MIG-MAG eng 260710 @1544

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MIG/M

AG&

FluxCoredArcWelding

KorayYU

RTIIK

yurtisik@gm

ail.com

yurtisik@me

tu.edu.tr

MIG/MAG

&FluxCoredArcWelding,2of85

Content

ReviewofPartIandII

Definition

Advantages

Disadvantages

ApplicationFields

Equipment

FillerMetals(Wireelectrodes)

ShieldingGases

InternalControlSystem(Principle)

ForcesactingontheA

rc

TypesofArc

Setting-upofaMIG/MAGW

eldingUnit

WeldingParameterInfluences

PulsedArc

PossibleDefectswhenMIG/MAGWelding

WeldBevelPreparation

Backing

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MIG/MAG


Definition

Afixedcompositionofgasshieldstheweldmetal.

Fillermetalisanelectrode

atthesametime(a

differencew.r.t.TIG)

Fillermetaliscontinuous(adifferencew.r.t.TIG&

MMA)

NaturallybornSemi-mechanized

DCEP(reversepolarity),

DCENisseldomused

becauseofpoortransfer

ofmoltenmetalfromthewireelectrodetothe

workpiece.

Advantages

Allpositionsareavaila

ble

Lessandsometimese

vennoslagremoval(man-

hour),

MetalDepositionRate

ishigh,

Fast(2timesmoretha

nMMA),

Lessdistortion,

Lowcostfillermetal(w

.r.t.MMA&UP)

Disadvantages

LackofFusion

Atstart

Fillermetalmeltsontocold

substrate

Whenlowlinear

weldingspeed

Weldpoolflowinginfrontofthearc

Sensitivetoenvironme

ntalconditions

MIG/MAG


FieldsofApplication

Constructionalsteeloralu

minummembers,

Shipyards,

Automotive,

PipeLines,

PressureVesselsandProcessingEquipments,

HeatExchangers,Boilers,Piping

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MIG/MAG


Eq

uipment

Powersupply

Wirefeedunit

Hoseassembly

Torch

Blowtorch

Powersupply

Wirefeed

unit

Hoseassembly

Torch

Blowtorch

Ves

selof

Shieldinggas

Wo

rkpiece

Neutralcable

Wireelectrode

Arc

.

MIG/MAG


Po

werSupply

Constantpotentialpowersupply

Thepotentialchangeb

etween3to5Voltscorrespo

ndstocurrentamplitudeof100A

Selfcorrectingarc

Kuralolarakgelemanlarayarlanabilenendktan

sasahiptir.

Endktanskaynakakmndakisapmalarazaltrveakmart

hzndeitirir.rneintutuma

srasndahzlbirakmartavantajlyken,ksadevreylearksrasndayavabirakmartdahaaz

srantoluturur.

Types;

Conventional

WithTrystor

Withtransistorrectifier

Withtransistorinverte

r

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MIG/MAG


WireFeedUnit

1.5m/min20m/min

MIG/MAG


WireFeedUnit

1.5m/min20m/min

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MIG/MAG


WireFeedUnit

Oneormorethanonedrivingunit

arepossible

MIG/MAG&

FluxCoredArcWelding,10of85

WireFeedUnit

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MIG/MAG&


Ho

seAssembly

Carries;

Coolingair(lower

than250A)or

water,

Wireelectrode,

Shieldinggas,

Weldingcurrentand

potential.

MIG/MAG&


To

rch

(1)

Torchhandle,

(2)

Mouldedphenolicdielectric(showninwhite)

andthreadedmetalnutinsert(yellow),

(3)

Shieldinggasdiffuser,

(4)

Contacttip,

(5)

Nozzleoutputface

[Reference:Mysid,TTlig

htningRod]

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MIG/MAG&


WireElectrodes

WireElectr

odes

Solid

FluxCo

red

Lessweldingcurrentforthe

samemetaldepositionrate.

