MY PRESENTATION TOPIC

Tungsten Inert Gas(TIG) Metal Inert Gas(MIG) Resistance Welding

Spot Projection seam Submitted By:- GIRISH KUMAR 1214340066(B2) 3rd yrs.

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Introduction Techniques advantages Disadvantages Application Safety Conclusion

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Contents

TIG WELDING

Introduction 4

What is TIG? Tungsten Inert Gas

Also referred to as GTAW Gas Shielded Tungsten Welding

In TIG welding, a tungsten electrode heats the metal you are welding and gas (most typically Argon) protects the weld from airborne contaminants

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TIG welding uses a non-consumable tungsten

Filler metal, when required, is added by hand

Shielding gas protects the weld and tungsten

Techniques for Basic Weld JointsArc Length Arc length normally one electrode diameter,

when AC welding with a balled end electrode When DC welding with a pointed electrode,

arc length may be much less than electrode diameter

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*Figure copied from “TIG Handbook”

Techniques for Basic Weld JointsGas Cup Size Inside diameter of gas

cup should be at least three times the tungsten diameter to provide adequate shielding gas coverage

Picture on right shows example of gas cup size and torch position

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1-Workpiece, 2-Work clamp, 3-Torch, 4-Filler rod, 5-Gas cup, 6-Tungsten electrode

*Figure copied from “TIG Handbook”

Techniques for Basic Weld Joints

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Electrode Extension Refers to distance the tungsten extends out

beyond the gas cup May vary from flush with the gas cup to no

more than the inside diameter of the gas cup Longer the extension, the more likely it may

contact something by accident General rule would be to start with an

extension of one electrode diameter

Techniques for Basic Weld JointsButt Weld and

Stringer Bead Be sure to center

weld pool on adjoining edges

When finishing a butt weld, torch angle may be decreased to aid in filling the crater

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Torch and rod position for welding the butt weld and stringer bead

*Figure copied from “TIG Handbook”

Techniques for Basic Weld JointsLap Joint Pool is formed so that the

edge of the overlapping piece and the flat surface of the second piece flow together

Torch angle is important because the edge will become molten before the flat surface

Enough filler metal must be added to fill the joint as illustrated on the right

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Torch and rod position for welding the lap joint

*Figure copied from “TIG Handbook”

Techniques for Basic Weld JointsT-Joint Edge will heat up and

melt sooner Torch angle illustrated

will direct more heat onto the flat surface

Electrode may need to be extended further beyond the cup in order to hold a short arc

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Torch and rod position for welding the T-joint

*Figure copied from “TIG Handbook”

Techniques for Basic Weld JointsCorner Joint Both edges of the

adjoining pieces should be melted and the pool kept on the joint centerline

Sufficient filler metal is necessary to create a convex bead as shown

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Torch and rod position for welding the corner joint

*Figure copied from “TIG Handbook”

TIG Shielding Gases Argon Helium Argon/Helium Mixtures

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TIG Shielding GasesArgon

Good arc starting Good cleaning action Good arc stability Focused arc cone Lower arc voltages 10-30 CFH flow rates

Helium Faster travel speeds Increased penetration Difficult arc starting Less cleaning action Less low amp stability Flared arc cone Higher arc voltages Higher flow rates (2x) Higher cost than

argon

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TIG Shielding GasesArgon/Helium Mixtures Improved travel speeds over pure argon Improved penetration over pure argon Cleaning properties closer to pure argon Improved arc starting over pure helium Improved arc stability over pure helium Arc cone shape more focused than pure helium Arc voltages between pure argon and pure helium Higher flow rates than pure argon Costs higher than pure argon

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Advantages Welds more metals

and metal alloys than any other process

High quality and precision

Pin point control Aesthetic weld beads No sparks or spatter No flux or slag No smoke or fumes

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Disadvantages Lower filler metal

deposition rates Good hand-eye

coordination a required skill

Brighter UV rays than other processes

Slower travel speeds than other processes

Equipment costs tend to be higher than other processes

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Safety Electric shock can kill.

Always wear dry insulating gloves Insulate yourself from work and ground Do not touch live electrical parts Keep all panels and covers securely in place

Fumes and gases can be hazardous to your health. Keep your head out of the fumes Ventilate area, or use breathing device

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Conclusion19

TIG welding is an exciting skill that proves itself useful in countless applications

Because it welds more metal and metal alloys than any other process, TIG welding should be regarded as an important tool where experience is the teacher

Welding parameters and tungsten electrode selection tables are recommended values and should be used as a guideline

Information presented here is only the tip of the iceberg, and further research and hands-on involvement should be pursued to be comprehensive

MIG WELDING

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Introduction

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MIG- Metal Inert Gas. Used for thin metals. Use for high strength metals. Used for low alloy steels. It has little or no slag.

Principles and Characteristics Welding wire is automatically fed at a

constant speed. Arc is generated between the base metal

and the wire. Resulting in heat joining the 2 base

metals together. Process ranges in frequency from 50 to

200 cycles a second. Mig uses reverse polarity.

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Starting the MIG welder

Open the gas valve. Set the voltage for the arc. Set the wire speed. Turn the welder on. Press the trigger on the gun.

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Types of wire feed welders Gas metal- arc

process (MIG)- This system has a continuous feed of solid wire.

Uses on DC current with reverse polarity.

Used a mild steel. Used on thinner

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Gases used to form a shield Carbon Dioxide. Argon. Helium. Combination of 1,2 and3.

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Advantege No flux required. High welding speed. Increased corrosion resistance. Easily automated welding. High economy.

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DisAdvantege Higher initial setup cost. Higher maintenance costs due to extra

electronic component. The setting of plant variables requires a

high skill level. Radiation effects are more server.

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RESISTANCE WELDING

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General principles Resistance welding is a thermo- electric

process in which heat is generated at the interface of the parts to be joined by passing an electrical current through the parts for a precisely controlled time and under a controlled pressure (also called force).

Process variables Current, Time, Force.

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Working Resistance welding is a

pressure welding technique using high current and low voltage.

In resistance welding the metal parts to be joined are heated to a plastic state over a limited areas by their resistance to the flow of an electric current .

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Cont… Electrode tips wear during service,

causing nugget size to decrease.

Zinc- coating on steel alloys with copper electrodes to form brass.

Copper base materials, divided into classes.

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Advantege Very short process time. No consumables. Operator safety because of low voltage. Clean and environmentally friendly.

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Types of resistance welding There are following typesi. Spot weldingii. Projection weldingiii. Seam welding

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Disadvantage of spot welding It can create only localized joins, which

may not be particularly strong

The strength of spot weld depend on the force & temperature that has been applied & cleanliness of the electrodes & metal

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Disadvantage of projection welding Production of projection may be more

costly.

Close tolerance must be held to obtain acceptable quality.

Weld size is limited by projection size.

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