the hot chamber is shown in fig. This is operated by hydraulic
plunger act inside a cylinder formed at one end of goose-neck type casting submerged in
molten metal. A part is provided near the top of cylinder to allow the entry of the molten metal
in it. When the bottom of plunger is above the port the cylinder is connected to the melting
pot threw this part. Down stroke of plunger closes this port, cuts of metal, supplies and applies
the pressure on the molten metal present in goose-neck to force same into the die cavity
threw injecting nozzle. After the certain period of time the plunger is raised up, casting the
remaining molten metal in nozzle & channel to fall back into goose neck casting. Just before
end of its up word stroke the plunger uncovers the port through which more molten metal
enters into cylinder. The dies are then opened & casting ejected. Zinc based low melting point
alloy are generally cast in these machines.
Cold Chamber Die-Casting Machine :-

16. The working principle of Cold Chamber Die-Casting Machine is illustrated in fig. The
ward cold chamber is used to denote the horizontal cylinder into which the injection plunger
works. For these machines the meal is melted separately in a furnace & transfer to these by
means of small hand ladle. After closing the die the moltan metal is poured the horizontal
chamber through metal inlet. The plunger is pushed forward hydraulically to force the metal
into die. After solidification die isopers of casting is ejected. The plunger is again drawn back
& the cycle is repeated as usual for next casting. These machines are widely used for casting
a good number of aluminum alloys & broses which can’t be cast in hot chamber machines as
they require higher pouring temperatures. Moreover the chances of iron pick up by aluminum
are almost finished in these machines as it takes place only at elevated temperatures & also
become the molten alloy remains in contact with the steel chamber and plunger for a very
small period.
EXPERIMENT NO : 5
AIM : Study of Powder Metallurgy
Introduction :
Preparation of powdered iron and non-ferrous metal is called powder metallurgy part
made in this way exhibit properties which cannot be produced in any other way. Simple
shaped part can be made to size with the higher precision without waste and completely or
almost already for installation.
Powder Manufacture and Conditioning :
The powder of almost all metals and a large quantity of alloys are used of the present
times. The powder most commonly used are copper base and iron-base material. But
stainless steel, titanium, nickel, chromium, metal powders are also used.
The particle size of powder falls into a range of 0.1µ to several millimeters (1µ = 10-
6
mm). In the majority of the powders, the size of the particle varies from several microns to 0.5
mm.
Most commonly method are used of follows.
Atomization :
In this process molten metal is forced through a nozzle into a steam of water or air.
The usually is supplied as a pressure of about 1 to 3x10-2
Kgf/mm2
( 2 to 3x105
N/M2
) upon
contact with the steam. The molten metal is solidified into particles of a wide range of sizes.
The fineness of powder is controlled by the air pressure, nozzle size of metal flow rate.
Reduction :
This is the process adopted for some at the refractory methods. For example,
pulverized tungsten oxide is heated in a current of hydrogen to produce a fine tungsten
powder.
Iron powder is also produce by reducing iron chloride in hydrogen. Copper is another
metal for which chemical reduction can be used.
Electrolysis:
In this process the metal plates are placed in a tank of electrolyte which is an acid
solution. The plated act as anodes, while other metal plated are placed into tank to act as

