Transcript 0067 tig mig

MY PRESENTATION TOPIC
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Tungsten Inert Gas(TIG)
Metal Inert Gas(MIG)
Resistance Welding
 Spot
 Projection
 seam
Submitted By:GIRISH KUMAR
1214340066(B2)
3rd yrs.
ENBE 499
Contents
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Introduction
Techniques
advantages
Disadvantages
Application
Safety
Conclusion
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TIG WELDING
Introduction
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What is TIG?
 Tungsten
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Also referred to as GTAW
 Gas
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Inert 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
Introduction
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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 Joints
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Arc Length
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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
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
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Gas Cup Size
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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
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
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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 Joints
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Butt Weld and
Stringer Bead
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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
Torch and rod position for welding the butt weld and stringer
bead
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
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Lap Joint
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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
Torch and rod position for welding the lap joint
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
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T-Joint
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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
Torch and rod position for welding the T-joint
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
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Corner Joint
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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
Torch and rod position for welding the corner joint
*Figure copied from “TIG Handbook”
TIG Shielding Gases
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Argon
Helium
Argon/Helium Mixtures
TIG Shielding Gases
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Helium
Argon
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Good arc starting
Good cleaning action
Good arc stability
Focused arc cone
Lower arc voltages
10-30 CFH flow rates
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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
TIG Shielding Gases
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Argon/Helium Mixtures
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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
Advantages
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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
Disadvantages
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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
Safety
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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
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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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Conclusion
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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.
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Principles and Characteristics
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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
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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
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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 metals.
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Gases used to form a shield
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Carbon Dioxide.
Argon.
Helium.
Combination of 1,2 and3.
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Advantege
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No flux required.
High welding speed.
Increased corrosion resistance.
Easily automated welding.
High economy.
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DisAdvantege
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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
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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
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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…
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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
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Very short process time.
No consumables.
Operator safety because of low voltage.
Clean and environmentally friendly.
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Types of resistance welding
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i.
ii.
iii.
There are following types
Spot welding
Projection welding
Seam welding
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Disadvantage of spot welding
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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
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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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THANK YOU
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