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WORKSHOP PRACTICE

MA’DIN POLYTECHNIC COLLEGE 1

LAB MANUAL

SEMESTER: I & II

REVISION 2015

WORKSHOP PRACTICE

WORKSHOP PRACTICE


SL.NO NAME DESIGNATION/SECTION MOBILE.NO 1 NAMSHEED. C. T HOS 9142031036

2 SAYYID MAHMOOD. P. K W/S SUPDT. 8086254383

3 MOHANAN. V. K FOREMAN 9567490401

4 NABEEL. N W/I - MACHINE SHOP 9656844140

5 ANAS MON. T T/I - FOUNDRY 9656509378

6 MADHU. M T/I - FITTING 9526733143

7 VINEESH KUMAR. C T/I - CARPENTRY 9744929108

8 SHINTU. K T/I - SHEET METAL 9645847427

9 DEEPAK. K T/M - WELDING 9895432625

10 AGEESH. P T/M - SMITHY 9656581908

STAFF DETAILS

WORKSHOP PRACTICE


COURSE TITLE : WORKSHOP PRACTICE

COURSE CODE :

COURSE CATEGORY : F

PERIODS/ WEEK : 3

PERIODS/ SEMESTER (I & II) : 90

CREDIT : 3

TIME SCHEDULE

MODULE TOPICS PERIODS 1 Carpentry, Foundry & casting 27

2 Smithy, Forging & Fitting 27

3 Sheet metal 18

4 Welding 18

Total 90

Course outcomes: STUDENT WILL BE ABLE TO:

Perform various exercises on given drawing and specifications in Carpentry shop, Foundry &

Casting shop.

Perform various exercises on given drawing and specifications in Smithy, Forging & Fitting

shop.

Perform various exercises on given drawing and specifications in Sheet metal shop.

Perform various exercise on given drawing and specifications in Welding shop. CONTENT DETAILS

MODULE I

Introduction, objectives, safety in the Carpentry shop, Foundry & Casting shop.

Familiarization of tools

Marking and measuring tools such as straight edge- meter square- try square- bevel square- combination

Square- marking knife- marking gauge- mortise gauge- cutting gauge- wing compares- trammel- divider outside

and inside calipers- spirit level and plumb bob.

Cutting tools such as Rip saw- Cross cut saw- panel saw- Tenon saw- bow saw- compass saw- key hole

Saw- firmer chisel- bevel edge firmer chisel- parting chisel- mortise chisel- jack plane- wooden and metal trying

Plane- smoothening plane- rebate plane- plough plane- router plate- spoke shave.

Boring tools such as Bradawl ratchet brace- wheel brace- shell bit- fostries bit- counter sunk bit.

Striking tools such as mallet etc

Holding devices – Bench vice- bench stop- sash clamp- G-clamp- hard screw.

Miscellaneous tools – Rasp cut file- scraper- glass paper- pincers- ratchet and cabinet type screw drivers.

Carpentry Practice

Marking- sawing- planning- chiseling- grooving- rebating exercises Preparation of carpentry joints.

Familiarization of Foundry tools

SYLLABUS

WORKSHOP PRACTICE


Hand tools – shovel- riddle- hammers- trowels- relic- lifters- strike off bar spruce- balloons- swab- gate

Cutter- mallet- vent rod- draw spike- lifting plate- pouring weight- gaggers- clamps, core & chaplets.

Moulding practice & casting

Preparation of moulding sand- Prepare moulds of different types using different patterns( single, double

& three piece patterns) - ferrous & Non- ferrous metal casting using simple patterns. MODULE II Familiarization of Smithy tools

Hand tools – anvil- swage block- hammers such as ball peen- straight peen- cross peen and sledge hammers.

Tongs such as flat- hallow- cold and hot chisels- swages- fullers- flatters- set hammers- pinch and drift.

Equipment: Open and closed hearth- heating furnaces- hand and power driven blowers- open and stock fire

fuels such as charcoal- coal- oil and gas

Smithy & Forging Practice

Building fire in the furnace- Upsetting- bending- drawing- setting down- pinching- cutting and welding

exercises

Familiarization of fitting tools

Hand tools & Marking tools – scriber- compass- dividers- outside and inside calliper- jenny calliperordinary

scribing block- universal scribing block- angle plate- V-block- center punch- prick punch- try square- bevel

square- surface plate- straight edge.

Cutting tools – chisels – flat- crosscut- half round- diamond point- side chisel. Files – single cut and double

cut files rough- bastard- second cut- smooth Dead smooth files – flat- square- pillar- round triangularhalf round-

knife- safe edge and needle files.

Scribers – Neck saw – solid and adjustable frames – blades – cutting with point rack saw

Striking tools: ball peen- straight peen- cross peen and double-faced hammers

Holding devices-vice-bench- leg- pipe- hand- pin and tool makers vice

Marking tools – scriber – ordinary and universal scribing block- center and prick punch.

Angle plate- v-block- Try Square- surface plate

Fitting Practice

Cutting - filing- scribing and simple joints exercises MODULE III

Familiarization of Sheet metal tools

Understand safety precautions.

Familiarization of sheet metal tools – scribers- dividers- trammel points- set square- punches – prick

Punches- centre punches – hand Grover- rivet- set- chisels hammers- riveting hammers- ball peen hammers –

mallet- snip- shears- pliers- hand reamers (tongs) files- stakes. Measuring instruments in sheet metal folding

rule- common rule- steel circumference rule- vernier calipers- micrometer- calipers thickness gauges (SWG)

sheet metal gauge.

Practice work

Sheet cutting- development- folding- bending and pipe bending- making right angle joints.

MODULE IV

Familiarization of welding tools & safety

Safety precautions- Study of various tools and equipments used in the welding shop for both arc welding and

gas welding.

Practice work

1. D.C. arc welding. 5. Horizontal -flat and vertical joints.

2. A.C. arc welding.

3. Gas welding.

4. Edge preparation of welded joint such as V and double V.

WORKSHOP PRACTICE


TOPICS PAGE NO. SAFETY PRECAUTIONS 6 CARPENTRY 7 – 15 FOUNDRY & CASTING 16 – 21 SMITHY 22 – 27 FITTING 28 – 36 SHEET METAL 37 – 46 WELDING 47 – 50

CONTENTS

WORKSHOP PRACTICE


Always wear protective clothing. Do not wear loose dress.

Wear hard leather shoes or safety shoes. Do not wear sandals or

rubber shoes.

Must be wear goggles, helmet, Apron, hand gloves and leg guard.

If you don‟t have knowledge about working of a machine, you

should not operate it without the help of a person who known it‟s

working.

Use suitable tools or machines for your work.

When carrying tools, point the sharp edge downwards.

A machine must always be operated by one student at a time.

Do not leave any tools, materials or waste on the bench, machine or

floor after working.

Never adopt a casual attitude in the workshop and always be

conscious of the potential hazards.

Take additional care when carrying or moving any potentially

hazardous material or substance.

Ensure that all safety equipment remains accessible to the workshop

personnel at all times.

Clean machines after use.

BE CAREFUL The best safety device is a

careful worker

Get the safety habit

SAFETY PRECAUTIONS

CARPENTRY WORKSHOP PRACTICE


CARPENTRY



INTRODUCTION

The carpentry deals with the constructional work such as making roofs, floors, partitions etc. Of building by

means of wood with the help of carpentry tools. The term joinery is used for connecting the wooden parts with the

different joints such as making of doors, windows, stairs etc.