17. cathodes, are removed from tank, rinsed to remove the electrolyte solution & then dried. After
a drying period. The deposit is scrapped off and pulverized to produced powder of desired
size.
Blending or mixing pf powder :
It only one powder of correct particle size distribution is being used, no blending is
required, but blending becomes essential when different metal powders are used or when
non metallic particles are added to impart some specific properties. The process consist of
through mixing of the constituent either wet or dry. Wet mixing reduces dust and minimize the
danger of explosions. Lubricants are added during blending to reduce friction.
Compacting :
It is a process of converting loose powder onto green compact of accurate shape and
size it is done in steel dies and punches. Due to interparticle friction the pressure applied from
one side is not uniformly distributed thought the mass. Two punches are, therefore employed
one form top and other from the bottom of the powder , as shown in the figure. The lower
punch also act an ejector for compressed part. Due to low flow ability of metal powder the
density variation is kept minimum by both side pressing.
Presintering:
Presintering means heating the
Green compact to a temp. below the sintering temp. It is done to increase strength of green
compact and remove the lubricants and binders added during blending. Some metals like
tungsten carbide are easily machined in presenting state as they become too hard after
sintering.
Sintering :
Sintering of briquette parts is done in large continues furnace having controlled
atmosphere for protection against oxidation and other chemical reactions. The parts are kept
at the correct temp. for a certain period, during which the particles are strongly banded
together by atomic forces.
The process of sintering is carried out of substantially high temp. but below the melting
point of the material being sintered actual values of sintering temp. for most materials range
between 70 to 80 % of their melting procedure,.
Production of synthesed structural components :
Self Lubricating Bearing :
It is type of bearing having purpose porous metal. For lubricating purpose. The
necessary oil is contained in the pores oil is forced into the interconnecting pares of sintered
compact. The process of powder metallurgy is used for producing these bearing. For this
purpose powder of copper , tin and graphite are sintered. To size it to correct dimensions, it
is passed through a sizing die. The porous natural metallic bearing produced can hold oil upto
one third of its volume in its pores. A continuous atomic supply will be ensured at the place of
need because a pressure in the bearing or a temp. rise would cause the oil to excide. For the
compact to remain porous even after occurrence of considerable densification and strengthing
its condition is adjusted while producing it.
Cemented Carbides :

18. These carbides are extremely hard and abrasive materials and are widely used for
making cutting tools and drawings dies etc. Carbides of tungsten, titanium and tantalum are
widely used for this purpose however these carbides are very brittle and therefore can’t be
employed for making cutting tools or tools likely to subjected impact or shock loads, such as
their particle need to be embedded in a relatively softer and ductile matrix which can hold
them firmly while they are being subjected to different types of loads.
Out of three main types of carbides used for making cutting tools,, titanium carbide is
the hordes followed by tungsten carbide and tantalum carbide in descending order of
hardness. The actual proportion of different types of carbide particle and the bonding agent to
be mixed into form the mixture for making a certain grade of tool material coil depend upon
the required application of these tools.
For making tungsten carbide bits or inserts the tungsten powder is first carburised to
convert into tungsten carbide. The tungsten carbide and cobalt powder are the mixed and
blended in ball mill thoroughly. Then they are screened and dried and paraffin is added to the
mixture to hold it together.
Ceramics :
Ceramic is used a heat resistance material produced without a metallic bonding quent
rich as cobalt. Aluminum oxide is the most popular material used to make ceramic cutting
tool.
Titanium oxide to titanium carbide may be used as an additive depending as the
cutting tool application. Ceramic permit high cutting speed. Increased tool life and better
surface finish than do carbide tools.
Composite Materials :
The term composite material is commonly use to describe material whose components
do not occurs naturally. As an alloy but have been repeatedly manufactured before being
combined together.
Classification of composite material :
A) Agglomerated materials.
i) Sintered Products
ii) Ceramics
B) Reinforced material
i) Reinforced material
ii) Glan fiber reinforced plastic
iii) Carbon fiber reinforced plastic
iv) Whiskers
C) Laminates
i) Laminated coating plastic sheet
ii) Tanfol
D) Surface coating
i) Metallic coating
ii) Organic chemical coating
iii) Organic coating

