1.introduction to smaw

7/23/2019 1.Introduction to SMAW

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Introduction to

Shielded Metal Arc Welding

(SMAW)

Yeong-Do Park, PhD

Associate Professor, Director of Center for Education of

Welding Engineering

Deart!ent of Ad"anced Materials Engineering

Dong-Eui #ni"ersit$



Content

• Introduction

• %$es of Welding

• Shielded Metal Arc Welding (SMAW)

– How is metal prepared for welding?

– Striking an arc and making a weld

– Electrode classifications

– Welding techniques

– Advantages and limitations

– Safety and Precautions



Introduction

Welding is joining two pieces of metal y!

Heating to temperature high enough to cause softening or

melting With or without application of pressure With or without use of filler metal

• "elting point same as metals eginning joined or melting

point elow metals ut aout #$$% &

'ew methods( applications and systems )remendous progress in short time

*sually est method to use when fastening metal

Applications! Aerospace( Automotive( Shipuilding( +onstruction(

Steel industries



)ypes of Welding



&usion Welding Processes

'MAW 'as Metal Arc Welding

SMAW Shielded Metal Arc Welding

SAW Su!erged Arc Welding

Consu!ale Electrode

*on-Consu!ale Electrode

'%AW 'as %ungsten Arc Welding

PAW Plas!a Arc Welding

SMAW 'MAW

SAW

'%AW



&usion Welding Processes

Electron Beam Welding

Radiant Energy Beam

Laser Beam Welding

EBW LBW



Solid State Welding Processes

&riction Welding

#ltrasonic Welding

+esistance Welding

Diffusion Welding

&riction elding

#ltrasonic elding +esistance sot elding

Diffusion onding



Arc Welding %$es-Su!!ar$



Shielded Metal Arc Welding(SMAW)




Electrode Core Wire

Shielded or Heavy Coating Flow

Weld Metal

Shielding Gas

Solidified Slag

Base Metal

Fusion or Molten Weld Metal

Schematic iew of SM! welding "rocess




• During this o"er"ie, e ill

discuss the folloing toics

• SMAW Basics

• Equipment Set-Up

•Welding Techniques

• Process Advantages and

imitations

• Sa!et" and precautions

%he SMAW rocess is great for

!aintenance and reair ork



Shielded Metal Arc Welding• #on successful co!letion of the

SMAW #nit of Stud$, $ou ill ha"e

learned to

• Properl" protect "oursel! and others#hile #elding

• Set up and operate SMAW equipment

• Stri$e and maintain an arc

• Ma$e #elds in !our positions usingdi!!erent electrodes

• Understand a #eld inspection process

• Appl" the AWS electrode classi!ications"stem

• Ta$e the ne%t step to &ecoming acerti!ied #elder

Most structural steel elders are

re.uired to e certified



Shielded Metal Arc Welding Process 'apa&ilit"

•Shielded !etal arc elding one of !ost used of "ariouselectric arc elding rocesses

42%

34%

13%

9% 2%

SMAW

GMAW/F

GTAW

SAW

Others



• %he A!erican Welding Societ$

defines SMAW as Shielded Metal

Arc Welding

• SMAW

– s commonl" $no#n as Stic$*#elding or manual arc #elding

– s the most #idel" used arc

#elding process in the #orld

– 'an &e used to #eld most

common metals and allo"s

Shielded Metal Arc Welding Principles



• Current flos through the electrode cale, to the electrodeholder, through the electrode, and across the arc

• /n the ork side of the arc, the current flos through the

ase !aterial to the ork cla! and ack to the elding!achine

Shielded Metal Arc Welding'ircuit



#

$ravel direction

Electrode

Arc%

Weld Puddle &

Shielding Gas'

Solidified Weld Metal(

Slag)

0et1s take a little closer look at the SMAW rocess2

#

$ravel direction

Electrode

Arc%

Weld Puddle&

Shielding Gas'

Solidified Weld Metal(

Slag)

