MST for external.pdf

Dr. K. Benarji, Assistant professsor, Mechanical
Department,CUTM
Multi Skill Technician – Manufacturing
CUTM3013
Dr. K. Benarji, Assistant professor, Mechanical Department, CUTM

The workshop technology gives the basic working knowledge for the production of various engineering products. It explains
the construction, function and the use of various working tools, measuring tools, equipment and machines as well as the
technique of manufacturing a product from its raw material. To understand the subject and to develop the skill, one has to
practice the workshop processes, starting from simple models to complicated products.

workshop practice, can be broadly divided into two sections as mentioned below.
1. Hand-working processes
2. Machining processes
Hand working processes: The shaping of a part of an equipment or machine by hand operations using hand tools
or equipment, can be considered as hand-working process.
1. Fitting
2. Welding
3. Sheet metal works
4. Carpentry
5. Smithy
6. Foundry

Machining processes: Using metal-cutting machine tools, the machining operations are executed to shape
parts. The loading of the workpiece, control of the machining operations, the unloading and inspection are done
manually
1. Turning
2. Drilling
3. Shaping
4. Slotting
5. Milling
6. Grinding

Safety Measures
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The following are the types of safety measures to be considered in a workshop
1. Safety of the worker
2. Safety of the job
3. Safety of machines, tools and equipment

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safety measures
Wear tight shirt or dress
shop apron
Wear shoes with thick soles
Do not wear rings, watches, bracelets, or other jewellery
Keep the workshop floor free of oil, grease or any other liquid
Do not try to clean or repair a machine, if it is in motion
Take precaution while using hand tools such as hammer, chisels, file and saw

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Preparing for the Workshop Practice
The student has to posses the following materials
(a) Work record of A4 size.
(b) Fair record approved by the workshop authorities.
(c) Pen, clutch pencil, eraser and a straight edge
Students are advised to wear tight dress, preferably pants and shirts
Girl, students have to tie their hair
Wearing of shoes instead of slippers is also recommended

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Writing of Work Record for a Practice
1. Heading, serial number with date, and aim are similar to that given in the study.
2. Work material: Details about the work material and other requirements are written under this subheading. This
should include the size, number of pieces or quantity, material specification, etc.
3. Tools required: A list of tools and equipment required for the practice is given under this subheading.

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4. List of operations: The operations to be carried out for making the model have to be given as a list, below the
subheading.
5. Procedure: After completing the work on the model, the procedure followed for making the model has to be
written in the second right page, using past tense and in third person. This should contain all details about
operations, controls, safety measures, etc., related to the making of model.
6. Result: It is a custom to write the result of the practice as the last paragraph of the record. This includes the
statement that whether the content of the aim is achieved or not by the practice.

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Fitting

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Fitting
The term fitting, is related to assembly of parts, after bringing the dimension or shape to the required size or form, in
order to secure the necessary fit
Introduction to Bench Work and Fitting
Work holding devices
1. Work bench
2. Bench vice
3. Hand vice
4. V-block with clamp

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Work Bench
A fitting process can be done at various places, but most of the important operations of fitting are generally carried out on
a table called work bench. The size of the work bench required is about 150 to 180 cm length, nearly 90 cm width and
approximately 76 to 84 cm height

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Bench vice is the most widely used device for holding the workpiece in position during various operations which are
carried out in a fitting shop
Bench vice

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Hand Vice
For gripping small objects like screws, rivets, keys, etc., a hand vice is used

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V-block with Clamp
Cylindrical objects can be clamped for drilling or similar operations by using a V-block and a U-clamp

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Cutting tools:
1. Files
2. Hack saws
3. Chisels
4. Hammers
5. Scrapers
6. Drills
7. Reamers
8. Tap and die
9. Drilling machine
10. Tool grinding machine

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Files
A file is a hardened piece of steel containing a high percentage of carbon or tungsten. Fine teeth are cut on the
surface of the piece in slanting rows. Figure shows the standard form of a file with wooden handle in detached
position. The end called heal has a pointed portion called tong, which is used to fix the wooden handle. Files are
classified according to the following factors:
1. The cut and spacing of teeth on file.
2. The shape and form of the cross-section of file.
3. The length of file.

