INTRODUCTION TO ARC INTRODUCTION TO ARC WELDINGWELDING(SMAW)(SMAW)

Terms & DefinitionsTerms & DefinitionsWelding - Joining of two or more Welding - Joining of two or more pieces of metal together by the fusion pieces of metal together by the fusion processprocess

NOTE: In arc welding, heat is produced by the NOTE: In arc welding, heat is produced by the electric arc created.electric arc created.

SMAW - Shielded Metal Arc WeldingSMAW - Shielded Metal Arc WeldingElectrode - Metal rod which conducts Electrode - Metal rod which conducts a current from the electrode holder to a current from the electrode holder to the base metalthe base metalBase Metal - Metal to be weldedBase Metal - Metal to be welded

ContinuedContinuedBead Weld - Made by one pass of Bead Weld - Made by one pass of the electrodethe electrodeBevel – Type of edge preparation Bevel – Type of edge preparation containing an anglecontaining an angleButt Joint - Weld located between Butt Joint - Weld located between the two edges of metal.the two edges of metal.Crater - Depression at the end of a Crater - Depression at the end of a weld weld

Safety precautions in SMAW Safety precautions in SMAW weldingwelding

Never look at the arc with the naked eye.Never look at the arc with the naked eye.Use a welding hood that is in good Use a welding hood that is in good condition and has a #12 shade.condition and has a #12 shade.Wear suitable clothing to protect all parts Wear suitable clothing to protect all parts of the body. (PPE) of the body. (PPE) personal protective personal protective equipmentequipmentLong sleeved shirtLong sleeved shirtLeather glovesLeather glovesCollar buttonedCollar buttoned

ContinuedContinuedCuffs turned downCuffs turned downHigh topped shoes or bootsHigh topped shoes or boots

Do not strike an arc or weld until Do not strike an arc or weld until you are sure those in the vicinity you are sure those in the vicinity have protective equipment or have protective equipment or will look in the other direction.will look in the other direction.

(Note) Yell “cover” before striking an arc.(Note) Yell “cover” before striking an arc.

ContinuedContinuedDo not weld around combustible Do not weld around combustible or flammable materials.or flammable materials.Do not pick up hot metal with the Do not pick up hot metal with the hands.hands.

(NOTE) Use a pair of pliers(NOTE) Use a pair of pliersDo not weld in confined places Do not weld in confined places without ventilationwithout ventilation

ContinuedContinuedAlways turn off main switch or Always turn off main switch or disconnect plug when checking over disconnect plug when checking over a welder.a welder.Do not leave electrode holder on the Do not leave electrode holder on the welding table or in contact with welding table or in contact with grounded metal.grounded metal.Do not use worn or frayed cables.Do not use worn or frayed cables.

ContinuedContinuedStand on dry footing when welding.Stand on dry footing when welding.

Keep area around welder clean.Keep area around welder clean.

Keep tools and metals in proper Keep tools and metals in proper location.location.

Types of Arc WeldersTypes of Arc WeldersA.C. – (Alternating current) Welder A.C. – (Alternating current) Welder current alternates direction 120 current alternates direction 120 times per second.times per second.D.C. – (Direct current) Welder D.C. – (Direct current) Welder current flows in the same direction.current flows in the same direction.TIG – (Tungsten Inert Gas) Welder TIG – (Tungsten Inert Gas) Welder may use either A.C. or D.C. with a may use either A.C. or D.C. with a non-consumable tungsten electrode non-consumable tungsten electrode and an inert shielding gas.and an inert shielding gas.

ContinuedContinuedMIG – (Metal Inert Gas) May use A.C. MIG – (Metal Inert Gas) May use A.C. or D.C. with a base wire filler or D.C. with a base wire filler material that is fed automatically material that is fed automatically into weld; also has an inert shielding into weld; also has an inert shielding gas.gas.

Common SMAW ToolsCommon SMAW ToolsWelderWelderElectrode HolderElectrode HolderGround clampGround clampShield or helmetShield or helmetGlovesGlovesChipping hammerChipping hammerSafety goggles or glassesSafety goggles or glassesWire brushWire brushElectrodesElectrodes

Types of ElectrodesTypes of ElectrodesMild SteelMild Steel

High Carbon SteelHigh Carbon Steel

Hard SurfacingHard Surfacing

Alloys – special purposeAlloys – special purpose

AWS CurrentClass Covering Requirements Position Characteristics

EXX 10 Cellulose DCEP All Deep Penetration,Sodium With Ripples

EXX 11 Cellulose AC, DCEP All Deep Penetration,Potassium Flat Decking With Ripples

EXX22 Rutile DCEN, AC Flat, Horiz. Fillet Deep Penetration,Sodium With Ripples

EXX 24 Rutile AC, DCEP, DCEN Flat, Horiz. Fillet High Deposition50% Iron Shallow PenetrationPowder

EXX 27 Mineral AC,DCEP, DCEN Flat, Horiz. Fillet High Deposition50% Iron Shallow PenetrationPowder

