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GMAW

(MIG W

elding)

GMAW Unit Topics

GMAW Unit Topics

•D

uring t

his

overv

iew

, w

e

will

dis

cuss t

he f

ollo

win

g

topic

s:

•Safety

•GMAW Basics

•Equipment Set-Up

2

•Equipment Set-Up

•Welding Variables

•Process Advantages and

Lim

itations

•AWS Connection

•National Academic

Standards Connection

Unit Objectives

Unit Objectives

•U

pon s

uccessfu

l com

ple

tion o

f th

e G

MA

W

Unit o

f S

tudy, you w

ill

have learn

ed a

bout:

–

Properly protecting

yourself and others while

welding

–The AWS electrode

classification system

–Taking the next step to

becoming a certified

welder

3

welding

–Setting up and operating

GMAW equipment

–Striking and m

aintaining

an arc

–Welding in four positions

using various electrodes

–Weld Inspection

GMAW Safety

GMAW Safety

4

GMAW Safety

GMAW Safety

GMAW Safety

GMAW Safety

•‘G

MA

W S

afe

ty’ is

supple

menta

l

and d

oes n

ot

repla

ce t

he

info

rmation f

ound in ‘A

rc W

eld

ing

Basic

s’

•U

nders

tand a

nd f

ollo

w a

ll safe

ty

pre

cautions lis

ted in ‘S

afe

ty in

Weld

ing,

Cutt

ing a

nd A

llied

Pro

cesses’ (A

NS

I Z

49.1

), a

nd A

rc

5

Pro

cesses’ (A

NS

I Z

49.1

), a

nd A

rc

Weld

ing S

afe

ty (

E205)

•U

nders

tand a

nd f

ollo

w a

ll w

arn

ing

labels

found:

–On w

elding equipment

–With all consumable packaging

–Within instruction m

anuals

•R

ead M

ate

rial S

afe

ty D

ata

Sheets

(MS

DS

)

If y

ou e

ver

have a

question a

bout

your

safe

ty o

r th

ose a

round y

ou,

PLE

AS

E A

SK

YO

UR

IN

ST

RU

CT

OR

!

GMAW Safety

GMAW Safety

•Fumes and Gases c

an

be

da

ng

ero

us

–Keep your head out of the fumes

–Use enough ventilation, exhaust at the arc, or both, to keep fumes and gases

from your breathing zone and the general area

–Local exhaust and m

echanical ventilation can be used without reducing weld

quality

•Electric Shock c

an

kill

–to

re

ce

ive

a s

ho

ck y

ou

r b

od

y m

ust

tou

ch

th

e e

lectr

od

e

an

d w

ork

or

gro

un

d a

t th

e s

am

e t

ime

–Do not touch the electrode or metal parts of the electrode holder with skin or wet clothing

–Keep dry insulation between your body and the m

etal being welded or ground

6

–Keep dry insulation between your body and the m

etal being welded or ground

–The coil of wire is ‘electrically hot’ when the trigger is pulled

•Arc Rays c

an

inju

re e

ye

s a

nd

skin

-C

ho

ose

co

rre

ct

filte

r sh

ad

e (

Se

e c

ha

rt b

elo

w)

** Info

rmation taken f

rom

AN

SI

Z49.1

:2005**

GMAW Safety

GMAW Safety

•R

EM

EM

BE

R –

Gas C

ylin

ders

require S

PE

CIA

L

safe

ty p

recautions

–Cylinders m

ust be secured in an upright position

–Cylinders should be located in an area away from arc

welding, cutting, heat, sparks, and flame

–Refer to ‘Safety in W

elding, Cutting, and Allied Processes’

7

–Refer to ‘Safety in W

elding, Cutting, and Allied Processes’

