Mechanizing Welding Process

8/12/2019 Mechanizing Welding Process

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Mechan ising w e ld ing p r ocesses

XA00097420


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C o n t e n t s

Me c h a n is i ng w e ld in g p ro c e ss e s . . . . . . . . . . . . . 4

MIG /MAG w elding w ith w ire e lec trod es . . . . . . . .6

S hie ld ing g a s es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Welding p a ramete rs . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Adv a n ta g es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Limit a t ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

P roduc t ivit y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

E q u ipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

C o re d w ire . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0

Weld y ie ld indica tes e f f ic iency . . . . . . . . . . . . . . . . . .11

S h ie ld ing g a s es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Applic a t ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Limit a t ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Adv a n ta g es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Inf luenc ing fac tors . . . . . . . . . . . . . . . . . . . . . . . . . . .13

S ui ta b le a pp lic a t ions . . . . . . . . . . . . . . . . . . . . . . . . . 1 3

Mechanisa t ion us ing a welding t r ac tor and Ra i l t r ac . .14

P roduc t c ho ic e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

E q uipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

P o in t s to c o ns ider . . . . . . . . . . . . . . . . . . . . . . . . . . . 15


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M e c h a n i s i n g w e l d i n g p r o c e s s e si s a s u r e i n v e s t m e n t f o r t h efuture

ESAB is th e w or ld s l ead in g m a n u fa c tu rer o f we l d in g c on su m a bl es ,

we l d i n g an d cu t t i n g equ i p m en t an d accessor i es f o r i m p r ov i n g th e

w orking e nvironme nt w ith in we lding a nd c ut t ing . The g roups o per-

a tes on a v i r tu a l l y wor l dwi de bas i s an d ESAB h as m an u f ac tu r i n g

units o n every cont inent . We ha ve a lmos t 100 yea rs exper ienc e of

the indus try.

Sem i - au tom at i c we l d i n g p r ocesses i n v o l v e au tom at i c a l l y f eed-

i n g a con t i n u ou s e l ec t r ode , wh i ch i s a l so u sed as a con du c to r t o

ge n er a te th e a r c . Th ese w e ld i n g m eth ods a r e m ech a n ised o r ev en

r obo t i sed . O v er a p er i od o f m an y year s , i m p r ov ed m ech an i sa t i on

eq u ip m en t h as bee n dev e l op ed w ith n ew , les s c om p l ex m on ito r in g/

control uni ts . I t i s now possible to construct h ighly complex equip-

ment where the only l imi t i s the user s imaginat ion . Gas-shieldedp r ocesses a r e com m on l y u sed on we l d i n g r obo t s i n m os t i n du s t r i a l

se c to r s . P LC (P rog r am m a bl e Log ic C on t ro l le r s ) a re a lso w i de l y use d

in th e m ech a n isa t ion o f we l d in g p r oces ses .

S u b m e rg e d a rc w e ld in g . . . . . . . . . . . . . . . . . . 1 6

Adv a n ta ges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Limit a t ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

P rod uc t ivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Cho ic e o f f lux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Tw o type s o f f lux . . . . . . . . . . . . . . . . . . . . . . . . . . . .19


S uit a b le a pp lic a t ions . . . . . . . . . . . . . . . . . . . . . . . . . 2 1

E q uipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

P o in t s to c o ns ider . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1

Aluminum . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Adv a n ta ges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Limit a t ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23


Applic a t ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

P rod uc t ivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

S uit a b le a pp lic a t ions . . . . . . . . . . . . . . . . . . . . . . . . . 2 6

E q uipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

P ow er s upplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

P o in t s to c o ns ider . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 7


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equ i p m en t con s i s t s o f a p ower sou r ce , a w i r e f eed-

er, a c ontro l unit and a w elding g un. The feed er

p u sh es th e w i re a lon g to th e w e l d in g g u n , wh er e cu r-

rent i s t r ansfer red to the wire v ia a

co nta c t no zz le . The w ire , w hich i s

n or m ally c on n ec ted to th e p os it iv ep o le , m a k e s c o n t a c t w it h t he n e g a -

t ive w orkpiec e. The w ire a nd the

w o r k p i e c e s u r f a c e s m e l t , g i v i n g

r ise to a f in ish ed we ld bea d . Th e

wi r e , wh i ch i s wou n d on a sp oo l

a n d p a c k e d i n a c a r t o n , s e r v e s a s

th e f ille r an d e lec t r ode a t th e s am e

t i m e an d h as th e t a sk o f t r an s f e r -

r ing current through the arc to the

wo rkpiece . The w ire pa ss es through

a h o s e p a c k a g e o n i t s w a y f r o m t h e s p o o l t o t h e

we lding g un. The mol ten poo l a nd the a rc in whichthe f i l ler mel ts must be protec ted f rom the a tmo-

sp here . A shielding g a s i s us ed for th is purpos e; i t is

t ran s p or ted to th e w e l d in g g u n in s i de th e h ose . Th e

m ol ten m eta l m us t be p ro tec ted f rom th e su r rou n d-

i n g a tm osp h er e as i t wou l d o th er w i se r eac t w i th th e

oxygen an d n i t r ogen i n th e a tm osp h er e , c au s i n g

we ld i n g de f ec t s . Th e s h ie ld i n g g as an d w i re e x it th e

h ose in to th e s wa n n eck o f th e g u n . Th ey em er ge

f r o m s e p a r a t e c o n d u i t s a t t h e g a s n o z z l e a n d c o n -

t ac t t ip .

M echanising or automatingwelding processes

The mechan i s a t i o n o f w e l d i n g p r o ce s ses i n c l u d e s we l d i n g me t h o d s i n w h i c h i t i s ea s y t o a u t om a t e t h e mo v emen t o f

t h e w e ld i n g g u n , w h i le p e r f o rm i n g w e ld i n g .

Th e we ld i n g gu n ca n be m ou n ted o n a b ea m wh i ch

m o v e s a c r o s s t h e w o rk pie c e o r is m o u nt e d a b o v e a

rota t ing p os it ioner in which the w orkpiec e i s f ixed. I t

c an a l so be m ou n ted on a se l f - p r o-

p e l l ed ca r r i age wh i ch m ov es a l on g

the w orkpiec e (welding t rac tor) or ism ou n ted on a r obo t a r m .

S u b m e r g e d a r c w e l d i n g h a s

b e e n m e c h a n i s e d b e c a u s e t h e

we ld i n g h ea d a n d th e f eed er fo r th is

m e t h o d a r e t o o h e a v y t o h a n d l e

m a n u a lly . Th e we ld i n g h ea d a n d

feeder uni t are f requent ly mounted

on a we l d i n g c r an e o r p or t a l w i th a

moving c a r ria ge . The m a in d if fer-

e n c e b e t w e e n s u b m e r g e d a r c w e l d -

i n g an d sem i - au tom at i c we l d i n g i s th a t th e m ol ten

p oo l i s p r o tec ted by f l u x i n s tead o f sh i e l d i n g gas .Su bm er ged a r c we l d i n g i s a h i gh l y p r odu c t i v e an d

p ro f it ab le we ld i n g m eth od .