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Cut and spacing of teeth on file
A single cut file will be having parallel teeth at 60° inclination to the centre line and is also known as flat files.
Double cut files have two times cut-teeth; one similar to those of single cut (at 60°) and the other running
diagonally across, making an angle of 80° to the centre line

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Shape or form of cross section of file
Different cross sections are required for shaping contour of different forms. For example, a round hole can be
shaped only by a round file. Figure gives the common cross sections of the files used

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Effective length of files
The distance from the point to the heal (excluding the tang) is considered as the effective length of a file. The length of
files used for heavy works varies from 200 to 450 mm, while that for medium works varies from 150 to 250 mm. For fine
works, files of length 100 to 150 mm are preferred
Hack Saw
For cutting off and for making thin cuts, a hack saw is frequently used by a fitter. It mainly consists of a metal frame with a
wooden handle on one end, a metal clip with a wing nut on the other end and the cutting blade as shown in Figure

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Chisels
Chisels are used to cut or chip off metal from workpiece. If the metal is cut in the cold state (below the recrystallization
temperature), the chisel used for that is called cold chisel.
Depending on the shape of the cutting end, the commonly used cold chisels are classified into the
following types:
1. Flat cold chisel
2. Crosscut cold chisel
3. Diamond-pointed cold chisel
4. Half-round cold chisel

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Hammers
Hammers are used to strike on a tool, fastener or workpiece. They are made up of steel by forging process. Depending
on the shape, weight and the use, the hammers for fitting work are classified as below
1. Ball peen hand hammer
2. Cross peen hand hammer
3. Straight peen hand hammer
4. Soft hammer (mallet)

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Scrapers
Scrapers are tools like a file or knife which have very hard cutting edges. Scraping means removal of a very thin layer of
metal similar to shaving.
1. Flat scraper—for scraping flat surfaces.
2. Triangular scraper—for curved surfaces and corners.
3. Half round scraper—for round and curved surfaces.

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Drills and Reamers
Drill is a tool used to make cylindrical holes by rotating and pressing the tool against a work piece.
1. Flat drill
2. Straight fluted-drill
3. Twist drill

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Twist drill of straight shank and taper shank are commonly used for drilling. The included angle between the cutting
edges of a twist drill is kept at 118°
Drilled surface of hole may not be smooth and may have dimensional variation. To correct this a process called
reaming is done using the tool called reamer.
Reamers

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Taps and Dies
A tap is used to cut internal threads on a hole drilled to the core diameter of the thread
1. First tap, or rougher—to start threading
2. Second tap or intermediate—to cut the thread
3. Bottoming tap or finisher—to finish the thread

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Dies
Dies are used to cut external threads on round rods.

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Measuring and marking tools:
1. Surface plate
2. Engineer's try-square
3. Scribers
4. Punches
5. Steel rule
6. Vernier caliper
7. Outside and inside calipers
8. Dividers
9. Combination set
10. Micrometers
11. Vernier height gauge
12. Miscellaneous gauges

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Surface Plate
It is a cast iron plate having perfectly smooth and flat surface, used as a reference surface for measuring and marking.
The flat surface is finished by grinding and scraping
Engineer's Try Square
The try square of shape is used in fitting shops for scribing straight lines at right angles to a true surface.

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Scribers
A scriber is a piece of hardened steel pointed at ends and the length ranges from 150 to 300 mm and diameter 3 to 5 mm. It
is used like a pencil to mark scratch lines on the workpiece for transfering the drawing on it
Punches
A punch is a tool similar to a chisel, but the cutting edge is replaced by a pointed edge. Punches are used to locate the
line drawn by a scriber as a permanent mark. Depending on the use and the shape of the marking edge, punches can be
classified as

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Steel Rule
Steel rule is the scale used in fitting shops for taking measurements up to 0.5 mm accuracy. One side is marked in
millimetre and the other side in inches.
Vernier Caliper
For more precise measurement of length, vernier calipers are used. There are vernier calipers to measure length with an
accuracy of 0.02 mm or 0.001 inch.