Shielded Metal Arc Welding Process



• Is a consu!ale - it gets !eltedduring the elding rocess

• Is co!osed of to arts

– 'ore +od (Metal ,iller) Carries elding current

3eco!es art of the eld

– ,lu% 'oating Produces a shielding gas

Can ro"ide additional filler

&or!s a slag

Shielded Metal Arc WeldingThe Electrode



• An arc occurs hen theelectrode co!es in contact iththe ork-iece and co!letesthe circuit 2 like turning on alight4

• %he electric arc is estalished inthe sace eteen the end of theelectrode and the ork

• %he arc reaches te!eratures of56,6667& hich !elts theelectrode and ase !aterial

Can $ou identif$ the eld 8oint and

osition eing used9

Shielded Metal Arc WeldingThe Arc



• As the core rod, flu: coating,

and ork ieces heat u and

!elt, the$ for! a ool of !olten

!aterial called a eld uddle

• %he eld uddle is hat a

elder atches and

!aniulates hile elding

5;<= E>65? at 5@ A!s AC

Electrode

Weld uddle

Shielded Metal Arc WeldingWeld Puddle



• A shielding gas is for!ed hen

the flu: coating !elts

• %his rotects the eld uddlefro! the at!oshere

re"enting conta!ination

during the !olten state

%he shielding gas rotects the !olten

uddle fro! the at!oshere hile

stailiBing the arc

@

?

Shielding 'as

Shielded Metal Arc Welding Shielding as



• As the !olten eld uddle

solidifies, it for!s a 8oint or

connection eteen to ieces

of ase !aterial

• When done roerl$ on steel,

it results in a eld stronger

than the surrounding ase

!etal

Weld ead

Shielded Metal Arc Welding Solidi!ied #eld Metal



Electrode

•Slag is a co!ination of the flu:coating and i!urities fro! the

ase !etal that float to the

surface of the eld

•Slag .uickl$ solidifies to for! asolid coating

• %he slag also slos the cooling

rate of the eld

• %he slag can e chied aa$ and

cleaned ith a ire rush hen

hard

%his elder chis the slag off of a eld during

the reair of railroad tracks

Shielded Metal Arc Welding Slag



• Co!ination of !elted flu: ase !etal i!urities

• uickl$ solidifies to for! a shell

• Slos the cooling rate of eld

• Chi and clean ith ha!!er rush

•If roer techni.ue is used it should co!e off eas$

• *e"er eld o"er slag44

AWA.S S/E '0P SA1 /23*T 0T

T 4E A 0AMME+

Slag

Shielded Metal Arc Welding Slag



5F %urn oer sul$ on

@F Connect ork cla!

?F Select electrode

a5 T"pe

&5 /iameter

F Ad8ust outut

a5 Polarit"

&5 Amperage

F Insert electrode into electrode holder

Shielded Metal Arc Welding Equipment Setup



• Settings on the !achine

– Polarit" 6 A'1 /'71 /'-

– Amperage 2utput

• /erator Controlled

Gariales

– Wor$ Angle

– Travel Angle

– Arc ength

– Travel Speed A straight AC !achine ill not ha"e a

olarit$ sitch like this AC;DC !achine

Shielded Metal Arc Welding Process 8aria&les




0o# is metal prepared !or#elding9



• Prearing the correct t$e of 8oint for each kind of !etal is

crucial to securing strong elded structuresF


• %he asic t$es of 8oints are the

5F 3utt

@F 0a

?F %ee

F Corner

F Edge

%hese 8oints !a$ e alied to the different t$es of elds

(5) &illet (@) 'roo"e (?) Plug () Slot and () Surface



Shielded Metal Arc WeldingThere are !ive &asic t"pes o! #elding :oints1 #ith each having a num&er o! variations in order to meet di!!erent needs

A utt eld, or a s.uare-groo"e, is the !ost co!!on and easiest to useF

%ee 8oints, considered a fillet t$e of eld, for! hen to !e!ers intersect at H67

resulting in the edges co!ing together in the !iddle of a co!onent or late

A corner eld is a t$e of 8oint that is eteen to !etal arts and is located at

right angles to one another in the for! of a 0F

%his is for!ed hen to ieces are laced ato each other hile

also o"er laing each other for a certain distance along the edgeF

Edge elding 8oints, a groo"e t$e of eld, are laced side $ sideand elded on the sa!e edgeF

