DEPARTMENT OF MECHANICAL ENGINEERING

LABORATORY MANUAL

MECHANICAL ENGINEERING WORK SHOP

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SlNo:

CONTENTS Page No:

1. Safety precautions in workshop 3

2. Engineering Materials 4

3.

Carpentry 7

i) Introduction

ii) Study of tools

iii) Model no.1 - T JOINT

iv) Model no.2 – Cross halved - Joint

4.

Fitting

i) Introduction

ii) Study of tools

iii) Model no.1 – Rectangular Block

iv) Model no.2 - V JOINT

5.

Smithy

i) Introduction

ii) Study of tools

iii) Model no.1 – Square Prism

iv) Model no.2 – Octagonal Prism

6.

Foundry

i) Introduction

ii) Study of tools

iii) Model no.1 – flange pattern

iv) Model no.2 – cone pulley pattern

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SAFETY PRECAUTIONS IN WORKSHOP

1. Enter the lab with proper dress code (shirt tuck in with belts and shoes).

2. Half shoes are not permitted.

3. Log hair should tie tightly or use hair nets.

4. Wearing bangles and long chains should be avoided.

5. Handle instruments /tools /equipments care fully.

6. Keep safe distance from moving parts.

7. Don’t shout or run inside the workshop.

8. Strictly follow the safety precautions of individual items while operating.

9. Place any hot job under the board “hot don’t touch “.

10. Be cautions while handling inflammable materials (petrol, diesel, Kerosene,

etc).

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CARPENTRY Introduction

Wood is a important engineering material that is extensively used in buildings and industries. Timber is another name for wood which is obtained from exogenous trees. Wood working means processing of wood by hand and machine for making article of different shapes and sizes.

Classification of timber

According to the manner of growth of trees, timber can be classified as

i) Exogenous or out ward growing ii) Endogenous or in ward growing

i) Exogenous or out ward growing

In exogenous trees the growth take place from the centre by the addition of concentric layers of fresh wood every year, known as annual rings. This variety of trees are suitable for building and other engineering uses the exogenous trees are

Again classified as

a) Conifers or ever green trees

b) Deciduous or broad leaf trees

The conifer give soft woods and the deciduous gives hard wood common example of hard wood are Sal, teak, rose wood, sandal, shisham, oak beach, ash ebony, mango, neem, babool, etc., soft wood include kail pine, deodar chir, walnut seemal etc.

ii) Endogenous or in ward growing timber

These trees grow in wards i.e. .every fresh layer of sap wood is added inside instead of outside. Cane, bamboo, coconut

Seasoning

Seasoning of wood carried out for removing the sap and reducing the moisture content the presence of sap and moisture will render the wood unsuitable for engineering works due to uneven shrinkage, crack, wrapping and decay.

Different methods of seasoning

1. Air seasoning or Natural seasoning

2. Water seasoning

3. Electrical seasoning

4. Kiln seasoning

Ply wood

Thick sheet formed by pasting veneers of wood is called ply. Three or more plys joined by glues is called plywood. The grains of adjacent layers are kept at right angle to

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each other in order to get better strengthening both directions the outer layer are called facing plys and good hard wood veneers are used for this inner ones are called core plys and low quality wood is used for this the ply wood is made by either cold pressing or hot pressing.

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Tools for wood working

The principle hand tools used in a carpentry workshop can be classified into

i) Marking and measuring tool ii) Cutting tooliii) Planning tooliv) Boring toolv) Striking toolvi) Holding tool

i) Marking and Measuring Tools

a) Rules

Rules are used for measuring dimensions. For measuring and setting out dimensions various types of rules are used in carpentry shop.

Steel Rule- Stainless Steel Rule of length 30cm and 60cm.

Flexible Measuring Rule- for measuring large dimensions as well as curved or angular surface dimensions.

b) Straight Edge and Squares

This is a machined flat piece wood or metal having perfectly straight and parallel edges.

c) Try square

Try square consists of rectangular steel blade fixed rigidly to cast iron stock. The length of blade varies from 150mm to 300mm.

d) Marking Knife or Scriber

Marking Knives are used to convert the pencil lines drawn on the wooden surface into deep scratch lines on the surface. They are made of steel with a sharp point at one end and flat blade at the other end.

a) Gauges

Gauges are used to mark lines parallel to the edges of a wooden piece. It mainly consists of a wooden stem sliding inside a wooden stock. The stem carries a steel point for marking lines. The stock position on the stem can be varied and fixed rigidly by tightening the thumb screw. To mark a line parallel to an edge the gauge stock is held freely against the edge and pushed along it, pressing the steel points to the surface.

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ii) Cutting tools

a) Saws

Saw is a cutting tool which has teeth on one edge and cutting is effected by reciprocating motion of the edge relative to the work piece. Cutting occurs during the forward motion , such a saw is called push type saws, the cutting occurs during the backward motion.

i. Hand Saw- This saw is used for short straight cuts. It has a blade of 25-40cm length 6- 10cm width. The number of teeth per cm length ranges from 3-5.