Metalzl

Crufzl

Rutile

Basic

MIG/MAG&


WireElectrodes

WireElectrodes

forSteels

Solid

FluxCo

red

C-steel

ISO17632

StainlessSteel

ISO17633

C-steel

ISO14341

StainlessSteel

ISO14343

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MIG/MAG&


WireElectrodesIS

O

14341

MIG/MAG&


ISO

14341

WireElectrodes

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MIG/MAG&


ISO

14341

WireElectrodes

MIG/MAG&


ISO

14341

WireElectrodes

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MIG/MAG&


ISO

14341

WireElectrodes

MIG/MAG&


ISO

14341

WireElectrodes

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MIG/MAG&


ISO17632-

WireElectrodes

MIG/MAG&


ISO17632-

WireElectrodes

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MIG/MAG&


ISO17632-

WireElectrodes

MIG/MAG&


ISO17632-

WireElectrodes

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MIG/MAG&


Sh

ieldingGases

MIG/MAG&


Sh

ieldingGases

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MIG/MAG&


ForcesinArcandontotheDroplet

20%

100%Ar

100%CO2

Surface

tension

P

incheffect;

Anelectromagneticforc

e

Proportionaltothesquareofcurrentamplitude,I

S

urfacetension;

Oxidepatchesonthed

ropletredusethesurface

tension

Thehighersurfacetens

ion,thebiggerdroplets

M

etalsevaporating;

Pressureagainsttothe

droplet

P

lasmabeam;

G

ravitation;

MIG/MAG&


ProcessVariationsMetalTransfer

S

hortCircuitTransfer(ShortArc)Welding[15

2

0V]

Metalistransferredfrom

thewiretotheweld

poolonlywhencontact

betweenthetwois

made,orateachshort

circuit.

Thewireshortcircuitst

otheworkpiece20to

200timespersecond

Usessmallwireinther

angeof.8to1.2mm

diameter

Operatesatlowarclen

gths(lowvoltages)and

weldingcurrents

Fast-freezingweldpuddleisobtained

Thisweldingtechnique

isparticularlyusefulfor

joining

thinmaterialsina

nyposition,

thickmaterialsin

theverticaland

overheadposition

,

andforfillinglargegaps

Shortarcweldingshouldalsobeusedwhere

minimumdistortionoftheworkpieceisa

requirementbecauseofitslowheatinput

C,M2andM3gases.

Hardtocontrolandeas

ytoleavedefect.

V

A

20

150

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MIG/MAG&FluxCoredArcWelding,31of85



G

lobularTransfer(LongArc)Welding[>20

V

]:

Metaltransferringthrou

ghthearc,

Usually,thedropsofmoltenmetalhavea

greaterdiameterthanthewireitself,

Themetaltransferwith

spatterand

occasionalshortcircuiting,

Occurswithgasescons

istingmorethan

20%CO2,

Suchgaseshavegood

thermal

conductivity,sotheinte

rfacebetweenthe

electrodeandthearcis

verynarrow,

Nouseforhardwelding

positions,

Metaltransferefficiency

isverylow,in

between87and93%,

Lackoffusionriskisve

ryhigh.

V

A

20

150


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S

prayarc[higherthan25V

]:

Byraisingtheweldingc

urrentandvoltagestill

further,themetaltransf

erwillbecomeatruespray

arc.

Theminimumwelding

currentatwhichthisoccursis

calledthetransitioncurrent,abovethetransition

currentpincheffectbecomeseffective.

Thetransitioncurrent

dependsonthemetalwire

diameterandshieldin

ggas.

However,iftheshield

inggasforweldingcarbonsteel

containsmorethanabout20%CO2thereisno

transitionfromglobulartransfertospraytransfer.

Themoltendropsfrom

thewireareverysmall,

affordinggoodarcstability,shortcircuitingisrare.

Littlespatter,highdepo

sitionratesofweldmetal,

morethan98%.