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The vernier scale for 0.02 mm least count has the scale length of 49 mm and it is divided to 50 equal divisions. Hence,
one division of vernier scale is 1/50 mm less than 1 mm. This gives a least count of 0.02 mm. The reading of the vernier
caliper is similar to any vernier scale. For example, if a dimension measured contains the main scale divisions (say, 12)
and the vernier scale division coinciding with main scale (say 42), then the measured dimension
= 12 + (0.02 x 42) = 12 + 0.84 = 12.84 mm
Total length= Main scale division + Least count x Vernier scale division

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Outside and Inside Calipers
To measure the size of or to transfer a dimension to a component, calipers are used.
1. Outside caliper
2. Inside caliper
3. Outside spring caliper
4. Inside spring caliper
5. Hermaphrodite (Jenny or odd leg) caliper

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Micrometer
Micrometer is a precision instrument used to measure the size up to an accuracy of 0.01 mm
Total reading = Main scale reading + (L.C x
Thimble scale reading)

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Vernier Height Gauge
To measure the height of parts or to mark height accurately on an object, vernier height gauges are used
This tool is used to transfer dimensions, scribing circles and for laying out the drawing in a work.
Dividers

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Tools for assembling and inspection:
1. Spanners
2. Pliers
3. Screw drivers
4. Allen keys
Spanners
To tighten and loosen nuts, bolts and studs, spanners are used.

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Pliers
Pliers are mainly used to hold a workpiece or small articles. They are also used to cut or bend wire or similar thin
components
Screw Drivers
To tighten or loosen different types of screws, screw drivers are used

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Allen Keys
Screws or bolts with allen heads (hexagonal sockets) are tightened or loosened by using L-shaped tool called alien key.

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Sheet Metal Work

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Hand working of metal sheets of thickness ranging from 0.31 mm to 1.63 mm is generally considered as sheet metal
work.A metal plate of thickness less than 6 mm is considered as sheet.
The metals used commonly for sheet metal works are:
1. Black iron (uncoated) sheets
2. Galvanized iron (GI ) sheets
3. Copper sheets
4. Aluminium sheets
5. Tin plates
6. Stainless steel sheets

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Measuring Tools
1. Steel rule
2. Vernier calliper
3. Micrometer
4. Sheet metal gauge
Marking Tools
1. Straight edge
For marking the straight lines on sheet metal, straight edges are used
2. Steel square
The use of steel square is similar to that of try square in bench work
3. Scriber
4. Divider
5. Centre punch

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Cutting Tools
To cut the sheet metal as per the pattern drawn and to make holes for rivets etc., the following types of tools are used.
1. Straight snips (shears)
2. Bent snips (shears)
3. Solid punches
4. Hollow punches
5. Cold chisels
6. Files
Straight snips (shears)
A straight snip having straight blades to cut along straight lines.

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Bent snips (shears)
A bent snip having curved blades to cut along curved lines. These snips are used for cutting thin sheets.
Solid punch
Solid punches are used to make small holes (2.5 to 10 mm) in sheets for riveting and similar works.
Hollow punches
Hollow punches are used to make large size holes (10 mm or larger) or to cut circular blanks

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Forming Tools
1. Stakes
2. Hammers
3. Mallet
4. Hand groovers.
5. Pliers
6. Bench vice
1. Stakes
The types of anvil (support) on which the sheet metal operations are done are called stakes. They are of various shapes and
sizes. The stakes act as supporting as well as the forming tool for the shaping operations like bending, seaming, cutting,
folding etc.
(a) Half moon stake
(b) Beak horn stake
(c) Hatchet stake
(d) Funnel stake
(e) Horse head stake
(f) Convex stake
(g) Square stake

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The sheet metal is shaped by hammering or striking with mallet, after keeping the work on suitable form of stake.
The hammers used for sheet metal work are
(a) Setting hammer, for setting down the edge while making double seam
(b) Raising hammer for forming curved or hollow shape from flat piece
(c) Riveting hammer for riveting purpose. Mallets are soft hammers used to give soft blows which will not damage
the sheet at the same time will shape them.