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ii. Tenon Saw (Back Saw)- It has a parallel blade of 25-40cm length and 6-10cm width. The number of teeth per cm length ranges from 5-8.

b) Chisels

The common type of chisels used is briefly explained below.

i. Firmer Chisels- they are most common and general purpose chisel used by a carpenter. They have flat blade of 15-50mm width and 125mm length.

ii. Dove Tail Chisel (beveled edge firmer chisel) - These chisels are used for fine and delicate works as well as for cutting corners.

iii. Mortise chisel – These chisels are used for heavy and deep cut to remove large quantity of wood. These chisels have width of about 15mm but the blade thickness may range from 6-15mm.

iii) Planing Tools

Planing tool is used to smoothen the wooden surfaces.

a) Wooden jack plane

This is the most commonly used plane in carpentry shop. The main part of a wooden jack plane is a wooden block called sole, in which steel blade having knife edge is fixed at an angle with the help of wooden edge. The angle of the blade is kept about 45 ° to bottom surface of the blade.

b) Metal Jack Plane

It serves the same purpose as the wooden jack plane but facilitates a smoother operations and better finish. The body of a metal jack plane is made from a grey iron casting with the side and sole machined and ground to better finish.

iv) Boring Tools

In a carpentry shop boring tools are used frequently for making round holes in wood.

a) Bradawl

It is used for drilling small holes in soft wood. Two types of commonly used gimlet are plane gimlet and twisted gimlet.

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v) Striking Tools

a) Mallet

This is wooden headed hammer of round or rectangular cross section. The striking face is made flat. Mallet is used for striking the cutting tools and has wooden handle

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b) Claw Hammer

This is a hammer having steel head and wooden handle. The flat face of the head is used to drive nails and claw portion for extracting nails out of the wood.

vi) Holding tools

a) Work Bench

This is a table of having size and raised construction made of hard wood. The size ranges from 50- 80 cm in length and about 90cm in width. Two or four carpenters can work at a time on the work bench.

Carpenters Bench Vice

It consists of jaw fixed on the table side and movable jaw kept in position by means of screw and handle. The body of vice is made of cast iron or steel. The jaws are lined with hard wood which can be removed when it is damaged. The screw moves inside the fixed half nut which can be engaged or disengaged by operating the lever. This is made up of a bar of steel. The work is clamped between jaws by rotating the screw using the handle. It is used for clamping glued pieces or holding the work piece of larger size together for various operations.

a) Sash-cramp

b) G Clamp: The clamp of the shape of letter C or G is used to clamp short pieces together as the bar clamp.

Wood working processes

Different operations performed in a carpentry shop can be broadly classified as

i) Marking, measuring and laying out.

ii) Sawing

iii) Planning

iv) Chiselling v) Mortising and Tenoning

i) Marking

It is the process of setting out dimension on wooden pieces to required shape. Marking and measuring operations are carried out collectively on a piece of wood to set out the given dimensions. Marking of wooden pieces is done from drawing or marking components.

ii) Sawing

It is the basic operation carried out in the carpentry shop for cutting wood to the required shape and size; eg: straight, inclined or curved. The sawing of wood may be required along the grains and across the grains.

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In the sawing operation the wood pieces are first fixed in a vice and moved up as sawing proceeds.

iii) Planning

It is an operation used for obtaining a perfectly smooth dimensionally true surface with the application of suitable planers. This operation is known as facing and edging. A perfectly planed surface should be perfectly straight and parallel in width and thickness and all edges square to the face. Before carrying out the planning operations the dimension of wood grains should be checked and planning must be done along the grains.

iv) Chiseling

It is an operation of cutting a small stock of wood for producing different designed shape.

v) Mortising and Tenoning

Mortising is an operation of producing rectangular and square hole in wooden pieces. In the beginning the portions were the mortising operation is to be carried out is marked accurately with a pencil then the mortising operation performed with a mortise chisel and mallet.

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Model No: 1 T- JOINT

Aim

To make a T- joint using given wooden piece.

Work Material

Hard wood, size.

Tools required

Steel rule, try square, marking gauge, jack plane, Hand saw, tenon saw, firmer chisel, mallet, bench vice.

List of operation

Marking, planning, sawing and chiseling.

Procedure

1. A wooden piece is taken and fixed in a carpenter’s bench wise. 2. One of its wider surfaces is planed with a jack plane check the flatness

with try square.3. One of the adjacent sides of the finished surface is planed and check for flatness and

squareness using try square.4. Mark the width and thickness dimension using steel rule, scribers and marking

gauge.5. Chiselling and planning is done to bring the work piece to the required cross section

and length. 6. Cut the work piece in to two piece mark the dimension of male and female pieces

using the marking tool and try square.7. Sawing and chiselling are done on both pieces to shape them in to required

dimension .join them as shown in figure.

Result

T- Joint of required dimension is made.

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Model No: 2 Cross halved - Joint

Aim

To make a cross halved- joint using given wooden piece.

Work Material

Hard wood, size.

Tools required

Steel rule, try square, marking gauge, jack plane, Hand saw, tenon saw, firmer chisel, mallet, bench vice.

List of operation

Marking, planning, sawing, and chiseling.

Procedure

1. A wooden piece is taken and fixed in a carpenter’s bench wise. 2. One of its wider surfaces is planed with a jack plane check the flatness

with try square.3. One of the adjacent sides of the finished surface is planed and check for flatness and

squareness using try square.4. Mark the width and thickness dimension using steel rule, scribers and marking

gauge.5. Chiselling and planning is done to bring the work piece to the required cross section

and length.6. Cut the work piece in to two piece mark the dimension of male and female pieces

using the marking tool and try square.7. Sawing and chiselling are done on both pieces to shape them in to required

dimension .join them as shown in figure.

Result Cross halved – joint of required dimension is made.

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FITTING The term fitting is related to assembly of parts after bringing the dimension or shape the required size or form, in order to secure the necessary fit.

Fitting operations are generally done by using hand tools, after holding and placing the work piece on work bench.

The tools used in fitting practice may be classified in to the following groups

i) Holding toolsii) Cutting toolsiii) Striking toolsiv) Marking toolsv) Measuring tools

i) Holding tools

Bench vice

It is the most widely used device for holding work piece in position during various operations which are carried out in a fitting shop. It consists of a movable jaw and one fixed jaw. The body of the vice is made up of iron or steel by casting. The base of the vice is bolted on the top of the work bench.