The MIG/MAG met hod use s f i ller w ire to tra ns fer

the a rc to the w orkpiec e a nd thus mel ts the f i ller wire

a n d w o r k p i e c e s u r f a c e s t o p r o d u c e a w e l d b e a d .

Th is m eth od o f w e ld i n g i s u sed w i th v a r iou s t yp es o f

con su m abl e su ch as u n a l l oyed , l ow a l l oy , s t a i n l ess

steel and a luminium. I t i s the dominant welding

method wi th in the industry , wi th vary ing degrees o f

m e c h a n i s a t io n . Th e m o r e s o p h is t i c a t e d w e l d in g


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Cop p er - coa ted w i r e e l ec t r odes a r e r es i s t an t t o co r -

r os i on an d h av e good cu r r en t t r an s f e r ch ar ac te r i s -

t ics . The s urfac e pur ity o f the w ire has a de cis ive

ef fec t on i t s feeding proper t ies . I f the sur face i s not

ent i rely c lean , th is wi l l cause the wire eventual ly tos t i ck i n th e l i n er , so th a t f eed i n g becom es u n ev en ,

th e cu r ren t v a r ies a n d w e l d in g m u s t be t e r m in a ted to

a llow the w ire liner to be c lea ned . This i s a grea t d is-

adv an t age i n a r obo t i sed i n s t a l l a t i on , wh er e th e cos t

p er h ou r is h i gh a n d th e w ire m u s t b e f ed w i th as f ew

p r ob l em s as p oss i b l e . A coa t i n g i s ap p l i ed to th e

n on - cop p er - coa ted w i r es wh i ch h av e been dev e l -

op ed in rece n t year s , t o p rov ide g ood cu r ren t t ra n s-

f e r, a s w e ll a s go od c or ros i on res i s t a n ce . I f non - cop -

per-coated wire i s used in a robot insta l l a t ion , there

i s n o n eed to wor r y abou t con t ac t p r ob l em s .

Shielding gases

Th ere a re tw o t yp e s o f s h ie ld i n g g a s ; in er t an d

a c t i ve . Iner t gas doe s n o t p a r tic i p a te i n th e ch em i ca l

rea c t i on s wh i ch t ake p l ace in th e a rc a n d th e m o lten

p oo l . An ac t i v e sh i e l d i n g gas con t a i n s c a r bon d i ox-

ide , oxyge n o r n it rog en o x ide . Th ese com p on en t s

t ake p ar t i n th e ch em i ca l r eac t i on s wh i ch occu r i n

th e a rc a n d i n th e m ol ten p oo l . Th is is h ow th e tw o

n a m e s h a v e b e e n d e r iv e d : M IG = M e ta l In e rt G a s a n d

MAG = Meta l Ac t i ve G a s . It i s p os s i b le to u se 100%

c a rb o n d io x id e a s t h e a c t iv e g a s , b u t m ix t ure s o f g a s

a r e m o r e c o m m o n a n d m i x e d g a s i s m o s t c o m -m on ly u sed . I t con s i s t s o f 80% a rgo n an d 20% ca r -

bo n d i ox ide .

The c ompo si t ion of the s hielding g a s in f luenc es

th e p r op er t i es o f th e we l d . Mi xed gas p r odu ces a

ca l m er a r c th an a gas wh i ch con s i s t s o f 100% car -

bon d i ox ide . With m ixed ga ses , s m a lle r d r op le t s a ref o r m ed i n th e a r c , we l d sp a t t e r an d f u m es a r e

r edu ced . Mor eov er , th e we l d bead i s n ar r ower w i th

m i xed gas th an w i th p u r e ca r bon d i ox i de , wh i ch

m e a n s t h a t t h e r e i s l e s s s i l i c o n a n d m a n g a n e s e

burn-of f in the a rc , produc ing few er fumes. This

g i v es th e w e ld b e t t e r m ech a n ica l p rop er t ies .

In MIG we ld i n g , p u re a rgo n is th e m os t co m m on

sh i e ld i n g ga s , bu t m i xtu res o f a rgo n a n d h e l iu m a re

a l so u s ed . In som e ca ses , a m ix tu re o f a rgo n , h e liu m

a n d o x y g e n is u s e d .

Ar gon w i th a sm a l l add i t i on o f oxygen i s som e-

t i m es u sed f o r we l d i n g s t a i n l ess s t ee l t o w i den th e

bea d a n d s u p p ly m or e en ergy to th e a r c . H e liu m an d

argon mixtures are preferable for welding th ick-

wal led copper or a luminium al loys . Pure argon is

use d fo r welding a luminium.

Welding parameters

MIG /MAG we lding i s be st for we lding s heet me ta l

th ickn ess es f rom 1 to 10 m m . Th e m eth od is co m -

m on l y u sed f o r we l d i n g ca r body com p on en t s , i n

sh i p yar ds an d f o r o th er ap p l i c a t i on s i n m an y en g i -

n e e r in g s e c t o r s . Th e a d v a n t a g e o f t h is w e ld i n g

method is the constant supply o f f i l ler , low hydrogenco ntent a nd h igher a rc/t ime f a c to r.

A good kn owl edge o f th e we l d i n g p r ocess i s

M IG/ M AG welding withcont inuous wire e lect rodes

B

H

Fa FaFa

F1

F1

F1

Argon Helium CO2

M inimal slag is produced when welding with a wire electrode.

Influence of protective gas on weld penetration profile

M IG /MAG w e ld i n g w i t h w i r e e le c t r o d e s i s a sem i - a u t oma t i c p r o ce s s i n w h i c h t h e f i l l er i s f e d au t oma t i c a l ly. We l d i n g

m ovemen t s a r e pe r f o rmed m anua l l y o r b y a mech an i c a l

d e v i c e . The r e a r e tw o t y p e s o f w i r e , c o ppe r c oa t e d and

n o n - c o p p e r c o a t e d .


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es se nt ia l when us ing MIG/MAG w elding in order to

se t th e c o r rec t re l a t ion sh i p be tw een c u rren t , v o l t age ,

gas f l ow , s t i ck- ou t , gu n an g l e an d we l d i n g sp eed .

Th ese p a ra m eter se t t i n gs dep e n d i n tu rn on th e

ba se mate ria l , the th ickness o f the wo rkpiece , the dia-

mete r of the f iller wire, the type of w eld joint , the w eld-

i n g p os i t i on an d th e sh i e l d i n g gas . G u i de l i n es f o r

th ese p ar am eter s c an be f ou n d i n we l d i n g r ecom -m en da t i on t ab l es i n we l d i n g con su m abl e c a t a l ogu es

or by ask i n g th e m an u f ac tu r er o f th e con su m abl es

direc t ly . I t i s impor tant that the chosen work point i s

w i th in th e r ecom m en d ed wo rk in g a rea f o r the s e l ec t -

ed w i re/sh i e ld i n g g as co m bi n a t ion to p rodu c e th e

cor rec t a r c p r op er t ies . Th e w e ld i n g s p eed , g u n an g le

an d s t i ck- ou t a r e p ar am eter s wh i ch th e we l der con -

tro ls manual ly dur ing the welding process .