(ANSI Z49.1) or Arc W

elding Safety (E205) for more

inform

ation on the handling of gas cylinders

8

GMAW Principles

GMAW Principles

GMAW Definition

GMAW Definition

•G

MA

W s

tan

ds fo

r G

as M

eta

l A

rc W

eld

ing

•G

MA

W is c

om

mo

nly

re

ferr

ed

to

as M

IG o

r M

eta

l In

ert

Ga

s

we

ldin

g

•D

uri

ng

th

e G

MA

W p

roce

ss, a

so

lid m

eta

l w

ire

is fe

d th

rou

gh

a

we

ldin

g g

un

an

d b

eco

me

s

9

a w

eld

ing

gu

n a

nd

be

co

me

s

the

fill

er

ma

teri

al

•In

ste

ad

of a

flu

x, a

sh

ield

ing

g

as is u

se

d to

pro

tect th

e

mo

lte

n p

ud

dle

fro

m th

e

atm

osp

he

re w

hic

h r

esu

lts in

a

we

ld w

ith

ou

t sla

g

GMAW is the m

ost widely used arc welding process in the

United States

GMAW Circuit

GMAW Circuit

•T

hre

e th

ing

s h

ap

pe

n

wh

en

th

e G

MA

W g

un

trig

ge

r is

pu

lled

:

–The w

ire electrode

begins to feed

10

begins to feed

–The circuit becomes

electrically ‘hot’

•C

urr

en

t flo

ws fro

m th

e p

ow

er

so

urc

e th

rou

gh

th

e g

un

ca

ble

, g

un

, co

nta

ct tip

to

th

e w

ire

an

d a

cro

ss th

e a

rc. O

n th

e o

the

r sid

e o

f th

e a

rc, cu

rre

nt flo

ws th

rou

gh

th

e b

ase

me

tal to

th

e

wo

rk c

ab

le a

nd

ba

ck to

th

e p

ow

er

so

urc

e

–Shielding gas flows through the gun and out the nozzle

GMAW Components

GMAW Components

•Let’s look a

little c

loser

at th

e G

MA

W p

rocess

Travel direction

Ge

ne

rally

, d

rag o

n th

in s

he

et

me

tal a

nd

pu

sh

on

th

icke

r

ma

teria

ls

11

Ele

ctro

de

1A

rc2

Wel

d P

ud

dle

3

Sh

ield

ing

Gas

4

5S

olid

ifie

d W

eld

Met

al

1 -Electrode

1 -Electrode

•A

GM

AW

ele

ctr

od

e is:

–A m

etal wire

–Fed through the gun by

12

the wire feeder

–Measured by its

diameter

GM

AW

ele

ctr

odes a

re c

om

monly

packaged o

n

spools

, re

els

and

coils

rangin

g f

rom

1lb

to 1

000lb

s

2 -Arc

2 -Arc

•A

n e

lectr

ic a

rc

occu

rs in

th

e g

as

fille

d s

pa

ce

be

twe

en

13

fille

d s

pa

ce

be

twe

en

the

ele

ctr

od

e w

ire

an

d th

e w

ork

pie

ce

Ele

ctr

ic a

rcs c

an g

enera

te

tem

pera

ture

s u

p t

o 1

0,0

00

°F

3 -Weld Puddle

3 -Weld Puddle

•A

s th

e w

ire

ele

ctr

od

e

an

d w

ork

pie

ce

he

at

up

an

d m

elt,

the

y

form

a p

oo

l o

f m

olte

n

ma

teri

al ca

lled

a w

eld

14

ma

teri

al ca

lled

a w

eld

pu

dd

le

•T

his

is w

ha

t th

e

we

lde

r w

atc

he

s a

nd

ma

nip

ula

tes w

hile

we

ldin

g.0

45”

