Tig Welding Min

TIG Welding TIG Welding IntroductionIntroduction

by Daniel Minby Daniel Min

ENBE 499 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

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BackgroundBackground

►What is TIG?What is TIG? Tungsten Inert GasTungsten Inert Gas

►Also referred to as GTAWAlso referred to as GTAW Gas Shielded Tungsten WeldingGas Shielded Tungsten Welding

► In TIG welding, a tungsten electrode In TIG welding, a tungsten electrode heats the metal you are welding and heats the metal you are welding and gas (most typically Argon) protects the gas (most typically Argon) protects the weld from airborne contaminantsweld from airborne contaminants

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BackgroundBackground

►TIG welding uses a non-consumable TIG welding uses a non-consumable tungstentungsten

►Filler metal, when required, is added Filler metal, when required, is added by handby hand

►Shielding gas protects the weld and Shielding gas protects the weld and tungstentungsten

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AdvantagesAdvantages

► Welds more metals Welds more metals and metal alloys and metal alloys than any other than any other processprocess

► 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

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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 Equipment costs tend to be higher than other to be higher than other processesprocesses

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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

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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 Arc rays can burn eyes and skin; Noise can damage hearing.can damage hearing. Wear welding helmet with correct shade of Wear welding helmet with correct shade of

filterfilter Wear correct eye, ear, and body protectionWear correct eye, ear, and body protection

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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 Welding, chipping, wire brushing, and

grinding cause sparks and flying metal; wear grinding cause sparks and flying metal; wear approved safety glasses with side shieldsapproved safety glasses with side shields

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SafetySafety

►Welding current can damage electronic parts Welding current can damage electronic parts in vehicles.in vehicles. Disconnect both battery cables before welding on Disconnect both battery cables before welding on

a vehiclea vehicle Place work clamp as close to the weld as possiblePlace work clamp as close to the weld as possible

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Preparation for TIG WeldingPreparation for TIG Welding► Basic preparations should be Basic preparations should be

made before establishing an arc, made before establishing an arc, including base metal prep, set up including base metal prep, set up of the machine and its controlsof the machine and its controls

► Picture on right shows front Picture on right shows front panel of a typical AC/DC machine panel of a typical AC/DC machine designed for TIG welding designed for TIG welding (L-TEC HELIARC 306)(L-TEC HELIARC 306)

► Control functions of the L-TEC Control functions of the L-TEC HELIARC 306 are named in the HELIARC 306 are named in the following slides, but the manual following slides, but the manual should be consulted for more should be consulted for more detaildetail

► Not all power sources will have Not all power sources will have all the features or controls of this all the features or controls of this machinemachine

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Control FunctionsControl Functions► A: Power On-Off SwitchA: Power On-Off Switch► B: Tig-Stick Mode SwitchB: Tig-Stick Mode Switch► C: Remote Contactor ReceptacleC: Remote Contactor Receptacle► D: Current Selector SwitchD: Current Selector Switch► E: Current Range Selector E: Current Range Selector

SwitchSwitch► F: Current Control PotentiometerF: Current Control Potentiometer► G: Current Panel-Remote Switch G: Current Panel-Remote Switch

and Remote Current Control and Remote Current Control ReceptacleReceptacle

► H: Post Flow ControlH: Post Flow Control► I: High Frequency Selector I: High Frequency Selector

SwitchSwitch► J: High Frequency Intensity J: High Frequency Intensity

ControlControl

Preparation for TIG WeldingPreparation for TIG Welding

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Control FunctionsControl Functions► K: Gas and Water Torch K: Gas and Water Torch

ConnectionsConnections► L: Soft Start SwitchL: Soft Start Switch► M: Arc Force PotentiometerM: Arc Force Potentiometer► N: Slope/Spotweld Control N: Slope/Spotweld Control

ModuleModule► O: AC/DC Analog Meter O: AC/DC Analog Meter

ModuleModule► P: Panel Mounted Pulse P: Panel Mounted Pulse

ControlControl► R: Balance Control FeatureR: Balance Control Feature► S: Front Panel 3-Amps FuseS: Front Panel 3-Amps Fuse► T: Rear Panel Auxiliary 115V T: Rear Panel Auxiliary 115V

ReceptacleReceptacle


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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 One of the most common is the improper

use of grinding wheelsuse of grinding wheels► Soft materials like aluminum may get Soft materials like aluminum may get

embedded with abrasive particles resulting embedded with abrasive particles resulting in excessive porosityin excessive 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


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CleaningCleaning► Oil, grease, shop dirt, paint, marking crayon, and Oil, grease, shop dirt, paint, marking crayon, and

rust or corrosion deposits must be removed from rust or corrosion deposits must be removed from the joint and metal surfaces to a distance beyond the joint and metal surfaces to a distance beyond the heat affected zonethe heat affected zone

► Their presence may lead to arc instability and Their presence may lead to arc instability and contaminated weldscontaminated welds


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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 Special abrasive wheels are available

for aluminumfor aluminum►Stainless steel wire brushes Stainless steel wire brushes

recommendedrecommended►Both sides of the joint should be Both sides of the joint should be

cleaned if it contains foreign materialcleaned if it contains foreign material


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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 which decreases the corrosion resistanceresistance

►Stainless steel wire brushes Stainless steel wire brushes recommendedrecommended