AdvantagesThe a dva nta ge of MIG /MAG w elding i s tha t it is e a sy

to m ech a n ise . In m ech a n isa t ion th e sa m e eq u ip m en t

is u s ed a s f o r m an u a l we ld i n g bu t it is n ow m ou n ted

on a m ech an i ca l dev i ce . In a r obo t ap p l i c a t i on i t i s

n eces sa r y to su p p lem en t th e w e ld i ng eq u ip m en t w i th

a p ower sou r ce wh i ch i s i n tegr a ted w i th th e con t r o l

sys tem an d wh i ch can com m u n i ca te w i th th e r obo t

insta l l a t ion . A separate feeder , which i s f requent ly

in s t a lled o n th e rob o t a rm , is a lso u sed tog e th er w ith

a d i ff e ren t t yp e o f w e l d in g g u n wh i ch su i t s th e r obo t .

MIG /MAG w elding is very f lex ible w hen i t c ome s to

m ech an i sa t i on an d i t s l i m i t s a r e se t by th e u ser si m ag i n a t i on . As s t an dar d equ i p m en t c an be u sed i n

m ech an i sa t i on , i t i s a v er y cos t - e f f ec t i v e way o f

implement ing mechanisat ion .

S o l id w ire o f f e rs th e g rea tes t b en e f it s w h en u sed

wi th th inner ma ter ia l below 4-5 mm. This i s b ec a use

th is i s a re l a t iv e ly c o l d w e ld i n g p roce ss co m p ar ed

wi th coa ted e lec t r odes a n d c or ed w i re . Th e redu ce d

h ea t i n p ut resu l t s in less de f o r m at i on an d a ss oc ia te d

mater ia l s t resses . In th icker mater ia l more care must

be t aken w i th we l d i n g sequ en ces an d h ea t i n p u t .

Low he a t input on th icker mate r ia l res ults in a l a ck of

f u s ion b e tw een th e we ld an d th e w or kp iece . Th isr esu l t s i n we l d de f ec t s su ch as i n com p l e te p en e t r a-

tion.

Limitations

As th e p r oces s i s p r o tec ted b y ga s , i t is s en s i t iv e to

ex ter n a l f ac to r s su ch as d r au gh t s . I f th er e i s a

dr au gh t , th er e i s a r i sk th a t th e sh i e l d i n g gas cou l d

b l o w a w a y a n d c a u s e w e l d i n g d e f e c t s i n t h e w e l d

bead . I t i s i m p or t an t t o p r o tec t th e a r c an d th e

mol ten poo l f rom the surround ing a tmos phere. The

oxygen i n th e a tm osp h er e r eac t s eas i l y w i th s i l i con

a n d m a n g a n e s e a n d f o r m s o x i d e s w h i c h c a u s e

f um e s a n d s l a g . Th is m e a n s t h a t t h e w e l d b e a d h a s

a l o w e r s i l i c o n a n d m a n g a n e s e c o n t e n t w h i c h c a n

l ead to a r edu c t i on i n th e m ech an i ca l p r op er t i es o f

th e we l d m eta l . Car e m u s t a l so be t aken w i th n i t r o-

g e n , a s i t c a n e a s i l y b e a b s o r b e d b y t h e m o l t e n

m eta l an d redu c e th e tou gh n es s i m p ac t . In s i tua t i on s

wi th v er y p oor gas sh i e l d i n g , de f ec t s su ch as p or es

in t h e w e l d c a n a l s o b e p r o d u c e d .

200 300 400 500 600A

24 28 32 36 40V

100

80

60

40

20

01 2 3 4 5

(600)

0

Influence of weld current on penetration depth.

Influence of arc voltage on penetration depth.

Influence of wind velocity and nitrogen content in weld metal.

Various types of circular container are easy to mechanise.

Wind Velocity (m/sec)

Nitrogencontent(ppm)


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Productivity

The w elding current a nd w ire feed ra te a re l inked to

p r odu c t i v i t y , wh i ch i s m easu r ed as k i l ogr am s o f

deposi ted weld metal per uni t o f t ime. A high wire

feed ra te prod uces a h igh w elding current . This rela-

t i on sh i p v ar i es , dep en di n g on th e c r oss- sec t i on a l

a rea o f th e f ille r w i re w h ich h a s a f un da m en ta l e f f ec t

on the elec tr ica l res is tance. Dur ing welding, the cur-r en t wh i ch p asses th r ou gh th e a r c i s m easu r ed i n

a mperes . The f iller wire tha t is us ed ha s a ce r ta in

d i am eter, f rom w h ich i ts c ros s- sec t ion ca n be c a l cu -

la ted in mm 2. The w elding current i s s pread over the

c r oss - sec t i on a l a r ea o f th e w i re a n d f rom th i s a u n it

k n o w n a s c u r r e n t d e n s i t y , w h i c h i s g i v e n i n

a mperes /mm 2, c a n be c a lcu la te d . Th is i s a m ea su r e

o f th e en er gy dev e l op ed i n th e a r c , i n o th er wor ds ,

th e h ea t . H i gh cu r r en t den s i t y a l so m ean s h i gh h ea t

product ion in the arc and rapid mel t ing o f the f i l ler

w ire . As w ith a ll o the r e lec tr ica l co nduc tors , the wire

h as r es i s t an ce wh i ch i s m easu r ed i n oh m s . I f th e

resis tance i s h igh , the arc vol tage , s t ick-out or wire

f e e d s p e e d m a y n e e d t o b e a d j u s t e d t o o b t a i n t h e

des i r ed we l d i n g p ar am eter s .

Equipment

Sol id wires are suppl ied in the fo l lowing diameters :

0 .6-0.8-1.0-1.2-1.4-1.6 mm and somet imes 2 .0 mm

f or gas - sh ie l ded w e ld i n g . Th e w e igh t o f a s p oo l o f

w i re c a n v ar y be twe en 0 ,5 an d 470 kg .

En dl ess P ac , wh i ch i s a f u r th er dev e l op m en t o f

t h e w e l l-kn o w n M a r a t h o n P a c c o n s i s t s o f t w o

s e r i e s - c o n n e c t e d p a c k a g e s o f w e l d i n g w i r e . B y

we ld i n g th e en ds o f the w ires c om i ng f rom ea ch p a c ,

i t i s easy to ch an ge th e dr u m wh i ch i s em p ty an di n s t a l l a n ew on e w i th ou t s top p i n g p r odu c t i on to

cha nge the w ire . This resul ts in uninter rupted pro-

duc t ion a nd the refore g rea ter prof i tab ility .