ER

70S

-6 a

t 400 ipm

wire f

eed

speed a

nd 2

8.5

Volts w

ith a

90%

Arg

on/ 10%

CO

2 s

hie

ldin

g g

as

4 -Shielding Gas

4 -Shielding Gas

•G

MA

W w

eld

ing

req

uir

es a

sh

ield

ing

ga

s to

pro

tect th

e

we

ld p

ud

dle

15

we

ld p

ud

dle

•S

hie

ldin

g g

as is

usu

ally

CO

2,

arg

on

,

or

a m

ixtu

re o

f b

oth

The g

auges o

n t

he r

egula

tor

show

gas flo

w r

ate

and b

ott

le p

ressure

5 -Solidified Weld Metal

5 -Solidified Weld Metal

•T

he

we

lde

r “l

ays a

be

ad

” o

f m

olte

n m

eta

l

tha

t q

uic

kly

so

lidifie

s

into

a w

eld

16

into

a w

eld

•T

he

re

su

ltin

g w

eld

is

sla

g fre

e

An a

lum

inum

weld

done

with t

he G

MA

W p

rocess

Application Activity


17



GMAW Components


GMAW Components


•1 __________

•2 __________

•3 __________

•4 __________

•Let’s r

evie

w t

he G

MA

W p

rocess

Travel direction

Genera

lly, dra

g o

n thin

sheet

meta

l and p

ush o

n thic

ker

mate

rials

18

•4 __________

•5 __________

12

3

4

5

Equipment Set Up

Equipment Set Up

19

Equipment Set Up

Equipment Set Up

GMAW Equipment Set Up

GMAW Equipment Set Up

1.

Co

nn

ect w

ork

cla

mp

2.

Se

lect e

lectr

od

e

a. Type

b. Diameter

3. S

ele

ct sh

ield

ing

ga

s

4. T

urn

po

we

r su

pp

ly o

n

20

4. T

urn

po

we

r su

pp

ly o

n

5. A

dju

st m

ach

ine

ou

tpu

t

a. Wire feed speed

b. Voltage

6. A

dju

st g

as flo

w r

ate

Why w

ould

GM

AW

be a

bett

er

choic

e t

han S

MA

W f

or

this

job?

GMAW Process Variables

GMAW Process Variables

•W

eld

ing

va

ria

ble

s

–Wire Feed Speed (WFS)

–Voltage

•O

pe

rato

r co

ntr

olle

d v

ari

ab

les

–Travel speed

–Gun angles

–Contact tip to w

ork distance

21

–Contact tip to w

ork distance

(CTWD)

–Gas flow rate

What is

the r

ela

tionship

betw

een W

FS

and a

mpera

ge?

Striking an Arc

and Making a Weld

Striking an Arc

and Making a Weld

22

and Making a Weld

and Making a Weld

Striking an Arc

Striking an Arc

•P

ositio

n th

e g

un

ove

r jo

int

•P

ositio

n th

e fa

ce

sh

ield

to

pro

tect

23

sh

ield

to

pro

tect

eye

s a

nd

fa

ce

•P

ull

the

gu

n t

rig

ge

r

an

d b

eg

in w

eld

ing

What are

som

e t

hin

gs t

o

consid

er

befo

re s

trik

ing a

n a

rc?

Laying a Bead

Laying a Bead

•M

ain

tain

a C

onta

ct

Tip

to W

ork

Dis

tance (

CT

WD

) of

3/8

” to

1/2

”

•U

se a

uniform

tra

vel speed

•M

ost Im

port

antly –

Watc

h the P

uddle

!

24

Th

e a

pp

ea

ran

ce

of

the

pu

dd

le a

nd

rid

ge

wh

ere

mo

lte

n m

eta

l so

lidifie

s

ind

ica

tes c

orr

ect

tra

ve

l sp

ee

d. T

he

rid

ge

sh

ou

ld b

e a

pp

roxim

ate

ly 3

/8”

(10

mm

) b

eh

ind

th

e w

ire

ele

ctr

od

e.

Mo

st

be

gin

ne

rs t

en

d t

o w

eld

to

o f

ast

resu

ltin

g in

a r

op

ey b

ea

d w

hic

h

me

an

s S

LO

W d

ow

n!

Th

e a

pp

ea

ran

ce

of

the

pu

dd

le a

nd

rid

ge

wh

ere

mo

lte

n m

eta

l so

lidifie

s

ind

ica

tes c

orr

ect

tra

ve

l sp

ee

d. T

he

rid

ge

sh

ou

ld b

e a

pp

roxim

ate

ly 3

/8”

(10

mm

) b

eh

ind

th

e w

ire

ele

ctr

od

e.