The timber is the material used for carpentry and joinery work. It is the wood obtained from exogenous trees by

cutting these trees after their full growth. “Wood Working” means processing of wood by hand and machines for making

articles of different shapes and size. It is further divided into two groups;

1. Carpentry. 2. Pattern making.

Carpentry is the common term used with any class of work with wood. Pattern making deals with the type and

construction of wooden patterns.

LIST OF TOOLS

MARKING AND MEASURING TOOLS

1. Steel rule. 6. Marking knife (Scriber).

2. Straight edge. 7. Marking gauge.

3. Try square. 8. Mortise gauge.

4. Mitre square. 9. Calipers (outside and inside).

5. Bevel square. 10. Spirit level and plumb bob

CUTTING TOOLS

Saw: - Hand saw, Rip saw, Panel saw, Bow saw, compass saw, keyhole saw.

Chisel: - Firmer chisel, Bevel edged firmer chisel, pairing chisel, mortise chisel, parting chisel.

PLANING TOOLS

1. Jack plane (wooden and metal). 5. Trying plane.

2. Smoothing plane. 6. Plough plane.

3. Rebate plane. 7. Router plane

4. Spoke shave.

BORING TOOLS STRIKING TOOLS

1. Bradawl. 1. Claw hammer. .

2. Brace (ratchet and wheel brace). 2. Mallet.

3. Shell bit. 3. Cross peen hammer.

4. Fostner bit.

5. Counter sunk bit.



MISCELLANEOUS TOOLS HOLDING TOOLS

1. Scraper. 1. Carpenter‟s bench vice.

2. Rasp file. 2. Sash cramp (Bar cramp or T-cramp).

3. Pincer. 3. G-cramp.

4. Star screwdriver.

5. Ratchet screwdriver.

MARKING AND MEASURING TOOLS

Steel rule: - Steel rule is made from steel. It is a measuring tool used to measure linear measurements of any objects. On

one of the flat faces, graduations are marked in inches and centimeters. The least count is 1/64 of an inch or 0.5mm.

Straight edge: - The straight edge is a machine flat piece made of wood or metal having truly straight and parallel edge.

One of the longitudinal edges is generally made leveled. This is used to test the trueness of large surfaces and edges.

Try square: - Try square is used for marking and testing angle of 90°. It consist of a steel blade, riveted in to a hard wood

stock at right angle or with two steel blade and cast iron stock sizes vary from 150 to 300mm according to the length of

the blade.

Mitre square: - It is used to measure an angle of 45°. They are made of all metal a nickel-plated finish or with a steel

blade, the blade varies from 200mm to 300mm long.

Bevel square: - The bevel square is similar to try square but has a blade may be swilled to any angle from 0 to 180°. This

tool is adjusted by releasing with a turn screw of suitable size in a machine screw running in a slot in the blade.

Marking knife: - Marking knife is used for converting the pencil lines in to cut lines. They are made of steel having one

end pointed and the other end formed into a sharp cutting edge.

Marking gauge: - It has one marking point. It gives an accurate cut line parallel to a true edge, usually with the grain.

The panel gauge is longer than the marking gauge and is used to gauge lines across wider surfaces.

Mortise gauge: - It has two marking points-one fixed near to the end of the stem and the other attached to a brass sliding

bar. These two teeth cut to parallel lines called mortise lines.

Caliper: caliper is used for measuring outside and inside diameters.

Spirit level and plumb bob: It is used for level or trueliness of horizontal and vertical positions of work.

CUTTING TOOLS

Hand saw or cross saw: Hand saw are used to cut across the grain in thick wood. They are 600 to 650mm long with 8 to

10 teeth per 25mm the action of the teeth is that of a serious of knives which cut the fibers and force out of the waste

wood in the form of saw cut.

Tenon or Backsaw: This saw is mostly used for cross cutting .The blade very thin, is reinforced with a rigid steel back.

Its blades are from 250mm -400mm long and the shapes are in the form of a equilateral triangle.

Dovetail saw: A small version of the ten on, this saw is used where the greatest accuracy is needed and finish allows cuts

are to be made. The number of teeth may be from 12-28 per 25mm, while the length may vary from 200-350mm.



CHISELS

Firmer chisel: Firmer chisel is the most useful for general purposed and may be used by hand pressure or mallet. It has a

flat blade about 125mm long the width of the blade varies from 1.5-50mm.

Bevel edge chisel: I t is used for more dedicate or fine work they are useful for getting in to curves.

Paring chisel: Both firmer and bevel edge chisel when they are made with long thin blade are known as paring chisel.

This is used for shaping and preparing the surfaces of wood and is manipulated by the hand. The length ranges from225-

500mm.

Mortise chisel: Mortise chisel used for chopping out materials. These chisels are designed to withstand heavy work.

Blades vary in width from 3 to 16 mm.

PLANNING TOOLS

Metal jack plane: It is used to get better finish in planning. The body of metal plane is made from gray cast iron with the

side and sole machined and ground to a bright finish.

Jack plane wooden: Used for leveling the bottom of grooves which are already formed by other tools like chisel.

Spoke shave: Spoke shave is used for clearing up quick curves. It is made of iron.

BORING TOOLS

Bradawl and gimlet: Bradawl and gimlet are hand operated tools and are used to bore small holes, such as for starting as

screws or large nail.

Ratchet brace: The ratchet brace is most useful for turning bits and drills for all kinds, being adaptable.

Fostner bit: It is used for sinking a clean hole partly through the wood and for cleaning out recesses.

Counter sink bit: It is used for counter sinking previously drilled holes to fit the heads of screws in wooden pieces.

STRIKING TOOLS

Claw Hammer: It is dual purpose hammer, the face which is used to drive nails and claw at the other end used to pulling

out nail from the wood. Its weights from 375 to 675 gm.

Wooden Mallet: It is used for operating the chisels made of hard wood and provided with a handle. The striking face is

made of flat or round or rectangular in cross section.

Ball peen Hammer: It is made of cast steel and weight of about 110gm to 910gm. The peen of the hammer it is in the

shape of ball and hence the name is ball peen hammer. It is also called also called engineers hammer. It is used for

reverting and forming.

Cross peen Hammer: The peen of this hammer is across the handle and hence the nail. It is used for all lights work

striking very thin nails, nailing in grew and bending sheet etc .It is weight is 100g to 250gm.



HOLDING TOOLS

Bench vice: Bench vice is used for holding work piece. It is made of iron and steel.

Bench hold fast: Bench hold fast is made to cast iron rod, square. Cut screws threads of steel bars, with a light vice

handle and a drop-forged steel arm.

Sash Cramp: The sash cramp or bar cramp is made up of a steel bar of rectangular section, width malleable iron fittings

and a steel screw. This is used for holding wide work such as frames or tops.

[FOUNDRY & CASTING] WORKSHOP PRACTICE


FOUNDRY & CASTING



INTRODUCTION

A foundry is a place where castings are produced. The casting is a process forming metallic products by melting

the metal, pouring into a cavity known as the mould, and allowing it solidify. When it is removed from the mould it will

be of the same shape as the mould.

Pattern is a model of an object made of wood or metal may be used for forming an impression called mould. The process

of making a pattern is known as pattern making.

FOUNDRY TOOLS AND EQUIPMENTS

The foundry tools and equipments are divided into the following five groups:

(1) Hand tools (2) Moulding boxes (3) Moulding machines (4) Melting equipments (5) pouring equipments.

Hand tools:-

Shovel: A shovel consists of a square pan fitted with a wooden handle. It is used for mixing and for moving the sand from

one place to another in the foundry.

Riddle: A riddle has standard wire mesh fixed into a circular or square wooden frame. It is used for cleaning the

moulding sand. The riddle is specified by the diameter of the frame and the mesh number.