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Joining Tools
The tools exclusively used for making and finishing joints are:
(a) Hand groovers
(b) Rivet set
(c) Soldering irons
Hand groovers
Hand groovers are used to flatten and shape joints made in sheet metal.
For shaping the second head of a rivet, a riveting tool called rivet set is used.
This can convert the rough shape of a rivet formed by hammering to a smooth round head by final hammering over the
tool.

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Carpentry
Carpentry is the process of shaping timber, using hand tools. The products Carpentry work mainly involves the
joining together of wooden pieces and finishing the surfaces after shaping them.
Materials
Timber
Plywood
Auxiliary materials
Nails, screws, adhesives, paints, varnishes, etc

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Timber
Wood obtained from exogenous (outward growing) trees. the growth is outward from the centre, by adding almost concentric
layers of fresh wood every year known as annual rings
Timber is available in market in various shapes and size
Classification of Wood
Soft wood
A soft wood is light in weight and light coloured. Not suitable for wood working
Hard woods are nearly equally strong both along and across the fibres. Hard wood is the material used for wood working
Indian Timber
Teak, Sissu, Sal, Mahogany, Deodar, Babul, Mango

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Plywood
Plywood is a thick sheet formed by pasting veneers of wood called plys together using glues
It can be made in very large sheet size without joints. Plywood sheets can be bent to shapes of different designs.
Due to the above advantages plywood sheets are very widely used for making furniture, boxes, doors,
cupboards, etc.
Auxiliary Materials
Screws
Bolts and nuts
Nails
Dowels
Adhesives
Surface coatings

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Tools for Wood Working
Measuring and Marking Tools
Steel rule
Try square
Scriber
Gauges
Marking gauge: To mark single line
Mortise gauge: To mark two parallel lines

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1. Wing compass: It is used to mark circles, arcs etc.
2. Trammel: This is a beam compass to mark large size radius.
3. Divider: It is used to divide and mark dimensions.
4. Spirit level: It is used to check the horizontality of flat surfaces.
5. Plumb bob: It is used to check the verticality of a surface.
Miscellaneous measuring tools
Cutting Tools
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
workpiece.
Cross cut saw: It is used to cut thick wooden pieces across the grains.

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Tenon saw (Back saw): This saw is used for short straight cuts
Rip saw: It is a saw similar to hand saw used to cut wood along the grains
Panel saw: This is similar to cross cut saw having finer blade and teeth, used for cutting panels of doors or similar pieces
Compass saw: This is a saw having tapered blade which is narrow, long and flexible. It is used to cut along straight or
curved lines.
Dove-tail saw: This is a saw of fine type like tenon saw, used to take fine and accurate cuts. The back side stiffener is
provided in the saw.
Key hole saw (pad saw): This is the smallest type of saw used to cut key holes or the starting of any interior cut.

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8. Bow saw: This saw has a narrow blade on a wooden frame of the shape of a bow. It is used to cut along sharp curves.
9. Coping saw: This saw has a narrow blade held in tension by a spring metal frame. It is used to cut small radius curves in
thin wooden pieces.
Chisels
1. Firmer chisel: They are the most common and general purpose chisel used by a carpenter
2. Bevelled edge firmer (dove-tail) chisel: These chisels are used for fine and delicate works as well as for cutting
corners
3. Mortise chisel: These chisels are used for heavy and deep cuts to remove a large quantity of wood. These chisels have
width of about 15 mm, but the blade thickness may range from 6 to 15 mm [Figure 6.6(c)].
4. Gouges: These are chisels with curved sections. They are used to cut curved shapes of internal or external type.