Mo

st

be

gin

ne

rs t

en

d t

o w

eld

to

o f

ast

resu

ltin

g in

a r

op

ey b

ea

d w

hic

h

me

an

s S

LO

W d

ow

n!

Fill the Crater

Fill the Crater

•F

ill t

he c

rate

r by p

ausin

g

or

usin

g a

slig

ht

back

ste

p

•R

ele

ase g

un t

rigger

and

pull

gun a

way f

rom

the

work

aft

er

the a

rc g

oes

25

work

aft

er

the a

rc g

oes

out

•Larg

e c

rate

rs c

an c

ause

weld

cra

ckin

g

Cra

ter

cra

cks c

annot

be

tole

rate

d o

n N

AS

CA

R r

adia

tors

.

Restarting a Bead

Restarting a Bead

•R

esta

rt the w

eld

bead b

y b

ack

ste

ppin

g into

the

last w

eld

’s c

rate

r

and t

hen c

ontinue

movin

g f

orw

ard

26

movin

g f

orw

ard

•T

his

techniq

ue

should

result in a

seam

less

transitio

n f

rom

one

weld

to the n

ext

2

Ba

ck s

tep

1

Modes of Metal

Transfer

Modes of Metal

Transfer

27

Transfer

Transfer

Modes of Metal Transfer


•G

MA

W is a

pro

ce

ss th

at

fea

ture

s s

eve

ral d

istin

ctive

,

ind

ivid

ua

l m

eth

od

s a

nd

typ

es

of m

eta

l tr

an

sfe

r

•T

he

mo

de

of m

eta

l tr

an

sfe

r is

de

term

ine

d b

y a

nu

mb

er

of

we

ldin

g v

ari

ab

les

28

we

ldin

g v

ari

ab

les

–Voltage

–Amperage

–Shielding G

as

•B

y c

ha

ng

ing

on

e o

r m

ore

va

ria

ble

s, yo

u c

an

go

fro

m

on

e m

eta

l tr

an

sfe

r m

od

e to

an

oth

er



•T

wo c

om

mon c

onventional

modes o

f m

eta

l tr

ansfe

r are

:

–Short arc

–Axial spray arc

Typic

al short

arc

applic

ation

29

–Axial spray arc

•T

he a

pplic

ation,

join

t desig

n,

base m

ate

rial th

ickness,

and

pro

pert

ies d

ete

rmin

e t

he

appro

priate

mode t

o u

se

Typic

al axia

l spra

y

arc

applic

ation

Short Arc Transfer

Short Arc Transfer

•In

sh

ort

arc

tra

nsfe

rM

–The arc is initiated

and a droplet is

form

ed on the end of

the wire

30

–The wire touches the

work piece and

produces a short

circuit

–The droplet is then

transferred to the weld

puddle

Axial Spray Arc Transfer

Axial Spray Arc Transfer

•In

axia

l sp

ray a

rc

tra

nsfe

r M

–Very high currents are

used

–A point form

s at the

31

–A point form

s at the

end of the electrode

and the fine droplets

–The puddle is very

fluid m

aking out of

position w

elding

difficult

Troubleshooting

Welds

Troubleshooting

Welds

32

Welds

Welds

Troubleshooting Welds

Troubleshooting Welds

•G

OA

L -

Ma

ke

Go

od

We

lds

•E

limin

ate

Ro

pe

y C

on

ve

x b

ea

d

33

•E

limin

ate

Po

rosity

•E

limin

ate

Exce

ssiv

e S

pa

tte

r

Advantages and

Limitations

Advantages and

Limitations

34

Limitations

Limitations

Advantages of GMAW

Advantages of GMAW

•H

igh o

pera

ting f

acto

r

•E

asy to learn

•Lim

ited c

leanup

•U

se o

n m

any d

iffe

rent

meta

ls: s

tain

less s

teel,

35

mild

(carb

on)

ste

el,

alu

min

um

and m

ore

•A

ll positio

n

•G

reat fo

r hom

e u

se w

ith

115V

and 2

30V

units

Limitations of GMAW

Limitations of GMAW

•Less p

ort

able

with

short

er

gun length

s (

15

foot guns)

