Chapter -1

1. WELDINGS
A cast iron is an alloy of iron, carbon, and silicon, in which the

amount of carbon is usually more than 1.7 percent and less than 4.5

percent. The overall weldability of cast iron is low and depends on the material

type, complexity, thickness, casting complexity and need for machinability.

Ductile and malleable irons have good weldability while grey cast iron and

white cast iron are only weldable for small attachments.

The most widely used type of cast iron is known as gray iron.

Gray iron has a variety of compositions, but is usually such that it is

primarily perlite with many graphite flakes dispersed throughout.

There are also alloy cast irons which contain small amounts of

chromium, nickel, molybdenum, copper, or other elements added to provide

specific properties.

Another alloy iron is austenitic cast iron, which is modified by

additions of nickel and other elements to reduce the transformation

temperature so that the structure is austenitic at room or normal

temperatures. Austenitic cast irons have a high degree of corrosion

resistance.

In white cast iron, almost all the carbon is in the combined

form. This provides a cast iron with higher hardness, which is used for

abrasion resistance.

1
Malleable cast iron is made by giving white cast iron a special

annealing heat treatment to change the structure of the carbon in the

iron. The structure is changed to perlitic or ferritic, which increases

its ductility.

Nodular iron and ductile cast iron are made by the addition of

magnesium or aluminum which will either tie up the carbon in a combined

state or will give the free carbon a spherical or nodular shape, rather

than the normal flake shape in gray cast iron. This structure provides a

greater degree of ductility or malleability of the casting.

A major factor contributing to the difficulty of welding cast iron

is its lack of ductility. If cast irons are loaded beyond their yield

points, they break rather than deform to any significant extent. Weld

filler metal and part configuration should therefore be selected to

minimize welding stresses.

MMA, flux cored arc, MIG, TIG and gas welding processes are

normally used with nickel-based welding consumables to produce

high-quality welds, but cast iron and steel electrodes can also

produce satisfactory welds in certain alloys.

2
 Chapter -2
2. Weldability by Metal Type

Figure - 2.1
Applications
These types of metal are widely used in: agricultural equipment onmachine

tools as bases, brackets, and covers for pipe fittings cast iron pipe automobile

engine blocks, heads, manifolds water preps repair defects in order to upgrade

or salvage a casting before service It is rarely used in structural work except for

compression members. It is widely used in construction machinery for

counterweights and in other applications for which weight is required.

Characteristics

Grey (Gray) or flake graphite

Where the graphite exists as branched interconnected flakes; this type of iron is

relatively cheap and has poor mechanical properties. Grey irons are usually

weldablewith MMA (SMA), MIG (GMA) or FCAW as long as special

consumables and procedures are used.

3
Gray cast iron has low ductility and therefore will not expand or

stretch to any considerable extent before breaking or cracking. Because

of this characteristic, preheating is necessary when cast iron is welded

by the oxyacetylene welding process. It can, however, be welded with

the metal-arc process without preheating if the welding heat is

carefully controlled. This can be accomplished by welding only short

lengths of the joint at a time and allowing these sections to cool. By

this procedure, the heat of welding is confined to a small area, and the

danger of cracking the casting is eliminated. Large castings with

complicated sections, such as motor blocks, can be welded without

dismantling or preheating. Special electrodes designed for this purpose

are usually desirable. Ductile cast irons, such as malleable iron,

ductile iron, and nodular iron, can be successfully welded. For best

results, these types of cast irons should be welded in the annealed

condition.

Nodular or spheroidal graphite (ductile iron)

Where the graphite exists as graphite in a spheroidal form and the mechanical

properties approach those of steel. Nodular irons are generally easier to weld

than grey irons, but still require special consumables and procedures.

Malleable CI

Where the graphite exists as nodules or rosettes produced by heat treatment.

Malleable irons have two main forms: blackheart malleable, which has similar

4
weldability to nodular cast iron, and whiteheart malleable, which is readily

weldable with ferritic consumables provided care is taken to limit penetration.

