Mechanical workshop practice 2 by sudarshan.bollapu

2013
Workshop Practice-II

B.SUDARSHAN M.Tech., (Ph.D.)

1/1/2013-2014

MECHANICAL WORK SHOP PRACTICE LAB MANNUAL
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Centurion University of Technology and Management
Mechanical work shop practice-2(BLME1214)

CYCLE OF EXPERIMENTS

 FOUNDRY

1. Pattern making –using wood turning lathe

2. Preparation of sand mould including gating system

3. Casting a product

 WELDING

1. Preparation of lap joint, butt joint(any one)

2. Preparation of t-joint

3. Fabrication of stool and hand grinding process

 PLUMBING

1. Basic pipefittings

2. Sanitary fittings

3. Pipe lay out installation with water meter

 BLACK SMITHY

1. Converting round rod into square

2. Converting round rod into square s-hook

3. Converting round rod into L-bend.

Total experiments (3+3+3+3) =12

Centurion University of Technology and Management –Department of Mechanical Engineering pg. 1

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Instructions to the students:

1. Enter the lab with proper dress- code (blue apron and shoes)

2. Maintain a 200 pages white long note book and divide it into four parts with the Titles of the

trades namely foundry, plumbing, black smithy and Welding.

3. Draw the figures of tools and equipment’s proportionately using pencil only on the left side of

the page.

4. Write the related theory part only on the right side of the page.

5. For every experiment, draw the related figure and write the individual procedure in the

observation book and take signature by the concerned technician. Write the date and Experiment

number in the observation book. And take signature of staff member on index page of lab manual.

6. Only after taking signature in the observation book, write the record. Both will be checked.

Marks are allotted for your regularity. Performance of the students will be assessed for every

session of workshop being conducted.

7. The records should be written up to date without delay. They should be signed by the concerned

faculty.

8. Medical kits provided in the First – Aid Box. The students can utilize the available Medicines if

at all there is any necessity.


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Welding

INTRODUCTION:

Welding is the process of joining similar metals by the application of heat, with or without application
of pressure or filler metal, in such a way that the joint is equivalent in composition and characteristics
of the metals joined. In the beginning, welding was mainly used for repairing all kinds of worn or
damaged parts. Now, it is extensively used in manufacturing industry, construction industry
(construction of ships, tanks, locomotives and automobiles) and maintenance work, replacing riveting
and bolting, to a greater extent.

The various welding processes are:

1. Electric arc welding,
2. Gas welding
3. Thermal welding
4. Electrical Resistance welding and
5. Friction welding
However, only electric arc welding process is discussed in the subject point of view.

3.2 ELECTRIC ARC WELDING:

Arc welding is the welding process, in which heat is generated by an electric arc struck between an
electrode and the work piece. Electric arc is luminous electrical discharge between two electrodes
through ionized gas.

Fig: Arc welding setup


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Any arc welding method is based on an electric circuit consisting of the following parts:
a. Power supply (AC or DC);
b. Welding electrode;
c. Work piece;
d. Welding leads: (Electric cables) connecting the electrode and work piece to the power supply
Electric arc tween the electrode and work piece closes the electric circuit. The arc temperature
may reach 10000°F (5500°C), which is sufficient for fusion the work piece edges and joining them.
When a long joint is required the arc is moved along the joint line. The front edge of the weld pool
melts the welded surfaces when the rear edge of the weld pool solidifies forming the joint.

Transformers

The transformers type of welding machine produces A.C current and is considered to be the least
expensive. It takes power directly from power supply line and transforms it to the voltage required
for welding. Transformers are available in single phase and three phases in the market.

Motor generators

These are D.C generators sets, in which electric motor and alternator are mounted on the same shaft
to produce D.C power as pert the requirement for welding. These are designed to produce D.C current
in either straight or reversed polarity. The polarity selected for welding depends upon the kind of
electrode used and the material to be welded.

Rectifiers

These are essentially transformers, containing an electrical device which changes A.C into D.C
by virtue of which the operator can use both types of power (A.C or D.C, but only one at a time).In
addition to the welding machine, certain accessories are needed for carrying out the welding work.

Welding cables

Two welding cables are required, one from machine to the electrode holder and the other, from
the machine to the ground clamp. Flexible cables are usually preferred because of the case of
using and coiling the cables. Cables are specified by their current carrying capacity, say 300 A,
400 A, etc.


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Electrodes

Filler rods are used in arc welding are called electrodes. These are made of metallic wire called
core wire, having approximately the same composition as the metal to be welded. These are
coated uniformly with a protective coating called flux. While fluxing an electrode; about 20mm of
length is left at one end for holding it with the electrode holder. It helps in transmitting full current
from electrode holder to the front end of the electrode coating. Flux acts as an insulator of
electricity. Figure. Shows the various parts of an electrode.

Figure: Parts of an electrode

In general, electrodes are classified into five main groups; mild steel, carbon steel, special alloy
steel, cast iron and non‐ferrous. The greatest range of arc welding is done with electrodes in the
mild steel group.
Various constituents like titanium oxide, potassium oxide, cellulose, iron or manganese, Ferro
silicates, carbonates, gums, clays, asbestos, etc., are used as coatings on electrodes. While
welding, the coating or flux vaporizes and provides a gaseous shield to prevent atmospheric
attack. The size of electrode is measured and designated by the diameter of the core wire in SWG
and length, apart from the brand and code names; indicating the purpose for which there are most
suitable.

Electrodes may be classified on the basis of thickness of the coated flux. As

1. Dust coated or light coated
2. Semi or medium coated and
3. Heavily coated or shielded

Electrodes are also classified on the basis of materials, as

1. Metallic and
2. Non‐metallic or carbon


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Metallic arc electrodes are further sub‐divided into

1. Ferrous metal arc electrode (mild steel, low/medium/high carbon steel, cast iron, stainless
steel, etc.)
2. Non‐ferrous metal arc electrodes (copper, brass, bronze, aluminum, etc.).In case of non‐
metallic arc electrodes, mainly carbon and graphite are used to make the electrodes.

WELDING TOOLS:

Electrode holder

The electrode holder is connected to the end of the welding cable and holds the electrode. It
should be light, strong and easy to handle and should not become hot while in operation. Figure
shows one type of electrode holder. The jaws of the holder are insulated, offering protection from
electric shock.

Figure: Electrode holder Figure: Ground clamp

Ground clamp:

The end of the ground cable and is clamped to the work or welding table to complete the electric

circuit. It should be strong and durable and give a low resistance connection.


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Wire brush and chipping hammer:

A wire brush is used for cleaning and preparing the work for welding. A chipping hammer is used

for removing slag formation on welds. One end of the head is sharpened like a cold chisel and

the other, to a blunt, round point. It is generally made of tool steel. Molten metal dispersed around

the welding heads, in the form of small drops, is known as spatter. When a flux coated electrode

is used in welding process, then a layer of flux material is formed over the welding bead which

contains the impurities of weld material. This layer is known as slag. Removing the spatter and

slag formed on and around the welding beads on the metal surface is known as chipping.

Figure: Wire brush Figure: Chipping hammer

Welding table and cabin:

It is made of steel plate and pipes. It is used for positioning the parts to be welded properly.

Welding cabin is made up by any suitable thermal resistance material, which can isolate the

surrounding by the heat and light emitted during the welding process. A suitable draught should

also be provided for exhausting the gas produced during welding.

Face shield:

A face shield is used to protect the eyes and face from the rays of the arc and from spatter or

flying particles of hot metal. It is available either in hand or helmet type. The hand type is


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convenient to use wherever the work can be done with one hand. The helmet type though not

comfortable to wear, leaves both hands free for the work. Shields are made of light weight

nonreflecting fiber and fitted with dark glasses to filter out the harmful rays of the arc. In some

designs, a cover glass is fitted in front of the dark lens to protect it from spatter.

