TIG Welding Introduction
Outline
► Background/Advantages
& Disadvantages
► Safety
► Preparation
for TIG Welding
► Techniques for Basic Weld Joints
► TIG Shielding Gases
► Welding Parameters
► Tungsten Electrode Selection
► Conclusion
2
Conclusion
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
►
3
Background
► 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
4
Background
► TIG
welding uses a non-consumable
tungsten
► Filler metal, when required, is added by
hand
► Shielding gas protects the weld and
tungsten
5
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
6
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
►
7
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
health.
and gases can be hazardous to your
 Keep your head out of the fumes
 Ventilate area, or use breathing device
8
Safety
► Welding




can cause fire or explosion.
Do not weld near flammable material
Watch for fire; keep extinguisher nearby
Do not locate unit over combustible surfaces
Do not weld on closed containers
► Arc
rays can burn eyes and skin; Noise can
damage hearing.
 Wear welding helmet with correct shade of filter
 Wear correct eye, ear, and body protection
9
Safety
► Hot
parts can cause injury.
 Allow cooling period before touching welded
metal
 Wear protective gloves and clothing
► Magnetic
fields from high currents can affect
pacemaker operation.
► Flying metal can injure eyes.
 Welding, chipping, wire brushing, and grinding
cause sparks and flying metal; wear approved
safety glasses with side shields
10
Safety
► Welding
vehicles.
current can damage electronic parts in
 Disconnect both battery cables before welding on a
vehicle
 Place work clamp as close to the weld as possible
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Techniques for Basic Weld Joints
Arc 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
12
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
Gas 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
1-Workpiece, 2-Work clamp, 3-Torch, 4-Filler rod,
5-Gas cup, 6-Tungsten electrode
*Figure copied from “TIG Handbook”
13
Techniques for Basic Weld Joints
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
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Techniques for Basic Weld Joints
Arc Starting with High
Frequency
►
►
►
Torch position on left shows
recommended method of starting
the arc with high frequency when
the torch is held manually
By resting gas cup on base metal
there is little danger of touching
the electrode to the work
After arc is initiated, torch can be
raised to proper welding angle
15
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
Manual Torch Movement
ENBE 499
*Figure copied from “TIG Handbook”
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Techniques for Basic Weld Joints
Manual Torch Movement
► Torch
and filler rod must be moved progressively
and smoothly so the weld pool, the hot filler rod
end, and the solidifying weld are not exposed to
air that will contaminate the weld metal area or
heat affected zone
► When arc is turned off, postflow of shielding gas
should shield the weld pool, electrode, and hot
end of the filler rod
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Techniques for Basic Weld Joints
Butt 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
Torch and rod position for welding the butt weld and stringer
bead
18
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
Lap 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
Torch and rod position for welding the lap joint
19
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
T-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
Torch and rod position for welding the T-joint
20
*Figure copied from “TIG Handbook”
Techniques for Basic Weld Joints
Corner 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
Torch and rod position for welding the corner joint
21
*Figure copied from “TIG Handbook”
TIG Shielding Gases
► Argon
► Helium
► Argon/Helium
Mixtures
22
TIG Shielding Gases
Helium
Argon
►
►
►
►
►
►
Good arc starting
Good cleaning action
Good arc stability
Focused arc cone
Lower arc voltages
10-30 CFH flow rates
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
►
23
TIG Shielding Gases
Argon/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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Welding Parameters
Aluminum weld parameters
25
*Figure copied from “TIG Handbook”
Welding Parameters
Aluminum with advanced squarewave weld parameters
26
*Figure copied from “TIG Handbook”
Welding Parameters
Stainless steel weld parameters
27
*Figure copied from “TIG Handbook”
Welding Parameters
Titanium weld parameters
28
*Figure copied from “TIG Handbook”
Welding Parameters
Mild steel weld parameters
29
*Figure copied from “TIG Handbook”
Tungsten Electrode Selection
Guide to selecting a tungsten electrode based on amperage range
30
*Figure copied from “Guidelines to Gas Tungsten Arc Welding (GTAW)”