Hand vice

It is used for gripping small objects like screws, rivets, keys etc.

V-Block with Clamp

It is used for clamping cylindrical objects. By keeping the round bar on the V-Groove the longitudinal axis of the bar coincides with that of the groove. This enables the working of centre live, drilling along the centre line.

ii) Cutting Tools

Files

A file is a hardened piece of steel containing high percentage of carbon or tungsten. Files are classified based on

i) The cut and spacing of teeth on file.ii) The shape and form of the cross section of file.iii) The length of the file.

Cut and spacing of teeth on the File : The teeth on the file may be of single cut or double cut. A single cut file will be having parallel teeth at 60 °inclination to the centre line. Double cut files have two lines cut teeth. The spacing between the teeth is known as pitch.

i) Rough (R) 8teeth/cmii) Second cut (Sc) 16 teeth/cmiii) Bustard(B) 12 teeth/ cm

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iv) Smooth(S) 24 teeth/ cmv) Dead smooth(Ds) 35 teeth/ cmvi) Super smooth (SS) 50 teeth /cm

Shape or Form of Cross Section of File: Files are also grouped according to their cross section of them; eg: round file, half round file, triangular files, flat files, hand file etc.

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b) Hack Saw

Hack saws are used for cutting metal rods, bars, and pipes job to be sawed is held in a vice and the blade is moved to and for cutting the material. The cutting operation takes place on the forward stroke and in the return stroke, no cutting action takes place.

Hack saw blades are made from different materials like high carbon steel, alloy steel, and high speed steel. They are used in hardened and tempered conditions. Different hacksaw blades have different number of teeth ranging from 5-15 teeth/cm. Blades having lesser number of teeth/cm are used for soft materials like aluminum, brass, bronze etc. Blades having larger number of teeth/cm are used for cutting hard materials like steel and cast iron.

c) Chisels

Different types of cold chisels are used by fitters for chipping and cutting operations chisels are made from high carbon steel or chrome- vanadium steel different type of chisels used in fitting shop

1. Flat chisel2. Cross cut chisel3. Half round chisel4. Diamond point chisel5. Side chisel

iii) Striking tools

Hammer

Hammers are used to strike on a tool or work piece. They are made up of steel by forging process. Hammers for fitting work are classified as

a) Ball Peen Hand Hammer.b) Cross Peen Hand Hammerc) Straight Peen Hand Hammer

The weight of the ball peen, straight peen, cross peen hammers varies from 0.11 to 0.91kg and mallet is used for giving soft blows.

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iv) Measuring and Marking Tools

a) Surface gauge

It consist of cast iron base a spindle and scriber the spindle can be set at any angle scriber can also be set at any angle and at any height from the base maximum up to the length of spindle it is used for marking purpose.

b) Surface Plate

It is a cast iron plate having perfectly smooth and flat surfaces,used as a reference surface for measuring and marking. The flat surface is finished by grinding and the bottom legs of the plate are also machined to keep the surface of the plate in perfect horizontal plane.

c) Angle plate

It is made up of cast iron in different sizes it has two planned surface at right angle to each other and has various slots in each surface to hold the work by means of bolts and clamps.

d) Scribers

It is a piece of hardened steel pointed at ends. It is used like a pencil to scratch lines on the work piece.

e) Punches

Punches are used to make permanent, Mark on the work the punches are classified as

i. Prick Punchii. Centre Punch

The prick punches have sharp point and the included angle is 40°. The centre punches have an included angle of about 60°. They are used to mark heavy punches to start drilling holes.

f) Try square

It is used for making and testing right angle it consist of a steel blade riveted in to a metal stock.

g) Steel rule

It consist of a hardened steel strip having line graduation etched or engraved in it they are usually 150 mm or 300mm long and is used to take linear measurement to an accuracy 1mm or 0.5mm.

h) Bevel protractor

It consist of a steel dial divided in to 360 divisions the dial can be marked or measured by the straight edge straight edge can be slided along the length.

i) Combination set

It is multipurpose instrument that can be used as a protractor, a level a centre square and a try square.

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j) Vernier caliper

A vernier caliper is a precision measuring instrument it is used to measure up to an accuracy of 0.02 .

Least count of vernier scale =1MSD – 1VSD

Dimensional formula of vernier caliper = (MSR +VSR) LC.

Fitting Process

i) Marking

Marking on the work piece is done by setting out dimensions as given in the working drawing or by directly transferring them from a similar point. The surface to be marked is coated with red lead, French chalks or copper sulphate and allowed to dry. After this the work piece is laid on the surface plate, V-block. Marking of vertical lines is done by means of height gauges.

ii) Sawing

Sawing is the process of cutting different metal pieces to the desired size and shape. While sawing the job is held in a vice. Cutting action in sawing takes place in the forward stroke, no pressure must be applied on the return stroke. Do not use new blades on hard materials directly.

iii) Filing

Normally the job is held in a vice, the file handle is held in the right hand and the other side of the file is held in the left hand. The right hand apply force while the left hand only act as guide. The worker stand with his foot forward and right foot behind. Normally the left foot is below the vice. The cutting action takes place in the forward direction only.

