TIG Welding Introduction

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*OutlineBackground/Advantages & DisadvantagesSafetyPreparation for TIG WeldingTechniques for Basic Weld JointsTIG Shielding GasesWelding ParametersTungsten Electrode SelectionConclusion

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*ConclusionTIG welding is an exciting skill that proves itself useful in countless applicationsBecause it welds more metal and metal alloys than any other process, TIG welding should be regarded as an important tool where experience is the teacherWelding parameters and tungsten electrode selection tables are recommended values and should be used as a guidelineInformation 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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*BackgroundWhat is TIG?

Tungsten Inert GasAlso referred to as GTAW

Gas Shielded Tungsten WeldingIn 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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*BackgroundTIG welding uses a non-consumable tungstenFiller metal, when required, is added by handShielding gas protects the weld and tungsten

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*AdvantagesWelds more metals and metal alloys than any other processHigh quality and precisionPin point controlAesthetic weld beadsNo sparks or spatterNo flux or slagNo smoke or fumes

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*DisadvantagesLower filler metal deposition ratesGood hand-eye coordination a required skillBrighter UV rays than other processesSlower travel speeds than other processesEquipment costs tend to be higher than other processes

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*SafetyElectric shock can kill.

Always wear dry insulating glovesInsulate yourself from work and groundDo not touch live electrical partsKeep all panels and covers securely in placeFumes and gases can be hazardous to your health.

Keep your head out of the fumesVentilate area, or use breathing device

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*SafetyWelding can cause fire or explosion.

Do not weld near flammable materialWatch for fire; keep extinguisher nearbyDo not locate unit over combustible surfacesDo not weld on closed containersArc rays can burn eyes and skin; Noise can damage hearing.

Wear welding helmet with correct shade of filterWear correct eye, ear, and body protection

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*SafetyHot parts can cause injury.

Allow cooling period before touching welded metalWear protective gloves and clothingMagnetic 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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*SafetyWelding current can damage electronic parts in vehicles.

Disconnect both battery cables before welding on a vehiclePlace work clamp as close to the weld as possible

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*Techniques for Basic Weld JointsArc LengthArc length normally one electrode diameter, when AC welding with a balled end electrodeWhen DC welding with a pointed electrode, arc length may be much less than electrode diameter

*Figure copied from TIG Handbook

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*Techniques for Basic Weld JointsGas Cup SizeInside diameter of gas cup should be at least three times the tungsten diameter to provide adequate shielding gas coveragePicture 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

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*Techniques for Basic Weld JointsElectrode ExtensionRefers to distance the tungsten extends out beyond the gas cupMay vary from flush with the gas cup to no more than the inside diameter of the gas cupLonger the extension, the more likely it may contact something by accidentGeneral rule would be to start with an extension of one electrode diameter

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*Techniques for Basic Weld JointsArc Starting with High FrequencyTorch position on left shows recommended method of starting the arc with high frequency when the torch is held manuallyBy resting gas cup on base metal there is little danger of touching the electrode to the workAfter arc is initiated, torch can be raised to proper welding angle

*Figure copied from TIG Handbook

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ENBE 499*Techniques for Basic Weld JointsManual Torch Movement*Figure copied from TIG Handbook

ENBE 499

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*Techniques for Basic Weld JointsManual Torch MovementTorch 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 zoneWhen 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 JointsButt Weld and Stringer BeadBe sure to center weld pool on adjoining edgesWhen 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

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*Techniques for Basic Weld JointsLap JointPool is formed so that the edge of the overlapping piece and the flat surface of the second piece flow togetherTorch angle is important because the edge will become molten before the flat surfaceEnough 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

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*Techniques for Basic Weld JointsT-JointEdge will heat up and melt soonerTorch angle illustrated will direct more heat onto the flat surfaceElectrode 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

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*Techniques for Basic Weld JointsCorner JointBoth edges of the adjoining pieces should be melted and the pool kept on the joint centerlineSufficient 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

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*TIG Shielding GasesArgonHeliumArgon/Helium Mixtures

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*TIG Shielding GasesArgonGood arc startingGood cleaning actionGood arc stabilityFocused arc coneLower arc voltages10-30 CFH flow rates

HeliumFaster travel speedsIncreased penetrationDifficult arc startingLess cleaning actionLess low amp stabilityFlared arc coneHigher arc voltagesHigher flow rates (2x)Higher cost than argon

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*TIG Shielding GasesArgon/Helium MixturesImproved travel speeds over pure argonImproved penetration over pure argonCleaning properties closer to pure argonImproved arc starting over pure heliumImproved arc stability over pure heliumArc cone shape more focused than pure heliumArc voltages between pure argon and pure heliumHigher flow rates than pure argonCosts higher than pure argon

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*Welding ParametersAluminum weld parameters*Figure copied from TIG Handbook

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*Welding ParametersAluminum with advanced squarewave weld parameters*Figure copied from TIG Handbook

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*Welding ParametersStainless steel weld parameters*Figure copied from TIG Handbook

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*Welding ParametersTitanium weld parameters*Figure copied from TIG Handbook

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*Welding ParametersMild steel weld parameters*Figure copied from TIG Handbook

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*Tungsten Electrode SelectionGuide to selecting a tungsten electrode based on amperage range*Figure copied from Guidelines to Gas Tungsten Arc Welding (GTAW)

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