CHETSA Welding ppt for fitter trade in ITI in Rajasthan

Welding fitter ppt

1. Welding IntroductionWelding Introduction

2. 2
OutlineOutline
►BackgroundBackground
►Advantages and DisadvantagesAdvantages and Disadvantages
►SafetySafety
►Preparation for TIG WeldingPreparation for TIG Welding
►Techniques for Basic Weld JointsTechniques for Basic Weld Joints
►TIG Shielding GasesTIG Shielding Gases
►Welding ParametersWelding Parameters
►Tungsten Electrode SelectionTungsten Electrode Selection
►ConclusionConclusion

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

4. 4
BackgroundBackground
►TIG welding uses a non-consumable TIG welding uses a non-consumable
tungstentungsten
►Filler metal, when required, is added by Filler metal, when required, is added by
handhand
►Shielding gas protects the weld and Shielding gas protects the weld and
tungstentungsten

5. 5
AdvantagesAdvantages
►Welds more metals Welds more metals
and metal alloys than and metal alloys than
any other processany other process
►High quality and High quality and
precisionprecision
►Pin point controlPin point control
►Aesthetic weld beadsAesthetic weld beads
►No sparks or spatterNo sparks or spatter
►No flux or slagNo flux or slag
►No smoke or fumesNo smoke or fumes

6. 6
DisadvantagesDisadvantages
►Lower filler metal Lower filler metal
deposition ratesdeposition rates
►Good hand-eye Good hand-eye
coordination a required coordination a required
skillskill
►Brighter UV rays than Brighter UV rays than
other processesother processes
►Slower travel speeds Slower travel speeds
than other processesthan other processes
►Equipment costs tend to Equipment costs tend to
be higher than other be higher than other
processesprocesses

7. 7
SafetySafety
►Electric shock can kill.Electric shock can kill.
Always wear dry insulating glovesAlways wear dry insulating gloves
Insulate yourself from work and groundInsulate yourself from work and ground
Do not touch live electrical partsDo not touch live electrical parts
Keep all panels and covers securely in placeKeep all panels and covers securely in place
►Fumes and gases can be hazardous to your Fumes and gases can be hazardous to your
health.health.
Keep your head out of the fumesKeep your head out of the fumes
Ventilate area, or use breathing deviceVentilate area, or use breathing device

8. 8
SafetySafety
►Welding can cause fire or explosion.Welding can cause fire or explosion.
Do not weld near flammable materialDo not weld near flammable material
Watch for fire; keep extinguisher nearbyWatch for fire; keep extinguisher nearby
Do not locate unit over combustible surfacesDo not locate unit over combustible surfaces
Do not weld on closed containersDo not weld on closed containers
►Arc rays can burn eyes and skin; Noise can Arc rays can burn eyes and skin; Noise can
damage hearing.damage hearing.
Wear welding helmet with correct shade of filterWear welding helmet with correct shade of filter
Wear correct eye, ear, and body protectionWear correct eye, ear, and body protection

9. 9
SafetySafety
►Hot parts can cause injury.Hot parts can cause injury.
Allow cooling period before touching welded Allow cooling period before touching welded
metalmetal
Wear protective gloves and clothingWear protective gloves and clothing
►Magnetic fields from high currents can Magnetic fields from high currents can
affect pacemaker operation.affect pacemaker operation.
►Flying metal can injure eyes.Flying metal can injure eyes.
Welding, chipping, wire brushing, and grinding Welding, chipping, wire brushing, and grinding
cause sparks and flying metal; wear approved cause sparks and flying metal; wear approved
safety glasses with side shieldssafety glasses with side shields

10. 10
SafetySafety
►Welding current can damage electronic parts in Welding current can damage electronic parts in
vehicles.vehicles.
Disconnect both battery cables before welding on a Disconnect both battery cables before welding on a
vehiclevehicle
Place work clamp as close to the weld as possiblePlace work clamp as close to the weld as possible

11. 11

12. 12
Preparing the Weld JointPreparing the Weld Joint
►Many problems are a direct result of using Many problems are a direct result of using
improper methods to prepare the weld jointimproper methods to prepare the weld joint
►One of the most common is the improper use One of the most common is the improper use
of grinding wheelsof grinding wheels
►Soft materials like aluminum may get Soft materials like aluminum may get
embedded with abrasive particles resulting in embedded with abrasive particles resulting in
excessive porosityexcessive porosity
►Grinding wheels should be cleaned and Grinding wheels should be cleaned and
dedicated only to the material being weldeddedicated only to the material being welded
Preparation for TIG WeldingPreparation for TIG Welding