White

A hard, brittle iron containing no free graphite. White irons are generally

considered unweldable.

Austenitic

Where the graphite may exist in either flake or nodular form, resulting in good

corrosion and heat resistance. Many grades of austenitic irons can be welded

with special consumables and procedures.

CI with High Silicon and Aluminum Content

Where the graphite exists mainly as flakes and the material has good corrosion

resistance. This alloy can be welded with special consumables and procedures.

5
 Chapter -3
3. Tips for Repairing a Crack in Cast Iron

Most problems have to do with the high carbon content. This results in cracking

problems and thermal control issues. Cast irons have approximately 2 to 4%

carbon.

Stick welding can be used to repair castings with several types of welds that are

machine friendly:

nickel 55 soft weld

nickel 99 soft weld

HTS-528 Brazing Rod (strongest brazing rod made for joining cast iron, with

the convenience of a built in flux)

Nickel is a non-ferrous alloy that does not absorb any carbon making it a good

choice for repair.

Pre-heat any casting to avoid cracking. Control the pre-heating with a temple

stick. When it melts it means that you can weld into the casting. Preheating a

casting before weld repair can be very useful in controlling the cooling rate after

welding. This is particularly important when repairing complex shapes since

different thicknesses of material respond differently to the heat from the weld

pool, which can result in damaging thermal stresses and distortion.

Clean any joints that will be repaired or welded including grease and dirt. Use

grinding or cleaning solvents.

If after the repair porosity is a problem, grind the area back to the sound metal

6
For repairs where there are casting imperfections, such as blow holes or cracks,

all defective areas should be removed by cold chiseling, gouging or grinding. If

gouging with a covered electrode or air-carbon arc, a heat affected zone will

form around the gouged area. The casting should be preheated to 300°C before

gouging to reduce the risk of cracking in this region. The groove should also be

lightly ground to remove hardened material before depositing the repair, since

graphite in this region may dissolve during gouging, increasing its sensitivity to

cracking during subsequent welding. When removing cracks or linear defects,

the ends of the crack should be blunted by drilling before gouging, to prevent

further propagation during the preparation for repair. The true ends of the crack,

which may be very fine, should be located by dye penetrant or magnetic particle

methods before drilling.

In video DC positive is used. Use the appropriate safety gear and eliminate

fume exposure.

Figure 3.1 Cast Iron Welding Repair Preheating Is Recommended

7
Benefits as a welding metal:

More fluid than steel (better castability)

Lower melting point than steel

Low cost material

Can be shaped with sand casting

Desirable Properties such as:

-Damping capacity

-Thermal conductivity

-Ductility

-Hardness

- Strength

8
Figure: 3.2 Modifications to Joint Design that Reduce Risk of Cracking

When Welding Cast Iron

9
 Chapter -4
4.1 WELDING PREPARATION

In preparing the casting for welding, it is necessary to remove all

surface materials to completely clean the casting in the area of the

weld. This means removing paint, grease, oil, and other foreign material

from the weld zone. It is desirable to heat the weld area for a short

time to remove entrapped gas from the weld zone of the base metal. The

skin or high silicon surface should also be removed adjacent to the weld

area on both the face and root side. The edges of a joint should be

chipped out or ground to form a 60° angle or bevel. Where grooves are

involved, a V groove from a 60-90° included angle should be used. The V

should extend approximately 1/8 in. (3.2 mm) from the bottom of the

crack. A small hole should be drilled at each end of the crack to keep

it from spreading. Complete penetration welds should always be used,

since a crack or defect not completely removed may quickly reappear

under service conditions.