Va r ious types o f a rc o cc ur dur ing w elding wi th

so l i d w i r e , n am el y sh or t a r c , m i xed a r c an d sp r ay

a rc . Th e t yp e o f a rc u se d d ep en ds on th e cu r ren t an d

v o l t a g e . S p r a y a r c w e l d i n g h a s t h e m o s t s t a b l e a r c

a n d th e lea s t a m ou n t o f we ld s p a t t e r. U s i n g a p u lse d

p ower sou r ce , a s t ab l e a r c w i th sm al l d r op l e t s o f

m eta l c a n be ob t a in ed , u s i n g a low er cu rren t th an i s

p oss i b l e w i th a con v en t i on a l p ower sou r ce . U s i n g a

p u lse cu r ren t p ow er sou r ce , d r op le t s iz e a n d t r an s f e rra te can be accurately contro l led whi le minimising

th e h ea t i n p ut .

The se t t ing o f w elding pa rame ters is impor tant .

Th e c or rec t re l a t ion sh i p m u s t b e ob t a i n ed b e tw een

cu r r en t , v o l t age , s t i ck- ou t , gas f l ow , we l d i n g sp eed

an d gu n a n g l es . S t ick-ou t is th e d is t a n ce f r om th e t ip

o f th e con t a c t n oz z l e to th e wor kp iece .

Various cross-sections of different filler wires.

M arathon Pa c Endless version increases availability in the

robot cell.

M echanisation using a loading jig and welding unit.

Solid wire C ored wire


10/28

10


11/28

11

Cor ed w i r es c an be d i v i ded i n to th r ee m a i n g r ou p s ,

depending on the composi t ion of the f lux : ru t i le ,

ba s i c a n d m eta l co red . Th ese c o r ed w i res a ll h av e

di f ferent proper t ies , which are used in di f ferent

ap p l i c a t i on s , sh ee t m eta l th i ckn esses an d we l d i n g

posi t ions . Rut i le wire i s an a l l - round wire , which

can be u sed to we l d a l a r ge n u m ber o f ap p l i c a t i on s

in a ll welding po si t ions . The rut ile p ow de r ad di t ion in

th e w i r e p r odu ces a s l ag wh i ch cov er s th e m ol ten

p oo l an d f o r m s th e we l d bead keep i n g th e m ol ten

p oo l in p l ace wh en we ld i n g ou t o f p os i t ion .

B a s i c w i res c on t a i n c a l c iu m an d p r odu ce a b as ic

s lag . The volume of the s lag is low er which ma kes i t

d i f f icul t to weld in the ver t ica l and overhead posi-

t i on s . O n l y th e h or i z on t a l an d down h an d v er t i c a l

posi t ions are normal ly recommended for welding

wi th bas i c co r ed w i r es . A bas i c we l d m eta l i s c l ean -

er th an a r u t i l e an d i t con t a i n s l ess m i c r o- s l ags an d

inpur it ies . This g ives t he ba sic w eld meta l a h ighe rc r ack r es i s t an ce .

The electrode recovery indicates

efficiency

Metal cored wire i s f i l led wi th a f ine metal powder

which mel ts dur ing welding. When the ef f ic iency ofthe f i l ler i s s tudied, the elec tr ic recovery i s the most

impo r tant f a c to r. The e lec tr ic recove ry o f s o l id wire

i s abou t 97% , wh i ch m ean s th a t 97% o f wh a t i s

m el ted down i n to th e w i r e en ds u p as we l d m eta l .

The las t 3% is fume a nd s pa t ters . The reco very is

85-88% for ru t ile c ored wires , 88-89% for ba sic a nd

96% for metal-cored wire . Metal-cored wire i s f re-

q u en t ly u sed in m ech a n ised we ld i n g as it h as a h i gh

recovery .

Th e w e ld i n g eq u ip m en t th a t i s u sed is ba s i c a lly

th e sam e as th a t u sed f o r we l d i n g w i th so l i d w i r e ,

but i t i s f requent ly retrof i t ted wi th a water-cool ing

u n i t a s h ea t gen er a t i on wh en we l d i n g co r ed w i r e i s

h igh er th an f o r so l id w ire . H ea t h as to b e t r an sp o r t-

ed away f r om th e we l d i n g gu n as i t cou l d o th er w i se

ea s i ly be com e ov er hea ted . Th e co o l in g w a te r is

t r an s f e r r ed to th e swan n eck , wh er e i t tu r n s r ou n dan d t akes th e h ea t away to th e coo l i n g u n i t . A t th a t

p o i n t , t h e w a t e r p a s s e s a h e a t e x c h a n g e r a n d i s

coo led , b e f o re be in g r e tu rn ed a ga in .

Cored wire

C ored wire cross sections.

A slag covering is produced when welding with cored wire.

The d i f f e r e n ce be tw een so li d and co r e d w i r e is

t h a t c o r e d w i r e is t u b u l a r. B y pu t t i n g va r i o u s

f i l l i n g f o rmu l a t i o n s i n t o a t u b e , i t i s p o s s i b l e

t o add a l lo y i n g m a t e r i a ls o r m i n e r a ls

t o ob t a i n t h e de s i r ed w e l d me t a l p r o pe r t i e s .

P rinciple diagram of cored wire manufacture.

Strip reel

Flux hopper

Draw die

Reel with formed electrode

Closing rolls

U forming rollsFlux poured at this point


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12

Shielding gases

Th e s h ie ld i n g ga se s th a t a re u se d f o r we ld i n g w i th

cor ed w i r e a r e f r equ en t l y m i xed gases con t a i n i n g

ar gon a n d c a r bon d iox ide . Th ere a re a la rge n u m ber

of di f ferent gas mixtures , a l l o f which have di f ferent

p r op er t i es f o r we l d i n g . Som e cor ed w i r es a r e de-

signed for welding w ith pure c a rbon d ioxide. The c a r-

bon d i ox i de p r odu ces a br oad p en e t r a t i on p r o f i l e ,wh i ch r edu ces th e r i sk o f we l d i n g de f ec t s . Wh en

wel d i n g con t am i n a ted , ox i d i sed o r p r i m er - coa ted

sh ee t m eta l , t h e c a r bon d i ox i de r edu ces th e r i sk o f

pores . The reas on for th is i s tha t the ca rbon dioxide

i s ac t i v e , wh i ch m ean s th a t i t i s b r oken down i n th e

a r c a n d r e a c t s w i t h t h e g a s e s f r o m t h e c o n t a m i n a -

t i on on th e sh ee t m eta l . Car bon d i ox i de i s a l so a

h eav y gas , wh i ch m ean s th a t i t i s m or e l i ke l y to r e-

main around the mol ten pool , thereby of fer ing bet ter

protec t ion .

Mi xed gases p r odu ce a m or e s t ab l e we l d i n g a r c

an d l ess we l d sp a t t e r , bu t th ey do n o t p r ov i de su che f f ec t i v e p r o tec t i on , a s a r gon i s a l i gh t gas . Som e-

t i m es , a th i r d com p on en t i s added , su ch as n i t r ogen

oxide. This g a s mixture reduc es the format ion of

oz on e a rou n d th e a r c . It is n o t a go od i dea to br ea th e

o z o n e , s i n c e t h e g a s d r i e s o u t m u c o u s m e m b r a n e s

a n d c a n c a u s e a lle rg i e s .