13. ENBE 499 13
CleaningCleaning
►Oil, grease, shop dirt, paint, marking crayon, and rust Oil, grease, shop dirt, paint, marking crayon, and rust
or corrosion deposits must be removed from the joint or corrosion deposits must be removed from the joint
and metal surfaces to a distance beyond the heat and metal surfaces to a distance beyond the heat
affected zoneaffected zone
►Their presence may lead to arc instability and Their presence may lead to arc instability and
contaminated weldscontaminated welds
Preparation for TIG WeldingPreparation for TIG Welding

14. 14
Preparing Aluminum for WeldingPreparing Aluminum for Welding
►Very susceptible to contaminantsVery susceptible to contaminants
►Surface oxide must be removedSurface oxide must be removed
►Special abrasive wheels are available for Special abrasive wheels are available for
aluminumaluminum
►Stainless steel wire brushes Stainless steel wire brushes
recommendedrecommended
►Both sides of the joint should be cleaned Both sides of the joint should be cleaned
if it contains foreign materialif it contains foreign material
Preparation for TIG WeldingPreparation for TIG Welding

15. 15
Preparing Stainless Steel for WeldingPreparing Stainless Steel for Welding
►Should be thoroughly cleanedShould be thoroughly cleaned
►Foreign material may cause porosity in Foreign material may cause porosity in
welds and carburetion of the surface welds and carburetion of the surface
which decreases the corrosion resistancewhich decreases the corrosion resistance
►Stainless steel wire brushes Stainless steel wire brushes
recommendedrecommended
Preparation for TIG WeldingPreparation for TIG Welding

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

17. 17
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Arc LengthArc Length
►Arc length normally one electrode diameter, Arc length normally one electrode diameter,
when AC welding with a balled end electrodewhen AC welding with a balled end electrode
►When DC welding with a pointed electrode, arc When DC welding with a pointed electrode, arc
length may be much less than electrode length may be much less than electrode
diameterdiameter

18. 18
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Gas Cup SizeGas Cup Size
►Inside diameter of Inside diameter of
gas cup should be at gas cup should be at
least three times the least three times the
tungsten diameter to tungsten diameter to
provide adequate provide adequate
shielding gas shielding gas
coveragecoverage
►Picture on right Picture on right
shows example of shows example of
gas cup size and gas cup size and
torch positiontorch position
1-Workpiece, 2-Work clamp, 3-Torch, 4-Filler
rod, 5-Gas cup, 6-Tungsten electrode

19. 19
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Electrode ExtensionElectrode Extension
►Refers to distance the tungsten extends out Refers to distance the tungsten extends out
beyond the gas cupbeyond the gas cup
►May vary from flush with the gas cup to no May vary from flush with the gas cup to no
more than the inside diameter of the gas cupmore than the inside diameter of the gas cup
►Longer the extension, the more likely it may Longer the extension, the more likely it may
contact something by accidentcontact something by accident
►General rule would be to start with an General rule would be to start with an
extension of one electrode diameterextension of one electrode diameter

20. 20
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Arc Starting with High Arc Starting with High
FrequencyFrequency
►Torch position on left shows Torch position on left shows
recommended method of recommended method of
starting the arc with high starting the arc with high
frequency when the torch is frequency when the torch is
held manuallyheld manually
►By resting gas cup on base By resting gas cup on base
metal there is little danger of metal there is little danger of
touching the electrode to the touching the electrode to the
workwork
►After arc is initiated, torch can After arc is initiated, torch can
be raised to proper welding be raised to proper welding
angleangle

21. ENBE 499 21
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Manual Torch MovementManual Torch Movement

22. 22
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Manual Torch MovementManual Torch Movement
►Torch and filler rod must be moved Torch and filler rod must be moved
progressively and smoothly so the weld pool, progressively and smoothly so the weld pool,
the hot filler rod end, and the solidifying weld the hot filler rod end, and the solidifying weld
are not exposed to air that will contaminate the are not exposed to air that will contaminate the
weld metal area or heat affected zoneweld metal area or heat affected zone
►When arc is turned off, postflow of shielding When arc is turned off, postflow of shielding
gas should shield the weld pool, electrode, and gas should shield the weld pool, electrode, and
hot end of the filler rodhot end of the filler rod