Hand gloves:

These are used to protect the hands from electric shocks and hot spatters Hand held type, Helmet

type

Figure: Hand gloves Figure: Face shield


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Figure 1 BALLPEEN HAMMER Figure 2 FLATBIT TONG

Figure 3 FACE SCREEN Figure 4 Flat File Figure 5 Chipping hammer

Figure 6STEEL RULE

Figure7 Trysquar Figure 8 Scriber Figure9 Benchvice

Figure10 Hacksaw
TECHNIQUES OF WELDING:


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Preparation of work:

Before welding, the work pieces must be thoroughly cleaned of rust, scale and other foreign

material. The piece for metal generally welded without beveling the edges, however, thick work

piece should be beveled or veed out to ensure adequate penetration and fusion of all parts of the

weld. But, in either case, the parts to be welded must be separated slightly to allow better

penetration of the weld.

Before commencing the welding process, the following must be considered

a) Ensure that the welding cables are connected to proper power source.

b) Set the electrode, as per the thickness of the plate to be welded.

c) Set the welding current, as per the size of the electrode to be used.

Table Electrode current vs. electrode size vs. plate thickness.

Plate thickness, (mm) Electrode size, (mm), Electrode current range, (amp)

Plate thickness, mm Electrode size, mm Electrode current range,

amp

1.6 1.6 40‐60
2.5 2.5 50‐80
4.0 3.2 90‐130
6.0 4.0 120‐170
8.0 5.0 180‐270
25.0 6.0 300‐400

NOTE: While making butt welds in thin metal, it is a better practice to tack weld the pieces intervals

to hold them properly while welding.


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Striking an arc:

The following are the stages and methods of striking an arc and running a bead

a) Select an electrode of suitable kind and size for the work and set the welding current at a proper

value.

b) Fasten the ground clamp to either the work or welding table.

c) Start or strike the arc by either of the following methods

Strike and withdraw:

In this method the arc is started by moving the end of the electrode onto the work with a slow

sweeping motion, similar to striking a match.

Touch and with draw:

In this method, the arc is started by keeping the electrode perpendicular to the work and touching

or bouncing it lightly on the work. This method is preferred as it facilitates restarting the

momentarily broken arc quickly. If the electrode sticks to the work, quickly bend it back and forth,

pulling at the same time. Make sure to keep the shield in front of the face, when the electrode is

freed from sticking.

d) As soon as the arc is struck, move the electrode along, slowly from left to right, keeping at 15º

to25º from vertical and in the direction of welding.

Strike and withdraw Touch and withdraw

Figure: striking an arc


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Weaving:

A steady, uniform motion of the electrode produces a satisfactory bead. However, a slight weaving
or oscillating motion is preferred, as this keeps the metal molten a little longer and allows the gas
to escape, bringing the slag to the surface. Weaving also produces a wider bead with better
penetration.

Brazing

It is a low temperature joining process. It is performed at temperatures above 840º F and it
generally affords strengths comparable to those of the metal which it joins. It is low temperature
in that it is done below the melting point of the base metal. It is achieved by diffusion without
fusion (melting) of the base

Brazing can be classified as

Torch brazing
Dip brazing
Furnace brazing
Induction brazing

Fig: Brazing
Advantages

• Dissimilar metals which cannot be welded can be joined by brazing
• Very thin metals can be joined
• Metals with different thickness can be joined easily
• In brazing thermal stresses are not produced in the work piece. Hence there is no distortion
• Using this process, carbides tips are brazed on the steel tool holders


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Disadvantages

• Brazed joints have lesser strength compared to welding
• Joint preparation cost is more
• Can be used for thin sheet metal sections

Soldering

• It is a low temperature joining process. It is performed at temperatures below 840ºF for joining.
• Soldering is used for,

• Sealing, as in automotive radiators or tin cans
• Electrical Connections
• Joining thermally sensitive components
• Joining dissimilar metals

TYPES OF JOINTS:

Welds are made at the junction of the various pieces that make up the weld ment. The junctions
of parts, or joints, are defined as the location where two or more numbers are to be joined. Parts
being joined to produce the weld ment may be in the form of rolled plate, sheet, pipes, castings,
forgings, or billets. The five basic types of joints are listed below.


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Figure: Types of welding joints.

A butt joint
Is used to join two members aligned in the same plane this joint is frequently used in plate, sheet
metal, and pipe work. A joint of this type may be either square or grooved.

Corner and tee joints
are used to join two members located at right angles to each other In cross section, the corner
joint forms an L‐shape, and the tee joint has the shape of the letter T. Various joint designs of
both types have uses in many types of metal structures.

A lap joint,
As the name implies, is made by lapping one piece of metal over another view. This is one of the
strongest types of joints available; however, for maximum joint efficiency, you should overlap the
metals a minimum of three times the thickness of the thinnest member you are joining. Lap joints
are commonly used with torch brazing and spot welding applications.

WELDING POSITIONS

Depending upon the location of the welding joints, appropriate position of the electrode and hand
movement is selected. The figure shows different welding positions.


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Figure: Welding positions
Flat position welding:

In this position, the welding is performed from the upper side of the joint, and the face of the weld

Is approximately horizontal. Flat welding is the preferred term; however, the same position is

sometimes called down hand.

Horizontal position welding:

In this position, welding is performed on the upper side of an approximately horizontal surface

and against an approximately vertical surface.

Vertical position welding:

In this position, the axis of the weld is approximately vertical as shown in figure.

Overhead position welding:

In this welding position, the welding is performed from the underside of a joint.


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ADVANTAGES & DISADVANTAGES OF ARC WELDING

Advantages:

1. Welding process is simple.

2. Equipment is portable and the cost is fairly low.

3. All the engineering metals can be welded because of the availability of a wide variety of

electrodes.

Disadvantages:

1. Mechanized welding is not possible because of limited length of the electrode.

2. Number of electrodes may have to be used while welding long joints.

3. A defect (slag inclusion or insufficient penetration) may occur at the place where welding is

restarted with a fresh electrode.

SAFE PRACTICE:

Always weld in a well-ventilated place. Fumes given off from welding are unpleasant and in some

Cases may be injurious, particularly from galvanized or zinc coated parts.

1. Do not weld around combustible or inflammable materials, where sparks may cause a fire.

2. Never weld containers, which have been used for storing gasoline, oil or similar materials,

without first having them thoroughly cleaned.

3. Check the welding machine to make sure that it is properly grounded and that all leads properly

Insulated.

4. Never look at the arc with the naked eye. The arc can burn your eyes severely. Always use a

face shield while welding.


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5. Prevent welding cables from coming in contact with hot metal, water, oil, or grease. Avoid

dragging the cables around sharp corners.

6. Ensure proper insulation of the cables and check for openings.

7. Always wear the safety hand gloves, apron and leather shoes.

8. Always turn off the machine when leaving the work.

9. Apply eye drops after welding is over for the day, to relieve the strain on the eyes.

10. While welding, stand on dry footing and keep the body insulated from the electrode, any other

parts of the electrode holder and the work.


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Exercise 1
Single V ‐ Butt joint

Aim: To make a single v‐butt joint, using the given mild steel pieces of and by arc welding.
Material used: Two mild steel pieces of 100X40X6 mm.

Equipment required:

A.C. Transformer with all welding accessories like Electrode holder, cables.

Tool Required:

1. Steel rule 2. Scriber 3. Flat file 4. Try square
5. Flat Tong 6. Chipping hammer 7. Ball peen hammer 8. Wire brush
9. Welding screen

Sequence of Operations: 1. Marking 2. Filing 3. Welding 4. Finishing

Sketch

Figure: Single‐V butt joint

Operations to be carried out:

1. Cleaning the work pieces
2. Tack welding
3. Full welding
4. Cooling
5. Chipping
6. Finishing

Procedure:

1. Take the two mild steel pieces of given dimensions and clean the surfaces thoroughly from
rust, dust particles, oil and grease.


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2. Remove the sharp corners and burrs by filing or grinding.
3. One edge of each piece is beveled, to an angle 30°.
4. The two pieces are positioned on the welding table such that, they are separated slightly for
better penetration of the weld.
5. The electrode is fitted in to the electrode holder and the welding current is set to a proper value.
6. The ground clamp is fastened to the welding table. The machine is switched ON
7. Wearing the apron, hand gloves, using the face shield, the arc is struck and the work pieces
are tack welded
At the ends and holding the two pieces together; first run of the weld is done to fill the root gap.
8. Second run of the welding is done with proper weaving and with uniform movement. During the
process of welding, the electrode is kept at angle of 15° to 25° from vertical and in the direction
of welding.
9. The slag formation on the weld is removed by chipping hammer.
10. Filing is done to remove spatters around the weld.