Vent rod: A vent rod is similar to a knitting needle. It has pointed edge at one end and a handle at the other end. It is used

to pierce holes in the rammed sand to provide artificial vents which permit the easy escape of steam and gases generated

by the hot metal in contact with the sand.

Slick: A slick is a double ended tool having a flat on one end and a spoon on the other. This tool is also made in a variety

of other shapes and is used for repairing and finishing the mould surfaces after the pattern is withdrawn.

Lifter: A lifter is made of thin sections of steel of various width and lengths with one end bent at right angles. It is used

for smoothing and cleaning out depressions in the mould.

Swab: A simple swab is a small brush having long hemp fibers. A bulb swab has a rubber bulb to hold the water and a

softer hair brush at the open end. It is used for moistening the sand around the edge before pattern is removed.

Bellow: The hand operated bellow is used to blow loose particles of sand from the cavities and surface of the sand.

Trowel: The trowels consist of a metal blade with a wooden handle. The small trowels of various shapes are used for

finishing and repairing mould cavities as well as for smoothing over the parting surface of the mould.

Gate cutter: A gate cutter is a U-shaped piece of thin sheet. It is used for cutting a shallow through in the mould to act as

a passage for the hot metal.

Draw spike: A draw spike is a pointed steel rod, with a loop at one end; it is driven into a wooden pattern to hold it when

the sand is withdrawn. The draw screw is similar in shape but threaded on the end to engage metal patterns.

Strike-off bar: A strike-off bar a straight bar of wood or steel usually of rectangular cross section. It is used to strickle or

strike off excess sand to provide a level and smooth surface.

Mallet: A raw hide mallet is used to loosen the pattern in the mould so that it can be withdrawn easily.

Gaggers: The gaggers (also called lifters) are iron rods bent at one end or both ends. It is used for reinforcement of sand

in the top part of a moulding box and to support hanging bodies of sand.

Clamps: The clamps are used for holding the cope and drag of the mould so that the cope should not rise when the molten

metal is poured into the mould.

Hammer: Hammers are used to strike a job or a tool. They are made of forged steel of various sizes and shapes to suit

various purposes. A hammer consists of 4 parts namely, peen, head, eye and face. The eye is made oval or elliptical inside

in shape and accommodate the handle. Hammers are classified according to the shape and peen.

(a) Ball peen hammer: This is the most common hammer. The peen has a shape of a ball which is

hardened and polished; size varies from 0.11 to 0.91 Kgs.



(b) Cross peen hammer: This is similar to ball peen hammer in shape and size except the peen which is

across the shaft or eye.

(c) Straight peen hammer: This hammer has a peen straight with the shaft or parallel to the axis of the

shaft.

Moulding boxes: - The sand moulds are prepared in specially constructed boxes called flasks, which are open at top and

bottom. They are made in two parts, held in alignment by dowel pins. The top part is called the cope and lower part is

called drag. In the flask is made in three parts, the intermediate part is called a cheek.

Melting equipments: Cast iron-Cupola furnace, electric furnace, rotary furnace. Steel - Open hearth furnace, electric &

Bessemer converter.

Non ferrous metal - Crucible furnace, rotary furnace, Electric furnace.

Moulding sand: The principle material used in making a mould is sand. The sand is defined as the granular particles

resulting from the breakdown of rocks. Quartz and other silica rocks are the source of silica sand which is commonly used

for moulding. The silica sand is found in nature on the bottoms and banks of rivers, lakes and larger bodies of water.

A good moulding sand contains the following ingredients:-

1. Silica sand- 80.80%

2. Alumina- 14.9%

3. Iron oxide- 1.3%

4. Combined water- 2.5%

5. Other inert materials- 1.5%

PROPERTIES OF MOULDING SAND

1. Porosity or permeability: - It is that property of sand which permits the steam and other gases to pass through the sand

mould. When hot metal is pured into the sand mould, it evolves a great amount of steam and other gases while coming in

contact with the moist sand. If these gases do not escape completely through the mould, the casting will contain gas holes

and pores.

2. Plasticity: - It is that property of sand due to which it flows to all portions of the moulding box or flask and acquires a

predetermined shape under ramming pressure and retains this shape when the pressure is removed.

3. Adhesiveness: - It is the property of the sand due to which it adheres or clings to the sides of the moulding box. Good

sand must have sufficient adhesiveness so that heavy sand masses can be successfully held in the moulding box or flask

without any danger of its falling out when the flask is removed.

4. Cohesiveness: - It is that property of sand due to which the sand grains stick together during ramming.

5. Refractoriness: - It is that property of the sand which enables it to resist high temperature of the molten metal without

breaking down or fusing.

6. Flowability: - It is that property of sand due to which it behaves like a fluid so that, when rammed, it flows to all

portions of a mould and distributes the ramming pressure evenly. Flow ability increases with decrees in green strength and

de- crease in grain size. It also varies with the moisture content.

7. Collapsibility: - It is that property of the sand due to which the sand mould collapses automatically after the

solidification of the casting in order to allow free construction of the metal.

PATTERN ALLOWANCES

1. Shrinkage of contraction allowance: The various metals used for casting contract after solidification in the mould.

Since the contraction is different for different metals, therefore their corresponding allowances also different and there is a

shrink or correction scale for each type of metal used in a casting.



2. Draft allowance: It is a taper which is given to all the vertical walls of the pattern for easy and clean withdrawal of the

pattern from the sand without damage the mould cavity. It may be expressed in millimeters per meter on a side or in

degrees. The amount of taper varies with the type of patterns.

3. Machining allowance: This allowance is provided on the pattern if the casting is to be machined. This allowance is

given in addition to shrinkage allowance. The amount of this allowance varies from 1.6 to 12.5mm which depends upon

the type of casting metal size, shape of casting, method of casting used, and method of machining.

4. Distortion allowance: This allowance is provided on pattern used for castings of such design in which the contraction

is not uniform throughout.

5. Rapping or shaking allowance: This allowance is provided in the pattern to compensate for the rapping of the mould

because the pattern is to be rapped before removing it from the mould. In small and medium -Silica sized casting, these

allowances can be neglected.

6. Core Prints: When a casting is required to have a whole, core is used in the mould to produce the same. To support the

core in the mould cavity, an impression or recess is made in the mould with the help of a projection suitably placed on the

pattern, i.e., A core print is an added projection on a pattern which forms an impression or processes in the mould to

locate the core in the correct place.

[SMITHY] WORKSHOP PRACTICE


SMITHY



INTRODUCTION

Forging is defined as the controlled plastic deformation of metals at elevated temperatures under hammering an

O-pressing. It consists of altering the shape and section of a specimen (work piece) above recrystallization temperature.

FORGING PROCESS

Forging process may be broadly classified in to two,

1) Hand forging or Smiting. 2) Machine forging.

Hand forging or smiting involves the shaping of metal with hand tools by heating them in an open fire or hearth.

The place where this type of work is done is called SMITHY SHOP. Accuracy depends up on the skill of the blacksmith.

It is used mainly for the repair of maintenance work and in the production of small articles and tools.

Machine forging is employed for the production of machine and large size forging. In machine forging the forging

operation are done with the help of power operated hammers and presses.

Fuels Used in Smith's Forge

1. Charcoal: it is produced by carbonization of wood in closed retorts in the absence of air.

2. Coal: bituminous coal, anthracite coal etc. Which are collected from mines is used. Pulverized or powdered

coal is used when high temperature is needed.

3. Coke: it is made by distilling bituminous coal in special oven in the absence of air. In addition to above solid

fuels other fuels like furnace oil, natural gas, producer gas, coke oven gas, Leco etc. used in closed furnaces.