23. 23
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Butt Weld and Butt Weld and
Stringer BeadStringer Bead
►Be sure to center Be sure to center
weld pool on weld pool on
adjoining edgesadjoining edges
►When finishing a butt When finishing a butt
weld, torch angle weld, torch angle
may be decreased to may be decreased to
aid in filling the crateraid in filling the crater
Torch and rod position for welding the butt weld and
stringer bead

24. ENBE 499 24
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Lap JointLap Joint
►Pool is formed so that Pool is formed so that
the edge of the the edge of the
overlapping piece and overlapping piece and
the flat surface of the the flat surface of the
second piece flow second piece flow
togethertogether
►Torch angle is important Torch angle is important
because the edge will because the edge will
become molten before become molten before
the flat surfacethe flat surface
►Enough filler metal must Enough filler metal must
be added to fill the joint be added to fill the joint
as illustrated on the rightas illustrated on the right
Torch and rod position for welding the lap
joint

25. ENBE 499 25
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
T-JointT-Joint
►Edge will heat up and Edge will heat up and
melt soonermelt sooner
►Torch angle illustrated Torch angle illustrated
will direct more heat will direct more heat
onto the flat surfaceonto the flat surface
►Electrode may need to be Electrode may need to be
extended further beyond extended further beyond
the cup in order to hold a the cup in order to hold a
short arcshort arc
Torch and rod position for welding the T-joint

26. ENBE 499 26
Techniques for Basic Weld Techniques for Basic Weld
JointsJoints
Corner JointCorner Joint
►Both edges of the Both edges of the
adjoining pieces adjoining pieces
should be melted and should be melted and
the pool kept on the the pool kept on the
joint centerlinejoint centerline
►Sufficient filler metal Sufficient filler metal
is necessary to create is necessary to create
a convex bead as a convex bead as
shownshown Torch and rod position for welding the corner joint

27. 27
TIG Shielding GasesTIG Shielding Gases
►ArgonArgon
►HeliumHelium
►Argon/Helium MixturesArgon/Helium Mixtures

28. 28
TIG Shielding GasesTIG Shielding Gases
ArgonArgon
►Good arc startingGood arc starting
►Good cleaning actionGood cleaning action
►Good arc stabilityGood arc stability
►Focused arc coneFocused arc cone
►Lower arc voltagesLower arc voltages
►10-30 CFH flow rates10-30 CFH flow rates
HeliumHelium
►Faster travel speedsFaster travel speeds
►Increased penetrationIncreased penetration
►Difficult arc startingDifficult arc starting
►Less cleaning actionLess cleaning action
►Less low amp stabilityLess low amp stability
►Flared arc coneFlared arc cone
►Higher arc voltagesHigher arc voltages
►Higher flow rates (2x)Higher flow rates (2x)
►Higher cost than argonHigher cost than argon

29. 29
TIG Shielding GasesTIG Shielding Gases
Argon/Helium MixturesArgon/Helium Mixtures
►Improved travel speeds over pure argonImproved travel speeds over pure argon
►Improved penetration over pure argonImproved penetration over pure argon
►Cleaning properties closer to pure argonCleaning properties closer to pure argon
►Improved arc starting over pure heliumImproved arc starting over pure helium
►Improved arc stability over pure heliumImproved arc stability over pure helium
►Arc cone shape more focused than pure heliumArc cone shape more focused than pure helium
►Arc voltages between pure argon and pure heliumArc voltages between pure argon and pure helium
►Higher flow rates than pure argonHigher flow rates than pure argon
►Costs higher than pure argonCosts higher than pure argon

30. 30
Welding ParametersWelding Parameters
Aluminum weld parameters
* “ ”

31. 31
Welding ParametersWelding Parameters
Aluminum with advanced squarewave weld parameters

32. 32
Welding ParametersWelding Parameters
Stainless steel weld parameters

33. 33
Welding ParametersWelding Parameters
Titanium weld parameters

34. 34
Welding ParametersWelding Parameters
Mild steel weld parameters

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

36. 36
ConclusionConclusion
►TIG welding is an exciting skill that proves itself useful TIG welding is an exciting skill that proves itself useful
in countless applicationsin countless applications
►Because it welds more metal and metal alloys than any Because it welds more metal and metal alloys than any
other process, TIG welding should be regarded as an other process, TIG welding should be regarded as an
important tool where experience is the teacherimportant tool where experience is the teacher
►Welding parameters and tungsten electrode selection Welding parameters and tungsten electrode selection
tables are recommended values and should be used as tables are recommended values and should be used as
a guidelinea guideline