•G

MA

W e

quip

ment

is

more

expensiv

e t

han

SM

AW

equip

ment

36

SM

AW

equip

ment

•E

xte

rnal shie

ldin

g g

as

can b

e b

low

n a

way b

y

win

ds

•H

igh r

adia

ted h

eat

•D

ifficult to u

se in o

ut of

positio

n join

ts

AWS Classification of

GMAW Electrodes


GMAW Electrodes

37

GMAW Electrodes

GMAW Electrodes

ER70S-X

Electrode

Rod


GMAW Electrodes


GMAW Electrodes

38

Rod

70,000 psi Min. Tensile Strength

Solid

Chemistry, Amount of Deoxidizers (Silicon,

Manganese and/or Aluminum, Zirconium and

Titanium) X=2,3,4,6,7 or G

39

Lesson Plans

Lesson Plans

GMAW Lesson #1

GMAW Lesson #1

•Objective: To run a stringer (straight) bead using short arc transfer and to fill the

crater

•Equipment:

–Single Process -Constant Voltage Power Source & W

ire Feeder

�P

ow

er

MIG

21

5 o

r P

ow

er

MIG

25

5C

–Multi-Process

�C

om

po

site

: P

ow

er

MIG

35

0 M

P

�C

om

bin

atio

n: V

-35

0/

LF

-72

pa

cka

ge

•Material:

40

•Material:

–Mild

Steel Plate –

3/16” or thicker

�.0

35”

SuperA

rc L

-56 (

ER

70S

-6)

�100%

CO

2 o

r 25%

CO

2/ 75%

Arg

on b

lend s

hie

ldin

g g

as

GMAW Lesson #2

GMAW Lesson #2

•Objective: To make a fillet weld on a lap joint in the horizontal position (AWS

position 2F)

•Equipment:


ire Feeder

�P

ow

er

MIG

21

5 o

r P

ow

er

MIG

25

5C

–Multi-Process

�C

om

po

site

: P

ow

er

MIG

35

0 M

P

�C

om

bin

atio

n: V

-35

0/

LF

-72

pa

cka

ge

•Material

41

•Material

–Mild

Steel Plate –

10 gauge

–.035” SuperArc L-56 (ER70S-6)

–100% CO2 or 25% C

O2/ 75% Argon blend shielding gas

2F

GMAW Lesson #3

GMAW Lesson #3

•Objective: To make a fillet weld on a tee joint in the horizontal position

(AWS position 2F)

•Equipment:


ire Feeder

�P

ow

er

MIG

215 o

r P

ow

er

MIG

255C

–Multi-Process –

�C

om

posite:

Pow

er

MIG

350 M

P

�C

om

bin

ation:

V-3

50/

LF

-72 p

ackage

42

�C

om

bin

ation:

V-3

50/

LF

-72 p

ackage

•Material:

–Mild Steel Plate –

10 gauge

–.035” SuperA

rc L-56 (ER70S-6)

–100% C

O2 or 25% C


2F

GMAW Lesson #4

GMAW Lesson #4

•Objective: To make a fillet weld on a lap joint in the vertical position welding

down (AWS position 3FD)

•Equipment:


ire Feeder

�P

ow

er

MIG

21

5 o

r P

ow

er

MIG

25

5C


�C

om

po

site

: P

ow

er

MIG

35

0 M

P

�C

om

bin

atio

n: V

-35

0/

LF

-72

pa

cka

ge

•Material:

43

•Material:

–Mild

Steel Plate –

10 gauge


–100% CO2 or 25% C


3F

D

GMAW Lesson #5

GMAW Lesson #5

•Objective: To make a fillet weld on a tee joint in the vertical position welding down (AWS

position 3FD)

•Equipment:


ire Feeder

�P

ow

er

MIG

215 o

r P

ow

er

MIG

255C


�C

om

posite: P

ow

er

MIG

350 M

P

�C

om

bin

ation: V

-350/ LF

-72 p

ackage

•Material:


