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ELECTRIC ARC WELDING

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UNIT

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ElectricArc Weldine Introduction Defi nition of Electricitv: Electricity ls the movementof electrons along a corductor. A conductor is a material that allows electrical cunent to easily pass through it. Examplesof a conductorar€ alumioum,brass,copper,gold, silver. A resistoris a material that will allow someelectrical current to passthlough it. A goodexampleof this is steel, An insulator is a material that will !A! allow electrical curent to pass through it. Examplesof insulatorsare glass,plastic, Iead, etc. Arc Welders: Ovgr the century there have been many welder designs. Welders have been manufacturedthat produce Alternaaing CuFent (AC) and Dircca Current (DC). (Thereare alsoAC/DC combinationwelders.)Alternatingcurrentpulsatesat; ra;e of 60 cyclesper secondin the United States,50 elsewherein the world. Direct current is usedfor weldeN as Dircct Curl€nt Straight polarity (DCSP) and Dircct Currrnt Reverse Polarity (DCRP).

DCRP Welding machinesget their power from 1i0 or 220 volt wall plugs. Be very careful about owning a 110 volt arc welder, as many of them are very hazardous- this instructor doesn't recornmendpurchase or ownership of 110 volt arc welders. Welding machinesalso are powered by gasoline or diesel which give them greal portability. Often studentsask about recommendationsfor purchasingarc welding equipment. The simplest arc welder recommended for purchase by this instructor- is an alternating current 220volt machine. This is a transformertyoe arc welder that will transform incoming high voltage, low amperageetectriCtyinto high amperage,low voltage welding current. An arc welder should be on a separatecircuii of its own with a 50 amp. breaker and #8 wire providing the power. -Besure to purchasethe conect the correct .eceptacleplug as their shape or configuration determinesthe maximum amperagefor which they are designed.

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,t 30 n,r'|e

30 A/A?. Examples

50 AIAP,

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Efect c Arc WeldingIntroduction(Con't.) --

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Sizesof Metal for Welding: Over 1/8"- seriouslyconsiderArc Welding,under1,E' Oxyacetylene. Proper Bead:

fu h c * e c , & Reasons: 1. Specdforwardtoo fast. 2. Amperagetoo low. 3. Irad angleof electrodeloo nearho zontal. 4. Electrodetoo closeto metal. Ildercutting

Incorrect Rgasons: 1 . Amperage too high. 2. t-ea-Oangte of electrode too near vertical.

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Reasons: All factors indicated above have been corrected. Positionof Elecfode: Bisecr the angle of th€ two metal surfaces. (Split the angle.) I-€ad Angle of Elecrrode: kad 10 degreesin the directionof travel. (Irad 10) Distance of Electrode off Metal Surface - Arc Gap; Equal to the core diameter of the electrode. Amperage: 1/16" - 2I to 40 amps 3132' - 30 to 80 amps 1/8" - 80 to 130 amps 582" - 150to 180 amps

Electric Arc Welding Introduction (C-on1.) '

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Defects: l. Pits - cause - moving too fast forward - no filling motion - arc gaP too high 2. SPatter- cause- electrode too far from metal surface - too much amperage 3. Uneven Slag C-oating - cause - type of electrode - could be if E-6011; however, you are being trained on E-6013 so this is not a good reason. - excessiveheat - base metal too hot from Previous welds or too much amPeragefor the electrode. - ungven motron 4. Uneven ripple CUnPY) - cause - distanca from elecFode to metal is not being maintaincd constant - changing the arc gap. - travel speed not maintained constant - shaking of the hand while welding' -

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Warning: Always wait until slag tuns black before chipping slag' Always wear EYE SAFETY Protection when chipping slag. Aooearanceof a Good Weld: Same as Oxyacetylene Welding with one addition: 1. 2. 3. 4. 5.