Smith Forging Operations:

1. Upsetting or jumping up 5. Welding

2. Drawing down or swaging 6. Cutting

3. Setting down 7. Punching

4. Bending 8. Fullering

1) Upsetting or jumping up: This is the process through which the cross section of metal stock is increasing with the

corresponding reduction on its length.

2) Drawing down or swaging: it is a forging operation during which the cross section of the metal is reduced and the

length increased.

3) Setting down: Setting down is the operation of reducing the thickness of the work piece in a small area.

4) Bending: Bending is an operation by which the metal pieces may be bent to form various shapes without damage to its

structure.

5) Welding: Welding in smithy is an important operation carried out in the smithy section.lt is the process of joining

together two pieces of metal after they have been raised to correct welding temperature and then applying external

pressure.

6) Cutting: Cutting the metal in the hot or cold stage done by means of hot or cold chisel.

7) Punching and drifting: it is the process of producing hole by using a hot punch over the pritchet hole of the anvil or

over a cylindrical die.

8) Fullering: it is actually same as drawing down and consists of reducing cross section of the work piece or lengthening

a portion.

TOOLS AND EQUIPMENTS

Smith forge or hearth: The work is placed in the smith's forge or hearth and is brought to the hot plastic condition so that

it may be worked in to the desired shape under a series of hammer blows .Stationary brick built hearth as well as portable

hearth of metal construction are being used. They may be open type or closed type.

Two types of fires are prepared in the smiths forge or hearth.

1) Open fire. 2) Stock fire



Open fire: This type of fire is highly convenient for general heating work and is made up in the hollow space in front of

tuyre nozzle with coke left from the last fire, covered with green petroleum.

Stock fire: This type of fire is commonly useful in dealing with large pieces, when a heat may have to be kept for some

time. The job or work has to be turned in all directions to ensure uniform heating of the job.

Heating Furnaces: in addition the open hearth the following types furnaces are used for forging by using gas, oil, or

electric fired to get temperature up to '13500C.

1. Box or bath furnace.

2. Rotary hearth.

3. Conveyer or continuous furnace.

4. Induction furnace.

5. Resistance furnace.

Anvil: Anvil is a supporting tool when hammering in smithy shop.lt is made of wrought iron. They are specified their

weights. Main parts of the anvil are body, face, tail, beak and cutting face. The punching hole is round and called as

pritchet hole. This hole is used for bending of small diameter rods and as a die for hot punching operations. The square

hole or hard die hole is used for holding square shanks of various fittings.

Swage block: This is forging shop tool, used for many squaring bending, sizing and forming operations.lt is made of cast

iron.lt is a block having different type of grooves on the face and channels on the four edges.

Hand hammers: Hammers are striking tools. They are specified by the weight and shape. They are classified as Ball peen

hammer, Cross peen hammer, straight peen hammer, Sledge hammer etc. They are made of cast steel. The main parts of

hammers are peen, edge, cheeks and face. Hammers are classified according to the shape and peen.

(a) Ball peen hammer: This is the most common hammer. The peen has a shape of a ball which is


(b) Cross peen hammer: This is similar to ball peen hammer in shape and size except the peen which is


(c) Straight peen hammer: This hammer has a peen straight with the shaft or parallel to the axis of the

shaft.

(d) Sledge hammer: These hammers vary from 3 to 9 kgs in weight and are fitted with long wooden

handles. These are used for heavy forging work. Heavy sledge hammers are used by strikers.

Tongs: Tongs is a holding tool, which is used to hold the heated or cold work pieces for striking. Tongs are classified as

flat tongs, round or hollow tongs, ring tongs.

The flat tongs are used for gripping thin section and small flat pieces. Round hollow tongs with curved surfaces are used

for holding round work. The ring tongs are used for holding bolt, rivets, and other work of circular section. They are made

of mild steel.

Chisels: Chisels are used for cutting metals. They are classified in to two types:

1) Cold chisel 2) Hot chisel

The main difference between these two is its cutting edge. The cold chisel is used for cutting cold metals. It has a cutting

angle of 60.The hot chisel is used for cutting hot metals.lts cutting angle is 30. They are made Of H.S.S. (high speed

steel).

Fullers: These tools are made of high carbon steel. They are used in pairs consisting of a top and bottom fullers. Its

working edges are normally rounded to make necks by reducing the cross section of a job and also in drawing out.

Swages: Like fullers they are also made of carbon steel in two parts called the Top and Bottom swages. Their working

faces carry the circular grooves to suit the size of work .They are used for increasing the length of a circular rod.

Flatters: They are made of high carbon steel and consist of a square body fitted with a handle and a flat square bottom.

They are used for levelling and finishing flat surfaces. They are also known as flatters or smoothers.



Set hammer: it is not a hammer but a finishing tool just like a flatter.lt is used for finishing corners formed by adjacent

surfaces at right angles.lt made of tool steel and hardened.

Punches: Punches are tapered tools made in various shapes. They are used for producing holes in red hot jobs.

Drift: Drift is a large sized punch.lt is used to expand the punched hole.

Showel: For putting coal into the forge a smithy showel is used.

Pocker: A pocker is a rod made of mild steel. It is used to shed the fire ash of the forge.

Swoop: it is similar to a pocker, one end of its ends is made flat and then turned. It helps in keeping the burning coal at

the required place in the forge.

[FITTING] WORKSHOP PRACTICE


FITTING



INTRODUCTION

Fitting consists of a handwork involved in fitting together components usually performed at a bench equipped

with a vice and hand tools. The matting components have a close relation with each other, and when the function together

is termed Fitting.

We have to use hand tools, precision tools and various operations, as well as the details of the tool such as identification,

material, parts, types, various uses, manipulation, specification, care and maintenance etc.

SAFETY PRECAUTIONS IN FITTING SHOP 1. Shop floor should be kept clean, free from debris, scrap, oil and grease.

2. Do not touch the chip as it comes out of the job.

3. When using grinding machine protect your eyes with goggles.

4. Always work under sufficient light.

5. Do not wear loose dress.

6. Never use hammers with loose heads.

7. Provide guards between opposite vices.

8. Files must have well fitted handles.

9. See that the job is properly fitted to the vice.

10. Do not blow filing when hack sawing.

11. Ease up the pressure when hack sawing is nearly through.

Use the right tool for the right job.

MEASURING TOOLS AND MARKING TOOLS

Steel Rule: A steel rule is a direct reading measuring instrument used to read an accuracy of 0.5mm. Available in various

lengths, widths and thickness with several graduations. They are made from high carbon steel, spring steel, stainless steel

and various alloy steel.

Caliper: It is a simple tool gauging legs. It is made of high carbon steel and the measuring points are hardened and

tempered. Calipers are mainly classified into Spring type and Firm joint caliper.

(a) Outside Caliper: They are used to measure the outer dimensions of the shafts, pulleys and square bars etc.

(b) Inside Caliper: They are used to measure the inner dimensions of holes, bores, slots etc.

(c) Jenny Caliper: They are used in layout work for locating and testing centre on cylindrical and other sections

lying of distance from an edge and to scribe parallel lines.

(d) Divider: This tool consists of two pointed legs having a joint at the top end. There are spring type and firm joint

dividers. It is made from high carbon steel and the points are hardened and tempered. It is used to scribe circles,

arcs, parallel lines and lying of distance. To divide straight or curved lines into number of equal spaces. To

transfer the dimension from a rule to job.

Try square: It is a marking and checking instrument right angles. It is made of two parts, the stock or beam made of cast

iron and the blade made of high carbon steel. It is classified by the length of the blade from the edge of the stock. It is

used to check up the right angles and also for checking the flatness of the object.