19. EXPERIMENT NO. : 6
AIM : Study of Joining Process.
Introduction to welding :
The art of joining metals by heating and then pressing together is very old one.
In most of the modern fabrication works welding science has numerous application in different
forms. Covering a fairly wide range of such work. Some time ago the application of this
science was largely confined to iron and steel only, but with the evolution of number of
techniques it has become possible to weld most of the metals and plastics now.
Welding is a process of joining similar metals by application of heat with or without
application of pressure & addition of filler material.
Soldering :
It is method of joining metals, particularly when they are inform of sheets by using
another metal or alloy which has a fairly low melting point as compared to metal to be joined.
The metal or alloy used for this purpose is known as solder. A soft solder is primary an alloy
of lead and tin which some other metals are sometimes added lower its melting point
compositions of the soft solder which are ingeneral use are as follows:
i) Tin 67% ; Lead 33%
ii) Tin 50% ; Lead 50%
iii) Tin 33% ; Lead 76%
Similarly hard solder is an alloy of copper and zinc to which silver, Zinc and nickel In
general classification of solder in the above two categories is according to their melting
points. Soft solder usually melts at a temp. below 350°C. and hard solder above 600°C. The
operation performed by using a soft solder is known as soft soldering and when using a hard
solder is known as hard soldering.
After soldering iron has been heated to desired heat its surface is cleaned by means
of filling the dipped in a mixture of flux and solder another practice is first dip it in a mass of
flux followed by application of solder. This enables the solder to melt and spread over it. This
operation is known as tinning . After this, the bit is again dipped in the flux to remove the
oxides from its surface if any, and then in the solder again to pick up its required quantity. It is
then ready for application to work.
Brazing :

20. It is the process through which metal pieces are joined by means of hard solder.
Brass is main usually constituents of this solder. The brazing solder used in modern practice
is commercially known as spellter, which is a mixture of copper, Zinc and tin. This method of
hard soldering provides a much stronger joint as compared to the soft soldering processes,
but here it is needed that the metal pieces to be joined should be heated sinister of the bit.
For this a muffle is best suited so that pieces are heated uniformly, although a smithies
furnace can also be used.
In operation the end of the metal pieces which are to be joined are cleaned well by
means of fillingete. Brass filling or speletter is then spread over the surface together with
the flux. The parts are either clamped or weld together through some other suitable means
and heated . The spelter, together with the flux, metals and flows along the contacting
surfaces unites with them and solidifies on cooling to force the joint. It is a good practice to
prepare the brazing mixture in the form of a paste and then apply is to the surface. This paste
is made by mixing the spelter and borax(flux) in equal parts and adding. Proper amount of
waiter to it to from the paste.
Welding of various metals :
Carbon sheet : Carbon sheet can be readily welded by forge welding, resistance welding, arc
welding and gas welding. The chief trouble likely to be en counted when welding carbon
steel by any fusion welding carbon method cracking.
Alloy steel : This group of steel contains small amounts of nickel, chromium or other element
in addition to carbon. Preheating is always advisable when welding such steels and slow
cooling is essential. If brittle or cracked welds are to be avoided.
Cast iron : Carbon may be present in cast iron in two forms : Combined or free. During
formation of weld in a C.I. base both free and combined carbon go into the solution in the
molten metal. Upon the removal of the welding heat. There is a quick solidification of metal
because of the cooling effect of the comparatively cold mass surrounding the place of
welding and the cooling effect of the air to which it is exposed.
Aluminum : For purpose of welding, aluminum and aluminum alloys may be classified into
two main groups i) Cast ii) wrought. One of the most important rules in welding aluminum
is to ensure the complete absence of every trace of oil or grease and for this reason the work
must given a de-greasing treatment of the edges cleaned down bright metal by filling or wire
brushing.
Inspection and testing of welds :
The principal objective of inspection or quality control is to find the defects of weld
melts to ensure the high quality of products through the careful examination of components
parts of each state of manufacture.
The principal defects of welding joints include :
i) Poor fusion : The lack of through and parent metal
ii) Parent metal : Under cut : A groove melted into the bas e adjacent to the toe of the weld.
The reasons for under cutting are non-uniform feed of the welding rod, improper position
of electrode or both tip. Or excessive heating.
iii) Porosity : The formation of blow holes, gas pockets or roughness on surface of the weld.
iv) Slag inclusion : The presence of a non metallic substances in the meta,. Slag inclusions
are due to the deposited metal by oxides, non-uniform melting of the electrode coating
high viscosity of the slag.
v) Cracks in weld may arise from locked up stress set up by non-uniform heating and
cooling, excess sulphur or phosphorus in the weld metal and some other causes.
Electrodes :
Electrodes commonly used for :
i) Bare Electrodes