Preheating is desirable for welding cast irons with any of the

welding processes. It can be reduced when using extremely ductile filler

metal. Preheating will reduce the thermal gradient between the weld and

the remainder of the cast iron. Preheat temperatures should be related

to the welding process, the filler metal type, the mass, and the

10
complexity of the casting. Preheating can be done by any of the normal

methods. Torch heating is normally used for relatively small castings

weighing 30.0 lb (13.6 kg) or less. Larger parts may be furnace

preheated, and in some cases, temporary furnaces are built around the

part rather than taking the part to a furnace. In this way, the parts

can be maintained at a high interpass temperature in the temporary

furnace during welding. Preheating should be general, since it helps to

improve the ductility of the material and will spread shrinkage stresses

over a large area to avoid critical stresses at any one point.

Preheating tends to help soften the area adjacent to the weld; it

assists in degassing the casting, and this in turn reduces the

possibility of porosity of the deposited weld metal; and it increases

welding speed.

Slow cooling or post heating improves the machinability of the

heat-affected zone in the cast iron adjacent to the weld. The post

cooling should be as slow as possible. This can be done by covering the

casting with insulating materials to keep the air or breezes from it.

11
4.2 ELECTRODES

Cast iron can be welded with a coated steel electrode, but this

method should be used as an emergency measure only. When using a steel

electrode, the contraction of the steel weld metal, the carbon picked up

from the cast iron by the weld metal, and the hardness of the weld

metal caused by rapid cooling must be considered. Steel shrinks more

than cast iron when ceded from a molten to a solid state. When a steel

electrode is used, this uneven shrinkage will cause strains at the joint

after welding. When a large quantity of filler metal is applied to the

joint, the cast iron may crack just back of the line of fusion unless

preventive steps are taken. To overcome these difficulties, the prepared

joint should be welded by depositing the weld metal in short string

beads, 0.75 to 1.0 in. long (19.0 to 25.4 mm). These are made

intermittently and, in some cases, by the backstep and skip procedure.

To avoid hard spots, the arc should be struck in the V, and not on the

surface of the base metal. Each short length of weld metal applied to

the joint should be lightly peened while hot with a small ball peen

hammer, and allowed to cool before additional weld metal is applied. The

peening action forges the metal and relieves the cooling strains.

The electrodes used should be 1/8 in. (3.2 mm) in diameter to

prevent excessive welding heat. Welding should be done with reverse

12
polarity. Weaving of the electrode should be held to a minimum. Each

weld metal deposit should be thoroughly cleaned before additional metal

is added.

Cast iron electrodes must be used where subsequent machining of

the welded joint is required. Stainless steel electrodes are used when

machining of the weld is not required. The procedure for making welds

with these electrodes is the same as that outlined for welding with mild

steel electrodes. Stainless steel electrodes provide excellent fusion

between the filler and base metals. Great care must be taken to avoid

cracking in the weld, contracts approximately 50 percent more than

because stainless steel expands and mild steel in equal changes of

temperature.

13
4.3 ARC WELDING

The shielded metal arc welding process can be utilized for

welding cast iron. There are four types of filler metals that may be

used: cast iron covered electrodes; covered copper base alloy

electrodes; covered nickel base alloy electrodes; and mild steel covered

electrodes. There are reasons for using each of the different specific

types of electrodes, which include the machinability of the deposit, the

color match of the deposit, the strength of the deposit, and the

ductility of the final weld.

When arc welding with the cast iron electrodes (ECI), preheat to

between 250 and 800°F (121 and 425°C), depending on the size and

complexity of the casting and the need to machine the deposit and

adjacent areas. The higher degree of heating, the easier it will be to

machine the weld deposit. In general, it is best to use small-size

electrodes and a relatively 1ow current setting. A medium arc length

should be used, and, if at all possible, welding should be done in the

flat position. Wandering or skip welding procedure should be used, and

peening will help reduce stresses and will minimize distortion. Slow

cooling after welding is recommended. These electrodes provide an

excellent color match cm gray iron. The strength of the weld will equal

the strength of the base metal. There are two types of copper-base

14
electrodes: the copper tin alloy and the copper aluminum types. The

copper zinc alloys cannot be used for arc welding electrodes because of

the low boiling temperature of zinc. Zinc will volatilize in the arc and

will cause weld metal porosity.

