Tig welding

1. TIG Welding Introduction

2. 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

3. 3
Background
►What is TIG?
 Tungsten Inert Gas
►Also referred to as GTAW
 Gas Shielded Tungsten Arc Welding
►In TIG welding, a tungsten electrode heats
the metal and sheilding gas (most typically
Argon) protects the weld from airborne
contaminants

4. 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. 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. 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. 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

8. 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. 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. 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

11. 11

12. 12
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
Preparation for TIG Welding

13. ENBE 499 13
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
Preparation for TIG Welding

14. 14
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
Preparation for TIG Welding

15. 15
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
Preparation for TIG Welding

16. 16
Preparing Mild Steel for Welding
►Should be mechanically cleaned
►Scale, rust, paint, oil, grease, or any surface
contaminants should be removed
Preparation for TIG Welding

17. 17
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

18. 18
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

19. 19
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

20. 20
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

21. ENBE 499 21
Techniques for Basic Weld Joints
Manual Torch Movement

22. 22
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

23. 23
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

24. ENBE 499 24
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

25. ENBE 499 25
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

26. ENBE 499 26
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

27. 27
TIG Shielding Gases
►Argon
►Helium
►Argon/Helium Mixtures

28. 28
TIG Shielding Gases
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

29. 29
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

30. 30
Welding Parameters
Aluminum weld parameters
* “ ”

31. 31
Welding Parameters
Aluminum with advanced squarewave weld parameters

32. 32
Welding Parameters
Stainless steel weld parameters

33. 33
Welding Parameters
Titanium weld parameters

34. 34
Welding Parameters
Mild steel weld parameters

35. 35
Tungsten Electrode Selection
Guide to selecting a tungsten electrode based on amperage range

36. 36
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