Th ere i s a g r ea t d ea l o f ch o i ce w h en it co m es to

selec t ing the gas mixture for welding wi th ru t i le and

ba s i c co red w i res . Th e r eas on f o r th is i s th a t th e

m ol ten dr op l e t s i n th e a r c a r e cov er ed by a l ayer o f

s l ag wh i ch p r o tec t s th em f r om th e a tm osp h er e . For

th i s r eason , sh i e l d i n g gases w i th a m i x tu r e o f u p to

25% car bon d i ox i de can be u sed w i th ou t p r odu c i n g

excess i v e bu r n - o f f . I t i s n o t n ecessar y to u se p u r e

i n er t gas a s th e sh i e l d i n g gas w i th s t a i n l ess co r ed

wi res . It is co m p le te l y fea s i b le to we ld s t a i n less co r-

ed w i r es w i th o r d i n ar y m i xed gases an d th i s i s a l so

m or e econ om i ca l . A h i gh er gas f l ow i s u sed wh en

wel d i n g w i th co r ed w i r e com p ar ed w i th so l i d w i r e .

This is be ca use more f i ller ma ter ia l is mel ted per unit

o f t ime and more shielding gas i s therefore required

to protec t the mol ten pool . However , i f th is i s t r ans-

la ted in to gas consumption in l i t res per l inear metre

o f we l d , n o m or e sh i e ld i n g ga s i s u sed wh en w e ld i n g

wi th co r ed w i re th a n w h en w e ld i n g w ith so lid w i re .

Applications

Cor ed w i r es h av e ap p l i c a t i on s i n h eav y i n du s t r y ,

su ch as sh i p bu i l d i n g , o f f sh or e , excav a to r an d t r u ck

m an u f ac tu r e . No sm al l com p on en t s a r e we l ded w i th

c o r e d w i r e ; l a r g e r c o m p o n e n t s s u c h a s f r a m e s ,

c h a s s i s a n d h e a v y b e a m s a r e m o re s u it a b l e . O ne o f

th e adv an t ages o f co r ed w i r e i s th a t i t i s easy to

m odi f y th e we l d m eta l a n a l ys is b y ch a n g i ng th e co m -

p os it ion o f th e p ow der s in th e w ire . B y a dd in g d if fe r -

en t co n s t i tu en t s t o a ru t ile c o r ed w ire , a la rge n u m -

ber o f d i f ferent sub-grades wi th speci f ic proper t ies

ca n be p r odu ced . Th e am o u n t o f s l ag th a t is g en er -

a te d c an b e i nc r eas ed o r redu c ed i n o rder to im p rov e

weldabi l i ty in speci f ic posi t ions . When sol id wire i s

m an u f ac tu r ed , th i s i s a l r eady t aken i n to con s i der a-

t ion a t the s teel mi l l when the raw mater ia l for the

wi re th a t i s go in g to b e dr aw n is p r odu ced .

Limitations

Weldi n g w ith co r ed w ire d oes h av e c er t a in d i sa dv a n -

tages , however . As cored wire has h igher product iv i-

t y , m or e i s dem an ded o f th e we l der du r i n g m an u a l

welding. As a resul t o f the h igher heat generat ion in

th e a r c , r ad i an t h ea t i n c r eases an d m akes l i f e h o t t e r

for the w elder. S light ly more w elding fume per unit o f

t ime is a lso generated . Welding fumes ca n be reduc ed

drama tica lly by integrating a fume e xtrac tor in the w eld-

in g g u n , h owe v er. I t sh ou ld be rem em b er ed th a t th is

could possibly a f fec t the shielding gas (see page 10) .

Advantages

When w elding w ith co red w ire , the a rc i s more s ta ble

com p ar ed to th a t p r odu ced by s o l id w i re . Th is is

becau se m or e en er gy i s dev e l op ed i n th e a r c w i th

the same current . When welding wi th a so l id wire a t

R obot welding wi th metal-cored wire produces a clean and

spatter-free weld bead.


13/28

Influence of shielding gas

P Z6138 - 1,2 mm

Pla te th ickness : 30 mmX - J o int 2/3 - 1/3P os i t ion : P AS hielding g a s : 92 Ar/8 C O2, 8 0 Ar/20 C O2

Analysis (%)Material 92 Ar/8 CO2 80 Ar/20 CO2

C 0,060 0,054

Mn 1,37 1,27

S i 0,42 0,41

Ni 0,85 0,98

Ti 0,078 0,059

ISO- V (40C): 30- 50J 130- 150J

S t r u c t ure : Ac i c u la r f e rrit e Ac i c u la r f e rrit e /primary ferrite

R educed burn-off of M n, S i och T i, more hardening and less

toughness with shielding gas 92/8.

13

2 00 a m p s a n d a c o r e d w i re a t 2 00 a m p s , t h e c o r e d

wi re h a s a h igh er f eed r a te . Th is m e a n s th a t m or e

wire per uni t o f t ime is fed in to the arc and th is nat-

u r a l l y m ean s th a t m or e we l d m eta l i s dep os i t ed , a s

th e c r oss- sec t i on o f th e w i r e (equ a l t o th e p h ys i ca l

cros s-s ec t ion) is sm a ller.

Calcula t ing the area in square mi l l imetres and

th en d i v i d i n g by 200 A p r odu ces th e am p er es p ersquare mi l l imetre . As cored wire i s tubular and the

f l u x i n s i de i s n on - con du c t i v e , th e c r oss- sec t i on a l

a rea for the current to pa ss throug h is s ma ller. The

cu r r en t th er e f o r e becom es m or e t i gh t l y p acked ,

ma king t he ene rgy in the a rc h ighe r.

Th e en er gy w h ich i s g en er a ted is h ea t a n d , i f t he

h ea t in th e a rc i s h igh , i t c a n m elt a la rge r am ou n t o f

f il ler ma terial more ea si ly. The w ire fee d ra te is high-

er becau se co r ed w i r e h as g r ea te r r es i s t an ce to cu r -

rent than so lid w ire . The pow er source s ens es th is

a n d c o m p e n s a t e s b y in c re a s in g t h e f e e d ra t e . As t h e

arc looks dif ferent, cored wire produces broader pene-

tra t ion . This red uces the r isk o f incomp lete p enetra -

tion a nd slag inclusions. The higher energy relea se a nd

the h igher temperature in the arc , together wi th the

broader penetra t ion make welding wi th cored wire

more forgiv ing . Cored wire i s su i table for welding

thicker ma teria l. Welding pla te thickness es o f below 4

mm should be a voided , as the proce ss i s too hot . How-

ever , there i s an a l ternat ive for robot appl icat ions .

Influencing factors

Th e s am e f ac to r s a p p ly a s f o r so l id w ire ; th ey a re

cu r r en t , v o l t age , s t i ck- ou t , we l d i n g sp eed an d gu n

a n g l e s .