When the copper base electrodes are used, a preheat of 250 to

400°F (121 to 204°C) is recommended. Small electrodes and low current

should be used. The arc should be directed against the deposited metal

or puddle to avoid penetration and mixing the base metal with the weld

metal. Slow cooling is recommended after welding. The copper-base

electrodes do not provide a good color match.

There are three types of nickel electrodes used for welding cast

iron. These electrodes can be used without preheat; however, heating to

100°F (38°C) is recommended. These electrodes can be used in all

positions; however, the flat position is recommended. The welding slag

should be removed between passes. The nickel and nickel iron deposits

are extremely ductile and will not become brittle with the carbon

pickup. The hardness of the heat-affected zone can be minimized by

reducing penetration into the cast iron base metal. The technique

mentioned above, playing the arc on the puddle rather than on the base

metal, will help minimize dilution. Slow cooling and, if necessary,

15
post heating will improve machinability of the heat-affected zone. The

nickel-base electrodes do not provide a close color match.

Copper nickel type electrodes cane in two grades. Either of these

electrodes can be used in the same manner as the nickel or nickel iron

electrode with about the same technique and results. The deposits of

these electrodes do not provide a color match.

Mild steel electrodes are not recommended for welding cast iron

if the deposit is to be machined. The mild steel deposit will pick up

sufficient carbon to make a high-carbon deposit, which is impossible to

machine. Additionally, the mild steel deposit will have a reduced level

of ductility as a result of increased carbon content. This type of

electrode should be used only for small repairs and should not be used

when machining is required. Minimum preheat is possible for small repair

jobs. Small electrodes at low current are recommended to minimize

dilution and to avoid the concentration of shrinkage stresses. Short

welds using a wandering sequence should be used, and the weld should be

peened as quickly as possible after welding. The mild steel electrode

deposit provides a fair color match.

16
4.4 CARBON-ARC WELDING OF CAST IRON

Iron castings may be welded with a carbon arc, a cast iron rod, and a

cast iron welding flux. The joint should be preheated by moving the

carbon electrodes along the surface. This prevents too-rapid cooling

after welding. The molten puddle of metal can be worked with the carbon

electrode so as to move any slag or oxides that are formed to the

surface. Welds made with the carbon arc cool more slowly and are not as

hard as those made with the metal arc and a cast iron electrode. The

welds are machinable.

Oxyfuel Gas Welding

The oxyfuel gas process is often used for welding cast iron. Most of the

fuel gases can be used. The flame should be neutral to slightly

reducing. Flux should be used. Two types of filler metals are available:

the cast iron rods and the copper zinc rods. Welds made with the proper

cast iron electrode will be as strong as the base metal. Good color

match is provided by all of these welding reds. The optimum welding

procedure should be used with regard to joint preparation, preheat, and

post heat. The copper zinc rods produce braze welds. There are two

classifications: a manganese bronze and a low-fuming bronze. The

deposited bronze has relatively high ductility but will not provide a

color match.

17
4.5 BRAZING AND BRAZE WELDING

Brazing is used for joining cast iron to cast iron and steels. In

these cases, the joint design must be selected for brazing so that

capillary attraction causes the filler metal to flow between closely

fitting parts. The torch method is normally used. In addition, the

carbon arc, the twin carbon arc, the gas tungsten arc, and the plasma

arc can all be used as sources of heat. Two brazing filler metal alloys

are normally used; both are copper zinc alloys. Braze welding can also

be used to join cast iron. In braze welding, the filler metal is not

drawn into the joint by capillary attraction. This is sometimes called

bronze welding. The filler material having a liquidous above 850°F

(454°C) should be used. Braze welding will not provide a color match.