Smooth surface weld after slag removal. Even riPPle Gloss or sheen to the surface after slag removal. Penetration Smooth Slag Coating on E-60i3 and E-7024

Reminder: Always remove little beads of spatter or'tterries" fiom surface before applying finish.)

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Electric Arc Welding Introduction (Con't )

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A-W.S. American Welding Society- standardizationorganizationtiat developswelding symbolson workingdrawings,compositionsof welding-electrodesand specifications regardingtheir use. The AmericanWeldingSocietyalsohasthe numberingsystem as mentionedhere and shownin more detail on the next page: E = Electrode(for Electric Arc Welding only) 60 = Thousandsof Poundsper squar€inch TensileStEngth whenin a weld deposit. 1 = Position the weldingelechodewill be successful' 3 = Flux Coatingand thereforethe type of WeldingCurr€nt to be usedwith the electrode. Purposesof an ElgctrodeFlux: 1. 2. 3. 4.

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HelDsestablishthe arc. Proiuces a slag coaaingto shieldweld while cooling. Prctects metal under arc from atmosphere. Muces a tluxing gas - Hydrogen or calbon dioxide.

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STANDARD AMERICAN WELDING SOCIETY CODE FOR WELDING ELECTRODE DESIGNATION 'ELECTRODE' WELDING POSITION IN SATTSFACTORYWELDS

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ELECTRODE IS CAPAITLE OF PRODUCING

I = All positions; Flat, Venical, Horizontal or Overhead.

2 = Flar Po6ition or Horizontal Fillets Only 3 = Flat Onb

TYPE OF COATING AND WELDING CURRENT o=not low hydrogen, d-c reverse polarity 1,2, or 3=not low hydrogen, a-c or d-c rev. polarity 4,7=not low hydrogBn, iron powder coaring, a-c or d-c reierse polarfty 5 = low hydrogen, d-c reverse polarity 6 = low hydrogen, a-c or d-c rev. polarity 8 = lor{ htdrogen, iron powder coating a-c or d-c rer€rs€ Dolaritv

18 CHEMICAL COMPOSINON OF pEPOSTT(AI-LOY) WELD DEPPSIT 60 = 70 = 80 = 90 = 100 = 110= 120=

60,0m b. per sq. inch 1O,WJ 80,0m 90,000 100,0m l10,U0O 120,000

WELD

None = Mild Sreel or Alloy not Designated A1 = Carbon Moly B | = l/2% C\tome. ln%, MoIy B 2 = 1 ll4Eo clvome, 1n% MoJy B3 = 2 ll4% Chtome, lqo MoIy

Cl C2 C3 D l D2 G M

= zlz Nickel = 312!l' Nickel = 1% Nickel = | 12 Ma'ng ll4 Moly ^e*, ll4 MoIy = | Sl4 Manqanes€, = Alloy not desienared = Conformsro alloy designatedby Military Spec.

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ELECTRI C ARCI,IELDING

V e n t i l a t i o n n u st b e p ro vi d e dw h enusing this ar ea Helinet'jacket' and q lov e s m u s t a l l b e w o rn w h e nw e l d i n gto pr otect eyes and skin fr on being bur nt 6 v t h e u l t r a v i o l e t ra-because vs. C ra cksi n l ens found in welding helnets m ust be of the dangerousultraviolet rays. l'leld in the i-nrnediatet v reolaced be t o o in o n t v l u s e e ve p ro te cti o n w h e nchipping slag. Hot cables lab' in the ' hould after re p o r t e di o t h e i n ;tru cto r. l f h o t n €tal is to be left out galvanized steel!!! r" \ o in o . t u U "t i t " h o t" ti i th so a p sto ne. Do not weld on Do not weld near t it ii' i u n o u i o u t to h e a l th b e ca u seo f the toxic zinc fum es.) power Suspend off. ila rn m a u l e s .W he nth ro u g ha n d l e a vi n g the booth, tur n the jn use' electrode holders so they do not touch any metal whennot