In straight filing the file is pushed and pressed forward at right angles to the length of the job. In draw filing the file is gripped at each end and pushed forward and drawn backward along the length of the job.

iv) Scraping

Scraping involves removing convex sports from machined surfaces and the tool used is known as the scraper. It is a very important hand operation employed in the fitting shop for obtaining the fine surface finish. Scrapers are usually made from worm out files. For manufacturing scrapers the files are heated to forging temperature and forged to the required shape. Further hardening and tapering are done on the files to set the required hardness.

v) Chipping

Chipping is the process of removing metal by means of a chisel. In chipping the angle of cutting must be throughout the operation. Incase the surface to be chipped is too large, it is advisable to cut the grooves throughout the surface by means of cross cut chisel and then clip off the remaining metal.

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vi) Drilling

It may be defined as the process of producing circular holes in a metal piece with the help of a drill. Drilling operation is carried out with the help of a drilling machine.

Before carrying out the drilling the location of the centre of the hole is marked and a deep punch indentation is made using a centre punch. The work is firmly held in vice over the table of drilling machine and the drill is fitted in the socket of the drilling spindle. After aligning the centre and the drill, machine is switched on and the rotating drill is pressed gradually into the work piece to produce the desired hole.

vii) Reaming

Reaming is accurate operation of finishing holes. The allowance generally provided for the job is 0.05 to 0.10mm. in this operation the reamer is held in the wrench and forced into the hole to be reamed. The rotary motion is provided the reamer with the help of handle by applying force to cut the metal. Different cutting teeth remove the extra metal and hole is finished to size.

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viii) Tapping and Dyeing

The process of cutting internal thread using a tap is called tapping. The hole of diameter equal to core diameter of the screw is initially drilled. The work is clamped on the bench vice and first tap end is inserted and rotated applying slight downward pressure. This makes rough thread form moves forward making the thread of incomplete depth. Frequent forward and backward of the tap is reamed for easy progress of thread cutting.

Similar to tapping dyeing is the cutting of external thread on round rod using a tool called die. The rod called blank is made to the correct size of the thread diameter and the end slightly tapered for easy entrance of the die. The die is turned forward applying slight pressure form the top. When the cutting is started the die should be turned backward and forward several times until threading is complete.

ix) Assembling

Assembling is joining of finished parts together to form the required component.

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Model No:1 RECTANGULAR BLOCK

Aim

To make rectangular block using given mild steel flat piece

Materials required

Mild steel flat size,

Tools required

Steel rule, scriber, centre punch, ball peen hammer, hacksaw, try square, bench vice, surface plate, flat file, triangular file, surface gauge.

Operations

Rough filling, marking, punching, smooth filling, checking and finishing.

Procedure

Copy the given drawing in the work record.

Collect the tools and select the blank piece.

Check the size of the blank for its suitability to make the model as per drawing.

File one of the edge to perfect flat and then adjacent edge to flat and mutually perpendicular to filed edge the edges to form a perfect rectangle.

Apply a thin coating of markin media (chalk powder mixed with water ) and get it dry.

Mark the dimensional lines by using surface plate, angle plate, steel rule and surface gauge.

Punch the witness marks by using dot punch and hammer.

File the excess material by using flat file.

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Check the accuracy and shape by using steel rule and try square.

If any error finish it by smooth file .Thus finish the work.

Result

Rectangular block given dimension is made.

Model No:2 V-JOINT25

Aim

To make V-Joint using given mild steel flat piece.

Materials required

Mild steel flat size.

Tools required

Steel rule, scriber, centre punch, ball peen hammer, hacksaw, try square, bench vice, surface plate, flat file, triangular file, surface gauge.

Operations

Rough filling, marking, punching, smooth filling, checking and finishing.

Procedure

Copy the given drawing in the work record.

Collect the tools and select the blank piece.

Check the size of the blank for its suitability to make the model as per drawing.

File one of the edge to perfect flat and then adjacent edge to flat and mutually perpendicular to filed edge the edges to form a perfect rectangle.

Apply a thin coating of markin media (chalk powder mixed with water ) and get it dry.

Mark the dimensional lines by using surface plate, angle plate, steel rule and surface gauge.

Punch the witness marks by using dot punch and hammer.

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Cut the excess material using hack saw and file and file the excess material by using flat file and triangular file.

Fit the male part to female part, Check the accuracy and shape by using steel rule and try square.

If any error finish it by smooth file .Thus finish the work.

Result

V- joint given dimension is made.

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SMITHY Forging may be defined as the plastic flow of metal by the application of

compressive forces in which a metal is altered in shape permanently without rupture the application of heat increases the plasticity is of metals. The main advantages of forging are;

1. Increases the strength of metals by producing directional grains.

2. Refine the structure of the metal and renders it more dense.

3. Any material having good malleability can be forged, since compressive forces are involved.

Some forgable materials in the order of forgability ;

1. Pure Aluminium 2. Pure Manganese3. Pure Copper 4. Most of pure metals5. Aluminium Alloys6. Copper Alloys7. Alloy Steels8. Maraging Steels9. Stainless Steels10. Tungsten Alloy etc

Forgability of materials depends on

a) Metallurgical Factors

b) Mechanical Factors

a)Metallurgical Factors

Pure metals possess good machinability and thus good forging properties. During forging a material is subjected to compressive and shearing stresses. Compressive should be applied to move forgeable position and tensile to less forgeable ones.

Forging temperature

Forging is a hot working process in which the metal is heated to a proper temperature so that its grains required plastic properties before deformation. Insufficient temperature will not induce sufficient plasticity in the metal to shape it properly by hammering.

Grain flow in forged part

Forging produces continuous and uninterrupted directional grains. It shows controlled fibrous structure and exhibit maximum mechanical strength for components subjected to shock and failure eg; gear blanks, crank shaft, highly stressed components.