Braze welding can also be accomplished by the shielded metal arc

and the gas metal arc welding processes. High temperature preheating is

not usually required for braze welding unless the part is extremely

heavy or complex in geometry. The bronze weld metal deposit has

extremely high ductility, which compensates for the lack of ductility of

the cast iron. The heat of the arc is sufficient to bring the surface

of the cast iron up to a temperature at which the copper base filler

metal alloy will make a bond to the cast iron. Since there is little or

no intermixing of the materials, the zone adjacent to the weld in the

18
base metal is not appreciably hardened. The weld and adjacent area are

machinable after the weld is completed. In general, a 200°F (93°C)

preheat is sufficient for most application. The cooling rate is not

extremely critical and a stress relief heat treatment is not usually

required. This type of welding is commonly used for repair welding of

automotive parts, agricultural implement parts, and even automotive

engine blocks and heads. It can only be used when the absence of color

match is not objectionable.

19
4.6 GAS METAL ARC WELDING

The gas metal arc welding process can be used for making welds

between malleable iron and carbon steels. Several types of electrode

wires can be used, including:

Mild steel using 75% argon + 25% CO2 for shielding.

Nickel copper using 100% argon for shielding.

Silicon bronze using 50% argon + 50% helium for shielding.

In all cases, small diameter electrode wire should be used at low current. With

the mild steel electrode wire, the Argon-CO2

shielding gas mixture issued to minimize penetration. In the case of

the nickel base filler metal and the Copper base filler metal, the

deposited filler metal is extremely ductile. The mild steel provides a

fair color match. A higher preheat is usually required to reduce

residual stresses and cracking tendencies.

20
4.7 FLUX-CORED ARC WELDING

This process has recently been used for welding cast irons. The more

successful application has been using a nickel base flux-cored wire.

This electrode wire is normally operated with CO2 shielding

gas, but when lower mechanical properties are not objectionable, it can

be operated without external shielding gas. The minimum preheat

temperatures can be used. The technique should minimize penetration into

the cast iron base metal. Post heating is normally not required. A color

match is not obtained.

21
4.8 OTHER PROCESSES

Other welding processes can be used for cast iron. Thermit welding has

been used for repairing certain types of cast iron machine tool parts.

Soldering can be used for joining cast iron, and is sometimes used for

repairing small defects in small castings. Flash welding can also be

used for welding cast iron.

Welding Techniques

Figure 4.1 : Studding Method for Cast Iron Repair

Cracks in large castings are sometimes repaired by studding (figure 7-10).

In this process, the fracture is removed by grinding a V groove. Holes

are drilled and tapped at an angle on each side of the groove, and studs

are screwed into these holes for a distance equal to the diameter of

the studs, with the upper ends projecting approximately 1/4 in. (6.4 mm)

above the cast iron surface. The studs should be seal welded in place

by one or two beads around each stud, and then tied together by weld

metal beads. Welds should be made in short lengths, and each length

peened while hot to prevent high stresses or cracking upon cooling. Each

bead should be allowed to cool and be thoroughly cleaned before

22
additional metal is deposited. If the studding method cannot be applied,

the edges of the joint should be chipped out or machined with a

round-nosed tool to form a U groove into which the weld metal should be

deposited.

23
4.9 JOINT DESIGN MODIFICATION

It is preferred that a full penetration weld is used over one where there is partial

penetration. Welds that have varying thickness can result in uneven contraction

stresses and uneven expansion during the welding cycle.

Changing welding designs to locate welds in an area where there is constant

thickness can be beneficial. Another tip is to use a backing fillet weld to support

stressed areas.

Groove Face Grooving

Figure: 4.2 Cast Iron Groove Face Grooving

Gouging or grinding grooves into the surface area of a prepared weld groove,

followed by using a weld bead to fill the grooves, before filling the whole joint

is sometimes a preferred method (see illustration below). This approach lowers

cracking risks by deflecting the crack path. Beads that are in contact with the

casting are deposited first, when the stress heat affected zone and fusion line are

at a low.

24
4.10 PEENING (HAMMERING)

Peening or hammering using a 13-19mm ball-peen hammer applied to a

deformable weld bead, putting it into a state of compressive stress, the tensile

stresses caused be thermal contraction can be opposed, thus reducing the risk of

cracking in and around the weld.