10 gauge

44


10 gauge


–100% CO2 or 25% CO2/ 75% Argon blend shielding gas

3F

D

GMAW Lesson #6

GMAW Lesson #6

•Objective: To make a butt weld with a gap in the vertical position

welding down

•Equipment:


ire Feeder

�P

ow

er

MIG

21

5 o

r P

ow

er

MIG

25

5C


�C

om

po

site

: P

ow

er

MIG

35

0 M

P

�C

om

bin

atio

n: V

-35

0/

LF

-72

pa

cka

ge

45

�C

om

bin

atio

n: V

-35

0/

LF

-72

pa

cka

ge

•Material:

–Mild

Steel Plate –

10 gauge


–100% CO2 or 25% C


3G

GMAW Lesson #7

GMAW Lesson #7

•Objective: To make a fillet weld on a tee joint

in the overhead position (AWS position 4F)

•Equipment:

–Single Process -Constant Voltage Power

Source & W

ire Feeder

�P

ow

er

MIG

215 o

r P

ow

er

MIG

255C


�C

om

posite: P

ow

er

MIG

350 M

P

�C

om

bin

ation: V

-350/ LF

-72 p

ackage

•Material:

46

•Material:


10 gauge


–100% CO2 or 25% CO2/ 75% Argon blend

shielding gas

4F

GMAW Lesson #8

GMAW Lesson #8

•Objective: To make a three pass fillet weld on a tee

joint in the horizontal position (AWS position 2F)

•Equipment:

–Single Process -Constant Voltage Power Source

& W

ire Feeder

�P

ow

er

MIG

215 o

r P

ow

er

MIG

255C


�C

om

posite: P

ow

er

MIG

350 M

P

�C

om

bin

ation: V

-350/ LF

-72 p

ackage

47

�C

om

bin

ation: V

-350/ LF

-72 p

ackage

•Material:


¼”


–100% CO2 or 25% CO2/ 75% Argon blend shielding gas

2F

GMAW Lesson #9

GMAW Lesson #9

•Objective: To run a horizontal fillet weld on a tee joint using axial

spray transfer (AWS position 2F)

•Equipment:

–Single Process -Constant Voltage Power Source

& W

ire Feeder

�P

ow

er

MIG

22

5C


�C

om

po

site

: P

ow

er

MIG

35

0 M

P

48

�C

om

po

site

: P

ow

er

MIG

35

0 M

P

�C

om

bin

atio

n: V

-35

0/

LF

-72

pa

cka

ge

Material:

–Mild

Steel Plate –

¼”


–90% Argon/ 10% C

O2 blend shielding gas

2F

49

AWS Connection

AWS Connection

American Welding Society

(AWS) Connection

American Welding Society

(AWS) Connection

•T

he G

MA

W u

nit o

f stu

dy

covere

d info

rmation r

ela

ted

to the follo

win

g A

WS

requirem

ents

for

cert

ific

ation:

–Setting up for GMAW

50

–Setting up for GMAW

operations on carbon steel

–Operating G

MAW equipment

on carbon steel

–Making G

MAW fillet welds on

carbon steel

English, Math, and Science


51


Connection


Connection

National Academic Standards

Crosswalk

National Academic Standards

Crosswalk

•T

his

un

it c

ove

red

aca

de

mic

co

nte

nt

liste

d in

th

e

Na

tio

na

l A

ca

de

mic

Sta

nd

ard

s a

s fo

llow

s:

–NM-M

EA.9-12.1:Understands m

easurable attributes of objects

and the units, systems, and processes of measurement

–NM-PROB.CONN.PK-12.3:Recognizes and applies

mathematics in contexts outside of mathematics.

52

mathematics in contexts outside of mathematics.

–NS-PHYSICAL SCIENCE: (Understands) structure and

property of matter

–NS-PHYSICAL SCIENCE: (Understands) chemical reactions

–NLA-STANDARD 3: U

ses grammatical and m

echanical

conventions in

written compositions

–NLA-STANDARD 10:Understands the characteristics and

components of the m

edia

Documents

GMAW (MIG Welding) - SharpSchoolp2cdn5static.sharpschool.com/UserFiles/Servers/Server_2992254/File...welding – The AWS electrode classification system ... Why would GMAW be a better