S i i



A tee eld is a t$e of fillet eldF %he !illet #eld has to

surfaces at right angles, and the ead is triangular in shae

%he groove #eld is a eld !ade in a groo"e

eteen the to ieces of !etal to e 8oinedF

%he lug and slot elds are used to 8oinieces that o"erlaF

%he elds are laced in lug or slot holesF

%hese t$es of elds co!!onl$ take the

lace of ri"ets in elded structuresF

#sed .uite often on light gauge !etal to

re"ent aring and heat distortion

%he Surfacing eld is not for 8oining arts

%he urose is to increase the thickness of the late orro"ide a rotecti"e coating on the surface

(5) &illet

(@) 'roo"e

(?) Plug and () Slot

() Surface elds

Plug Slot

Surface

'roo"e

&illet


Shi ld d M l A W ldi



Stri$ing an Arc and Ma$ing a Weld





• %o egin the SMAW Process, $ou !ust first strike an arcF

%his can e done using one of the folloing techni.ues

– Scratch start ; scratch the electrode on the &ase metal

li$e a match

– Tap Start ; tap the rod against the &ase metal

Shielded Metal Arc Welding Stri$ing an arc




• %he ork angle is theangle eteen the

electrode and the ork as

deicted on the left

• Work angles can "ar$

deending on the osition

the eld is eing !ade in

Shielded Metal Arc WeldingWor$ angle

Shi ld d M t l A W ldi



• Work angles can "ar$ deending on the osition the eld is

eing !ade in

6

?66

66

Shielded Metal Arc WeldingWor$ angle




• Also co!!onl$ called 0ead

Angle

• %he tra"el (lead) angle isthe angle eteen the

electrode and the lane

erendicular to the eld

a:is

20-30°

Shielded Metal Arc WeldingTravel angle




• After striking the arc, !aintain a 5;<= distance eteenthe electrode and the orkiece

– ! the arc length &ecomes too short1 the electrode #ill get

stuc$ to the #or$piece or short out*

– ! the arc length &ecomes too long< spatter1 undercut1and porosit" can occur

Shielded Metal Arc Welding Arc ength

Arc 0ength J 5;<=




• %he tra"el seed is the seedat hich the electrode !o"esalong the ase !aterial hileelding