Scriber: A scriber is a pointed tool used for marking lines on metals. Scribers are made from high carbon steel and the

points are hardened and tempered.

Types: Straight Scriber, Bent type scriber, Offset scriber, Adjustable Scriber etc.

Universal Scribing Block: It is often needed in connection with a surface plate, to scribe lines at a given vertical height

from the base of the work or test the parallelism of the work. It consists of 6 parts. The major difference between the

ordinary and universal scribing block are (1) a clamping nut which will adjust the movement of the spindle and (2) a fine

adjusting screw which helps the fine adjustment of the scriber point.



Bevel Square: This instrument is used for marking lines at a given angle to an edge or for checking the angular accuracy

of inclined surfaces. It consists of a blade, stock and knurled nut. The blade can be swiveled through 3600 and locked in

any desired position.

Straight Edge: Straight edges are used for checking the straightness of an edge of a work piece and also for checking

surface uniformity. It‟s both edges are finished level and parallel with one edge usually beveled.

Angle plate: If the shape is such that it does not have a base, it has to be clamped to an angle plate. The faces of these

plates are provided with slots to fasten the work to the plate by bolt and nut. Solid angular plates and adjustable angle

plates are available.

Punches: Punches are important tools used for marking outward, locating centre for holes. The punch marks are made

along the marked out lines to make them clear till the operation is over. Punches are made from carbon tool steel of length

90 to 150mm. The head is hardened and tempered. The point is ground to the proper angle according to the purpose of the

punch;

(a) Dot Punch: are used to make dots or points along the scribed line. The angle of dot punch is 60°.

(b) Centre Punch: are used for locating the centre of holes to be drilled to keep the drilling correct position. The

angle of centre punch is 90°.

(c) Prick punch: Punches are using for the above said purposes. Its point angle is 300, so that their points are

sharper.

Surface plate: Surface plate is the basic tools used for marking. It is a plane table of fine grained cast iron. Even though

surface plates are made indifferent sizes and shapes, the most common shapes are rectangular and square. The surface

plate is specified in its sizes.

V-block: This is a block of steel or cast Iron, which provide with V-shaped groove on its top or bottom or both surfaces.

All its faces are truly machined. It is used to hold round bars during marking and drilling. The round bars clamped firmly

on the V-block by a U-clamp the slots cut at the 2 sides of the V-block.

CUTTING TOOLS

Chisels: Chisels are used for cutting and chipping away pieces of metal and are made of carbon steel usually of

rectangular, hexagonal cross section. They are forged to shape roughly ground and then hardened and tempered. The edge

is correct to the cutting angle. Care being taken not to overheat the steel and draw the temper. The cutting angles given to

the chisel is determined mainly by the nature of the metal to be chip. It varies between 350 and 70

0. It is generally

specified by the length and width of the cutting edge.

(a) Flat Chisel: The flat chisel is the most common of all the chisels used in engineering. It is the chisel

which is used for most of the general chipping operation. It may be used for removing surplus metal

from surface of jobs.

(b) Cross cut chisel: The cross cut chisel or cape chisel as it is sometimes called, is used cutting grooves in

large surfaces. The cutting edge is slightly wider than the supporting metal to provide clearance length of

this chisel various from 100 to 400 mm, and width of the edge varies from about 4 to 12 mm.

(c) Half round chisel: A half round chisel is particularly useful for cutting oil ways or grooves in bearing,

pulleys, and bushes. They are also used for setting over pilot holes.

(d) Diamond point chisel: It is made square at the point and then beveled to make a cutting edge. It is used

to make a cutting edge. It is used for cutting grooves and square corners.

Files: The most widely used hand tool in an engineering shop is the file. A file is a hardened piece of high grade steel with

standing row of teeth. The cuts all metals except hardened steel. The file consists of the following parts, tang, heel, face,

edge, and point. Files are classified according to four principal factors, sizes, shape, grade and types of cut of teeth.

Size: The size of the file is its length. This is the distance from the point to the heel.

Shape: The shape of a file is its general outline and cross section; commonly used shapes are as follows



(a) Flat file: This is tapered in width and thickness and one of the most commonly used file to general work.

They are always double cut on faces and single cut on edges.

(b) Hand file: This is parallel in its width and tapered in thickness. It is used for finishing flat surfaces. It has

one safe edge.

(c) Square file: This Square in cross section, double cut and tapered towards the point used for filing square

corners, enlarging square or rectangular openings.

(d) Round file: They are round in cross section and usually tapered towards the point.

(e) Half Round file: Its tapered, double cut, and its cross section is not a half circle but only about 1/3 of a

circle. This file is used for round cuts and filing curved surfaces.

(f) Triangular file: It is triangular in shape and it is used for filing sharp corners and angles.

(g) Knife edge file: It is shaped like knife edge, tapered in width and thickness and double cut. They are

used for filing narrow slots, notches and grooves.

(h) Needle file: It is made in sizes from 100mm to 200mm of various shapes and cuts are extremely delicate

and are used for fine work.

Grade: It is the coarseness is spacing between the rows of teeth, they are Rough, Bastard, Second cut, smooth, dead

smooth and super smooth.

Cut: Cut of files is classified into two groups: (1) Single-cut, and (2) Double-cut

On single cut files, the teeth are cut parallel across the file at an angle of about 600 to the centre of the file. Double-cut file

at an angle of teeth, the over-cut teeth being cut at about 600, and the up-cut at 70

0 to 80

0 to the centre line.

Rough File: It is used to removing large quantity of metal. It is mostly used for filing rough edges of soft metal.

Bastard File: The file is used in cases where there is a heavy reduction of metal.

Second Cut File: It is used for filing in hard metals. It is also useful for filing the job bringing close to the finishing

size.

Smooth File: it is also used to remove small quantity of material and to given a good finish.

Dead Smooth File: It is used to bring to accurate size with a high degree of finish.

Hacksaw: The hacksaw is used for sawing metals. A hand hacksaw consists of a frame, handle, and prongs, tightening

screw and nut and blade. The frame is made to hold the blade tightly. It is of two

Types: - The solid frame, in which the length cannot be changed, and the adjustable frame, which has a back that can be

lengthened or shortened to hold blades of different length. Hack saw blades are made of either low alloy steel or standard

lengths 225, 250 & 300mm.

Push type blades - those which cut in forward stroke only are generally used. Two types of hacksaw blades are available,

all hard and flexible. The all hard blade is hardened throughout and being more rigid - it is said to an accurate sawing in

hard metals. It requires skill to use, as it is easily broken. The flexible blade is hardened on the cutting edge only. They are

suitable for general work for cutting.

STRIKING TOOLS Hammer: Hammers are used to strike a job or a tool. They are made of forged steel of various sizes and shapes to suit

various purposes. A hammer consists of 4 parts namely, peen, head, eye and face. The eye is made oval or elliptical inside

in shape and accommodate the handle. Hammers are classified according to the shape and peen.

(d) Ball peen hammer: This is the most common hammer. The peen has a shape of a ball which is


(e) Cross peen hammer: This is similar to ball peen hammer in shape and size except the peen which is


(f) Straight peen hammer: This hammer has a peen straight with the shaft or parallel to the axis of the

shaft.



WORK HOLDING DEVICES

Vice: Vice the most common tool for holding the work various types of vices are used for various purposes.