Safety Precautions:

1. Use welding screen leather apron and leather hand gloves while welding
2. Use flat tong and hand gloves for handling of work pieces during and after welding.

Result: The single v‐butt joint is thus made, using the tools and equipment as mentioned above.


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Exercise 2
Double ‐Lap joint

Aim:

To make a double lap joint, using the given mild steel pieces and by arc welding.

Material used:

Two mild steel pieces of 100X40X6 mm.

Equipment required:


Tool Required:

9. Welding screen


Sketch

Figure: Double lap joint
Operations to be carried out

2. Tack welding
3. Full welding
4. Cooling
5. Chipping
6. Finishing


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Procedure:

2. Remove the sharp corners and burrs by filing or grinding and prepare the work pieces.
3. The work pieces are positioned on the welding table, to form a lap joint with the required
overlapping.
5. The ground clamp is fastened to the welding table.
6. Wearing the apron, hand gloves, using the face shield and holding the over lapped pieces the
arc is struck and the work pieces are tack‐welded at the ends of both the sides
7. The alignment of the lap joint is checked and the tack‐welded pieces are reset, if required.
8. Welding is then carried out throughout the length of the lap joint, on both the sides.
9. Remove the slag, spatters and clean the joint.

Safety Precautions:


Result: The double lap joint is thus made, using the tools and equipment as mentioned above.


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Exercise 3
T‐ joint

Aim

To make a T‐ joint, using the given mild steel pieces and by arc welding.

Material used

Two mild steel pieces of 100X40X6 mm.

Equipment required:


Tool Required:

9. Welding screen

Sketch:

Figure: T‐joint
Operations to be carried out

2. Tack welding
3. Full welding
4. Cooling


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5. Chipping
6. Finishing
Sequence of Operations:

1. Marking 2. Filing 3. Welding 4. Finishing

Procedure

3. The work pieces are positioned on the welding table such that, the T shape is formed.
6. Wearing the apron, hand gloves, using the face shield and holding the pieces the arc is struck
and the work pieces are tack‐welded at both the ends.
7. The alignment of the T joint is checked and the tack‐welded pieces are reset, if required.
8. Welding is then carried out throughout the length of the T joint as shown in the figure.

Safety Precautions:


Result: The Tee joint is thus made, using the tools and equipment as mentioned above.


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Exercise 4:
Fabrication of Stool and Hand Grinding Practice

Aim:
To Fabrication of Stool and Hand Grinding Practice using the given mild steel pieces and by arc
welding.

Material used

Six mild steel pieces of 6X253 mm, 1X354mm and4X584mm

Equipment required:


Tool Required:

9. Welding screen
Sketch:

Procedure:

1. Take the elven mild steel pieces of given dimensions and clean the surfaces thoroughly from
3. The work pieces are positioned on the welding table such that, the L shape is formed.


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6. Wearing the apron, hand gloves, using the face shield and holding the pieces the arc is struck
and the work pieces are tack‐welded at both the ends.
7. The alignment of the L joint is checked and the tack‐welded pieces are reset, if required.
8. Welding is then carried out throughout the length of the T joint as shown in the figure.

Safety Precautions:


Result: The fabrication of stool thus made, using the tools and equipment as mentioned above.


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PLUMBING
INTRODUCTION:

Plumbing deals with the laying of a pipeline. A craftsman may be perfectly proficient with the
hammer, saw and other tools, but the faces difficulties with leaking pipes and overflowing toilets.
Many people rush to a plumber on seeking a tripping pipe, but a person with a little knowledge of
the sanitary system can control this problem easily, saving time and, one with help of few tools.

Domestic plumbing:
The domestic plumbing employs for house hold appliance such as fresh water supply, waste
water treatment supply, rainwater drain, gas supply, air conditioning, firefighting systems, garden
waters and irrigation.

Industrial plumbing:
The industrial plumbing is mainly used in industrial equipment such as a petroleum plant, a power
plant, etc. the fittings like gauges, indicators, regulators, valve etc. are added in pipelines

Plumbing tools:
The tools used by a plumber can be classified as follows
1. Pipe wrench 4. Pipe vice
2. Hacksaw 5. Dies
3. plumb bob 6. Pipe cutter
7. Files and Rasps
Pipe wrench
A pipe wrench is used for holding and turning the pipes, rods and machine parts. Wrenches are
classified as follows.1.Fixed wrenches 2. Adjustable wrenches


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Pipe vice:
A pipe vice is fitted on the work bench. This has a set of jaws to grip the pipe and prevent it from
turning while cutting, threading and fitting of bends, couplings etc. The yoke vice is commonly
used in plumbing used in plumbing practice

Pipe cutter:
The pipe cutter mainly consists of three wheels which are hardened with sharp cutting edges
along their periphery. Of these three wheels, one can be adjusted to any desired distance to
accommodate different size of pipes. After adjusting the cutter on a pipe, it is around the pipe, so
that the cutter wheels cut the pipe along a circle as shown in fig.

Hacksaw:
A hacksaw is used for cutting metal rods, bars, pipes, etc.


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Threading dies and taps:
It is used for cutting external thread on pipes. Threads are produced in various shape and sizes
which are used for fitting inside a handle.

Files and rasps:

The file surface is covered with sharp edged teeth and its used for removing metal by rubbing. A
rasp is used for finishing the surface of the work piece

Plumb bob:
It is used for check the vertical line and made up of steel or brass.

Pipe fittings:


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Fig: Pipe Fittings

Pipe fittings are made up of wrought iron. The size of pipe fitting is designated by the size of the
pipe on which it fits. Some of the common pipe fittings are shown in fig.

Coupling:
It is a short a cylindrical sleeve with internal threads throughout. A couplings is used for joining
two pipes in a straight and bend where at least one pipe can be turned.


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Union:
A union is used for joining two pieces of pipes, where either can be turned. It consists of three
parts, two parts joint can be screwed, in to two pipe ends, and the third on for tightening called
center part.

Nipple:
A nipple is a short piece of pipe with external threads at both ends. It is used to make up the
required length of a pipe line.
Elbow:
An elbow is to make an angle between adjacent pipes.
Tee:
A tee is a fitting that has one side outlet at a right angle to the run. It is used for a single outlet
branch pipe.
Reducer:
It is used to connect two different sized of pipes
Plug:
It is used to screw on to a threaded opening, for closing it temporarily
Valves
Valves are used for regulating the flow of fluid through a pipe. The commonly used valves in
plumbing’s are
1. Gate valve
2. Globe valve
3. Plug valve
4. Check valve
5. Air relief valve

Fig: Types of pipe joints


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Bell and spigot joints

A connection between two sections of pipe i.e. the straight spigot end of one section is inserted
into the flared out end of the adjoining section. The joint is sealed by a sealing component
Flanged joints:

A flanged joint helps to connect and disconnect two pipes as per the need. A similar
example is as shown in fig.
Bolted joints:

The use of bolted joint is advantageous in the following circumstances


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1. The component that cannot be serviced in line.
2. The components being joined that are not capable of being welded.
3. Quick field assembly is required.
4. The component or pipe section that needs to be frequently removed for surface
Threaded joints:
Threads are cutted in a pipe, flange coupling to connect them with each other and these joints
are called threaded joints.
Flexible joints
The flexible joints are generally used to connect between a washbasin and an angle valve.
Swing joints
Swing joints are special purpose joints mainly used for industrial oriented purposes wherea long
bend is required

Welded and brazed joints:

Welded and brazed joints are the most commonly used joints for joining pipe components.
Expansion joints:

Expansions joints are specially designed in pipeline where a small extension of pipe is required


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Single line diagram:

Single line diagram are most commonly used in plumbing diagram. All power plants and bottling
plant pipes are made by the single line piping diagram.
Double line diagram:

It is used for catalogs and other applications where the visual appearance is more important.