When the hammer is applied manually, it strikes a moderate blow perpendicular

to the weld surface.

The process requires a ductile weld metal. Nickel fillers are used, particularly

when working with gray cast iron. Peening is performed at higher temperatures

while the metal is soft.

25
4.11 CARES IN WELDING

Welding fumes Welding fumes, or smoke consists of a mixture of gases and dust par -

ticles. The composition of the fumes depends on: 1. The filler material and method of

welding. 2. The base material. Different welding methods and dif - ferent metals,

means that the fumes given off may contain numerous com - ponents which can be

dangerous if inhaled. The best protection is the use of a smoke extraction unit. When

cor - rectly positioned, this unit will protect the welder against fume inhalation and

also prevent the smoke spreading in the surrounding area and contami - nating the area

for others. If it is not possible to use a smoke extraction unit, the welder can mini -

mize the risk of fume inhalation by positioning himself so that the smoke rises some

distance from his nose and mouth or by using a welding face shield with fresh air

supply. For on board use a self contained unit with filter is a safe and flexible solution.

Electric arc welding with coated elec - trodes, may comprise several different

components depending on the type of electrode. The composition of the smoke will

therefore vary depending on the type of electrode. Electrodes are divided into smoke

classes 1 to 7, which indicates the degree of smoke pollution. See the Coated

Electrodes section on smoke classes.

26
4.12 RISKS

The fumes given off when welding unalloyed or low-alloyed steel which has not been

surface treated, are not considered to be particularly danger - ous as long as inhalation

of these fumes is kept at a reasonable level. When the base metal has been sur - face-

treated, the smoke may contain substances which could constitute a health risk.

Welding of galvanized materials or materials surface treated with substances

containing zinc, gives off fumes which contain zinc oxide. Inhalation of these fumes

can result in zinc poisoning with very unpleas - ant effects. It should be avoided by the

use of a good extraction unit, or the use of a face shield with fresh air connection.

Cadmium plating is sometimes used instead of zinc plating. Welding or cutting

cadmium-plated material can produce fumes which contain cad - mium oxide.

Figure: 4.3 Use fume extractor

Lung damage can result from the inhalation of this substance. When welding or

cutting old steel plating, remember that the surface coating may contain lead or

mercury. Fumes from these substances can result in serious health damage if inhaled.

27
When welding or cutting any type of material that has been plated or surface coated,

precautions must be taken against dangerous fumes before welding commences.

Welding of stainless or acid-resist - ant steel produces smoke containing nickel and

chrome. Copper alloys (tin bronze, leaded gun metal, leaded tin bronze and brass)

contains items such as tin, zinc, lead, etc. Welding temper - ature tends to vaporise

these items. Inhaling these substances canseri - ously affect the respiratory system.

When weIding these types of steel or materials plated or coated with sub - stances

containing chrome, cadmium, nickel lead or mercury, it is essential that a smoke

extractor unit is used. If this is not possible, the welder must be equipped with, and

must use a face shield with fresh air connection. Welding, cutting and brazing with a

gas torch can produce smoke which may contain several toxic substances. Of the gases

given off, it is primarily the nitrous gases (NO2 + NO) that are a health hazard. The

amount of nitrous gases in the smoke depends on several conditions.

Figure: 4.4 Use fresh air

28
The use of large size torches in confined spaces can quickly produce dangerous

concentrations. No warning is given of the presence of these gases in the form of

irritation of the muceous membrane in eyes, nose or throat. Proper ventilation must be

arranged, and when working in confined spaces, the welder must not leave the torch

alight when he is not actually using it. Carbon monoxide may be given off due to

incomplete combustion of the gases or if the material being welded or cut is plastic

surfaced, varnished, painted or oily. High concentrations, which constitute a health

risk, can be formed in confined spaces, tanks, pipes etc. Inhalation of large quantities

of carbon monoxide can lead to suffocation. This section points out some of the more

usual risks connected with welding smoke. There are special books on the subject, and

welding smoke is also undergoing continuous research. The result of this research

work may bring new important factors to light and all those involved in welding

should keep themselves informed of the development in this area, so precautions can

be taken to protect against health risks which may, as yet, be unknown.