Bench vice: The most commonly used vice is engineer‟s parallel jaw bench vice. It must be firmly fixed to a bench with

nuts and bolts or screws. The vice essentially consists of a cast iron body. A fixed jaw, a movable jaw-both made of cast

steel, a handle, a square the ended screw and a nut all made of mild steel, separated cast steel plated called jaw plates are

fixed to the jaws by means of set screws and they can be replaced when worn. The holding faces of Jaw plate, have teeth

to hold the work firmly. The movement of the vice is caused by the movement of the screw through the nut fixed under

the movable jaw. The size of the vice is known, by the width of its jaws.

Pipe Vice: Pipe vice is used for holding round metals, tubes, pipes etc. In this case the screw is vertical and the movable

jaw works vertically. It grips the work at 4 points on its surfaces.

Pin Vice: Pin vice is used for holding round materials of smaller diameter such as wire and pins during working. It also

forms handles for small files. It consists of a handle and tapered nose covering a small collect chuck at its end. The chuck

carries the jaws which are operated by turning the handle.

Hand vice: It consists of two jaws hands. Which are hinged together in a pivot on the opposite end. It is used for holding

light work. Such as holding sheet metals.

[SHEET METAL] WORKSHOP PRACTICE


SHEET METAL



INTRODUCTION

Sheet Metal work is generally regarded as the working of metal from 16 gauge down to 30 gauge, with hand tools

and simple machines in to various forms, by cutting forming in to shape, and joining. It has its own significance as a use

full trade in engineering works and also for our day to day requirements. Common examples of sheet metalwork are

hoppers, canister, guards, covers, pipes, hoods, funnels, bends, boxes, etc. such articles are found less expensive, lighter in

weight and at many place they easily replace the use of the castings or forgings.

In sheet metalwork knowledge of geometry , menstruations and properties metal is most essential since nearly all

patterns comes from the development of the surface of the a number of geometrical models such as cylinder, prism, cone

and pyramid a good pattern properly means saving of time and money.

In sheet metal work, sheet metal used black iron , galvanized iron, stainless steel ,copper, brass, zinc, aluminum ,

tin plate and lead. The sheet is specified by standard gauge. Each gauge designates a definite thickness. The larger the

gauge number, the lesser the thickness. In sheet metal work, different types of metal sheets are used. The sheets are

specified by standard gauge numbers. It is very essential to know the different uses and applications of these metal sheets.

METALS USED IN SHEET METAL WORK

Black iron: The cheapest sheet metal is black iron, which is rolled to the desired thickness. It has a bluish- black

appearance, and is often referred to as uncoated sheet. Since it is uncoated, it corrodes rapidly. The use of this metal is

limited to articles that are to be painted or enameled such as tanks, pans, stoves, pipes etc.

Galvanized iron: Zinc-coated iron is known as galvanized iron. This soft iron sheet is popularly known as GI sheet. The

zinc coating resist rust, improves the appearance of the metal and permits it to be soldered with greater ease. Articles such

as pans, buckets, furnaces, heating ducts, cabinets, gutters etc.

Stainless sheet: This is an alloy of steel with nickel, chromium and other metals. It has good corrosive resistance and can

be welded easily. Stainless steel used in a sheet metal shop can be worked as galvanized iron sheet, but is together than GI

sheets. The cost of stainless steel is very high. This is used in dairies, food processing, chemical plants, kitchenware etc.

Copper sheet: Copper sheets are available either as cold-rolled or hot-rolled sheets. Cold-rolled sheets being resistant to

corrosion and worked easily are commonly used in sheet metal shops. Copper sheet has better appearance than other

metals. Gutters, expansion joints, roof flashings, hoods and boiler plates are some of the common examples where copper

sheet in used.

Aluminium: Aluminium cannot be used in its pure form, but it mixed with a very small amount of copper, silicon,

manganese and iron. It is whitish in color and is light in weight. It is highly resistant to corrosion and abrasion. It is now

widely used in the manufacture of articles such as household appliances, refrigerator trays, lighting fixtures, windows, and

also in the construction of airplanes and in many electrical and transport industries.

Tinned plate: Tinned plate is sheet iron coated with tin to protect it against trust. This is used for nearly all solder work,

as it is the easiest metal to join by soldering. This metal has a very bright silvery appearance and is used in making of

roofs, food containers, dairy equipments, furnace fittings, cans and pans etc.

SHEET METAL HAND TOOLS

Steel rule: This is particularly useful in measuring and laying out small work. Steel rules are made of spring steel or

stainless steel. The reading accuracy of the steel rule is 0.5mm.

Folding rule: The folding rule is very helpful in measuring and laying out large work, the accuracy being 0.5mm.

Steel circumference rule: This is used to find out directly the circumference of a cylinder.



Swing blade protractor: This is used for marking and measuring angles.

Vernier caliper: A Vernier caliper is a precision measuring instrument. It used to measure up to an accuracy of 0.02mm.

Micrometer caliper: This is used to measure the thickness of metal sheets accurately upto 0.01mm

Wire gauge: The wire gauge is used to check the diameter of wires or thickness of sheet metal. The commonly used wire

gauge is imperial standard wire gauge (known as SWG).The most common wire gauge used in sheet metal has 21 slots

with gauges varying from 4 to 24.

Straight edge: This is a flat graduated bar of steel with one longitudinal edge beveled. This bar comes in a variety of

lengths ranging from 1 to 3 meter. It is useful for scribing long straight lines.

Steel square: It is a L-shaped piece of hardened steel with graduation on the edges for measuring and marking. It is used

for marking in the perpendicular direction to any base line. The short arm of the square or blade and the corner is called

the heel. The size of a L-square is specified by the length of the body and the angle.

Scratch awl and scriber: These are used for marking or layout purposes. A scratch awl is used where the marking lines

are deeper, and the pressure is exerted over the wooden handle. The scriber is used to make sharp clean lines on sheet

metal surfaces. The body of the scriber is knurled for a proper grip. The tips of the scriber and scratch all are hardened and

tempered. They are tapered to 15° to 20° to get a sharp point.

Dividers: Dividers are used for drawing circles or arcs on sheet metal .They are also used to mark a desired distance

between points and to divide lines into equal parts.

Trammel points: The trammel points, consists of two straight, removable legs tapered to needle points and attached to

separate heads. These heads or holders slide on wood or steel bars or beams and are held in place by thumb screws. A

special clamp for a pencil can be attached to one of the points. The trammel points are used to draw large arc and circles

that are beyond the limit of dividers.

Punches: Centre punch - 90°: It is used to mark centers to be drilled or mark centre for drawing circles on jobs.

Dot punch - 60°: It is a light type centre punch and is used to scribe lines with a chain of dots.

Prick punch -30°: It is sharply pointed punch and penetrates small mark but deeper along the Scribed line.

Solid punch: In riveting sheet metal, holes must be equally spaced and lined up. The holes in the metal are

usually punched with solid punches.

Hollow punch: These punches are also used punch holes in thin sheet metal, leather, plastic-cork etc. Hollow

punches have sharp, tubular end.

Pin punch: Pin punches are used to drive locating or locking pins, dowels and rivets out of their holes. Pin

punches are available in a set of 5 pins of dia.3, 4, 5, 6 and 8mm.

Chisels: Chisels are generally used in sheet metal work for cutting sheets, rivets, bolts and chipping

operations. The flat chisel is most widely used in sheet metal works.

Snips: These are usually called hand shear and are cutting tools like scissors. There are several types of snips available for

making straight or circular cuts, but the most common are Straight snips and Bent - snips. Straight snips are used for

making straight cuts and large external curves. Bent snips have curved blades for making circular cuts. They are also used

for trimming cylindrical or conical work in sheet metal. Snips are specified by the overall length and the shape of the

blade. The main parts are pivot, blade, handle.



