1. GTAW
Escalon High School

2. 3 basic parts to TIG TIG welding uses a non-consumable tungsten
Filler metal, when required, is added by hand
Shielding gas protects the weld and tungsten

3. The thing you weld with - - TIG Torch

4. Introduction and what….
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

5. Things we will cover…. AC or DC Aluminum or Steel Tungsten?
Tungsten set up
How to put the Torch together – What a TIG torch is…
Filler Rods
Need to know about Shield Gas
Set up your machine
Summary of what we have and what you will use

6. Parts you need to know to get by….
Gas Tungsten Arc Welding is also known as TIG welding or Tungsten Inert Gas Welding. You can weld almost any material – not all but most…. Titanium, Stainless, Aluminum, and Mild Steel. You can achieve this by utilizing different features available on most TIG Welders in todays industry.

7. AC or DC? What the heck is Tungsten?
AC or Alternating Current is used to weld Aluminum. -For materials, such as aluminum, which has an oxide film on the surface, AC power must be used. By switching between electrode positive and electrode negative polarity at typically fifty times a second, the periods of electrode positive will be sufficient to remove the oxide and clean the surface The industry calls this cleaning.--- Some machines will have the option to adjust the frequency or the amount of cleaning on the metal. DC or Direct Current is used for Steel

8. So we know AC… what else?
DC- (the one that is most commonly used for steel) concentrates about 70% of the heat on the work. The electrons flow from the electrode to the work. DC+ concentrates about 70% of the heat on the electrode. The electrons flow from the work to the electrode. This would be mostly for SMAW. So, you would typically want DC-, or else your electrode takes the brunt of the heat and tends to ball up. There is a useful purpose for DC+, though, when welding very thin sheet metal. Shallow penetration then becomes an advantage.

9. So what about Tungsten?

10. What about Steel?
Steel needs to be welded with Direct Current therefore you can only use the Tungsten that is appropriate for DC welding.

11. Correct Amperage for the Tungsten

12. Tungsten Preparation

13. What shield gas do I need? What is Shield gas?
Shield gas keeps oxygen out of your weld much the flux on a SMAW electrode
Helium
Faster travel speeds
Increased penetration
Difficult arc starting
Less cleaning action
Less low amp stability
Flared arc cone
Higher arc voltages
Higher cost than argon
Argon
Good arc starting
Good cleaning action
Good arc stability
Focused arc cone
Lower arc voltages

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

21. 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
*Figure copied from “TIG Handbook”

22. 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”

23. 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

24. 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
*Figure copied from “TIG Handbook”

25. Techniques for Basic Weld Joints
Manual Torch Movement
ENBE 499
*Figure copied from “TIG Handbook”

26. 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

27. 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
*Figure copied from “TIG Handbook”

28. 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
*Figure copied from “TIG Handbook”

29. 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
*Figure copied from “TIG Handbook”

30. 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
*Figure copied from “TIG Handbook”

31. Welding Parameters Aluminum weld parameters
*Figure copied from “TIG Handbook”

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

33. Welding Parameters Stainless steel weld parameters
*Figure copied from “TIG Handbook”

34. Welding Parameters Titanium weld parameters
*Figure copied from “TIG Handbook”

35. Welding Parameters Mild steel weld parameters
*Figure copied from “TIG Handbook”