Electrode CharacteristicsElectrode Characteristics

AWS CurrentClass Covering Requirements Position Characteristics

EXX 12 Rutile DCEN, AC All Mild to Medium PenetrationSodium

EXX 13 Rutile AC, DCEP, DCEN All Mild PenetrationSodium

EXX 14 Rutile AC, DCEN All Medium Penetration30% IronPowder

EXX 18 Low-Hydrogen DCEP, AC All Medium Penetration30% IronPowder

EXX 28 Low-Hydrogen AC, DCEP Flat, Horiz. Fillet High Deposition50% IronPowder

Electrode Characteristics Electrode Characteristics continuedcontinued

Common Sizes of ElectrodesCommon Sizes of Electrodes1/8”1/8”5/32”5/32”

Sizes of electrodes range from 1/16” Sizes of electrodes range from 1/16” to 3/8”.to 3/8”.Electrode size is determined by the Electrode size is determined by the diameter of the wire core.diameter of the wire core.

E70XX-H4RE70XX-H4R•ElectrodeElectrodeTensile in KsiTensile in KsiWelding Position:Welding Position: 1 = All Position, 2 = Flat & Horizontal1 = All Position, 2 = Flat & HorizontalType of Current and CoatingType of Current and Coating*Hydrogen:*Hydrogen: H4 = Less than 4ml/100g weld metal, H8 = Less than 8ml/100g Weld MetalH4 = Less than 4ml/100g weld metal, H8 = Less than 8ml/100g Weld Metal or H16 = Less than 16ml/100g weld metal or H16 = Less than 16ml/100g weld metal

*Meets Requirements of Absorbed Moisture Test*Meets Requirements of Absorbed Moisture Test *Optional Designators*Optional Designators

AWS ClassificationAWS Classification

Electrode Coating FunctionsElectrode Coating Functions

To Provide Deoxidizers & Scavengers To Provide Deoxidizers & Scavengers To Produce Shielding GasesTo Produce Shielding GasesTo Produce a Slag CoveringTo Produce a Slag CoveringTo Provide Mechanical and Physical To Provide Mechanical and Physical PropertiesPropertiesTo Increase Deposit RatesTo Increase Deposit Rates

Effects of Raising & Lowering Effects of Raising & Lowering CurrentCurrent

Raising currentRaising currentProduces more heatProduces more heat

Lowering currentLowering currentProduces less heatProduces less heat

(Note: On thicker metals more heat is (Note: On thicker metals more heat is necessary in order to get penetration necessary in order to get penetration of the weld.)of the weld.)

Methods of Establishing an ArcMethods of Establishing an ArcScratchingScratching

Similar to striking a matchSimilar to striking a match

TappingTappingStraight down and up Straight down and up

Characteristics of Proper Arc Characteristics of Proper Arc LengthLength

End of electrode is the same distance End of electrode is the same distance from the base metal as the diameter from the base metal as the diameter of electrode.of electrode.

1/8” electrode = arc length 1/8”1/8” electrode = arc length 1/8”Correct arc length makes a steady Correct arc length makes a steady hum of the welder.hum of the welder.Correct arc length makes a “frying” Correct arc length makes a “frying” sound at the arcsound at the arc

Like bacon frying in a panLike bacon frying in a pan

Parts of the welding processParts of the welding processElectrodeElectrodeWire coreWire coreCoating (flux)Coating (flux)ArcArcGaseous shieldGaseous shieldWeldWeldSlagSlag

Parts ContinuedParts ContinuedHeat linesHeat linesBase metalBase metalPenetrationPenetrationCraterCrater15 – 30 degree angle15 – 30 degree angleDirection of travelDirection of travel

Principles of the SMAW Principles of the SMAW ProcessProcess

Kinds of WeldsKinds of WeldsFillet Fillet

GrooveGroove

BeadBead

Fillet WeldFillet Weld

Groove WeldsGroove Welds

ContinuedContinued

Types of Weld JointsTypes of Weld JointsButt JointButt Joint

Lap JointLap Joint

Tee JointTee Joint

Corner JointCorner Joint

Edge JointEdge Joint

Square Butt JointSquare Butt Joint

Tee JointsTee JointsA- plain teeA- plain teeB- single beveledB- single beveledC- double beveledC- double beveledD- single JD- single JE- double JE- double J

Lap JointsLap JointsA- single lap joint, A- single lap joint, one weld.one weld.B- single lap joint, B- single lap joint, two welds.two welds.C- offset lap joint.C- offset lap joint.

Corner JointsCorner Joints

Edge JointsEdge Joints

Welding PositionsWelding PositionsFlatFlat

1F & 1G1F & 1GHorizontalHorizontal

2F & 2G2F & 2GVerticalVertical

3F & 3G3F & 3GOverheadOverhead

4F & 4G4F & 4G

Weld PositionsWeld Positions

Reason for Poor WeldsReason for Poor WeldsMachine adjustment too hot or too Machine adjustment too hot or too coldcoldElectrode size too large or too smallElectrode size too large or too smallImproper movement of electrodeImproper movement of electrodeImproper angle of holding electrodeImproper angle of holding electrodeImproper base metal preparationImproper base metal preparationArc length too long or too shortArc length too long or too short