Lever shear (Bench shear): Lever shears are used to cut sheets which cannot be cut with hand shears. The lever shear

possesses a fixed lower blade and a moving upper blade. The sheet being cut is prevented from tilting by a clamping

device which can be adjusted to the thickness of the sheet. The knife-edge cutter of the upper blade is curved so that the

opening angle at the point of cut remains constant.

Folding bar: Folding bar is a rectangular bar whose edges are brought together with a ring neck. This is used for bending

and folding on sheet metals.

Groover: A groover is a hand tool used for closing and locking of seams the end of the tool is recessed to fit over the lock

making the grooved seams.

Rivet: Rivet is an element used to fasten together two or more parts. It is a round piece of material having a head and

body. Chief rivet materials are mild steel, brass, copper and aluminium.

Rivet set: Rivet set is used to shape the head of the rivet. It carries two holes in which one straighten the rivets through

metal and the other shaping the head. Rivet set is also known as cup tool or snap. It depends upon the size of the rivet.

Hand reamer: A reamer is a multi point cutting tool used for enlarging and finishing previously drilled holes to accurate

sizes. Reaming produces high quality surface finish to close limits. Also small holes which cannot be finished by other

processes can be finished by reaming.

Files: The most widely used hand tool to be found in an engineering workshop is the file. A file is a hardened piece of

high grade steel with slanting rows of teeth. It is used to cut, smooth or fit metal parts. It cuts all metals except hardened

steel' the head is next to the handle. The safe edge or side of a file is that which has no teeth. Files are classified and

named according to the three principle factors-sizes, type or cut of teeth and sectional form.

Size: The size of a file is its length. This is the distance from the point to the heel, without the tang. Files for fine

work are usually from 100 to 200 mm and those for heavier work from 200 to 450 mm in length.

Cut of teeth: Cuts of files are divided into two groups: (1). single cut (2) Double cut. On single cut files the teeth

are cut parallel to other across the file is an angle of about 60° to the centre line of the file. Such files are frequently

termed as flats and are chiefly used on very hard metal. Double cut files have two sets of teeth; the over cut teeth being cut

at about 60° and the up cut at 75 to 80° to the centre line. Single cut and double cut files are further divided according to

the coarseness or spacing between the rows of the teeth. In descending order of roughness they are listed as,

1. Rough (R) 2.Bastard (B) 3 Second cut (SC) 4.Smooth (s) 5.Death smooth (DS)

Pliers: The pliers are used in sheet metal work for holding, cutting and bending work.

(a) Flat nose plier: The flat nose plier has flat jaws with small grooves. It is used for forming and holding work.

(b) Round nose plier: The round nose plier has long jaws rounded on the outside. It is used for holding and

forming the various shapes and patterns.

Hammers: The hammers, in sheet metal work, are used for forming shapes by hollowing, stretching or throwing off

processes. They are many types of hammers, but the most commonly used hammers, in sheet-metal work are follows:

(a) Ball peen hammer: The ball peen hammer has a round, slightly curved face and a round head. It is general

purpose hammer.

(b) Riveting hammer: The riveting hammer has a square, slightly curved face with beveled edges to prevent the

head of the hammer from marking the metal. The peen side is double tapered and has a slightly rounded end. It is

used for spreading rivets and for hammering a rivet set.

(c) Setting hammer: The setting hammer has a square, flat face and a tapered peen with beveled end. The flat

face is used for flattering seams without damage to the metal while peen end is used for peening operation.



(d) Hollowing or blocking hammer: The hollowing or blocking hammer has a dome face without any sharp

corner. It is used for hollowing discs into bowl shapes.

(e) Raising hammer: The raising hammer has an oblong flat face with concern slightly rounded off. It is used in

raising circular discs and many other raising and bumping operations.

(f) Planishing hammer: The planishing hammer has a round face. It is used on domed circular work.

(g) Collet hammer: The collet hammer has an oblong shaped faces. It is used on cylinders and in curved collects.

(h) Tray hammer: The tray hammer has oval shaped faces. It is used to sink the bottom when shaping a tray.

(I) Mallets: The mallets may be made from hide, fiber or wood. The best size of mallet is 5cm diameter. These

may be obtained in various shapes to suit special work.

Stakes: The stakes are steel anvils used to perform operations like bending, seaming or forming on sheet metal, when

suitable machines are not available. The stakes are available in various shapes and sizes.

(a) Blow horn stakes: The blow horn stakes has a short tapered horn at one end and a long tapered horn at the

other end. It can be held in a vice or in square hole in a wooden block or bench top. It is used for forming, riveting

operations.

(b) Beak horn stake: The beak horn stake has a round tapered horn at one end and a square tapered horn at the

other end. The round tapered end may be used for many purposes like bending of sheet metal into cylinders and

conical shapes, for setting down seams when used with a grooving punch or a seam set, for truing work to make

circular when the seam is folded or soldered etc.

(c) Hatchet Stake: It consists of a horizontal sharp straight edge and is used for making sharp bends, folding the

edges of the sheet metal.

(d) Half Moon Stake: This stake has a sharp edge in the form of an arc of a circle, beveled along one side. It is

used for circular folding and seaming.

(e) Funnel Stake: This stake is used when shaping and seaming funnels and tapered articles.

(f) Creasing Stake: This has two rectangular shaped horns. One is plane and the other contains a series of

grooved slots of various sizes. These slots are used for wiring „sinking‟ a bead on the straight edges of the flat

sheet, and for making small diameter tubes with thin gauge metal.

(g) Planishing Stake: This is slightly polished on its working surface and is used for planishing all types of flat

and shaped works.

(h) Horse head Stake: It is double ended holder for small stakes - one of which is cranked downwards for

clearance purpose and has square holes at both ends. It is used for working beads, flats etc. on cylindrical work.

(I) Bottom Stake: It consists of a single vertical piece with a flared end. This is used mostly for burring or

flanging circular bottoms by turning the edges of discs at right angles to fir circular stake.

(j) Hollow mandrel Stake: It is single horizontal metal piece, one end of which has a flat surface while the other

end has round section. The rounded section has a slot which permits the stake to slide on a bolt so that it can be

fastened on different positions on the bench. The stake is used for riveting, seaming and forming.

[WELDING] WORKSHOP PRACTICE


WELDING



INTRODUCTION

The welding is a process of joining two similar or dissimilar metals by fusion, with or without the application of

pressure and with or without the application of filler metal. The fusion of metal takes place by means of heat. The heat

obtained from blacksmith fire, electric arc, electrical resistance, or by chemical reaction.

SAFETY PRECAUTIONS

1. Workshop Safety 3. Equipment Safety

2. Personnel Safety 4. General Safety

(1) Workshop Safety

(a) Welding shop must be away from the storage of petrol, oil, or any inflammable materials

(b). Welding shop must be ventilated.

(c). Natural light, water and transport must be available.

(d). Fire fighting equipments must be instant in the shop.

(e). Lay out the electric and gas welding machine.

(f). Always keep a first aid box with accessories and containing eye drops, iodine, burnol with some cotton and

bandage.

(2). Personnel Safety

(a). Must be protective clothing‟s for the body.

(b). Must be wear goggles, helmet, Apron, hand gloves and leg guard.

(c). Must be used wire brush, chipping screen, etc.

(3). Equipment Safety

(a). Follow the manufactures instructions while seating the electric welding and gas welding equipments.

(b). Store the oxy acetylene cylinder must be made separately.

(c). Welding equipments must be free from, oil or grease.

(d). don‟t try with faulty equipments.

(e). Always have periodically inspect of machine.