21. ii) Coated Electrodes
Bare electrodes are cheaper but the welds produced through these are of poor
quality and their use all for a very high degree of skill on the part off welds satisfactory results
are to be expected. They are therefore rarely used in modern welding. However in coil for m
they are used with insert gases in special welding process called insert gas metal are welding.
More popularly used in metal arc welding are the coated electrodes which
carry a core of base metallic wire provided with a coating or covering on the outside surface.
Mild steel is most commonly use material for core wire but electrodes with core of other
metals and alloys are also manufactured to suit welding of different metals and alloys.
Electrode covering it has been discussed in the earlier article that the flux
coating provided on the electrode perform many functions such as providing a a reducing
atmosphere to prevent oxidation forming slag with metal impurities stabilizing are providing
necessary alloying elements to the weld metal and so on to meet those requirements many
different materials are used for making electrode covering.
EXPERIMENT NO. : 7
AIM : Study of Joining Process
Types of Welding :
Modern method of welding may be classified under two broad welding :
i) Plastic Welding
ii) Fusion Welding
In the plastic welding or the pressure welding, the pieces of the metal to be joined
are heated to a plastic state and then forced together by external pressure. This procedure is
used in forge welding resistance welding “thermit” welding of gas welding in which pressure is
required.
In the fusion welding or non-pressure welding the material at the joints is heated to a
moltlen state allowed to solidify. This includes gas welding, arc welding, thermit welding etc.
ARC Welding :
Electric arc welding is divided into the following two main points :
i) Metallic arc welding
ii) Carbon arc welding
Metal ARC welding :
In this a metal electrodes is used and the arc is maintained between this electrode
and welding which respectively form the two terminals. Bore electrode have the same or
nearly the same composition as that of the parent metal they have the disadvantage that their
surface may be subjected to oxidation.
ARC welding Principle :
Principle of shielded metal arc welding consist of establishing an electric arc
between a metal electrode and the work piece to be welded. The arc can be described as a
stream of incandescent vapour which acts as stream conducting medium for electric current

22. from one terminal to the other to complete the circuit. The electric current has a fairly high
voltage to overcome the extra resistance offered by the vapour.
The process is illustrated by means of a schematics diagram in fig. The metal of the
workpiece to be joined is called base metal or parent metal and that provided by the
electrode as filler metal. The metal electrode is coated with flux which performance the
following functions :
i) It produce a gas which provides a shield around the arc to protect it form atmosphere
ii) It forms slag by mixing with impurities of the molten metal and thus refines the metal.
iii) The slag, being lighter, floats over the surface of the molten metal and solidification forms
a thin layer over the weld met and prevent its oxidation during cooling.
iv) It promotes conduction of electric current across the arc & helps in stabilizing the arc.
Gas Welding :
Gas welding is done by burning a combustible gas with air oxygen in a concentrated
flame of high temp. As with other welding methods the purpose of the flame is to be heat and
melt the parent metal and filler rod of a joint. It can weld most common materials equipment
is inexpensive. Versatile and serves adequately in many job and general repair shops.
Oxy-acetylene welding :
It is a accomplished by melting the edges or surface to be joined by gas flame and
solid continuous joint upon cooling . This process is particularly suitable for joining metal
sheets and plates having thickness of 2 to 50 mm with material thicker than 15 mm.
Additional metal called filler metal is added to the weld in the form of welding rod. The
composition of the filler rod is usually the same or nearly the same as that of the part being
welded. To remove the impurities and oxides present on the surface of metal to be joined
and to obtain sates. Factory bond a flux is always employed during the welding except mild
steel which has more maganise and silicon that acts as de-oxidizing agents.