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Forging temperature

i) Mild steel- 1250°c

ii) Medium carbon steel- 1220 °c

iii) High Carbon Steel- 1150 °c

iv) Wrought Iron- 1250°c

v) Stainless Steel- 1250°c

vi) High Speed Steel- 1250°c

vii)Copper and its alloys- 950°c

viii) Aluminium and Magnesium alloys- 500°c

Tools and equipments in smithy

Tools and equipments in smithy shop classified into

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i) Heating equipment

ii) Work supporting tool

iii) Striking tool

iv) Holding tool

v) Cutting tool

vi) Metal shaping tool

vii)Measuring tool

i) Heating equipment

a) Smiths Hearth

The purpose of a forge is to contain the fine necessary for heating the metal before hammering. Heating is necessary to impart sufficient plasticity to the metal. The simplest forge used by the blacksmith is an open heater fired forced draft furnace. It consists of rubest cast iron or steel structure erected on four legs. It has an iron bottom known as hearth, a chimney for escape of flue gases at the top and tuyuere to let in a blast of air at the bottom. The hearth is provided with fire brick lining and carries coke. Air under pressure is supplied from the blower through the tuyere opening in the hearth. The amount of heat produced in the hearth largely depends upon the supply of air.

ii) Work supporting tool

a) Anvil

Forging of hot metal pieces is done by supporting the pieces on the anvil. The body of the anvil is of mild steel and to give hard top face, piece of high carbon steel about 20 to 25mm thick is welded on. In the top of the anvil is a square hole to take the shank of various tools. Anvil vary up to about 150 kgs.

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b) Swage Block

It is made of cast steel or forged steel. It carries a number of blocks of different shapes and sizes along its four side faces. A swage block is used for giving finishing to a work piece.

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The work piece is given a rough shape on the anvil by hammering and then placed in a similar shaped recess in the side of the swage block. The swage block of similar shape is then placed on top of the work piece and hammered to finish the component to the desired shape.

iii) Striking tool

a) Hammers

Hammers are the principal tools used in forging. Hammers are produced by forging steel to the desired shape. Forging hammers are classified according to size and weight of the hammers.

A sledge hammer is heavier than the smithy hard hammers and weighs from 3kg to 8 kg.

b) Tongs

Tongs are used by the smith for holding and turning the hot metal work piece. They are made of steel. Tongs are classified according to the shape of their jaws as close flat tongs, duck neck tong, square hollow tong, round hollow tongs etc.

iv) Metal Shaping Tools

a) Fullers

Fullers are used for checking down a piece of work, the reduction often serving as the starting point for reduction. They are made in top and bottom tools, the bottom tool fitting in the hard die hole and the top held by the smith and struck by the striker.

b) Swage

Swages are used for work which has to be reduced and finished to round or hexagonal form and are made with half grooves of dimensions to suit the work being reduced. Swages may be in separate top and bottom halves are connected by strips of spring steel.

c) Flatter and Set Hammer

Flatter and Set Hammers are used for finishing flat surfaces about 75mm square and are made with a perfectly flat surfaces. As the work is supported directly on the anvil for flattering, only the top handled tool is necessary. The set hammer is a smaller tool used for finishing corners and confined spaces.

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v) Cutting tool

a) Chisel

Chisels are used for cutting metals and for nicking prior to breaking. They may be hot or cold depending on whether the metal to be cut is hot or cold. The cold chisel has its edge hardened and tempered with an angle of 60° while hot chisel is 30°. Hardening is not necessary.

b) Punches Drift

When metal is at forging heat holes may be put in it by punching and opened out by driving through a larger tapered punch called a drift. When punching a hole it should be carried out from both sides to avoid driving the punch onto the hard anvil face.

vi) Measuring Tools

The dimension and shape of a hot work piece has to be inspected between forging and after finishing.

i) Steel rule

ii) Outside and Inside caliper

iii) Gauges

iv) Temperatures measuring instruments

Forging Operations

i) Upsetting

This consisting of increasing the thickness of a bar at the expense of its length and is brought about the end pressure. The pressure may be obtained by driving the end of the bar against the anvil, by separating on the anvil and hitting with hammer or try clamping in a vice and hammering. The position and nature of upsetting will depend on heating and upon the type blow delivered.

ii) Drawing Down

It is the process of increasing the length of a bar at the expense of its width or thickness or both. When the primary drawing down in this way the work may be finished with the flatter.

iii) Setting Down

It is a local thinning down effected by the set hammer. Bends may be either.

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SQUARE PRISM

Aim

To make a square prism of given dimensions using the given cylindrical iron piece.

Materials required

Cylindrical iron piece, coke for heating.

Tools required

Hammer tongs, flatter, anvil, forge, steel rule.

List of operations

i) Heating.

ii) Hammering.

iii) Jumping to reduce the length.

iv) Hammering to rectangular shape.

Procedure

1) Heat the given cylindrical piece to red hot temperature using forge.

2) Take the heated piece using tongs and hammer it after placing lengthwise and face of the anvil to form rectangular prism.

3) Reduce the length of the prism to the required length by jumping, after holding in vertical over the anvil face.

4) Flatten the four faces using flatter.

5) Shape one end to conical form by hammering.

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6) Square form is made by hammering and by placing the work on the anvil.

Result

Square prism required dimension is made.

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Model No: 2 OCTAGONAL PRISM

Aim

To make a octagonal prism of given dimensions using the given cylindrical iron piece.

Materials required

Cylindrical iron piece, coke for heating.

Tools required

Hammer tongs, flatter, anvil, forge, steel rule.

List of operations

1. Heating.2. Hammering.3. Jumping to reduce the length.4. Hammering to rectangular shape.

Procedure

1) Heat the given cylindrical piece to red hot temperature using forge.