Sewage plumbing system:
The sewage plumbing system is shown in figure. Here the waste line from the bath tub, sink, toilet,
bathroom, shower etc. is connected to a single outlet pipe using pipe pitting’s, directly to sewage.
An emergency cleaning out let is provided to clean the sludge if any block occurs in the pipe line.
A vent is provide for the harmful gas to lead out and to avoid air lock


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Connect two lavatories in series:
Figure shows the connection of two lavatories in series. Here with a single pipe using cross bends
and elbows, the lavatory is coupled with the outlet drain.


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Ex.no:
Plumping of one tap water distribution system

Aim:
To construct the one tape water distribution system by using plumbing components.
Fittings required
1. PVC pipes
2. Tank fitting (GI)
3. Union (GI)
4. MTA (PVC)
5. Gate valve
6. Elbow
7. Reducer (GI)
8. Bend (PVC)
9. FTA (PVC)
10. TAP (PVC)
Procedure:
1. The given PVC pipes are measured out to the required size.
2. The suitable die is selected.
3. Gate valve is connected between the two MTA.
4.1” x ¾” reducer connected between 1” pipe and ¾” pipe.
5.1” (GI) bend is connected between the two pipes.
6.¾”x1/2” reducer connected between ¾” pipe and ½”.
7.½” bend connected between ¾” and ½” pipe.
8. At the end of the pipe ½” MTA tap is connected.
Result:
Thus the plumbing of one tap water distribution system was constructed


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FOUNDRY
INTRODUCTION:
There are large number of tools and equipment’s used in foundry shop for carrying out different
operations such as sand preparation, molding, melting, pouring and casting. They can be broadly
classified as hand tools, sand conditioning tool, flasks, power operated equipments, metal melting
equipments and fettling and finishing equipments. Different kinds of hand tools are used by molder
in mold making operations. Sand conditioning tools are basically used for preparing the various
types of molding sands and core sand. Flasks are commonly used for preparing sand moulds and
keeping molten metal and also for handling the same from place to place. Power operated
equipments are used for mechanizing processes in foundries.

They include various types of molding machines, power riddles, sand mixers and conveyors,
grinders etc. Metal melting equipment includes various types of melting furnaces such as cupola,
pit furnace, crucible furnaces etc. Fettling and finishing equipments are also used in foundry work
for cleaning and finishing the casting.

General tools and equipment used in foundry are discussed as under.

HAND TOOLS USED IN FOUNDRY SHOP
The common hand tools used in foundry shop are fairly numerous. A brief description of the
following foundry tools (Fig.) used frequently by molder is given as under.

Hand riddle:
Hand riddle is shown in Fig. It consists of a screen of standard circular wire mesh equipped with
circular wooden Frame. It is generally used for cleaning the sand for removing foreign material
such as nails, shot metal, splinters of wood etc. from it. Even power operated riddles are available
for riddling large volume of sand.


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Shovel:
Shovel is shown in Fig. It consists of a steel pan fitted with a long wooden handle. It is used in
mixing, tempering and conditioning the foundry sand by hand. It is also used for moving and
transforming the molding sand to the container and molding box or flask. It should always be kept
clean.

Rammers:
Rammers are shown in Fig. These are required for striking the molding sand mass in the molding
box to pack or compact it uniformly all around the pattern.

The common forms of rammers used in ramming are hand rammer, peen rammer, floor rammer
and pneumatic rammer which are briefly described as

(i) Hand rammer:
It is generally made of wood or metal. It is small and one end of which carries a wedge type
construction, called peen and the other end possesses a solid cylindrical shape known as butt. It
is used for ramming the sand in bench molding work.

(ii) Peen rammer:
It has a wedge-shaped construction formed at the bottom of a metallic rod. It is generally used in
packing the molding sand in pockets and comers.

(iii) Floor rammer
It consists of a long steel bar carrying a peen at one end and a flat portion on the other. It is a
heavier and larger in comparison to hand rammer. Its specific use is in floor molding for ramming
the sand for larger molds. Due to its large length, the molder can operate it in standing position.


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(iv) Pneumatic rammers
They save considerable time and labor and are used for making large molds. Sprue pinSprue pin
is shown in Fig. It is a tapered rod of wood or iron which is placed or pushed in cope to join mold
cavity while the molding sand in the cope is being rammed. Later its withdrawal from cope produce
a vertical hole in molding sand, called sprue through which the molten metal is poured into the
mould using gating system. It helps to make a passage for pouring molten metal in mold through
Gating system

Sprue pin
Sprue pin is shown in It is a tapered rod of wood or iron which is placed or pushed in cope to join
mold cavity while the molding sand in the cope is being rammed. Later its withdrawal from cope
produce a vertical hole in molding sand, called sprue through which the molten metal is poured
into the mould using gating system. It helps to make a passage for pouring molten metal in mold
through gating system

Strike off bar:
Strike off bar is a flat bar having straight edge and is made of wood or iron. It is used to strike off
or remove the excess sand from the top of a molding box after completion of ramming thereby
making its surface plane and smooth. It’s one edge is made beveled and the other end is kept
perfectly smooth and plane.


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Mallet
Mallet is similar to a wooden hammer and is generally as used in carpentry or sheet metal shops.
In molding shop, it is used for driving the draw spike into the pattern and then rapping it for
separation from the mould surfaces so that pattern can be easily withdrawn leaving the mold
cavity without damaging the mold surfaces.

Draw spike
Draw spike is shown Fig. It is a tapered steel rod having a loop or ring at its one end and a sharp
point at the other. It may have screw threads on the end to engage metal pattern for it withdrawal
from the mold. It is used for driven into pattern which is embedded in the molding sand and raps
the pattern to get separated from the pattern and finally draws out it from the mold cavity.

Vent rod
Vent rod is shown in Fig. It is a thin spiked steel rod or wire carrying a pointed edge at one end
and a wooden handle or a bent loop at the other. After ramming and striking off the excess sand
it is utilized to pierce series of small holes in the molding sand in the cope portion. The series of
pierced small holes are called vents holes which allow the exit or escape of steam and gases
during pouring mold and solidifying of the molten metal for getting a sound casting.

Lifters
Lifters are shown in Fig. They are also known as cleaners or finishing tool which are made of thin
sections of steel of various length and width with one end bent at right angle. They are used for
cleaning, repairing and finishing the bottom and sides’ of deep and narrow openings in mold cavity
after withdrawal of pattern. They are also used for removing loose sand from mold cavity.


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Trowels
Trowels are shown in Fig. They are utilized for finishing flat surfaces and joints and partings lines
of the mold. They consist of metal blade made of iron and are equipped with a wooden handle.
The common metal blade shapes of trowels may be pointed or contoured or rectangular oriented.
The trowels are basically employed for smoothing or slicking the surfaces of molds. They may
also be used to cut in-gates and repair the mold surfaces.

Slicks
Slicks are shown in Fig. They are also recognized as small double ended mold finishing tool which
are generally used for repairing and finishing the mold surfaces and their edges after withdrawal
of the pattern. The commonly used slicks are of the types of heart and leaf, square and heart,
spoon and bead and heart and spoon. The, nomenclatures of the slicks are largely due to their
shapes.


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Smoothers
Smothers are shown in Fig. According to their use and shape they are given different names.
They are also known as finishing tools which are commonly used for repairing and finishing flat
and round surfaces, round or square corners and edges of molds

Swab
Swab is shown in Fig. It is a small hemp fiber brush used for moistening the edges of sand mould,
which are in contact with the pattern surface before withdrawing the pattern. It is used for
sweeping away the molding sand from the mold surface and pattern. It is also used for coating
the liquid blacking on the mold faces in dry sand molds.

Spirit level
Spirit level is used by molder to check whether the sand bed or molding box is horizontal or not.


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Gate cutter
Gate cutter (Fig.) is a small shaped piece of sheet metal commonly used to cut runners and
feeding gates for connecting sprue hole with the mold cavity.