23. EXPERIMENT NO. : 8
Aim : Study of Plastics.
Thermoplastics :
Thermoplastics are linear polymers the molecules of which are synthesized in the
shape of long threads. They undergo no chemical change in the moduling operation and is
often with the application of heat and harden upon cooling. They can be reshaped while in the
softened state and become to soft to use at temp. from 66 to 315°C . Since they become
increasingly softer with increase temp. certain members of the thermoplastics family are
liable to permanent distortion under under mechanical strain at relatively low temp. They may
flow to an appreciable extent under load at room temperature.
Properties of thermoplastics :
Cellulasics: The cellulasics have good strength toughness transparency, chemical resistance
and mouldability from various grades. It is also made as an electrical insulting tape.
Nylons : Its outstanding features are a low coefficient of friction and its resistance to heat
abrasion and chemicals. It is strong tough and light weight.
Polystream : It has an excellent ensile strength but it can be used only up to 66 to 90°c. It is
easily produced in any form and easily can be joined by the cementing.
Polyoropylene : It is an excellent insulator and used for automobile accelerator pedals luggage
and hospital equipment.
Poly Carbonates : It is a easy to handle for moulding, extrusion and moulding. It can be nailed
and riveted without cracking.
Acetal : Ita has good tensile strength resistance of temp. (115°c) low friction characteristic
resistance to most solvent and low moisture absorption.
Vinyle Plastics : It can stand outdoor exposure and is quite abrasion resistant but it has low
tensile strength .

24. Thermo-stetting plastics : Thermo-setting plastics are made from chains which have been
linked together referred to as crass linked. These have three dimensional network of
molecules and will not soften when heated they are partially insoluble, fireproof and usually
hard and brittle. These plastic cannot be reused.
Epoxy Resins : Epoxy have excellent chemical resistance and electrical insulating properties.
There working temp is from 50 to 260°c with fillers and additives.
Amino Resins : It is used as adhesive in making plywood and melamine is laminated with
cloth make table and counter tops. The melamine can be mould into very hard business
machine housing, electric switch cover plates radio cabinates, etc.
Phenolics : These are hard brittle heat resistance. They are inexpensive, excellent insulator
and have heat distortion temperature up to 180 °c and working temp upto 260°C.
EXPERIMENT NO. : 9
AIM : Study of General Plastic Process.
Following methods are commonly employed for processing plastics into various usable
particle.
i) Compression moulding.
ii) Transfer moulding
iii) Injection moulding
iv) Extrusion
v) Castings
vi) Slush moulding
vii) Calendering
viii)Wire drawing
ix) Embossing
1. Compression Moulding :
Most of the thermosetting plastics and few thermoplastics can be mould
through this process The process consist of placing a correct amount of plastic compound
in a heated mould, A punch called force, compresses the compound to P into the required
shape and density. The mould is kept closed for sufficient time to allow the chemical close to
complete. So that the product is sufficiently hardened. Although loose compound can be
used but for faster production a previously shaped cold-compressed tables called perform is
used.
2. Transfer Moulding :
It is also known as extrusion moulding or gate moulding. It is actually a
modified form of compression moulding. In this the heat and pressure are applied to the
compound separately outside the mould and when the letter becomes fluid. It is
transferred to the mould the under pressure, though us sprue and gate, where it cures
finally. With mould it costlier, but the operation is easier and enables trouble free
production of intricate parts with thinnsections. As the mould is not directly subjected to
the compression force. An example is illustrated in fig.