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Striking Tools
Mallet: This is a wooden-headed hammer of round or rectangular cross section
Claw hammer: This is a hammer having steel head and wooden handle.

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Planing Tools
To smoothen the flat wooden surfaces, planing tools are used
1. Wooden jack plane: This is the most commonly used plane in carpenters
shops
2. Iron jack plane: In an iron jack plane the wooden sole is replaced by a cast iron channel-shaped bod
3. Smoothing plane: A smoothing plane is practically a wooden plane of smaller size, used for smoothening and
finishing operations

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Work Holding Devices
Work bench
Carpenter's bench vice:
Miscellaneous Tools
Rasps and files: Rasp is a rough file used to remove wood from the surface, corners
Sand paper: This is a thick paper coated with sharp-edged sand or glass particles of fine type on one side of it
Pincer: This is a tool similar to pliers and is used while screw is extracted from or driven into the wood.
Screw drivers: They are used to drive wood screw into or from the workpiece.
Hand drill: To make small size holes of less depth, hand drills are commonly used
Auger: For making large size deep holes of diameter from 8 mm to 25 mm, augers of suitable size and length are used in
carpentry shops

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Wood Working Processes
1. Marking
2. Sawing
3. Planing
4. Chiselling
5. Mortising
6. Tenoning
7. Grooving and tongueing
8. Rebating
9. Recessing
10. Boring
11. Moulding

A power tool is a tool that is actuated by an additional power source and
mechanism other than the solely manual labor used with hand tools
POWER TOOL:
Circular saws, jigsaws, drills, hammer-drills, sanders,
grinders, routers and numerous other power tools, save
time and effort on the job
Power Hacksaw,
Circular saw,
Jig saw
Drilling ( Bench drilling, Pillar drills, Hand drills)
Grinding ( Surface grinding, Pedestal Grinding, Hand Grinder.
Milling ( Vertical milling ,Horizontal Milling, Universal Milling)

Power hacksaws are used to cut large sizes (sections)
of metals such as steel.
Cutting diameters of more than 10/15mm is very hard work with a normal hand
held hacksaw. Therefore power hacksaws have been developed to carry out the
difficult and time consuming work.
POWER HACKSAWS

CIRCULAR SAWS:
The circular saw is a woodworking and do-it-yourself
power tool used to cut wood by the cutting action of a
toothed blade rotating at high speed.
Its most common function is to make cuts in a straight
line on pieces of lumber.

Jigsaws are best used for cutting shapes and curves in wood with
its narrow blade, which is attached to the tool's body by a spring-
loaded clamp at the front.
JIG SAWS:
A jigsaw is best for making curved or intricate cuts, while a
circular saw is better suited for making straight cuts, such as rip
cuts and crosscuts.

Welding
• Welding is a process of joining similar or dissimilar
metals by application of heat with or without
application of pressure and additional of filler material.
• In welding heat is supplied either electrically or by
means of a gas torch.
• It is also called secondary manufacturing process
Aircraft, ships, bridges, building constructions

Advantages
• Welding is more economical and is
much faster process as compared to
other processes (riveting, bolting,
casting etc.)
• Welding, if properly controlled results
permanent joints having strength equal
or sometimes more than base metal.
• Large number of metals and alloys both
similar and dissimilar can be joined by
welding.
• General welding equipment is not
costly.
• Portable welding equipment can be
easily made available.
• Welding permits considerable freedom
in design.
• Welding can also be mechanized.
Disadvantages
• It results in residual stresses and
distortion of the work pieces.
• Welded joint needs stress relieving and
heat treatment.
• Welding gives out harmful radiations
(light), fumes and spatter.
• Jigs, and fixtures may also be needed to
hold and position the parts to be
welded
• Edges preparation of the welding jobs
are required before welding
• Skilled welder is required for production
of good welding
• Heat during welding produces
metallurgical changes as the structure of
the welded joint is not same as that of
the parent metal.