3mmandgreaterinthickness

V

A

20

150



S

prayarc

V

A

20

150


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P

ulsedArc;

Avariationofthespray

arctechniqueisknownasp

ulsedspraywelding.

Thecurrentisvariedbe

tweenahighandlowvalue.

Thelowlevelofcurre

ntisbelowthetransitioncurrentwhilethehighleveliswellintothesp

rayarcregion.

Metalisonlytransferred

totheworkduringtheperio

dofhighcurrent.

Usuallyonedropletis

transferredduringeachhighcurre

ntpulse.

Thepeakcurrentisin

thesprayarcregion,arcstabilityissimilartothatofconventionalsprayarcwelding.

Theperiodoflowcurrentmaintainsthearcandserv

estoreducetheaveragecurrent.

Producingasprayarc

atloweraveragecurrentlevelsthanarerequiredforconventionalsp

rayarcwelding.

Theloweraveragecu

rrentmakesitpossibletoweldthin

nergaugematerialswithspraytyp

etransfer

Itcanalsobeusedforout-of-positionweldingofheavier

sections.

LWSof1.2meterperm

inute.



P

ulsedArc


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P

ulsedArc

Pro

cessVariationsMetalTransfer


V-I

CharacteristicsforPowerSupply

V1,I1

V2,I2

(V1)(I1)=P=(V2)(

I2)

V

I

V1,I1

V2,I2

100A

5V

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R

I

VV-I

CharacteristicsfortheArc

R=

L

/A

V=

IR

LA


I

V

StableArcZone

Minimumpossiblearclength

V-I

CharacteristicsfortheArc

Maxim

umpossiblearclength

Optimuma

rclength

Shortarc

lengths

Longarclengths

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Setting-upofaMIG/MAGWeldingUn

it

V

-ICharacteristicsforPowe

rSupply

Constantpotentialcharacteristics

I

V



it

V

-ICharacteristicsforPowe

rSupplyandfortheArc

I

V

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(Nearly)ConstantPotential

3V

100A

I

VV1

V2

I2

I1

10

0A

3V


it


C

onstantpotential

C

onstantwirefeedspeed

I

WFS

5.6m/dk

5.6m/dk

5.6m/dk

5.6m/dk

5.6m/dk

I

200A

150A

200A

250A

200A

MeltingRate

5.6m/dk

4.3m/dk

5.6m/dk

6.8m/dk

5.6m/dk

I

V

150A

I

V

200A

I

V

250A

InternalControlSystem(SelfCorrectingPrinciple)inM

IG/MAG

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Setting-upofaMIG/

MAGWeldingUn

it

The

singleswitch

operation


S

implepowersupplies

s

howtwobuttonsforthe

a

rcset-up;

thevoltageand

thewirefeed.

B

etterequippedwelding

u

nitsalsocontainan

a

djustableinductivity

(valve).

Setting-upofaMIG/

MAGWeldingUn

it

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MIG/MAG&F

luxCoredArcWelding,47of85

A

nincreasingwirefeed

velocityalwaysrequiresa

h

igherarcvoltage.

Setting-upofaMIG/

MAGWeldingUn

it

MIG/MAG&F


S

implepowersupplies

s

howtwobuttonsforthe

a

rcset-up;

thevoltageand

thewirefeed.

B


u

nitsalsocontainan

a

djustableinductivity

(valve).

Setting-upofaMIG/

MAGWeldingUn

it

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MIG/MAG&F


S

implepowersupplies

showtwobuttonsforthe

arcset-up;

thevoltageand

thewirefeed.

B


u

nitsalsocontainan

adjustableinductivity

(valve).


it

MIG/MAG&F


S

implepowersupplies


arcset-up;

thevoltageand

thewirefeed.

B


u

nitsalsocontainan


(valve).


it

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MIG/MAG&F


S

implepowersupplies


arcset-up;

thevoltageand

thewirefeed.