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Preparing Titanium for WeldingPreparing Titanium for Welding► Essential that weld area and filler metal be Essential that weld area and filler metal be

cleanedcleaned► Mill scale, oil, grease, dirt, grinding dust, and Mill scale, oil, grease, dirt, grinding dust, and

any other contamination must be removedany other contamination must be removed► If titanium is scale free, only degreasing If titanium is scale free, only degreasing

requiredrequired► Joint should be brushed with stainless steel wire Joint should be brushed with stainless steel wire

brush and degreased with acetonebrush and degreased with acetone► Be cautious of fine titanium dust particles as Be cautious of fine titanium dust particles as

they are flammablethey are flammable


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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 surface contaminants should be removedremoved


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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 when AC welding with a balled end electrodeelectrode

►When DC welding with a pointed electrode, When DC welding with a pointed electrode, arc length may be much less than electrode arc length may be much less than electrode diameterdiameter

*Figure copied from “TIG Handbook”

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Gas Cup SizeGas Cup Size► Inside diameter of gas Inside diameter of gas

cup should be at least cup should be at least three times the three times the tungsten diameter to tungsten diameter to provide adequate provide adequate shielding gas shielding gas coveragecoverage

► Picture on right shows Picture on right shows example of gas cup example of gas cup size and torch size and torch positionposition

1-Workpiece, 2-Work clamp, 3-Torch, 4-Filler rod, 5-Gas cup, 6-Tungsten electrode


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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

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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 held frequency when the torch is held manuallymanually

► By resting gas cup on base metal By resting gas cup on base metal there is little danger of touching there is little danger of touching the electrode to the workthe electrode to the work

► After arc is initiated, torch can be After arc is initiated, torch can be raised to proper welding angleraised to proper welding angle


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Manual Torch MovementManual Torch Movement


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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 progressively and smoothly so the weld pool, the hot filler rod end, and the pool, the hot filler rod end, and the solidifying weld are not exposed to air that solidifying weld are not exposed to air that will contaminate the weld metal area or will contaminate the weld metal area or heat affected zoneheat 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, gas should shield the weld pool, electrode, and hot end of the filler rodand hot end of the filler rod

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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 When finishing a butt weld, torch butt weld, torch angle may be angle may be decreased to aid in decreased to aid in filling the craterfilling the crater Torch and rod position for welding the butt weld and

stringer bead


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Lap JointLap Joint► Pool is formed so that the Pool is formed so that the

edge of the overlapping edge of the overlapping piece and the flat surface piece and the flat surface of the second piece flow of the 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


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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 Electrode may need to be extended further be extended further beyond the cup in beyond the cup in order to hold a short order to hold a short arcarc Torch and rod position for welding the T-joint


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Corner JointCorner Joint► Both edges of the Both edges of the

adjoining pieces adjoining pieces should be melted should be melted and the pool kept on and the pool kept on the joint centerlinethe joint centerline

► Sufficient filler metal Sufficient filler metal is necessary to is necessary to create a convex create a convex bead as shownbead as shown

Torch and rod position for welding the corner joint


ENBE 499 30

TIG Shielding GasesTIG Shielding Gases

►ArgonArgon►HeliumHelium►Argon/Helium MixturesArgon/Helium Mixtures

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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

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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

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Welding ParametersWelding Parameters

Aluminum weld parameters


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Aluminum with advanced squarewave weld parameters


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Stainless steel weld parameters


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Titanium weld parameters


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Mild steel weld parameters


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Tungsten Electrode SelectionTungsten Electrode Selection

Guide to selecting a tungsten electrode based on amperage range

*Figure copied from “Guidelines to Gas Tungsten Arc Welding (GTAW)”

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ConclusionConclusion

► TIG welding is an exciting skill that proves itself TIG welding is an exciting skill that proves itself useful in countless applicationsuseful in countless applications

► Because it welds more metal and metal alloys than Because it welds more metal and metal alloys than any other process, TIG welding should be regarded any other process, TIG welding should be regarded as an important tool where experience is the as an important tool where experience is the teacherteacher

► Welding parameters and tungsten electrode Welding parameters and tungsten electrode selection tables are recommended values and selection tables are recommended values and should be used as a guidelineshould be used as a guideline

► Information presented here is only the tip of the Information presented here is only the tip of the iceberg, and further research and hands-on iceberg, and further research and hands-on involvement should be pursued to be involvement should be pursued to be comprehensivecomprehensive

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ReferencesReferences

► ““Gas tungsten arc welding.” Gas tungsten arc welding.” WikipediaWikipedia. . http://en.wikipedia.org/wiki/Gas_tungsten_arc_welding. 19 http://en.wikipedia.org/wiki/Gas_tungsten_arc_welding. 19 February 2008.February 2008.

► ““Guidelines to Gas Tungsten Arc Welding (GTAW).” Guidelines to Gas Tungsten Arc Welding (GTAW).” Miller Miller Electric Mfg CoElectric Mfg Co. July 2003.. July 2003.

► ““Installation and Operating Instructions for HELIARC 306 Installation and Operating Instructions for HELIARC 306 Welding Power Supply.” Welding Power Supply.” L-TEC Welding and Cutting SystemsL-TEC Welding and Cutting Systems. . January 1988.January 1988.

► ““TIG Handbook.” TIG Handbook.” Miller Electric Mfg CoMiller Electric Mfg Co. July 2003.. July 2003.► ““TIG Welding.” TIG Welding.” American Metallurgical ConsultantsAmerican Metallurgical Consultants. .

http://www.weldingengineer.com/1tig.htm. 18 October 2007.http://www.weldingengineer.com/1tig.htm. 18 October 2007.► ““TIG Welding Tips.” TIG Welding Tips.” Miller Electric Mfg CoMiller Electric Mfg Co. .

http://www.millerwelds.com/education/tech_tips/TIG_tips. 29 http://www.millerwelds.com/education/tech_tips/TIG_tips. 29 January 2008.January 2008.

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Tig Welding Min