Gaggers
Gaggers are pieces of wires or rods bent at one or both ends which are used for reinforcing the
downward projecting sand mass in the cope are known as gaggers. They support hanging

Bodies of sand. They possess a length varying from 2 to 50 cm. A gagger is always used in cope
area and it may reach up to 6 mm away from the pattern. It should be coated with clay wash so
that the sand adheres to it. Its surface should be rough in order to have a good grip with the
molding sand. It is made up of steel reinforcing bar.

Spray-gun
Spray gun is mainly used to spray coating of facing materials etc. on a mold or core surface.
Nails and wire pieces
They are basically used to reinforce thin projections of sand in the mold or cores. Wire pieces,
spring and nails they are commonly used to reinforce thin projections of sand in molds or cores.
They are also used to fasten cores in molds and reinforce sand in front of an in-gate.

Bellows
Bellows gun is shown in Fig. It is hand operated leather made device equipped with compressed
air jet to blow or pump air when operated. It is used to blow away the loose or unwanted sand
from the surfaces of mold cavities.


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Clamps, cotters and wedges
They are made of steel and are used for clamping the molding boxes firmly together during
pouring.
FLASKS
The common flasks are also called as containers which are used in foundry shop as mold boxes,
crucibles and ladles.
1. Moulding Boxes
Mold boxes are also known as molding flasks. Boxes used in sand molding are of two types:
(a) Open molding boxes.
Open molding boxes are shown in Fig. They are made with the hinge at one corner and a lock on
the opposite corner. They are also known as snap molding boxes which are generally used for
making sand molds. A snap molding is made of wood and is hinged at one corner. It has special
applications in bench molding in green sand work for small nonferrous castings. The mold is first
made in the snap flask and then it is removed and replaced by a steel jacket. Thus, a number of
molds can be prepared using the same set of boxes.

(b) Closed molding boxes.
Closed molding boxes are shown in Fig. which may be made of wood, cast-iron or steel and
consist of two or more parts. The lower part is called the drag, the upper part the cope and all the
intermediate parts, if used, cheeks. All the parts are individually equipped with suitable means for
clamping arrangements during pouring. Wooden Boxes are generally used in green-sand
molding. Dry sand moulds always require metallic boxes because they are heated for drying.
Large and heavy boxes are made from cast iron or steel and carry handles and grips as they are


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manipulated by cranes or hoists, etc. Closed metallic molding boxes may be called as a closed
rectangular molding box or a closed round molding box

2. Crucible

Crucibles are made from graphite or steel shell lined with suitable refractory material like fire clay.
They are commonly named as metal melting pots. The raw material or charge is broken into small
pieces and placed in them. They are then placed in pit furnaces which are coke-fired. In oil- fired
tilting furnaces, they form an integral part of the furnace itself and the charge is put into them while
they are in position. After melting of metals in crucibles, they are taken out and received in crucible
handle. Pouring of molten is generally done directly by them instead of transferring the molten
metal to ladles. But in the case of an oil fired furnace, the molten metal is first received in a ladle
and then poured into the molds

3. Ladle
It is similar in shape to the crucible which is also made from graphite or steel shell lined with
suitable refractory material like fire clay. It is commonly used to receive molten metal from the


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melting furnace and pour the same into the mold cavity. Its size is designated by its capacity.
Small hand shank ladles are used by a single foundry personal and are provided with only one
handle. It may be available in different capacities up to 20 kg. Medium and large size ladles are
provided with handles on both sides to be handled by two foundry personals. They are available
in various sizes with their capacity varying from 30 kg to 150 kg. Extremely large sizes, with
capacities ranging from 250 kg to 1000 kg, are found in crane ladles. Geared crane ladles can
hold even more than 1000 kg of molten metal.

POWER OPERATED EQUIPMENTS
Power operated foundry equipments generally used in foundries are different types of molding
machines and sand slingers, core making, core baking equipment, power riddles, mechanical
conveyors, sand mixers, material handling equipment and sand aerators etc. Few commonly used
types of such equipments are discussed as under.

Moulding Machines
Molding machine acts as a device by means of a large number of co-related parts and
mechanisms, transmits and directs various forces and motions in required directions so as to help
the preparation of a sand mould. The major functions of molding machines involves ramming of
molding sand, rolling over or inverting the mould, rapping the pattern and withdrawing the pattern
from the mould. Most of the molding machines perform a combination of two or more of functions.
However, ramming of sand is the basic function of most of these machines. Use of molding
machine is advisable when large number of repetitive castings is to be produced as hand molding
may be tedious, time consuming, laborious and expensive comparatively.

Classification of Moulding Machines:
1. Squeezer machine
2. Jolt machine
3. Jolt-squeezer machine
4. Slinging machines
5. Pattern draw machines
6. Roll-over machine


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MOLD AND CORE MAKING:
A suitable and workable material possessing high refractoriness in nature can be used for mould
making. Thus, the mold making material can be metallic or non-metallic. For metallic category,
the common materials are cast iron, mild steel and alloy steels. In the non-metallic group molding
sands, plaster of Paris, graphite, silicon carbide and ceramics are included. But, out of all, the
molding sand is the most common utilized non-metallic molding material because of its certain
inherent properties namely refractoriness, chemical and thermal stability at higher temperature,
high permeability and workability along with good strength. Moreover, it is also highly cheap and
easily available.

MOLDING SAND
The general sources of receiving molding sands are the beds of sea, rivers, lakes, granular
elements of rocks, and deserts. The common sources of molding sands available in India are as
follows:

1. Batala sand (Punjab)
2. Ganges sand (Uttar Pradesh)
3 .Oyaria sand (Bihar)
4. Damodar and Barakar sands (Bengal- Bihar Border)
5 .Londha sand (Bombay)
6 .Gigatamannu sand (Andhra Pradesh) and
7 .Avadi and Veeriyambakam sand (Madras)
Molding sands may be of two types namely natural or synthetic. Natural molding sands contain
sufficient binder. Whereas synthetic molding sands are prepared artificially using basic sand
molding constituents (silica sand in 88-92%, binder 6-12%, water or moisture content 3-6%) and
other additives in proper proportion by weight with perfect mixing and mulling in suitable
equipments.

Properties of molding sand:
The essential requirement of a good molding sand it should produce sound castings which are
free from defects. For producing sound castings, molding sand or mold should possess the
following properties


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1. Porosity or permeability:
When molten metal is poured into a mold, gases and steam be formed. The sand mold should
have sufficient porosity to allow the gases and steam to pass through it. If they are not removed,
casting defects such as blow holes will be formed

2. Plasticity:
It is the property of the molding sand by virtue of which, it flows to all the corners around pattern
in the mold

3. Cohesiveness:
It is the property of the molding sand by which the sand particles stick to each other. Coarse-
grained sand particles give better cohesiveness than spherical grained sand particles

4. Adhesiveness:
Sticking of the sand particles to another body is known as adhesiveness. The molding sand sticks
to the sides of the cope and drag parts of the molding box.

5. Refractoriness:
It is the property of the molding sand, to resist high temperature, without undergoing any changes.
6. Collapsibility:
It is the property of the molding sand by which the mould should disintegrate with minimum force
after the casting has solidified

KINDS OF MOULDING SAND
Molding sands can also be classified according to their use into number of varieties which are
described below.

Green sand
Green sand is also known as tempered or natural sand which is a just prepared mixture of silica
sand with 18 to 30 percent clay, having moisture content from 6 to 8%. The clay and water furnish
the bond for green sand. It is fine, soft, light, and porous. Green sand is damp, when squeezed
in the hand and it retains the shape and the impression to give to it under pressure. Molds
prepared by this sand are not requiring backing and hence are known as green sand molds. This
sand is easily available and it possesses low cost. It is commonly employed for production of
ferrous and non-ferrous castings.


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Dry sand
Green sand that has been dried or baked in suitable oven after the making mold and cores, is
called dry sand. It possesses more strength, rigidity and thermal stability. It is mainly suitable for
larger castings. Mold prepared in this sand are known as dry sand molds.

Loam sand
Loam is mixture of sand and clay with water to a thin plastic paste. Loam sand possesses high
clay as much as 30-50% and 18% water. Patterns are not used for loam molding and shape is
given to mold by sweeps. This is particularly employed for loam molding used for large grey iron
castings.