B


u

nitsalsocontainan


(v

alve).


it

MIG/MAG&F


S

implepowersupplies


arcset-up;

thevoltageand

thewirefeed.

B


u

nitsalsocontainan


(v

alve).


it

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MIG/MAG&F


S

implepowersupplies


arcset-up;

thevoltageand

thewirefeed.

B


unitsalsocontainan


(v

alve).


it

MIG/MAG&F


S

implepowersupplies


arcset-up;

thevoltageand

thewirefeed.

B


unitsalsocontainan


(v

alve).


it

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MIG/MAG&F



it

Changingth

evoltagewhileWFSis

constant:

Lengthofthe

arcandweldprofile

change,

Thecurrenta

ndandtherateof

depositionremainconstant.

Thearcvoltagedeterminesthearc

lengthandthereforetheseamwidth.

HighV

fla

tandwideseam

Undercutssu

chasinconvenientseam

changescan

occurbecauseofthe

magneticbloweffect.

Ifthearcisto

olongalloyelementscan

becombustedinthearcandthesmoke

formationrais

es.

LowV

narrowandstrongly

reinforcedseams

Short-circuits.

MIG/MAG&F



it

Changingth

evoltagewhileWFSis

constant:

Lengthofthe

arcandweldprofile

change,

Thecurrenta

ndandtherateof

depositionremainconstant.

Thearcvoltagedeterminesthearc

lengthandthereforetheseamwidth.

HighV

fla

tandwideseam

Undercutssu

chasinconvenientseam

changescan

occurbecauseofthe

magneticbloweffect.

Ifthearcisto

olongalloyelementscan

becombustedinthearcandthesmoke

formationrais

es.

LowV

narrowandstrongly

reinforcedseams

Short-circuits.

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MIG/MAG&F



it

ChangingtheWFSwhile

retainin

gthevoltageconstant:

Lengthofthearc,weldprofile,the

currentandandtherateof

depositionchange.

WFS

thedeposition

efficien

cy,thewelding

ampera

ge.

Araisingwirespeedincreasesthe

amperageandthepenetration

depth.

Thesea

mwidthisbarely

influenced.Theseam

reinforcementraisesbecauseof

theincreaseddeposition

EfficiencyifLWSisconstant.

MIG/MAG&F



it

Combin

ationsofVandWFS

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MIG/MAG&F


Set

ting-upofaMIG/MAGWeldingUn

it

MIG/MAG&F


Set


it

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MIG/MAG&F


Theconnectionbetweenaw

ire

electrodewithathicknessof1.2mm

anddifferentshieldinggases:

CO2mixedgasesanda

rgon-

containingmixedgase

swith

higheramountsofCO2

demand

anincreasedarcvoltag

ewhich

contrastsargonmixed

gasesor

mixedgaseswithahig

hamount

ofargoncontainingles

sthan

20%ofCO2.

Set


it

MIG/MAG&F


Pos

itioningtheWeld

ingTorch

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MIG/MAG&F


Pos

itioningtheWeld

ingTorch

MIG/MAG&F


LinearWeldingSpee

d,LWS

Atconstantweldingdata,thehigherLWS,thenarrowerseamcrosssection.

Theergonomicmanualweld

ingvelocitiesareatbetween40and60cm/min:

Istheweldingspeedred

ucedtovaluesbelow40cm/min,amoltenpoolrunningaheadoftheweldingarea

canstronglyreducethepenetrationwithpoorfusiona

saresult.

Itisbettertoquicklyweldaseaminthreelayersthan

toslowlywelditinonlyone.

Usuallyforseriesproductionsareweldingvelocitiesof11.5m/min.

Attoohighspeedundercuts

canoccurandtheweldtu

rnsouttobereinforcedan

dnarrow.

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Setting-upofthePulsedMIG/MAG

Fivesettingpointsareneededtocorrectlysetupthem

etaltransfer:

wirespeed,

impulsefrequency,

pulsewidth,

pulseheight,and

backgroundcurrentheight.