Suitable applications

Meta l co r ed w i r e i s u sed i n bo th s i m p l e m ech an i sa-

t ion in the shipbui lding indus try, for exa mple, w here

th e gu n i s m ou n ted o n a t ra c to r, o r on a p or t a l wh ich

m ov es . Cor ed w i r es a l so f u n c t i on we l l i n l a r ge ,

sop h i s t i c a ted i n s t a l l a t i on s w i th on e o r m or e r obo t s .

FMS i n s t a l l a t i on s a r e a com bi n a t i on o f we l d i n g an d

h an d l i n g r obo t s , wh er e r obo t s p i ck com p on en t s an dplac e the m in a f ix ture . The f ix ture i s then a utoma t i-

ca lly t r an sp o r ted to th e we ld i n g r obo t . Af te r we l d in g ,

an o th er r obo t t akes ov er an d r em ov es th e f i n i sh ed

component f rom the f ix ture . Volvo s hauler produc-

t ion i s a go od exam p l e ; th e w e ld i n g h ere i s do n e w i th

m eta l co red w i re i n an FMS in s t a lla t ion . S aa b- Sc an i a

i n L u l e a l so h as an FMS i n s t a l l a t i on , wh er e r ea r

ax l es f o r i t s t r u cks an d bu ses a r e we l ded w i th m eta l

cored wire .

In r obo t i sed we l d i n g w i th m eta l co r ed w i r e , th e

wel d i n g r obo t i s com bi n ed w i th a p os i t i on er wh i ch

cont inuously puts the workpiece in the best posi t ion .This i s d one in order to o bta in the ma ximum b enef i t

f rom the h igh product iv i ty o f the metal cored wire .

R obot and positioner in collaboration.


14/28

14

Mechanisation with welding tractor

and Railtrac

Ruti le cored wire i s seldom used in robot ic or FMS

insta l l a t ions . On the o ther hand, ru t i le cored wire i s

v ery co m m on ly u sed in m ech a n isa t ion w h ere a we ld-

i n g t r ac to r an d R a i l t r ac a re used . This typ e of

mechanisat ion i s o f ten found in the shipbui lding

industry , where long f i l le t welds , which are eminent-

ly sui ted for welding wi th a welding t rac tor , are f re-

qu en t l y u sed . Wh en sh i p s a r e des i gn ed , th e i n c l u -

s i on o f a s m a n y f ille t we lds as p os s i b le i s com m o n .

Another application for ruti le wire is the butt

welding of p ipel ines . An exper ienced and ski l led

we lding op erato r is ne ed ed to d o th is ma nual ly . This

t yp e o f we l d i n g i s p h ys i ca l l y v er y dem an di n g an d

there is a rea l r is k of mus c ulos keleta l injury. The

wo r k ca n be m ech a n ised w i th an o r b i ta l we ld i n g u n it ,

which involves insta l l ing a t r ack around the outs ide

o f th e p ip e . Th e t rac k ha s a ge ar rac k an d a c a rr iag e

is mo unted o n the t rac k and c a n c i rc le the p ipe. The

c a r r i a g e h a s a w e l d i n g g u n a t t a c h m e n t a n d c a n

os c i lla t e th e w e l d in g g u n . Th e p ow er sou rce ca n be

p r ogr am m ed to a l l ow we l d i n g to be p er f o r m ed w i th

th e co r r ec t p ar am eter s a l l th e way r ou n d th e p i p e .

Th e a dv a n t ag e o f th is p r oced u re i s v ery s t ea dymovement in the welding gun, making i t possible to

co ntrol the w elding proc es s mo re exa ct ly . The q ual i-

t y o f th e w e l d is a lso im p rov ed .

Product choiceWh en ch oos i n g be tween m eta l co r ed , r u t i l e an d

b a s i c c o r e d w i r e s , t h e c h o i c e s h o u l d b e b a s e d o n

the a ppl ica t ion . In a rob ot insta lla t ion , where we lding

i s a l ways p er f o r m ed i n th e bes t p os i t i on , a m eta l

c o r e d w i re c a n b e s e l e c t e d .

When welding vertical up with R ailtrac , the welding operator can control the process via a remote control.


15/28

15

If m ech a n ised we ld i n g is g o i ng to be u sed in d i f-

ferent posi t ions , a ru t i le cored wire should be cho-

sen . I f r oo t beads a r e go i n g to be we l ded i n a j o i n t

u n der con s i der ab l e r es t r a i n t , a bas i c co r ed w i r e i s

su i t ab l e .Th ere a re v a riou s g r ad es o f p r odu c t i n eac h

gr ou p o f w ires , so th e s t ren g th r eq u irem en ts sh ou l d

go v er n th e ch o i ce f rom ea ch g rou p .

Equipment

In m ech a n ised o r robo t ic w e ld i n g , on e o f th e a im s i s

to m i nim ise s top p a ges in p rodu c t ion . A go od w ay to

r edu ce down t i m e i s t o u se a bu l k w i r e p ackage , a

Mar a th on P ac . Th is p a ckag e h o lds 250 k ilog r am s

o f w i r e an d can be su p p l em en ted w i th a p l as t i c

h ou s i n g an d a s t r a i gh ten er wh i ch i s m ou n ted on th edr u m . Fr om th er e , th e w i r e p asses th r ou gh a w i r e

gu i de on i ts w a y to th e f eed er.

Points to consider

I t i s impor tant carefu l ly to s tudy the workpiece that

is g o i ng to be we lded . Wh en th e roo t b ea d i n a jo i nt

is w e lded u n der con s i der ab l e res t r a i n t , the r oo t bea d

m u s t b e a b l e t o a b s o r b t h e m o v e m e n t b e c a u s e t h ep l a tes c an n o t m ov e . I f a r u t i l e co r ed w i r e i s u sed ,

th ere i s a c on s i der ab l e r isk th a t th e r oo t bea d c ou ld

c r ac k . Th is risk ca n be redu c ed by cu t t in g th e we ld-

in g c u rren t an d redu c in g th e a rc v o l t ag e a n d w e ld i n g

sp e ed . Th ese m ea su r es r edu ce th e r isk o f c r ac k in g ,

bu t th ey a l so cu t p r odu c t i v i t y a t th e sam e t i m e . For

t h is r e a s o n , t h e c h o ic e o f a b a s i c c o r e d w i re c a n b e

justi f ied.

In a ll w elding wi th co red wire , i t is impor ta nt tha t

th e op er a to r o f th e r obo t o r m ech an i ca l dev i ce h as

co n s i der ab le kn owl edg e o f th e p r oces s . Th is i s

essent ia l in order to create the correct re la t ionshipb e t w e e n t h e w e l d i n g p a r a m e t e r s a n d t h u s a c h i e v e

the o pt imum res ult .

R obot welding of small, thin-walled components (2. 0 mm ) using cored wire.