2) Take the heated piece using tongs and hammer it after placing lengthwise and face of the anvil to form rectangular prism.

3) Reduce the length of the prism to the required length by jumping, after holding in vertical over the anvil face.

4) Flatten the eight faces using flatter.

5) Shape one end to conical form by hammering.

6) Octagonal form is made by hammering and by placing the work on the anvil.

Result

Octagonal prism required dimension is made.

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FOUNDRYFoundry or casting is the process of forming metal object by melting metal and

pouring it into mould cavities sand casting is the most common of all casting process.

Sand Casting Processes

Sand casting Process consist of the sand mould having properly shaped cavity and pouring molten metal into it to produce a casting. The process of producing sand casting contains the following sections.

i) Pattern making.

ii) Moulding.

iii) Melting pouring.

iv) Fettling, Cleaning and Inspection.

i) Pattern making

A pattern is form made of wood, plastic or any other suitable material around which moulding and is packed to shape the casting cavity of a mould pattern generally make wood ,plastic, plaster of paris ,wax, ferrous and non ferrous metal.

Types of patterns

a) Solid patterns

The pattern is made in one piece and carries no joint.

b) Split Patterns

These patterns are split along the parting surface of mould.

c) Loose Piece Patterns

This is a pattern with loose piece so that the pattern can be removed from the mould in pieces after moulding.

d) Match Plate Patterns

They are split pattern separated by a plate of the required thickness and shape. Match plate pattern are usually made of metal or plastic and used for machine moulding of small components.

e) Gated Patterns

The passage for flowing molten metal are also made using these types of patterns.

f) Sweep Patterns

Moulds which are symmetrical and regular in shape can be made with the use of wooden piece called sweep.

g) Segmental Patterns

They are sections of a pattern arranged in such a manner as to form a complete mould by moving from one segment of the mould to the next.

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Pattern allowances

i) Shrinkage allowance - 9-13mm/meter length.

ii) Machine finish allowance- 3mm is given as extra for machining surfaces.

iii) Pattern draft and tapper allowances.

iv) A taper of 10 -20mm / meter length.

Classified depending on the shape and size of the casting.

The shape of a casting is initially made using wood or plastic which is called pattern. Using the pattern a cavity is made inside the sand mould and the process is called moulding. Metal to be cast is melted in a furnace and poured to the cavity of the mould. After solidification and cooling the sand mould is broken and the casting is taken out. Unnecessary projections are removed and the surface is cleaned to finish the casting for inspection.

Metals commonly cast in foundries can be grouped as below.

1) Ferrous metals- cast iron and steel

2) Non ferrous metals- copper, lead and its alloys.

3) Aluminum and its alloys

Colour coding for patterns

The important parts or surface of a pattern are represented by different colors for their identification

i) Red – surface to be machined.

ii) Black-surface to be un machined.

iii) Yellow – core prints.

iv) Black strips on yellow base –stop –offs.

v) No color – parting surfaces.

ii) Moulding:

The process of making this cavity or mould in the compact sand is called moulding.

Mould materials

The mould or cavity in to which the molten metal is poured is made of some heat resisting material it classified in to two

(1) Metals – cast iron , steel and aluminum, bronze etc

(2) Non metals – moulding sand, graphite plaster of Paris silicon carbide ceramics, wax etc.

Moulding Sand

Sand is widely used mould material for casting ferrous and non ferrous metals

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It is lower cost and easy for handling. Moulding sand classified into,

i) Natural moulding sand

ii) Synthetic sand.

i) Natural moulding sand

It is also called green sand which contain sufficient amount of clay and is mined from river beds or from sand pits it contain 5-20 % clay and 5-8%water before making mould.

ii) Synthetic sand

High silica sand is artificially compounded by mixing with some other constituents like binders and additives are known synthetic sand synthetic sand are used for casting steel other ferrous and nonferrous alloys.

Classification of moulding sands according to specific uses

i) Green sand

It is a mixture of silica sand with 18- 30% clay, having a total water of from 6-8%. The clay and water furnish the bond for green sand it is fine soft and light and porous. Being damp when squeezed in the hand it retain the shape. Moulds prepared in the sand are known as green sand moulds.

ii) Dry Sand

Green sand that has been dried or brooked after the mould is made is called dry sand. They are suitable for large casting.

iii) Facing Sand

Facing sand forms the face of the mould. It is used directly next to the surface of the pattern and it comes into contact with the molten metal when the mould is poured. Consequently it is subjected to the dry condition and must possess high strength and refractoriness. It is made of silica sand and clay without without addition of used sand. Different forms of carbon are used to prevent the metal from burning into the sand.

iv )Parting Sand

It is used to keep the green sand from sticking to the pattern and also allow the on the pasting surface of the cope and drag to separate with out adhering Clean clay free silica sand serves the purposes as pasting dust.

v) Loam sand

It is mixture of 50% clay and 50 %sand loam sand is used for heavy large casting.

Main constituents of moulding sand

(1) Silica sand

(2) Binders

(3) Additives

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(4) water

1) Silica sand

Silica sand is the granular particle resulting from the break down of quarts and other silica rocks moulding sand contain 50% to 95%of silica sand in it.

2) Binders

A material present in moulding sand which imparts cohesiveness to it is called binder. Common binder used in foundry is Organic binders, linced oile dextrin, resins In organic binders- clay, sodium silicate etc.

3) Sand additives

Additives are those material other than binders which are added moulding sand to develop certain desirable properties in the mould the commonly used additives are, coal dust, silica flour, graphite wood flour.