– Too !ast o! a travel speed resultsin a rope" or conve% #eld

– Too slo# o! a travel speed results

in a #ide #eld #ith an e%cessivemetal deposit

%he tra"el seed i!acts the

shae of the ead

Shielded Metal Arc WeldingTravel Speed




• At the end of the eld, the oerator reaks the arc hich

creates a Kcrater1

• #se a short ause or slight ack ste at the end of the eld to

fill the crater

• 0arge craters can cause eld cracking

3ack steing is a short !o"e in the oosite direction of eld tra"el

Shielded Metal Arc Welding,illing the 'rater




• Lere is the roer techni.ue for restarting a eld

Shielded Metal Arc Welding +estarting a Bead

5F Strike arc here




! * E

%hese elds ere cut and etched ith nitric acid to sho enetration

Shielded Metal Arc WeldingTrou&leshooting Welds




• A 'ood Weld Proper +urrent( Speed and Arc ,ength

• 3 Current lo -opey( conve. ead appearance

• C Current too High! E.cess spatter / urn0through

• D Arc 0ength too short Poor wet0in at toes

• E Arc 0ength too 0ong Spatter( undercut and porosity

• & %ra"el Seed too slo Wide weld with e.cess deposit

•' %ra"el Seed too high -opey and conve. ead

Shielded Metal Arc WeldingTrou&leshooting Welds





Electrode 'lassi!ications




E6Electrode

%ensile in 6,666 si

Welding Position5 J All Position, @ J &lat LoriBontal, J Gertical don

%$e of Current and Coating

Shielded Metal Arc WeldingAWS Electrode Classification




• What t$e of elder do I ha"e, AC or DC9

• What a! I elding, steel, cast, stainless, etc9

• What is the !etal condition, dirt$ or clean9

• Is it a root or co"er ass9• Lo strong does it ha"e to e9

• What electrodes do I ha"e to chose fro!9

Shielded Metal Arc Welding Electrode Selection




Shielded Metal Arc Welding Electrode Selection




•A!erage is deendent on electrode dia!eter, electrodet$e, and !etal thickness

• +eference charts hene"er ossileF

Shielded Metal Arc Welding Amperage 'hart




• Electrodes !ust e ket dr$

– Da!ness ill introduce h$drogen

into the eld causing cracking or rittleness

– Da! electrodes !a$ cause the flu: to Nlo aa$= cause orosit$

– 3ake .uestionale electrodes for se"eral hoursF

– >656 >655 (fast freeBe) are e:e!t

• /ur electrodes are stored in a dr$ o"en

Shielded Metal Arc Welding Electrode care




• 3urn electrodes don to nu!ers4

• Place stus in stu o:

• Put unused electrodes ack in o"en

• /nl$ gra se"eral electrodes at a ti!e

• Electrodes are not chea


Electrode care




Welding Techniques





• Stringer (drag) (hi)

• Wea"e

– Circles

– Crescent – Big Bag

– o: ea"e

– doule O

Shielded Metal Arc WeldingTechniques ; Electrode Movement




• A weld resulting from a pass

Stringer 3eadWea"e 3ead

Weld Bead





• Weld Pass - A single rogression of elding along a 8ointF

%he result of a ass is a eld ead or la$er

Weld Pass


=5 Single Pass >5 Multi pass




+oot PassLot Pass

&ill Pass

Co"er Pass

Ailit$ to !ake !ultiass eldssuch as this one, on late and ie,

led to groth of industr$F Welds are

sound and ha"e unifor! aearanceF

Pass 5

Pass @

Pass ?

Shielded Metal Arc Welding Multipass




• %he flat osition roduces elds that are stronger than in an$

other osition

%here are four ositions used hen elding


=5 ,lat Position






>5 8ertical






?5 0ori@ontal

• &illet;'roo"e - stringers (s!all ea"e !a$ e used in tight lace)