Facing sand
Facing sand is just prepared and forms the face of the mould. It is directly next to the surface of
the pattern and it comes into contact molten metal when the mould is poured. Initial coating around
the pattern and hence for mold surface is given by this sand.. It is made of silica sand and clay,
without the use of used sand. Different forms of carbon are used to prevent the metal burning into
the sand. A facing sand mixture for green sand of cast iron may consist of 25% fresh and specially
prepared and 5% sea coal. They are sometimes mixed with 6-15 times as much fine molding
sand to make facings. The layer of facing sand in a mold usually ranges from 22-28 mm. From
10 to 15% of the whole amount of molding sand is the facing sand.

Backing sand
Backing sand or floor sand is used to back up the facing sand and is used to fill the whole volume
of the molding flask. Used molding sand is mainly employed for this purpose. The backing sand
is sometimes called black sand because that old, repeatedly used molding sand is black in color
due to addition of coal dust and burning on coming in contact with the molten metal.

System sand
In mechanized foundries where machine molding is employed. A so-called system sand is used
to fill the whole molding flask. In mechanical sand preparation and handling units, no facings and
is used. The used sand is cleaned and re-activated by the addition of water and special additives.
This is known as system sand. Since the whole mold is made of this system sand, the properties
such as strength, permeability and refractoriness of the molding sand must be higher than those
of backing sand.


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Fig .Schematic illustration of the sequence of operations for sand casting
Source: Steel founders society of America
Melting and Pouring of Metals
The next important step in the making of casting is the melting of metal. A melting process must
be capable of providing molten metal not only at the proper temperature but also in the desired
quantity, with an acceptable quality, and within a reasonable cost.

In order to transfer the metal from the furnace into the molds, some type of pouring device, or
ladle, must be used. The primary considerations are to maintain the metal at the proper
temperature for pouring and to ensure that only quality metal will get into the molds. The
operations involved in melting of metal in oil fired furnace/induction furnace and pouring of liquid
metal into the mold cavity will be shown during the demonstration.

Removal and Finishing of Castings
After complete solidification, the castings are removed from the mold. Most castings require some

Cleaning and finishing operations, such as removal of cores, removal of gates and risers, removal
of fins and flash, cleaning of surfaces, etc.


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PATTERN MAKING
For producing a mould or impression of desired shape in Moulding sand or other materials, one
needs to have a wooden or metallic pattern similar to the shape of the mould. The art and science
of preparing the pattern is called pattern making.

Patterns:
A pattern is a replica of the desired casting, which when packed in a suitable material, produces
a cavity called the mould. This cavity filled with molten metal, produces the desired casting after
solidification

Pattern Materials
Some of the common materials used for pattern making are wood, metal, plaster, wax and plastic.
Wood
Wood is the most common material used for pattern making as it satisfies most of the essential
requirements which are considered for a good pattern. It is light in weight and easily available at
low cost, may be easily shaped into different forms as obtained good surface finish easily. The
most common woods used for pattern are Deodar, Teak, Shishum and Mahogany.

Metal
It is used for pattern when a large number of casting with a closer dimensional accuracy is desired.
The pattern of metal has a much longer life than wooden pattern as it does not change its shape
when subjected to moist conditions. A metal pattern is itself cast from a wooden pattern called
“Master Pattern”. Cast-iron, aluminium and its alloys, brass and white metal are commonly used
as a pattern metals.

Plaster
Plaster of Paris (gypsum cement) is also used for making patterns and core-boxes. It can be
easily worked and casted into desired shape. It has a high compressive strength (up to 300 kg/
cm2). Its specific use is in making small patterns and core-boxes involving intricate shapes and
closer dimensional control.

Wax
Patterns which are generally used in investment casting process are made by wax. The wax
patterns are made by pouring the heated wax into a split die or metal mould. The die is kept cool
by circulating the water around it. After complete cooling, the die parts are separated and wax in
shape of pattern is taken out.


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Plastic
At present, plastics are finding their place as a pattern materials due to their specific
characteristics such as high strength and resistance to wear, lightness in weight, fine surface
finish and low solid shrinkage etc.

Types of patterns:
Wood or metal are used in foundry practice. These are difficulty of Moulding on account of design
or typical shape of casting. The most common types of pattern are listed and described below:

(a) Solid or Single Piece Pattern
(b) Split Pattern
(c) Gated Pattern
(d) Loose Piece Pattern
(e) Sweep Pattern
(f) Match Plate Pattern
(g) Multipiece Pattern
Solid or Single Piece Pattern
This type of pattern is the simplest of all the patterns. It is made without joints, partings or loose
pieces For Moulding with two patterns, one or two Moulding boxes may be used. Moulding
operation with this pattern takes more times as the moulder has to cut his own runners, risers and
feeding gates. This type of patterns are usually used for simple and large sizes of casting.

Split Pattern
Whenever the design of casting offers difficulty in making of mould and withdrawal of pattern with
a single piece pattern, split or two-piece pattern is most suitable. This type of pattern eliminates
this difficulty and can be used to form the mould of intricate design or unusual shape of casting.
Split patterns are made in two parts so that one is placed in cope and other in drag with the dowel
pins holding the two together (Figure The surface formed at the line of separation of the two parts,
usually at the center line of the pattern, is called parting line.

Gated Pattern Workshop Technology
In mass production, a number of castings are prepared in a single multi cavity mould by joining a
group of patterns. In such type of multi cavity mould, gates or runners for the molten metal are
formed by connecting parts between the individual patterns as shown in Figure These are made
of wood or metal and specially used for mass productions of small castings.


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Loose Piece Pattern
As per requirement, some solid or single piece type of patterns are made as assemblies of loose
component pieces. Loose pieces are arranged in such a way that it can be removed from the
mould easily as shown in Figure. Usually, this type of pattern requires much maintenance and are
slower to mould.

Sweep Pattern
Large sizes of symmetrical moulds are generally prepared by means of sweep patterns. It consists
of a base, a wooden sweep board and a vertical spindle. The outer end of sweep board carries a
shape corresponding to the shape of desired casting. Usually, sweep patterns are employed for
Moulding part carrying circular sections. The sweep board is attached with the vertical spindle.
After holding the spindle in vertical position, the Moulding sand is rammed in place.

Multipiece Pattern
Sometimes, it is necessary to prepare a pattern in more than two parts in order to facilitate an
easy Moulding and withdrawal of pattern

This type of pattern is known as Multipiece pattern. This type of pattern is used for casting having
a more complicated design. For the preparation of mould this type of pattern requires generally
three Moulding boxes.

Pattern Making Allowances
Usually, the pattern is always made larger than the desired size of the casting on account of
allowance which should be allowed for machining, shrinkage, distortion and rapping etc. For a
pattern, the following allowances are provided:

Machining Allowance
The extra amount of metal provided on the surfaces of casting to be machined is called as a
machining allowance. The amount of this allowance depends upon the method of casting used,
metal of casting, method of machining. Size and shape of casting etc. Ferrous types of metals
require more allowance comparative to non-ferrous metals.

Shrinkage Allowance
Metals used for casting usually shrink and contract due to solidification and cooling. It is
compensated by providing adequate amount of allowance in the pattern which is called as
shrinkage allowance.


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Distortion Allowance
Casting of irregular shape and design tend to distort during cooling period. Distortion of casting
will take place due to uneven metal thickness, shrinkage and rate of cooling. To eliminate this
defect, distortion in opposite direction is provided in the pattern so that this effect of distortion may
be neutralized.

Rapping Allowance
When a pattern is withdrawn from a mould, rapping is used in the pattern. As a result of this
rapping, the cavity in the mould is slightly increased. Therefore, a negative allowance is to be
provided in the pattern to compensate the same.

Draft Allowance
To facilitate easy and early with drawl of pattern from the mould without injuring the vertical
surfaces and edges of mould, patterns are given a slight taper on all vertical surfaces. This slight
taper inward on the vertical surfaces of a pattern is known as the draft or draft allowance. Draft
allowance may be expressed either in degrees or in terms of millimeter per meter on a side. Its
amount varies from 10 mm to 25 mm per meter on external surfaces and from 40 mm to 70 mm
per meter on internal surfaces.