(f) Never repair regulators, blow pipes as this are specialized job and must be to the maintenance repair.

(4). General Safety

(a). Arc welding booth should be pointed with black color as it has the property of observing the harmful rays

produced by the arc.

(b). Always use hammer and file with handle.

(c). Always use chipping goggles while grinding or chipping.

(d). Always store the scrap metals in a bin provided for the purpose.

ELECTRIC WELDING ACCESSORIES

The following accessories are used for electric arc welding.

1. AC or DC welding machine. 8. Face Shield. 15. Flat file.

2. Electrode. 9. Safety Goggles. 16. Hammers.

3. Electrode holder. 10. Hand gloves. 17. Flat chisel.

4. Cable and Cable connector. 11. Apron. 18. Hack saw with blade.

5. Chipping Hammer. 12. Sledge Hammer 19. Scriber.

6. Earth Clamp. 13. Punch. 20. Centre punch.

7. Wire Brush. 14. Tongs.

Electrode: Welding electrodes are use for providing extra metal to the weld. This extra metal is obtained by

melting the end of this rod. The size of electrode depends upon the core wire diameter of it, various size of

electrode and their melting or welding ampere is shown below.



Size of electrode Welding ampere

1.6mm

2mm

2.5mm

3.15mm

4mm

5mm

6mm

25Amp – 40Amp

40Amp – 60 Amp

60Amp – 90 Amp

90 Amp – 130 Amp

130 Amp – 180 Amp

180 Amp – 220 Amp

220 Amp – 280 Amp

Electrode holder: Electrode holder is used to hold the electrodes when welding operation is one.

Cable: It is used to connect the electric system.

Chipping hammer: It is used to remove slag from welded material.

Earth clamp: It used to connect the electric system on the work.

Wire brush: It used to clean the work.

Face shield: It used to protect the light and heat when welding is done.

Tongs: It is used to pick the work in hot stage.

Apron: It is used to protect the body from welding rays and heat. Apron is made by leather or asbestos.

Chisels: Chisels are generally used in sheet metal work for cutting sheets, rivets, bolts and chipping

operations. The flat chisel is most widely used in sheet metal works.

Files: The most widely used hand tool to be found in an engineering workshop is the file. A file is a hardened piece of

high grade steel with slanting rows of teeth. It is used to cut, smooth or fit metal parts. It cuts all metals except hardened

steel' the head is next to the handle. The safe edge or side of a file is that which has no teeth.

Electric Arc: An electric arc is nothing but more continuous spark between two terminals is called arc.

Arc Length: The distance between the tip of the electrode and surface of base metal is called arc length. It may be

classified in to three, they are:-

1. Long Arc: The distance between the tip of electrode and surface of base metal is greater than the diameter of

core wire of electrode.

2. Short Arc: The length of the arc is less than the diameter of core wire of electrode.

3. Medium Arc: The length of the arc equals to the diameter of the core wire of electrode.

Ordinary working in down hand position we keep normal arc.

Welding positions:

Flat position: In this position the filler metal is deposited from the upper side of the joint with the face of weld.

Horizontal position: In this position the filler metal is deposited upon the side of a horizontal and against a

vertical surface.

Vertical position: In this position the line of weld is in a vertical plane and the weld is deposited on vertical

surface.

Over head position: In this position the weld is deposited from the underside of the joint and the face of the weld

is in horizontal.

Polarity: Polarity is the direction in which the current flows when using direct current.

Straight polarity: When the electrode is connected with negative pole of DC welding plant is called straight

polarity.

Reverse polarity: When the electrode is connected with positive pole of DC generator is called reverse polarity.

Distortion: To metal the uneven expansion or contraction while welding is called distortion. There are three types of

distortion.

1. Angular distortion. 2. Longitudinal distortion. 3. Transverse distortion.



COMPARISON BETWEEN AC AND DC ARC WELDING MACHINES

AC Arc welding Machine DC Arc welding Machine

AC welding plant has no rotating parts DC welding plant has rotating parts like

motor and generator

Maintenance cost of the transformer is

low

Maintenance cost of DC plant is high

The transformer initial cost is low The initial cost of DC welding set is high

Distribution of heat is equal and there is

no change in polarity

Heat distribution is different in both

poles,2/3 of the heat obtained positive

pole and 1/3 at negative pole

The problem of arc blow does not arise

as it is very easy to controlling AC

welding.

The problem of arc blow is ever and

easily control.

All type of electrode can‟t be used in AC:

only coated electrode can be used

effectively.

Bare and coated electrode can be used in

DC welding generator.

Usually ferrous metals are welded by AC

and non ferrous can‟t be welded.

All type of metals can be welded by DC

welding generator.

Joint design: The basic types of joints used in

1. Butt joint 2.Lap joint. 3. Edge joint 4.T-fillet joint 5.Corner joint.

GAS WELDINGPROCESS

Gas welding is a group of welding process where in heat is produced by heating with a gas flame or flames with

or without the application of pressure and with or without the application of pressure and with or without the use of filler

material.

Common gas used in welding:

Oxy acetylene :- Its temperature is 3100°c to 3300°c

Oxy-coal gas: - Its temperature is 2200°c.

Oxy- propane: - Its temperature is 2480°c.

Natural gas with oxygen: - Its temperature is 2800°c to 3000°c.

Oxy-butane: - Its temperature is 2800°c to 3000°c.

Oxy hydrogen: - Its temperature is 2800°c and used for under water cutting and lights alloy welding.

OXY-ACETYLENE WELDING

Oxy- acetylene welding is a method of joining metals by heating them to the melting point using of mixture of

oxygen and acetylene gas in this gas welding additional metal called filler.

Metal or filler rod added to the welding in the form of welding rod. The composition of filler rod is usually the same of

nearly the same as that of part being welded.

Oxy-Acetylene Welding Equipments & Accessories

Oxygen cylinder: It is a cylindrical container for storing and supplying compressed oxygen for gas welding and

cutting purposes. Cylinders are painted in black color and cylinder valve are right hand threaded.

Acetylene cylinder: It is steel cylinder, filled with a porous substance creating a number of small cells in a

cylinder. These cells are filled with acetylene gas under pressure, cylinder painted maroon color and that outlet

valve has left hand threads.

Pressure Regulator: Regulators are generally used for reducing the high pressure inlet of cylinder to a suitable,

stable working pressure for welding purpose.



Hose Pipes: These are used to carry gas from the regulator to the blow pipe. These are made of strong canvas

rubber having good flexibility. Hose pips which carry oxygen is black color and acetylene are maroon color.

Welding blow pipe: Blow pipe is a device which is used for mixing oxygen and a fuel gas in required quantity

and producing a flame for welding purpose.

Filler Rode: Pieces of wires or rods of standard diameter and length used as filler metal in the join during gas

welding process are called filler rod or welding rod.

Goggles: They are used to protect the eyes from invasion of flame like high illumination, hot etc.

Spark Lighter: It is used to ignite the gases to avoid danger.

Tip cleaner: It is a wire with a rough end surface whose diameter corresponds to the diameter of the tip passage.

It removes the metal particles and other impurities from nozzle tip.

Types of flame: There are three types of oxy acetylene flames. They are Neutral flame

Carburizing flame and oxidizing flame.

Neutral Flame: In this flame, the ratio of oxygen and acetylene are equal in volume. Its temperature is 3200 to

33000C.

Carburizing flame: In this flame the ratio of acetylene gas is greater, then the ratio of oxygen gas. The flame

temperature is 31000C.

Oxidizing flame: In this flame the ratio of oxygen gas is greater than the volume of acetylene gas. The flame

temperature is upto 30000C.

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