Thepulsewidthandheighti

stoselectinordertoachieveanarcwithlowspatter

formationandnoshort-

ci

rcuits.

Advantages:

Lowspatter,

Flatterbeads,

Betterseamshape,

Lowerheatinput.

Disadvantages:

Higherinvestmentcost,

Setting-upisdiffucult,

Goodwirequalityisneeded,

Gap-bridgingabilityispo

or.


Pos

sibleWeldingDe

fects

Cracking

Porosity

LackofFusion

Spatter

UnfavorableSeamGeometry

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Pos

sibleWeldingDe

fects

La

ckofFusion

Itispossiblethatthefirstdropstransferringin

thearcmeetanincompletelymoltenbase

material.Thedropenerg

yitselfisnotenough

tomeltthebasematerial.Thedroplays

withoutanyfusiontothe

basematerial.

Whenweldbevelangleislessthanenough

(60degreestotal).

Whentherootfaceistoo

highorrootopening

istoolow.

WhenthereisHi-Lowon

Fit-up.

Whenthethicknessofth

ereinforcementis

toomuch.


Pos

sibleWeldingDe

fects

La

ckofFusion

Toolowarcpower,toom

uchLWSandtoo

hightorchspacingorarc

length.

Whenmoltenpoolisrunningaheadofthearc

duetotooLWS,imprope

rtorchinclination.

Wrongbeadsequenceorplacement.

Restrictedweldingacces

s.

Wrongtorchpositioning.

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Pos

sibleWeldingDe

fects

La

ckofFusion

Toolowarcpower,toom

uchLWSandtoo


length.


duetotooLWS,imprope

rtorchinclination.



s.



Pos

sibleWeldingDe

fects

La

ckofFusion

Toolowarcpower,toom

uchLWSandtoo


length.


duetotooLWS,imprope

rtorchinclination.



s.


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Pos

sibleWeldingDe

fects

La

ckofFusion

Toolowarcpower,toom

uchLWSandtoo


length.


duetotooLWS,imprope

rtorchinclination.



s.



Pos

sibleWeldingDe

fects

La

ckofFusion

Toolowarcpower,toom

uchLWSandtoo


length.


duetotooLWS,imprope

rtorchinclination.



s.


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Pos

sibleWeldingDe

fects

Po

rosity

Dirtsanddefectsonthetorch.


Magneticbloweffect.

Draught.

Toolongarc.

Inappropriateshieldinggas.

Contamination.

Cavities.

Nitrogenonedgescutby

laser,plasma.


Pos

sibleWeldingDe

fects

Po

rosity



Magneticbloweffect.

Draught.

Toolongarc.


Contamination.

Cavities.


laser,plasma.

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Pos

sibleWeldingDe

fects

Po

rosity



Magneticbloweffect.

Toolongarc.


Contamination.

Cavities.


laser,plasma.


Pos

sibleWeldingDe

fects

Po

rosity



Magneticbloweffect.

Draught.

Toolongarc.


Contamination.

Cavities.


laser,plasma.

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Pos

sibleWeldingDe

fects

Po

rosity



Magneticbloweffect.

Toolongarc.


Contamination.

Cavities.


laser,plasma.


Pos

sibleWeldingDe

fects

Po

rosity



Magneticbloweffect.

Toolongarc.


Contamination.

Cavities.


laser,plasma.

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Pos

sibleWeldingDefects

Po

rosity

Dirtsanddefectsonthet

orch.


Magneticbloweffect.

Toolongarc.


Contamination.

Cavities.


laser,plasma.


Pos

sibleWeldingDefects

Finalizing

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WeldBevel

Steel

>60o

1-2

3-4


WeldBevel

Aluminium

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Bac

king

MIG-MAG eng 260710 @1544

Documents

Transcript of MIG-MAG eng 260710 @1544