TIG Welding Introduction

Introduction.

• TIG welding uses a non-consumable tungsten.• Filler metal, when required, is added by hand.• Shielding gas protects the weld.

• TIG welding uses a non-consumable tungsten.• Filler metal, when required, is added by hand.• Shielding gas protects the weld.

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Operation of TIG welding

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Schematic of TIG

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Shape of electrodes

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Equipments

1. Power sourceIt may be AC or Dc

2. GTAW torch Air cooled torch:-current upto 150 amp

Water cooled torch:- current upto 1000 amp

To cool down the supply cables

1. Power sourceIt may be AC or Dc

2. GTAW torch Air cooled torch:-current upto 150 amp

Water cooled torch:- current upto 1000 amp

To cool down the supply cables

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Equipments3. Wire feeding mechanism:• Wire drive mechanism: Gear drive• Speed control of wire feed• wire guide attachment

give the path to wire.

3. Wire feeding mechanism:• Wire drive mechanism: Gear drive• Speed control of wire feed• wire guide attachment

give the path to wire.

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Equipments

4. Materials:---Tungsten electrode:- It may be thoriated

(DC) or zirconiated(AC).--Filler metal:---Shielding gas.

4. Materials:---Tungsten electrode:- It may be thoriated

(DC) or zirconiated(AC).--Filler metal:---Shielding gas.

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TIG Shielding Gases

• Argon• Helium• Argon/Helium Mixtures

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TIG Shielding Gases

Argon• Good arc starting• Good cleaning action• Good arc stability• Focused arc cone• Lower arc voltages

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

Argon• Good arc starting• Good cleaning action• Good arc stability• Focused arc cone• Lower arc voltages

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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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

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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Welding parameters

• Current :-Too much current can lead to spatter and workpiece damage.In thin materials, it can lead to a widening of the material gap. Too littlecurrent can lead to sticking of the filler wire. This can also lead to heatdamage and a much larger weld affected area, as high temperaturesmust be applied for much longer periods of time in order to deposit thesame amount of filling materials. Current limiting helps to preventsplatter when the tungsten tip accidentally comes too close or in contactwith the workpiece. Fixed current mode will vary the voltage in order tomaintain a constant arc current.

• Voltage:-A high initial voltage allows for easy arc initiation and allows fora greater range of working tip distance. Too large a voltage, however, canlead to greater variability in workpiece quality (depending on theworkpiece distance and a greater variation in power and heat deliveredto the workarea

• .• Current :-Too much current can lead to spatter and workpiece damage.In thin materials, it can lead to a widening of the material gap. Too littlecurrent can lead to sticking of the filler wire. This can also lead to heatdamage and a much larger weld affected area, as high temperaturesmust be applied for much longer periods of time in order to deposit thesame amount of filling materials. Current limiting helps to preventsplatter when the tungsten tip accidentally comes too close or in contactwith the workpiece. Fixed current mode will vary the voltage in order tomaintain a constant arc current.

• Voltage:-A high initial voltage allows for easy arc initiation and allows fora greater range of working tip distance. Too large a voltage, however, canlead to greater variability in workpiece quality (depending on theworkpiece distance and a greater variation in power and heat deliveredto the workarea

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Advantages

• Welds more metals andmetal alloys than any otherprocess

• High quality and precision• Pin point control• Aesthetic weld beads• No sparks or spatter• No flux or slag• No smoke or fumes

.• Welds more metals andmetal alloys than any otherprocess

• 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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Disadvantages

• Lower filler metal depositionrates

• Good hand-eye coordinationa required skill

• Brighter UV rays than otherprocesses

• Slower travel speeds thanother processes

• Equipment costs tend to behigher than other processes

• Lower filler metal depositionrates

• Good hand-eye coordinationa required skill

• Brighter UV rays than otherprocesses

• Slower travel speeds thanother processes

• Equipment costs tend to behigher than other processes

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Applications

It is used to weld:-• High quality welds in aluminium• Stainless steel,• Ni-Cr alloys,• copper for use in chemical plants,• Longitudinal seams of thin walled SS and

alloy steel pressure pipes• Pipework required for high pressure steam

lines

.It is used to weld:-• High quality welds in aluminium• Stainless steel,• Ni-Cr alloys,• copper for use in chemical plants,• Longitudinal seams of thin walled SS and

alloy steel pressure pipes• Pipework required for high pressure steam

lines

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Applications

• .

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