16/28

16


17/28

17

In su bm er ged a r c we l d i n g , th e m ol ten p oo l i s p r o-

tec ted by a f lu x . Th is f lu x is su p p l ied by a sep ar a te

feed system. Surplus f lux i s re-cycled by a f lux

recovery uni t . Wire diameters ranging f rom 1.6 mm

to 6 .0 m m ar e u sed . As th e w i re h a s a la r ger d ia m e-

ter , h eav i e r ob j ec t s c an be we l ded an d m os t o f th e

wel d i n g wh i ch i s don e u s i n g a su bm er ged a r c i s

m e c h a n i s e d .

Wh en we ld i n g w i th the s u bm er ged a rc p r oces s , a

f lu x is su p p l ied to th e w e ld i n g h ea d a t th e s am e t im e

as th e we l d i n g w i r e . Wh en th e p r ocess con t r o l l e r

a c t i va tes th e p o we r so u rce a n d th e w i re f eed u n it , an

ar c i s s t r u ck wh en th e w i r e m akes con t ac t w i th th ewo rkp iece . Th e a rc is su bm e rged ben ea th th e f lu x

dep o s i t . P a rt o f th e f lu x m elt s a s a resu l t o f th e h ea t

created in the arc and the surplus in fused f lux i s

recycled by a f lux recovery uni t .

Advantages

O n e m aj or adv an t age o f su bm er ged a r c we l d i n g i s

tha t the metho d is environme nta lly f r iend ly . The a rc

i s con cea l ed by th e f l u x an d th e s l ag , wh i ch cou n -

te r ac t s h ea t an d u l t r a- v i o l e t l i gh t r ad i a t i on . Su b-

m er ged a r c we l d i n g i s th e on l y m eth od o f we l d i n gwh i ch does n o t gen er a te an y we l d i n g f u m e , th er eby

benef i t ing the welder s working environment .

Submerged arc welding

Flux is deposited through the flux nozzle in submerged arc

welding.

P rinciple of using submerged arc welding.

kg/h

16

14

12

10

8

6

4

2

200 400 600 800 1000 Amp

1,6mm

2,0mm 2

,4mm

3,2mm 4

,0mm

5,0mm

6,0mm

Typical welding data using single wire.

Subme rg ed a r c we l d i n g d i f f e r s con s i d e r a b ly f r om sem i -

a u t om a t i c we l d i n g w i t h so l id o r co r e d w i r e . I n s t e a d o f

p r o t e c t i n g t h e m o l t e n poo l w i t h a sh i el d i n g ga s , a f l u x

i s used .

Deposi t ion ra te

Welding current

Welding speed

Welding current

slag

weld metalmolten pool

welding flux

POWERPOWER

S O U R C ES O U R C E

Ve


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18

Weld i n g w ith th e s u bm er ged a rc p roce ss o f fe r s

con s i der ab l e f r eedom , becau se i t i s p oss i b l e tom odi f y th e p r op er t i es o f th e con su m abl es u sed i n

th is proc es s . There are se veral d if ferent c omb ina -

t ions o f f lux and wire .

F l u xes a r e su bd i v i ded i n to ac i d an d bas i c t yp es .

Th e p r op ert ies o f a n a c i d f lu x m ake th e w e ld bea d

f l ow ou t be t t e r . B as i c f l u xes p r odu ce c l ean er we l ds

wh i ch a r e l ess p ron e to c r ac k in g .

Mos t f lu xes a re n eu t r a l an d a r e on l y in ten ded to

protec t the mo lten me ta l. There a re a lso a lloying

f luxes . The a lloying c ompo nents in thes e f luxes mel t

i n th e a r c an d m i x w i th th e we l d m eta l . In th i s way ,

d i f f e r en t m ech an i ca l p r op er t i es c an be ach i ev ed i n

th e we l d .

Limitations

The l imi ta t ion of th is metho d is the m a ter ia l th ick-

n ess an d th e con f i gu r a t i on o f th e wor kp i ece to be

we lded . No t a ll jo i nt s a re s u it ab le f o r su b m erged a rc

we ld i n g . Th e p l a te th ickn ess sh ou l d n o t b e l ess th an

2.5-3 mm. Al l cy l indr ical objec ts , such as tanks wi th

wa ll thickn ess es o f 4- 5 m m , a r e exce llen t ob jec t s f o r

su bm er ged a r c we l d i n g . In th i s c ase , a p os i t i on er o r

ro l le r bed i s a dd ed to ro t a te th e ob jec t .

As la rge d i am eter w i res a re u s ed , th e i nc r eas e i nar c v o l t age an d cu r r en t m ean s th a t th e we l d dep os i -

t ion ra te (product iv i ty) i s f ar h igher than that pro-

du ced by sem i - au tom at i c we l d i n g . Su bm er ged a r c

we l d i n g i s h i gh l y p r odu c t i v e an d i s th e m os t eco-nomical welding method, but i t i s l imi ted to welding

in the f l a t a nd ho r izonta l-vert ica l pos it ions .

Productivity

The produc t ivity o f sub merged a rc w elding is c on-

s i der ab l y h i gh er th an th a t p r odu ced by th e sem i -

a u t o m a t ic p ro c e s s .

Th e w e ld m e ta l dep o s i t ion r a te i n c rea se s a n d

decr eases accor d i n g to v a r i a t i on s i n th e s t i ck- ou t

leng th . The w elding w ire is fed through insula ted

wi re l in er s an d is g u ided th rou gh th e c on t ac t tu be to

th e con t ac t j aws wh er e th e cu r r en t i s t r an s f e r r ed tothe w ire . As a res ult , the w ire fee d i s very s ta ble . The

d i s t an ce f r om th e w i r e f eed m otor to th e we l d i n g

h ead ca n th en v ar y f rom 250 m m to 2 ,000 m m .

S i n g l e w i r e o r tw i n w i r e f eed sys tem s a r e av a i l -

a ble . Welding w ith tw in w ire (suc h a s 2 x 2 .5 m m)

i n cr eases th e dep os i t i on r a te com p ar ed w i th s i n g l e

wire . Twin-wire w elding us es a s ingle pow er so urce ,

norma lly DC . Ta nde m w elding is a lso pos sible ; in th is

c a s e , t h e r e a r e t w o s e p a r a t e w i r e s a n d t h e l e a d i n g

wire runs on DC, whi le the t ra i l ing wire runs on AC.

Two p ow er sou rces an d two p roc ess co n t ro l le r s a re

ut i l i sed in th is case .Syn er g i c co l d- wi r e f eed can be u sed wh en a n on -

current-bear ing wire i s fed in to a mol ten pool , gen-

Example of multi-electrode array for high productivity welding.


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er a ted by a w i re b ea r in g a cu r ren t . P rodu c t iv it y (dep -

os i t i on r a te ) i n c r eases , t oge th er w i th tou gh n ess .

Addi n g co l d w i r e r edu ces th e h ea t i n p u t an d th e

mol ten pool f reezes more rapidly , g iv ing the weld a

f iner grain structure.