Properties of moulding sand

i) Porosity

It is also called permeability when hot metal poured in to mould large volume of gas and steam evolved porosity the properties of allows the passage of gas and steam trough the mould.

ii) Refractoriness

It is ability molding sand with stand high temperature.

iii) Adhesiveness

It is the property of ad hearing surface of the moulding box it is help heavy mass of sand successfully held in moulding flask.

iv) Cohesiveness

This is ability moulding sand particle to stick together.

v) Collasability

It is the property due to which sand mould automatically collapse after solidification of the casting.

vi) Flow ability

It is that property of the moulding sand due to which it flows during ramming to all positioned the moulding flask and pack around the pattern.

Preparation of moulding sand

Preparation of moulding sand includes, mixing of sand, tempering of sand, sand conditioning and sand testing.

a) Mixing of sand

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some times artificial means are adopted to make the sand suitable for use sand mixing is the process trough which we add those material to the sand which are rich in such characteristic in which the sand lacks.

b) Tempering of sand

The process by which adequate amount of moisture is added to moulding sand to make workable.

c) Sand conditioning

The proper sand conditioning means the uniform distribution of binder around the sand grains.

Sand testing

A common physical test which is generally followed by most of the moulders for judging the sand condition is to grip a hand full of the reappeared foundry sand and then relieve the pressure of the fingers in fully mechanized foundry.

The sand mixing riddling and sand testing of sand are done by machine following tests are conducted their by equipment ,moisture content test ,grain fines test , clay content test ,permeability test , strength test , hardness test.

Defects in Casting

i) Shifts – This is an external defect in a casting caused due to core misplacement or mismatching of top and bottom parts of the casting usually at a parting line. Mismatch of flasks in another likely cause of shift.

ii) Warpage- warpage is undesirable deformation in a casting that occurs during or after solidification. Due different rates of solidification different sections of a casting, stresses are set up in adjoining walls resulting in warp age in these areas. Large or flat sections or intersecting sections such as ribs are particularly prone to warp age.

iii) Fin- A thin projection of metal surface of the casting

iv) Swell- a swell is an enlargement of the mould cavity by metal pressure resulting in localized or enlargement of the casting.

v) Blow holes- blow holes are smooth round holes appearing in the form of large no. of small holes below the surface of a casting.

vi) Drop- a drop occurs when the upper surface of the mould cracks and pieces of sand fall into the molten metal.

vii)Dirt- in some cases dirt and sand are embedded in the casting surface.

Honey combing- this is an external defects consisting of a no. of small cavities in close proximity.

Metal penetration and rough surfaces- an uneven and rough external surface of the casting.

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ix) Sand holes-sand holes are formed on external surface or inside the casting.

viii) Pin holes- are numerous small holes usually less than 2mm, visible on the surface of the casting cleaned by shot blasting.

ix) Scabs- liquid metal penetrate behind the surface layer of sand

x) Shrinkage cavity- is a void in the casting caused mainly by uncontrolled solidification of the metal.

xi) Hot tears- they are internal or external cracks having ragged edges occurring immediately after the metal has solidified.

Tools and equipments in foundry

The tools used in foundry practice may be classified in to the Following group

a) Hand tools

b) Moulding box

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c) Core box

d) Moulding machine

e) Melting equipment

f) Pouring ,shake out and finishing equipments

g) Inspection and testing equipments

Hand tools

a) Shovel

It is used to mix and condition the foundry sand. It is also used to transfer sand from one place to another.

b) Hand Riddle

This is a circular frame fitted with a standard wire mesh at the bottom it can be used to riddled (sieved) and remove lumps and foreign materials.

c) Hand Rammers

To compact the sand by ramming it is made out of wood or metal.

d) Striking Bar

A metal bar to remove excess sand over box.

e) Went Wire

It is used for piercing holes in the rammed sand to permit easy escape of steam and gases generated during pouring of the molten metal.

f) Trowels

A trowel consist of metal blade fitted with wooden handle the trowels of various shapes are used for finishing and repairing mould cavities.

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g) Lifters

Lifters are made of thin section of steel it is used to clean and finish the bottom of mould cavity to finish vertical surfaces and to remove loose sand from mould.

h) Sprue pin and flow off pin

sprue and flow off pins top make the own sprue ( the inlet hole of molten metal) or riser hole.

i) Swab

A brush to water the mould surface during finishing

j) Draw spike and draw screw

It is tapered steel rod sharp point other end it is used to rap and draw the pattern draw screwed one end is threaded to draw big patterns from the mould with the help of rapping plate.

k) Bellows

For blowing off loose sand from mould cavities.

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Moulding Flasks

The sand moulders are prepared in specially constructed boxes called flask they consist of to or more parts the lower part called drag the upper part is cop if is the flask is made in three parts the intermediate parts called cheek These boxes can be made of either wood or metals common type of moulding box are box flask, snap flask, wooden moulding box.

Core and core box

A core is essentionally a body of material which forms the contour of casting that is not moulded with a pattern are mainly used to form internal cavities or holes in casting core box are used to make cores.

Moulding machine

The main function done by a moulding machine rare given below

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a) Ramming of moulding sand –this may be achieved by jolting ,squeezing blowing slinging

b) Rolling over or inverting the moulds through 1800

c) Rapping the pattern

d) With drawing the pattern from the mould

Most of the machines perform a combination of two or more of the above mentioned functions and are available in different models and size

Melting equipment

Furnaces suitable for melting some important metals are given below.

1) Cast iron- cupola furnace, electric furnace, rotary furnace.

2) steel- open hearth, electric &Bessemer furnace.

3) Non ferrous metal- crucible furnace, rotary furnace & electric.