• 3ead Place!ent - otto! to to






5 2verhead

• Sa!e as horiBontal for &illets

• >656 oen root hi for flat face and ke$hole control

• 65<1s stringers

• /"er head 3utt Ooints can e stringers or ea"es




Advantages and imitations





• 0o initial cost

• Portale

• Eas$ to use outdoors

• All osition caailities

• Eas$ to change eteen

!an$ ase !aterials

What safet$ recautions should e

taken $ these elders9

Shielded Metal Arc Welding Advantages




• 0oer consu!aleefficienc$

• Difficult to eld "er$ thin

!aterials

• &re.uent restarts• 0oer oerating factor

• Ligher oerator skill

re.uired for SMAW than

so!e other rocesses

3uilding a arge in a large shi$ard

Shielded Metal Arc Welding imitations




• Discontinuities associated ith!anual elding rocess that

utiliBe flu: for ool shielding

– Slag inclusions

– 0ack of fusion

• /ther ossile effects on .ualit$

are orosit$, and h$drogen

cracking

Shielded Metal Arc Weldingualit" ssues




Sa!et" and Precautions





Shielded Metal Arc Welding Sa!et" - 0and and 0ead Shields

• 3rilliant light caused $ electric arc contains to kinds of

in"isile ra$s hich in8ure e$es and skin

– #ltra"iolet

– Infrared

• +a$s affect e$es ithin 6 feet

and skin an$ distance ithin

@6 feet

&ire-Metal Products CoF

Land shield so erson !a$ hold

shield in front of face




Shielded Metal Arc Welding Sa!et" - 0and and 0ead Shields

• Also called hood or hel!et – Attached to ad8ustale headand

• Allos it to e !o"ed u or don as earer desires

• Deendale rotection

– 3oth hands free to gras electrode holder

• Partial rotection

– Must also ear leather or

nonfla!!ale ca for ade.uate rotection




Shielded Metal Arc Welding Sa!et" - lasses

• Should e orn

– Also ehind hood to re"ent se"erearc flash reaching e$es

• Can Asor !ore than HHFHQ har!ful

ultra"iolet ra$s

• Worn $ others ho ork ith elders

•0ight in eight, ell "entilated, andco!fortale

• 0enses ha"e light tint (*ot dark4) andtented side shields

R +oCrandall;%he I!age Works




Shielded Metal Arc Welding Sa!et" ; Protective 'lothing

• 'lo"es to rotect hands

– Made of leather or so!e other t$e of fire-resistant

!aterial

•

0eather caes, slee"es, shouldergar!ents ith detachale is,

arons

• Slit-t$e aron if sitting don

– *o lace to collect hot articles

• Ligh-to shoes

–0eggings and sats

Deart!ent of 0aor




Shielded Metal Arc Welding Sa!et" ; Protective 'lothing

• 566Q cotton or ool

• %hick enough to re"ent

in8urious ultra"iolet ra$s fro!

enetrating to skin• 0ong slee"es

• Shirts uttoned to neck

• Shirttails tucked

• Cuffless ants long enough toco"er to of leather oots




Shielded Metal Arc Welding Sa!et" ;,urther Protection

• Ear Protection – &ull ear !uffs that co"er entire ear or ear lugs

– Dangers

• *oise

• Lot eld satter or slag entering ear canal

• &lu!e Protection

– Ala$s use roer "entilation to kee head out of fu!e

lu!e




• KSMAW Safet$1 is sule!entaland does not relace the

infor!ation found in KArc Welding

3asics1

• #nderstand and follo all safet$

recautions listed in KSafet$ in

Welding, Cutting, and AlliedProcesses1 (A*SI HF5) and Arc

Welding Safet$ (E@6)

• #nderstand and follo all arning

laels found

–2n #elding equipment

– With all consuma&le pac$aging

– Within instruction manuals

• +ead Material Safet$ Data Sheets

(MSDS)

If $ou e"er ha"e a .uestion aout $our safet$ or thosearound $ou, P0EASE AST Y/#+ I*S%+#C%/+4

Shielded Metal Arc Welding Sa!et"- ,urther Protection




• &u!es and 'ases can e dangerous

– 4eep "our head out o! the !umes – Use enough ventilation1 e%haust at the arc1 or &oth1 to $eep !umes and gases !rom

"our &reathing @one and the general area

– The SMAW process can #ithstand #ind and e%haust near the arc !romventilation equipment

• Electric Shock can kill to recei"e a shock $our od$ !ust touch the electrode and

ork or ground at the sa!e ti!e – /o not touch the electrode or metal parts o! the electrode holder #ith s$in or #et

clothing

– 4eep dr" insulation &et#een "our &od" and the metal &eing #elded or ground

• Arc +a$s can in8ure e$es and skin - Choose correct filter shade (See chart elo)

UU Infor!ation taken fro! A*SI HF5@66UU

S e ded e c We d g Sa!et"- ,urther Protection




• Indoors or outdoors

• *ois$

– Learing rotection needed

• Akard ositions

• Sacious surroundings or

cra!ed .uarters

• Ligh off ground in scaffolds ithsafet$ harness

g Sa!et" ;Wor$ing 'onditions




• &ire danger• 3urns (including VsunurnV fro! electric arcs)

• *o:ious fu!es fro! !aterials "aoriBed at high

te!eratures

• E$e strain• Welders flash

• Electric shock LaBards can e !ini!iBed

or eli!inated $ use

of roer rotecti"e

clothing and e.ui!entF

g Sa!et" ;Co& 0a@ards




5F +ead trade 8ournals, ser"ice !anuals, te:t ooks, andtrade catalogs

@F Ooin associations such as the A!erican Welding Societ$

?F +esearch toics on the Internet

F %rade tris ith $our eers

g Sa!et" ;Wa" to Sta" 'urrent



Questions and Answers



hank

You!

*ong+Eui ,niversity

Center for Education of Welding Engineer

1.introduction to smaw

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