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 pieces of metal together by the fusion processfusion process

NOTE: In arc welding, heat is produced by NOTE: In arc welding, heat is produced by the electric arc created.the 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 a current from the electrode holder to the base metalto the base metalBase Metal - Metal to be weldedBase Metal - Metal to be welded

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Bead Weld - Made by one pass of Bead Weld - Made by one pass of the electrodethe electrode

Bevel – Type of edge preparation Bevel – Type of edge preparation containing an anglecontaining an angle

Butt 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 Never look at the arc with the naked eye.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 Wear suitable clothing to protect all parts of the body. (PPE) parts of the body. (PPE) personal protective personal protective equipmentequipment

Long sleeved shirtLong sleeved shirt

Leather glovesLeather gloves

Collar buttonedCollar buttoned

ContinuedContinuedCuffs turned downCuffs turned down

High 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.

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Do 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 pliers

Do not weld in confined places Do not weld in confined places without ventilationwithout ventilation

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Always 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.

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Stand 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.

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MIG – (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 Electrodes

Mild 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 Electrodes

1/8”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 Ksi

Welding Position:Welding Position: 1 = All Position, 2 = Flat & Horizontal1 = All Position, 2 = Flat & Horizontal

Type 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 Gases

To Produce a Slag CoveringTo Produce a Slag Covering

To Provide Mechanical and Physical To Provide Mechanical and Physical PropertiesProperties

To 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 Arc

ScratchingScratching

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 process

ElectrodeElectrode

Wire coreWire core

Coating (flux)Coating (flux)

ArcArc

Gaseous shieldGaseous shield

WeldWeld

SlagSlag

Parts ContinuedParts Continued

Heat linesHeat lines

Base metalBase metal

PenetrationPenetration

CraterCrater

15 – 30 degree angle15 – 30 degree angle

Direction of travelDirection of travel

Principles of the SMAW Principles of the SMAW ProcessProcess

Kinds of WeldsKinds of Welds

Fillet Fillet

GrooveGroove

BeadBead

Fillet WeldFillet Weld

Groove WeldsGroove Welds

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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 tee

B- single beveledB- single beveled

C- double beveledC- double beveled

D- single JD- single J

E- 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 Positions

FlatFlat1F & 1G1F & 1G

HorizontalHorizontal2F & 2G2F & 2G

VerticalVertical3F & 3G3F & 3G

OverheadOverhead4F & 4G4F & 4G

Weld PositionsWeld Positions

Reason for Poor WeldsReason for Poor Welds

Machine adjustment too hot or too Machine adjustment too hot or too coldcold

Electrode size too large or too smallElectrode size too large or too small

Improper movement of electrodeImproper movement of electrode

Improper angle of holding electrodeImproper angle of holding electrode

Improper base metal preparationImproper base metal preparation

Arc length too long or too shortArc length too long or too short