8/6/2019 MIG-MAG eng 260710 @1544

1/43

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

8/6/2019 MIG-MAG eng 260710 @1544

2/43

MIG/MAG

&FluxCoredArcWelding,3of85

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

&FluxCoredArcWelding,4of85

FieldsofApplication

Constructionalsteeloralu

minummembers,

Shipyards,

Automotive,

PipeLines,

PressureVesselsandProcessingEquipments,

HeatExchangers,Boilers,Piping

8/6/2019 MIG-MAG eng 260710 @1544

3/43

MIG/MAG

&FluxCoredArcWelding,5of85

Eq

uipment

Powersupply

Wirefeedunit

Hoseassembly

Torch

Blowtorch

Powersupply

Wirefeed

unit

Hoseassembly

Torch

Blowtorch

Ves

selof

Shieldinggas

Wo

rkpiece

Neutralcable

Wireelectrode

Arc

.

MIG/MAG

&FluxCoredArcWelding,6of85

Po

werSupply

Constantpotentialpowersupply

Thepotentialchangeb

etween3to5Voltscorrespo

ndstocurrentamplitudeof100A

Selfcorrectingarc

Kuralolarakgelemanlarayarlanabilenendktan

sasahiptir.

Endktanskaynakakmndakisapmalarazaltrveakmart

hzndeitirir.rneintutuma

srasndahzlbirakmartavantajlyken,ksadevreylearksrasndayavabirakmartdahaaz

srantoluturur.

Types;

Conventional

WithTrystor

Withtransistorrectifier

Withtransistorinverte

r

8/6/2019 MIG-MAG eng 260710 @1544

4/43

MIG/MAG

&FluxCoredArcWelding,7of85

WireFeedUnit

1.5m/min20m/min

MIG/MAG

&FluxCoredArcWelding,8of85

WireFeedUnit

1.5m/min20m/min

8/6/2019 MIG-MAG eng 260710 @1544

5/43

MIG/MAG

&FluxCoredArcWelding,9of85

WireFeedUnit

Oneormorethanonedrivingunit

arepossible

MIG/MAG&

FluxCoredArcWelding,10of85

WireFeedUnit

8/6/2019 MIG-MAG eng 260710 @1544

6/43

MIG/MAG&

FluxCoredArcWelding,11of85

Ho

seAssembly

Carries;

Coolingair(lower

than250A)or

water,

Wireelectrode,

Shieldinggas,

Weldingcurrentand

potential.

MIG/MAG&

FluxCoredArcWelding,12of85

To

rch

(1)

Torchhandle,

(2)

Mouldedphenolicdielectric(showninwhite)

andthreadedmetalnutinsert(yellow),

(3)

Shieldinggasdiffuser,

(4)

Contacttip,

(5)

Nozzleoutputface

[Reference:Mysid,TTlig

htningRod]

8/6/2019 MIG-MAG eng 260710 @1544

7/43

MIG/MAG&

FluxCoredArcWelding,13of85

WireElectrodes

WireElectr

odes

Solid

FluxCo

red

Lessweldingcurrentforthe

samemetaldepositionrate.

Metalzl

Crufzl

Rutile

Basic

MIG/MAG&

FluxCoredArcWelding,14of85

WireElectrodes

WireElectrodes

forSteels

Solid

FluxCo

red

C-steel

ISO17632

StainlessSteel

ISO17633

C-steel

ISO14341

StainlessSteel

ISO14343

8/6/2019 MIG-MAG eng 260710 @1544

8/43

MIG/MAG&

FluxCoredArcWelding,15of85

WireElectrodesIS

O

14341

MIG/MAG&

FluxCoredArcWelding,16of85

ISO

14341

WireElectrodes

8/6/2019 MIG-MAG eng 260710 @1544

9/43

MIG/MAG&

FluxCoredArcWelding,17of85

ISO

14341

WireElectrodes

MIG/MAG&

FluxCoredArcWelding,18of85

ISO

14341

WireElectrodes

8/6/2019 MIG-MAG eng 260710 @1544

10/43

MIG/MAG&

FluxCoredArcWelding,19of85

ISO

14341

WireElectrodes

MIG/MAG&

FluxCoredArcWelding,20of85

ISO

14341

WireElectrodes

8/6/2019 MIG-MAG eng 260710 @1544

11/43

MIG/MAG&

FluxCoredArcWelding,21of85

ISO17632-

WireElectrodes

MIG/MAG&

FluxCoredArcWelding,22of85

ISO17632-

WireElectrodes

8/6/2019 MIG-MAG eng 260710 @1544

12/43

MIG/MAG&

FluxCoredArcWelding,23of85

ISO17632-

WireElectrodes

MIG/MAG&

FluxCoredArcWelding,24of85

ISO17632-

WireElectrodes

8/6/2019 MIG-MAG eng 260710 @1544

13/43

MIG/MAG&

FluxCoredArcWelding,25of85

Sh

ieldingGases

MIG/MAG&

FluxCoredArcWelding,26of85

Sh

ieldingGases

8/6/2019 MIG-MAG eng 260710 @1544

14/43

8/6/2019 MIG-MAG eng 260710 @1544

15/43

MIG/MAG&

FluxCoredArcWelding,29of85

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&

FluxCoredArcWelding,30of85

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

8/6/2019 MIG-MAG eng 260710 @1544

16/43

MIG/MAG&FluxCoredArcWelding,31of85

ProcessVariationsMetalTransfer

MIG/MAG&FluxCoredArcWelding,32of85

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

ProcessVariationsMetalTransfer

8/6/2019 MIG-MAG eng 260710 @1544

17/43

MIG/MAG&FluxCoredArcWelding,33of85

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

ProcessVariationsMetalTransfer

MIG/MAG&FluxCoredArcWelding,34of85

S

prayarc

V

A

20

150

ProcessVariationsMetalTransfer

8/6/2019 MIG-MAG eng 260710 @1544

18/43

MIG/MAG&FluxCoredArcWelding,35of85

P

ulsedArc;

Avariationofthespray

arctechniqueisknownasp