WOODEN PATTERN AND WOODEN CORE BOX MAKING TOOLS
1. Measuring and Layout Tools
1. Wooden or steel scale or rule 2. Dividers
3. Calipers 4. Try square
5. Caliper rule 6. Flexible rule
7. Marking gauge 8. T-bevel
9. Combination square
2. Sawing Tools
1. Compass saw 2. Rip saw
3. Coping saw 4. Dovetail saw
5. Back saw 6. Panel saw
7. Miter saw


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3. Planning Tools
1. Jack plane 2. Circular plane
3. Router plane 4. Rabbet plane
5. Block plane 6. Bench plane
7. Core box plane
4. Boring Tools
1. Hand operated drills 2. Machine operated drills
3. Twist drill 4. Countersunk
5. Brace 6. Auger bit
7. Bit gauge
5. Clamping Tools
1. Bench vice 2. C-clamp
3. Bar clamp 4. Hand screw
5. Pattern maker’s vice 6. Pinch dog
6. Miscellaneous Tools
1. Screw Driver 2. Various types of hammers
3. Chisel 4. Rasp
5. File 6. Nail set
7. Screw driver 8. Bradawl
9. Brad pusher 10. Cornering tool
Colour Coding for Patterns
Representation of different types of surfaces by means of different colours is known as colour
coding. By accepted colour code on pattern, we can judge the casting surfaces either to be
machined or not. Parts of pattern as a core print or seat for loose piece are also justified by it. A
widely accepted colour code for common practice is given below:

 Black color -Surfaces to be left unmachined
 Red color - Surfaces to be machined
 Yellow colour -Core prints
 Red strips on Yellow base Seats for loose pieces
 Black strips on Yellow base Stop offs
 No colour or Clear Parting surface


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WOODEN PATTERN AND WOODEN CORE BOX MAKING MACHINES
Modern wooden pattern and wooden core making shop requires various wood working machines
for quick and mass production of patterns and core boxes. Some of the commonly machines used
in making patterns and core boxes of various kinds of wood are discussed as under.

1. Wood Turning Lathe. Patterns for cylindrical castings are made by this lathe.
2. Abrasive Disc Machine. It is used for shaping or finishing flat surfaces on small pieces of
wood.
3. Abrasive Belt Machine. It makes use of an endless abrasive belt. It is used in shaping the
patterns.
4. Circular Saw. It is used for ripping, cross cutting, beveling and grooving.
5. Band Saw. It is designed to cut wood by means of an endless metal saw band.
6. Jig or Scroll Saw. It is used for making intricate irregular cuts on small work.
7. Jointer. The jointer planes the wood by the action of the revolving cutter head.
8. Drill Press. It is used for drilling, boring, mortising, shaping etc.
9. Grinder. It is used for shaping and sharpening the tools.
10. Wood Trimmer. It is used for mitering the moldings accurately.
11. Wood Shaper. It is used for imparting the different shapes to the wood.
12. Wood Planer. Its purpose is similar to jointer but it is specially designed for planning larger
size.
13. Tennoner. These are used for sawing (accurate shape and size).
14. Mortiser. It is used to facilitate the cutting of mortise and tenon.


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Exercise-1
Pattern making –using wood turning lathe
Aim:
To shaping a wood black into a round and cylindrical object such as table leg by using wood
turning lathe.
Job: a soft wood having length of 550mm and the diameter of 45mm
jobaaaa

Tools and equipment required:
1. Wood turning lathe
2. Gouge tool
3. Skew chisel tool
4. Parting tool
5. Round nose scrapping tool
6. Steel rule and outside caliper


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Theory:
A wood turning lathe machine consists of a cast iron bed, a head stock, a tailstock, a tool rest,
live and dead centers, a speed control device, a main motor, a cone pulley system and spindle.
The wooden piece to be turned is held between two centers (live and dead centers).the live center
is attached to the spindle of the head stock. The work piece is rotated through the spindle by a
motor using a cone pulley system .the dead center is attached to the tailstock through bearing
and it provides support to the work piece. As the work piece revolves between these two centers,
it is cut with a chisel or gouge shaped turning. The tool can be either held on a tool post of the
machine or it can be held in hand by the operator. The tool is moved along the work piece to carry
out turning or grooving action

Procedure:

1. Job is mounted between the centers on wood turning lathe

2. Job is rotated and gouge tool is used for removing material from the job so as to obtain a
diameter of 41mm.

3. Tool is changed and skew chisel used to produce a smooth surface. Diameter is maintained at
40mm.

4. Tool is again changed and parting tool is used to obtain the V-grooves on the surface.

5. Tool is again changed and a scrapping tool is used to obtain a round groove on the surface.

6. Tool is again changed and a parting tool is to be found out and marked with a punch before
mounting the work piece on the correct length

Result: the shape and length leg is obtain as shown in figure.
Precautions:
1. The correct centers the work piece is to be found out and marked with a punch before
mounting the work piece on the machine.
2. Depth of cut should as small as possible to avoid any vibration of the job.
3. Grooves to cut a correct places.
4. Machine is to be stooped while using calipers for measurements.


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Exercise-2

MAKING A SAND MOLD
Aim:

To prepare a sand mold, using the given double piece pattern for a connecting rod

Tools required:

Molding board, drag and cope boxes, molding sand, parting sand, rammer, strike-off bar, bellows.
Riser and sprue pins, gate cutter, vent rod, and draw spike.

Procedure:

Steps Involved In Making a Sand Mold:

1. place the pattern on the molding board, with its flat side on the board
2. place the drag over the board after giving a clay wash inside
3. sprinkle the parting sand on the pattern
4. Pour loose sand, preferably through a riddle over the pattern, until it is covered to a depth
of 4 to 5 cm.
5. pack the molding sand around the pattern and is the corners of flask, with the fingers
6. ram the molding sand in the drag flask uniformly using rammers
7. Strike off the excess sand from the top surface of the drag with the help of strike-off bar.
8. Turn the drag upside down
9. Blow-off the loose sand particles with the bellows and smoothen the upper surface.
10. Place the cope part of the pattern on the top of the drag in position.
11. Locate riser pin on the highest point of the pattern.
12. Place the sprue pin at about 5-6cm. from the pattern on other side the riser pin
13. Sprinkle the upper surface with parting sand
14. Repeat steps 3-7 appropriately
15. Make holes with the vent rod from the surface of the flasks to the pattern
16. Remove the sprue and riser pins by carefully drawing them out. Make a funnel shaped
cavity at the top of sprue hole, called the pouring basin
17. Lift off the cope flask and place it a side on its edge.
18. Insert the draw pin into the pattern, wet the edges around the pattern loosen the pattern
by rapping. Then draw the pattern straight up.
19. Adjust and repair the mould by adding bits of sands, if necessary.


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20. Cut gate into the drag from the sprue to the mold, blow-off any loose sand particles in the
mold
Safety Precautions:
1. Do not let sand too wet. Water is an enemy of molten metals
2. Never sand or look over the mold drawing the poring or immediately after poring
because of the metal might sprut out of the hole.
3. While working with the molten metal wear protective clothing such as face shield or
safety.
Goggles, asbestos or leather gloves, which are tight at the wrist, protective aprons that
will protect from heat as well as molten particles of metal.
4. Provide adequate ventilation to remove smoke and fumes.
5. Do not shake-out a casting too hastily, which may result in second and third degree
burns.


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Result: The sand mold for a solid flange is thus made, which is ready for pouring the molten metal


62 CUTM
MOLD MAKING & CASTING

Aim:

1. To prepare a pattern for given object for lost form casting.
2. To prepare a molasses sand mold from the prepared pattern.
3. To melt and pour iron metal into the mold.

Equipment and Materials

Pattern, core box, molding flasks, molding tools, sand Muller, riddle, sand, molasses, Bentonite,
core baking oven, thermocole, melting furnace, fluxes, pouring ladle, pyrometer, hacksaw, file.