Pouring equipment

Ladles are used to pouring molten metal in to the mould.

They classified into

1) Pouring ladle, (hand ladle)47

2) Shank ladle, trolleys rail cranes, etc.

Inspection and testing equipments

Inspection and testing are done for finding both surface and sub surface defects. In casting they are,

1) Destructive inspection method tensile test, hardness test, fatigue, creep etc.

2) Non destructive inspection methods, x- ray, ultra sonic test, magnet particle test.

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Model No.1 FLANGE PATTERNS

Aim

To make sand mould using the given flange pattern

Materials required

Moulding sand, parting sand and water

Tools required

Moulding box, shovel, hand rammer ,strike off bar ,vent wire, trowel , lifter .sprue and flow off pin swab ,hand riddle

List of operation

1) Preparation of moulding sand

2) Clay applying around the box

3) Pattern placing

4) Compacting the of sand over the pattern

5) Turn over the box

6) Parting sand spreading

7) Cope box and sprue pin, flow off pin placing

8) Same as drag

9) To make vent hole and pouring and riser basin

10) Marking and detaching and turn over the box

11) Finishing the both surface cutting gating system

Procedure

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Place the moulding board on the work bench and keep the pattern over it with its flat surface down.

Set the drag over the board keeping the up side down, so that the pattern is located approximately at the centre.

Fill about 15-20mm layer of facing sand over the pattern and compact it by hand around the pattern.

Fill the backing sand in two- three layers followed by ramming, to fill the drag slightly in excess level.

Remove the excess sand using the strike of bar to get a level surface and finish it by using trovel.

Make small pin holes with the help of vent wire. So that permeability is improved for removal of gases during casting.

Turn the drag box up side down, so that the parting line face of the pattern comes to the top.

Fit the cope over the drag in alignment and place the top part of the pattern in position. Place the spruce pin in vertical position on the pasting face of mould, nearby pattern and place the flow off pin on the top most point of the pattern .a layer of facing sand is filled and compacted with hand over pattern for holding the pins in position.

Fill the backing sand in two three layers followed by ramming so that the cope is fitted to a slightly excess level.

Remove the excess sand using strike of bar and level the surface with a trovel.

Make vent holes using vent wire.

Remove the spruce and flow off pins carefully and cut the sprue funnel(pouring basin)

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Detach the cope from drag and lift it carefully. Place the cope over the board bench keeping the pasting plane upwards.

Cut the runner and gate (opening to mould cavity) from sprue hole to the pattern using pointed small trowels slicks and lift.

Moisture the sand around the pattern with the help of swab and draw out the pattern using a draw screw or spike.

Clean the mould cavity and surface using bellows. Inspect the finish and filling of corners of the cavity.

Dust the two halves of mould cavity with graphite or coal powder for better finish of casting.

Assemble the two halves carefully, after keeping the core in position and bolt them to keep ready for pouring metal. If dry sand moulds are required the moulds are dried in sun lights or ovens.

Result

Sand mould of given flange pattern is made.

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Model No: 2 CONE PULLEY PATTERN

Aim

To make sand mould using the given cone pulley pattern

Materials required

Moulding sand, parting sand and water

Tools required

Moulding box, shovel, hand rammer, strike off bar, vent wire, trowel, lifter, sprue and flow off pin swab, hand riddle

List of operation

1) Preparation of moulding sand.

2) Clay applying around the box.

3) Pattern placing.

4) Compacting the of sand over the pattern.

5) Turn over the box.

6) Parting sand spreading.

7) Cope box and sprue pin, flow off pin placing.

8) Same as drag.

9) To make vent hole and pouring and riser basin.

10) Marking and detaching and turn over the box.

11) Finishing the both surface cutting gating system.

Procedure

Place the moulding board on the work bench and keep the pattern over it with its flat surface down.

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Set the drag over the board keeping the up side down, so that the pattern is located approximately at the centre.

Fill about 15-20mm layer of facing sand over the pattern and compact it by hand around the pattern.

Fill the backing sand in two- three layers followed by ramming, to fill the drag slightly in excess level.

Remove the excess sand using the strike of bar to get a level surface and finish it by using trovel.

Make small pin holes with the help of vent wire. So that permeability is improved for removal of gases during casting.

Finish the top surface with trovel and sprinkle the parting sand over the surface to form a very thin layer for separation.

Finish the top surface with trovel and sprinkle the parting sand over the surface to form a very thin layer for separation.

Fit the cope over the drag in alignment and place the top part of the pattern in position.

Place the spruce pin in vertical position on the pasting face of mould, near by pattern and place the flow off pin on the top most point of the pattern .a layer of facing sand is filled and compacted with hand over pattern for holding the pins in position.

Fill the backing sand in two three layers followed by ramming so that the cope is fitted to a slightly excess level.

Remove the excess sand using strike of bar and level the surface with a trovel.

Make vent holes using vent wire.

Remove the spruce and flow off pins carefully and cut the sprue funnel(pouring basin).

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Detach the cope from drag and lift it carefully. Place the cope over the board bench keeping the pasting plane upwards.

Cut the runner and gate (opening to mould cavity) from sprue hole to the pattern using pointed small trowels slicks and lift.

Moisture the sand around the pattern with the help of swab and draw out the pattern using a draw screw or spike.

Clean the mould cavity and surface using bellows. Inspect the finish and filling of corners of the cavity.

Dust the two halves of mould cavity with graphite or coal powder for better finish of casting.

Assembled the two halves carefully, after keeping the core in position and bolt them to keep ready for pouring metal. If dry sand moulds are required the moulds are dried in sun lights or ovens.

Result

Sand mould of given cone pulley pattern is made.

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