Types of welding
Plastic welding (Pressure welding)
• In this type of welding the piece of metal to be joined are heated to a plastic state
and then forged together by external pressure.
• This processes is used in forge welding, resistance welding
Fusion welding (Non-pressure)
• The fusion of metal takes place by means of heat. The heat may be generated
either from combustion of gases, electric arc, electric resistance or by chemical
reaction
• In this method filler material is required during the process like arc welding, gas
welding

1. Gas welding
a. Oxy-acetylene b. Air-acetylene c. Oxy-hydrogen
2. Arc welding
a. Carbon arc welding d. Metal arc g. Gas-metal arc(MIG)
b. Plasma arc welding e. Electro-slag h. Gas-tungsten arc (TIG)
c. Submerged arc weld f. Flux-cored i. Atomic-hydrogen arc
3. Resistance welding
a. Butt c. Spot e. Seam
b. Projection d. Percussion
4. Thermit welding

5. Solid state welding
a. Friction c. Ultrasonic
b. Explosive d. Diffusion
6. Newer welding (Radiant Energy welding)
a. Electro-beam b. Laser

Definitions
 Backing: It is the material support provided at the root side of a weld to aid in the control
of penetration.
 Base metal: The metal to be joined or cut is termed as the base metal.
 Bead or weld bead: Bead is the metal added during a single pass of welding. The bead
appears as a separate material from the base metal.
 Crater: In arc welding, a crater is the depression in the weld metal pool at the point where
the arc strikes the base metal plate.

• Root: It is the point at which the two pieces to be joined by welding
are nearest.
• Tack weld: A small weld, generally used to temporarily hold the two
pieces together during actual welding, is the tack weld.

Arc welding
• An arc is generated between two
conductors of electricity, cathode and
anode, when they are touched to
establish the flow of current and then
separated by a small distance.
• An arc is a sustained electric discharge
through the ionised gas column called
plasma between the two electrodes.

Equipment
1. Arc welding power source
2. Welding cables
3. Electrode holder
4. Welding Electrodes
(1) Consumable Electrodes
(a) Bare Electrodes
(b) Coated Electrodes
(2) Non-consumable Electrodes
(a) Carbon or Graphite Electrodes
(b) Tungsten Electrodes
5. Goggles
6. Hand glows
7. Chipping hammer & brush

Shielded Metal Arc Welding (SMAW) or Manual
Metal Arc Welding (MMAW)
• (SMAW) is a commonly used arc welding process manually carried by
welder.
• Heat for welding is produced through an electric arc set up between a flux
coated electrode and the workpiece.
• The flux coating of electrode decomposes due to arc heat and serves
many functions, like weld metal protection, arc stability etc.
• Inner core of the electrode supply the filler material for making a weld.
• If the parent metal is thick it may be necessary to make two or three
passes for completing the weld.

Advantages
• Shielded Metal Arc Welding (SMAW)
can be carried out in any position
with highest weld quality.
• MMAW is the simplest of all the arc
welding processes.
• Big range of metals and their alloys
can be welded easily
• Automatic welding machines can be
easily accomplished by flux shielded
m
• The MMAW welding equipment is
portable and the cost is fairly low
• Due to flux coated electrodes, the chances of
slag entrapment
• Duo to fumes and particles of slag, the arc and
metal transfer is not very clear
• Due to limited length of each electrode and
brittle flux coating on it, mechanization is
difficult.
Applications
• Today, almost all the commonly employed
metals and their alloys can be welded by this
process.
• (a) Building and Bridge construction
• (b) Automotive and aircraft industry, etc.
• (c) Air receiver, tank, boiler and pressure
vessel fabrication
• (d) Ship building
• (e) Pipes and
• (f) Penstock joining
Disadvantages

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