29
 Chapter -5

5. WELDING SLAG

Welding slag is a form of slag, or vitreous material produced as a byproduct of

some arc welding processes, most specifically shielded metal arc welding (also

known as stick welding), submerged arc welding, and flux-cored arc welding.

Slag is formed when flux, the solid shielding material used in the welding

process, melts in or on top of the weld zone. Slag is the solidified remaining

flux after the weld area cools.

Shielded metal arc welding process, showing slag

Welding flux is a combination of carbonate and silicate materials used in

welding processes to shield the weld from atmospheric gases. When the

heat of the weld zone reaches the flux, the flux melts and outgasses. The

gases produced push the atmospheric gas back, preventing oxidation (and

reactions with nitrogen).

The melted flux covers the molten metal in the weld zone. Flux materials

are chosen so that the density of the melted flux / slag is lower than that of

the metal being welded, so that the flux floats to the top of the weld puddle

and leaves pure or nearly pure metal to solidify below.

Flux materials may also contribute to metal behavior in the molten metal,

with physical or chemical alterations to the molten metal.

cooling rate.

Flux-core arc welding process, showing slag

Inclusions

Submerged arc welding process, showing slag

It is possible for areas of slag to become embedded within the solidified

metal, if it did not float to the top of the molten metal for some reason.

These are called inclusions and are a form of welding defect. Inclusions

may be visible on the surface after cleaning, or may be completely

contained within the metal, in that case they can only be detected on X-rays

of the weld, requiring grinding or drilling to remove (followed by re-

welding that section).

31
 APPLICATION
This device find in.

 It is used almost in all types of industries (Large, Small & medium scale

Industries).

 This machine is mainly used in manufacturing - oriented Industries.

 This device is suitable to hold flat type plate. (maximum length 1.5 feet)

32
 CONCLUSION

The linkage mechanism replaces the servo DC motith encoder and de-coder

arrangemenorswt used in the automatic machines to carry out the same indexing

activity. This makes a considerable saving in budget for machine. A wire brush

will work on surfaces that aren’t flat and can be best when you have to clean

areas of intricate metal work. This is because a wire brush can be forced into

nooks and crannies that a needle gun wouldn’t be able reach. The size of the

wheel also makes it more flexible for small areas. Depending on what you’re

stripping, a wire brush can be an excellent complement to a needle gun. A wire

brush works fairly quickly. This machine requires less space, hence most

suitable for small industries. It is semi-automatic machine giving more accurate

results. It requires less skilled persons and provides more safety to human than

chipping hammer.

33
 REFERENCES BOOKS:

[1]. „P S G DESIGN DATA‟ Compiled by Faculty of Mechanical

Engineering PSG College of Technology

[2]. „DESIGN OF MACHINE ELEMENTS‟ by V B Bhandari Tata

McGraw-Hill Education, 2010

Journal Papers:

[3]. "Slag-Metal Reactions in Arc Welding," By Belton, C. R., Moore, J.,

and Tankins, Welding journal, 42 (7), July 1963, Research Suppl., pp. 289-s

to 297-s.

[4]. “Gas/Metal/Slag Reactions in Submerged Arc Welding Using CaO-

AI203 Based Fluxes” By T. Lau, G. C. Weatherly And A. MC Lean ,

Supplement to Welding Journal, Feb 1986 Sponsored by the American

Welding Society and the Welding Research Council

[5]. “Novel Method of Productivity Improvement and Waste Reduction

Through Recycling of Submerged Arc Welding Slag” By DalgobindMahto,

Anjani Kumar Jordan Journal of Mechanical and Industrial Engineering

Sept 2010

34