25. 3. Injection Moulding :
It is very commonly used for thermoplastics the process is illustrated in fig. The
powdered plastics compound is first heated to drive of moisture and then fed into the
hopper, when the rumis drawn back, some of the powder drops down into chamber, after
closing the mould the rum is moved forward applying pressure behind the powder . This
compressed the material & forces it forward through the thin space around heated
torpedo. The material being in contact with the heated surface of the torpedo and the
water cooled mould through the nozzle. During heatingin chamber the temp. of the
material rises to between 177°C to 274°C. After plastic has been cooled and sufficiently
hardened in the mould, the mould is opened and the produced part knocked out. It is
faster process and suits between for large quantity production.
4. Calendering:
This process is vastly used for making plastic films and sheets. In this a heated
doughly paste of plastic compound is passed through a series of hot rollers, where it is
squeezed into the form of thin sheet of uniform thickness as shown in fog. The last roll is
water cooled and is called the chilling roll.
5. Bloke Moulding :
t is used for producing narrow neck plastic containers, like bottle and similar
other articles. An example solving the production of screwed neck plastic bottle is
illustrated in fig. In given process a heated clsoded end thermoplastic tube is applied to in
flate it to acquire the shape of mould cavity. After the plastic is cooled the mould is opened
and product taken out.
6. Wire Drawing :
Wire drawing is an old drawing process. For wire drawing the rolled bars
obtained from the mills are first pickled washed and coated to prevent oxidation. They are
then passed through a die to provide the desired reduction in size. Depending upon the
material to be drawn and the amount of reduction, required. Total drawing may be
accomplished in a single die or in a series of successive dies.
One end of the rod to be drawn in to the wire is made pointed, entered through
the die and gripped at other end by means of tongs. After pulling a certain length this
length is wound to a reel or draw pulley. When the pulley or reel is rotated the rod the rod
is pulled through the die and its diameter reduced. A die and its diameter reduced. A die
and reduction of bar diameter are depicted in fig.
7. Embossing :
It is the process which blanks of sheet metal are stretched to shape under
press, by means of a punch and die. The punch operates at a low speed to allow time for
proper stretching. A simple example is depicted in fig. A operation gives a stiffening effect
to the metal being embossed stress in the material may be reduced by producing deep
parallel ridges reduced by producing deep parallel. A large numbers of ornamental wares
such as plates, in sheet metal are produced by embossing. A simple form of this process
called open embossing. Consist of producing simple shallow shapes by the punch only.

26. JOB NO. : 1
AIM : Step Turning and Threading
Job Material : M.S. Round Bar, 75 X 35 φ, produce & operation.
i) Cut the required size of bar, by power hacksaw.
ii) Work piece is made in accurate lathe machine length of dia. And length of lathe
machine.
iii) Perform the operation of the step turning . Lathe machine facing & threading on
lathe.
iv) Now keyway is introduced into the lathe machine the job.
v) Check the final job of required by steel rule.
Precaution:
1. Keep sufficient distance between machine and yourself to avoid wires physical
injuries.
2. Clean the machine parts after used.
JOB NO. : 2
AIM : To perform step operation on Shaper Machine.
Job Material : M.S. Bar (120 X 28 X 28)
Working Procedure :
Operation
No.
Observation Tools
01
First of all given bar is check with
dimensions.
Scale
02
Then the bar is marked and punch hold in
small size
Punch,
Hammer
03
To adjust the job on shape machine and
start to cut one by one cut side of given
marking
Shaper tool,
Marker
04 Check Proper dimensions Scale
Precaution :
i) Shaper Machine should be handled carefully.
ii) Depth of cut should be given in only forward or working stroke.

27. JOB NO. : 3
AIM : Key way Milling
Job Material : 35 X 40 φ, M.S. Round Bar
Procedure: Tool
1. Cut the required size of bar from work piece Power Hacksaw
2. The work piece is made accurate dimension Lathe Machine
3. Fix the job on vice of the milling machine Milling Machine
4. Give feed with the help of milling cutter and Milling Machine
accurate feed to the work piece
5. Perform operation until job is satisfactory produced Milling Machine
Precaution :
i) The milling cutter is to be continuously supplied with coolant.
ii) Accurate feed is to be given carefully.