Procedure

Core making

(i) Prepare the core sand
(ii) Assemble (clamp) the core-box after applying some parting sand
(iii) Fill the core box cavity with core sand and ram it
(iv) Make vent holes or insert reinforcing wire as desired
(v) Tap the mold box on all sides to loosen the core from the box, unclamp the core box and
carefully transfer the core on to a baking plate or stand.
(vi) Keep the core in the baking oven and bake it for desired length of the time at a predetermined
temperature. After baking take the core out of the oven and allow it to coolant room temperature.

Mold Making

(i) Place the drag part of the pattern with parting surface down on ground or molding board at the
center of the drag (flask).
(ii) Riddle molding sand to a depth of about 2 cm in the drag and pack this sand carefully around
the pattern with fingers.
(iii) Heap more molding sand in the drag and ram with rammer carefully.
(iv) Strike off the excess sand using strike bar.
(v) Make vent holes to within 1 cm of the pattern surface in the drag.
(vi) Turn this complete drag and place the cope portion (flask) over it.
(vii) Place the cope half of the pattern over the drag pattern matching the guide pins and apply
parting sand over the parting surface. Also place the sprue pin and riser pin in proper positions.


63 CUTM
(viii) Complete the cope half by repeating steps (ii) to (v).
(ix) Remove the sprue and riser pins and make a pouring basin. Separate the cope and drag
halves, and place them with their parting faces up.
(x) Moisten sand at the copes of the pattern and remove pattern halves carefully using draw
spikes.
(xi) Cut gate and runner in the drag. Repair and clean the cavities in the two mold halves.
(xii) Place the core in position, assembled the two mold halves assemble and clamp them
together.

Melting and Pouring

(i) Melt the metal in the furnace. Use appropriate fluxes at proper stages and measure metal
Temperature from time to time.
(ii) Pour the molten metal into the pouring ladle at a higher temperature (say 100oC higher) than
the pouring temperature. As soon as the desired pouring temperature is reached, pour the liquid
metal into the mold in a steady stream with ladle close to the pouring basin ofthe mold. Do not
allow any dross or slag to go in.
(iii) Allow sufficient time for the metal to solidify in the mold. Break the mold carefully and remove
the casting.
(iv) Cut-off the riser and gating system from the casting and clean it for any sand etc.
(v) Inspect the casting visually and record any surface and dimensional defects observed.

Fig: Sand Casting Diagram


64 CUTM
FORGING
Introduction:

Forging is an oldest shaping process used for the producing small articles for which accuracy
in size is not so important. The parts are shaped by heating them in an open fire or hearth by the
blacksmith and shaping them through applying compressive forces using hammers. Thus forging
is defined as the plastic deformation of metals at elevated temperatures into a predetermined size
or shape using compressive forces exerted through some means of hand hammers, small power
hammers, die, press or upsetting machine. It consists essentially of changing or altering the shape
and section of metal by hammering at a temperature of about980°C, at which the metal is entirely
plastic and can be easily deformed or shaped under pressure.
Hand forging process is also known as black-smithy work which is commonly employed for
production of small articles using hammers on heated jobs. It is a manual controlled process even
though some machinery such as power hammers can also be sometimes used.
Black-smithy is, therefore, a process by which metal may be heated and shaped to its
requirements by the use of blacksmith tools either by hand or power hammer. In smithy small
parts are shaped by heating them in an open fire or hearth. Shaping is done under hand control
using hand tools. This work is done in a smithy shop. In smith forging or hand forging open face
dies are used and the hammering on the heated metal is done by hand to get the desired shape
by judgment.
Forging by machine involves the use of forging dies and is generally employed for mass
production of accurate articles. In drop forging, closed impression dies are used and there is
drastic flow of metal in the dies due to repeated blow or impact which compels the plastic metal
to conform to the shape of the dies. The final shape of the product from raw materials achieved
in a number of steps. There are some advantages, disadvantages and applications of forging
operations which are given as under.

Advantages of forging

Some common advantages of forging are given as under.
1. Forged parts possess high ductility and offers great resistance to impact and fatigue loads.
2. Forging refines the structure of the metal.
3. It results in considerable saving in time, labor and material as compared to the production of
similar item by cutting from a solid stock and then shaping it.
4. Forging distorts the previously created unidirectional fiber as created by rolling and increases
the strength by setting the direction of grains.


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5. Because of intense working, flaws are rarely found, so have good reliability.
6. The reasonable degree of accuracy may be obtained in forging operation.
7. The forged parts can be easily welded.

Disadvantages of forging

Few dis-advantages of forging are given as under.
1. Rapid oxidation in forging of metal surface at high temperature results in scaling which wears
the dies.
2. The close tolerances in forging operations are difficult to maintain.
3. Forging is limited to simple shapes and has limitation for parts having undercuts etc.
4. Some materials are not readily worked by forging.
5. The initial cost of forging dies and the cost of their maintenance is high.
6. The metals gets cracked or distorted if worked below a specified temperature limit.
7. The maintenance cost of forging dies is also very high.

Applications of forging

Almost all metals and alloys can be forged. The low and medium carbon steels are readily hot
forged without difficulty, but the high-carbon and alloy steels are more difficult to forge and require
greater care. Forging is generally carried out on carbon alloy steels, wrought iron, copper-base
alloys, aluminium alloys, and magnesium alloys. Stainless steels, nickel based super-alloys, and
titanium are forged especially for aerospace uses.
Producing of crank shaft of alloy steel is a good example which is produced by forging. Forging
processes are among the most important manufacturing techniques utilized widely in
manufacturing of small tools, rail-road equipments, automobiles and trucks and components of
aero plane industries. These processes are also extensively used in the manufacturing ofthe parts
of tractors, shipbuilding, cycle industries, railroad components, agricultural machinery etc.

FORGABLE MATERIALS

Two-phase and multi-phase materials are deformable if they meet certain minimum requirements.
The requirement of wrought metals is satisfied by all pure metals with sufficient number of slip
planes and also by most of the solid solution alloys of the same metal. Wrought alloys must
possess a minimum ductility that the desired shape should possess. To be a forgeable metal, it
should possess the required ductility. Ductility refers to the capacity of a material to undergo
deformation under tension without rupture.


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Forgeable metals are purchased as hot-rolled bars or billets with round or rectangular cross the
sections. Forgeable materials should possess the required ductility and proper strength. Some
forgeable metals are given as under in order of increasing forging difficulty.
1. Aluminium alloys
2. Magnesium alloys
3. Copper alloys.
4. Carbon and low alloy steels
5. Martensitic stainless steels
6. Austenitic stainless steels
7. Nickel alloys
8. Titanium alloys
9. Columbium alloys
10. Tantalum alloys
11. Molybdenum alloys
12. Tungsten alloys

HEATING DEVICES

Forgeable metals are heated either in hearth or in a furnace. The hearths are widely used for
heating the metals for carrying out hand forging operations. Furnaces are also commonly used
for heating metals for heavy forging. The forging job is always heated to the correct forging
temperature in a hearth (Fig. 1) or in a furnace (Fig.2) located near the forging arrangements.
Gas, oil or electric-resistance furnaces or induction heating classified as open or closed
hearths can be used. Gas and oil are economical, easily controlled and mostly used as fuels.
The formation of scale, due to the heating process especially on steel creates problems in
forging. A non-oxidizing atmosphere should, therefore, be maintained for surface protection.
Special gas-fired furnaces have been developed to reduce scaling to minimum. Electric
heating is the most modern answer to tackle scaling and it heats the stock more uniformly
also. In some cases, coal and anthracite, charcoal containing no sulphur and practically no
ash are the chief solid fuels used in forging furnaces. Forge furnaces are built raise
temperatures up to 1350°C in their working chambers


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Box or batch type furnaces

These furnaces are the least expensive furnaces widely used in forging shops for heating
small and medium size stock. There is a great variety of design of box-type furnaces, each
differing in their location of their charging doors, firing devices and method, employed for.
Charging their products. These furnaces are usually constructed of a rectangular steel frame,
lined with insulating and refractory bricks. One or more burners for gas or oil can be provided
on the sides. The job-pieces are placed side by side in the furnace using a slot through a
suitable tong. It is therefore sometimes called slot type furnace.


Mechanical workshop practice 2 by sudarshan.bollapu

Mechanical workshop practice 2 by sudarshan.bollapu

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