1. TIG Welding Introduction
by Daniel Min

2. Outline Background Advantages and Disadvantages Safety
Preparation for TIG Welding
Techniques for Basic Weld Joints
TIG Shielding Gases
Welding Parameters
Tungsten Electrode Selection
Conclusion
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3. Background What is TIG? Also referred to as GTAW
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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4. Background TIG welding uses a non-consumable tungsten
Filler metal, when required, is added by hand
Shielding gas protects the weld and tungsten
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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
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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
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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 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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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
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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
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10. Safety Welding current can damage electronic parts in vehicles.
Disconnect both battery cables before welding on a vehicle
Place work clamp as close to the weld as possible
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11. Preparation for TIG Welding
Basic preparations should be made before establishing an arc, including base metal prep, set up of the machine and its controls
Picture on right shows front panel of a typical AC/DC machine designed for TIG welding (L-TEC HELIARC 306)
Control functions of the L-TEC HELIARC 306 are named in the following slides, but the manual should be consulted for more detail
Not all power sources will have all the features or controls of this machine
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12. Preparation for TIG Welding
Control Functions
A: Power On-Off Switch
B: Tig-Stick Mode Switch
C: Remote Contactor Receptacle
D: Current Selector Switch
E: Current Range Selector Switch
F: Current Control Potentiometer
G: Current Panel-Remote Switch and Remote Current Control Receptacle
H: Post Flow Control
I: High Frequency Selector Switch
J: High Frequency Intensity Control
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13. Preparation for TIG Welding
Control Functions
K: Gas and Water Torch Connections
L: Soft Start Switch
M: Arc Force Potentiometer
N: Slope/Spotweld Control Module
O: AC/DC Analog Meter Module
P: Panel Mounted Pulse Control
R: Balance Control Feature
S: Front Panel 3-Amps Fuse
T: Rear Panel Auxiliary 115V Receptacle
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14. Preparation for TIG Welding
Preparing the Weld Joint
Many problems are a direct result of using improper methods to prepare the weld joint
One of the most common is the improper use of grinding wheels
Soft materials like aluminum may get embedded with abrasive particles resulting in excessive porosity
Grinding wheels should be cleaned and dedicated only to the material being welded
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15. Preparation for TIG Welding
Cleaning
Oil, grease, shop dirt, paint, marking crayon, and rust or corrosion deposits must be removed from the joint and metal surfaces to a distance beyond the heat affected zone
Their presence may lead to arc instability and contaminated welds
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16. Preparation for TIG Welding
Preparing Aluminum for Welding
Very susceptible to contaminants
Surface oxide must be removed
Special abrasive wheels are available for aluminum
Stainless steel wire brushes recommended
Both sides of the joint should be cleaned if it contains foreign material
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17. Preparation for TIG Welding
Preparing Stainless Steel for Welding
Should be thoroughly cleaned
Foreign material may cause porosity in welds and carburetion of the surface which decreases the corrosion resistance
Stainless steel wire brushes recommended
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18. Preparation for TIG Welding
Preparing Titanium for Welding
Essential that weld area and filler metal be cleaned
Mill scale, oil, grease, dirt, grinding dust, and any other contamination must be removed
If titanium is scale free, only degreasing required
Joint should be brushed with stainless steel wire brush and degreased with acetone
Be cautious of fine titanium dust particles as they are flammable
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19. Preparation for TIG Welding
Preparing Mild Steel for Welding
Should be mechanically cleaned
Scale, rust, paint, oil, grease, or any surface contaminants should be removed
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20. 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
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*Figure copied from “TIG Handbook”

21. 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
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*Figure copied from “TIG Handbook”

22. 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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23. 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
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*Figure copied from “TIG Handbook”

24. Techniques for Basic Weld Joints
Manual Torch Movement
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*Figure copied from “TIG Handbook”

25. 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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26. 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
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*Figure copied from “TIG Handbook”

27. 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
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*Figure copied from “TIG Handbook”

28. 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
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*Figure copied from “TIG Handbook”

29. 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
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*Figure copied from “TIG Handbook”

30. TIG Shielding Gases
Argon
Helium
Argon/Helium Mixtures
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31. 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
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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32. 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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33. Welding Parameters Aluminum weld parameters ENBE 499
*Figure copied from “TIG Handbook”

34. Welding Parameters Aluminum with advanced squarewave weld parameters
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*Figure copied from “TIG Handbook”

35. Welding Parameters Stainless steel weld parameters ENBE 499
*Figure copied from “TIG Handbook”

36. Welding Parameters Titanium weld parameters ENBE 499
*Figure copied from “TIG Handbook”

37. Welding Parameters Mild steel weld parameters ENBE 499
*Figure copied from “TIG Handbook”

38. Tungsten Electrode Selection
Guide to selecting a tungsten electrode based on amperage range
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*Figure copied from “Guidelines to Gas Tungsten Arc Welding (GTAW)”

39. 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
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40. References
“Gas tungsten arc welding.” Wikipedia February 2008.
“Guidelines to Gas Tungsten Arc Welding (GTAW).” Miller Electric Mfg Co. July 2003.
“Installation and Operating Instructions for HELIARC 306 Welding Power Supply.” L-TEC Welding and Cutting Systems. January 1988.
“TIG Handbook.” Miller Electric Mfg Co. July 2003.
“TIG Welding.” American Metallurgical Consultants October 2007.
“TIG Welding Tips.” Miller Electric Mfg Co January 2008.
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