Choice of flux

The c hoice of f lux/w ire c om bina tions is ve ry impo r-

t an t a s sp ec i f i c a t i on s an d r equ i r em en ts m u s t be

compl ied wi th . An order for a pressure vessel , for

exam p l e , i n c l u des a sp ec i f i c a t i on wh i ch s t a t es th e

s t a n d a r d a c c o r d in g t o w h ic h t h e w e l d m u s t b e c l a s -

s i f ied . The f i rs t s te p i s to s elec t the w ire , w hich i s

f a i r l y easy as th er e a r e n o t th a t m an y g r ades to

ch oose f r om .

C er ta in f lux/w ire comb ina t ions a re a pproved b y

di f ferent c lass i f ica t ion societ ies for di f ferent grades

o f p la te . Th ere a re c a t a l ogu es a v a i la b l e f o r th is t a s k

and they o f fer in format ion about the wire and f lux

com bi n a t i on s th a t m a tch th e r equ i r ed m ech an i ca lp rop er t ies . It is c om m on p r ac t ice to t ake a cc ou n t o f

th e y i e ld s t r ess , t en s i le s t ren g th a n d i m p ac t p r op er-

t ies . They d if fer dep end ing o n the b a sic i ty o f the f lux

in q ues t ion . When s elec t ing the co rrec t f lux , the f i rs t

t h i n g t o c o n s i d e r i s t h e w e l d d e p o s i t a n d t h e

dem an ds i m p osed on th e f i n a l p r odu c t .

Agglomerated and fused fluxes

B oth agg l om er a ted an d f u sed f l u xes a r e av a i l ab l e .

Fused f luxes are produced by f i r s t mixing a l l the

i n gr ed i en t s t oge th er an d th en h ea t i n g th em to m el t

them. When the f lux has hardened, i t i s crushed in to

kg/h

A = 35 mm

B = 65 mm

C = 100 mm

15,7

13,6

11,3

9,1

6,8

4,5

200 300 400 500 600 700 Ampere

Influence of stick-out on deposition.

Co m bi n a t ion o f r o lle r bed a n d c o l um n a n d b oom f o r in te r na l we l d in g .

Deposition rate

Welding current


20/28

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21

smal l gra ins ,1-2 mm in s ize . Agglomerated f lux i s

produced by mixing a l l the ingredients and s i f t ing

them in a mixer be fore a dd ing f lu id . The s emi-we t

mixture i s then t ipped out in to an inc l ined ro ta t ing

oven and, a f ter a whi le , the mixture turns in to gran-

ules .

Wh en th e g r an u les rea ch a cer t a i n s i z e , th ey f a l l

o f f an d a r e a llow ed to d r y. Th e g ra in s o f ag g l om er a t -ed f l u x a r e n o t a s s t r on g as f u sed f l u x . As a r esu l t ,

agg l om er a ted f l u x i s sen s i t i v e to r ou gh h an d l i n g .

Agglomerated f lux i s a l so sensi t ive to moisture and

ca n a bs or b i t from th e a i r. I t m u s t th ere f o re b e h a n d-

l ed w i th ex t r em e car e an d sh ou l d be s to r ed i n sp e-

c i a l p la ted f l ux sys tem s .

Influencing factors

There are ce r ta in th ings to ta ke in to c ons ide rat ion

w h e n u s in g s u b m e rg e d a r c w e ld in g . F a c t o r s s u c h a s

s t i ck- ou t , cu r r en t , a r c v o l t age an d we l d i n g sp eed

inf luence the resul t o f the f in ished weld in di f ferentw a y s .

Magn e t i c a r c b l ow can occu r wh en we l d i n g w i th

D C as a m agn e t i c f i e l d f o r m s a r ou n d a l l e l ec t r i c a l

co n du c to r s . Th e m a gn e t ic f i e ld s u rrou n di n g th e

we ld i n g w ire a f fec t s th e s t a b i lit y o f th e a rc , e sp e c i a l -

ly when welding diss imi lar mater ia ls wi th di f ferent

m agn e t i c p r op er t i es . Wh en th ese two p l a tes a r e

jo ined together , the magnet ic f ie ld surrounding the

a rc c a n shi f t it f rom o ne s ide o f the jo in t to the o ther,

resu l t in g in w e l d de f ec t s .

Wh en th e a rc p u l ls t o on e s ide a n d d oes n o t m el t

i n to th e o th er s i de , i n com p l e te p en e t r a t i on occu r s .

This c a n be in f luence d b y re-es ta bl ish ing the po si-

t ion of the ear th c lamp. An al ternat ing current can

a l so be p assed th r ou gh on e o f th e p l a tes . I f th e

ob jec t i s c y lin dr ic a l, a f ew tu r n s o f w e l d in g c ab le c an

b e w r a p p e d r o u n d i t a n d A C c a n t h e n b e p a s s e d

th rou gh th e ca b l e to n eu t r a l ise th e m a gn e t i c f ie ld .


All cyl indrical objects with longitudinal or circumfer-

ent ia l jo in ts are ideal for submerged arc welding.

This a ppl ies in pa r t icular to do wnha nd/hor izonta l

but t jo in ts a nd do wnha nd/hor izonta l vert ica l fille tw elds (PA a nd P B p os it ions ). There are a la rge num-

ber o f a p p lic a t ion s f o r th ese t yp es o f we ld , f ir s t an d

foremos t in the s hipb uilding indus try.

F i xed we l d i n g h eads wh er e th e wor kp i ece p ass-

es underneath are f requent ly used in industry . One

c a n a l s o c h o o s e t o m e c h a n is e t h e m o v e m e n t o f th e

we ld i n g h ead . Th e we l d in g h ea d c an b e m ou n ted on

a t rac tor. There a re a numbe r o f d if ferent type s o f

we ld i n g t r ac to r s wh i ch ca n w e ld th e wo rkp iece . Th e

wel d i n g h ead can be eas i l y r ep os i t i on ed u s i n g a

remote contro l wi th joyst ick . Moreover , the process

co n t ro l box is ea sy to p r ogr am .

Su bm er ged a r c we l d i n g i s on l y don e i n m ech a-

nised form. Robots are rarely used in SAW appl ica-

t io n s b e c a u s e o f t h e e x c e s s w e i g h t o f t h e h e a v y w i re

an d th e f l u x th r ou gh th e r obo t a r m . In th i s c ase , a

m or e p ower f u l r obo t wou l d be n eeded to bear th e

wei gh t .

EquipmentAs su bm er ged a r c we l d i n g i s on l y c a r r i ed ou t i n

m ech an i sed f o r m , m or e com p r eh en s i v e an d exp en -

s i v e equ i p m en t i s n eeded com p ar ed w i th m an u a l

we lding. The w ires ha ve a l arge r diam eter, which

m ea n s th a t h eav y- du ty w i re f eede rs a re n eed ed . Th e

b a s i c e q u i p m e n t c o n s i s t s o f a n A C o r D C p o w e r

sou r ce w i th a c ap ac i t y o f a t l eas t 1 ,000 am p er es , a

f lux del ivery sys tem, a wire fee d uni t and a f ix ture for

th e we l d i n g h ead . A co l u m n an d boom i s f r equ en t l y

u sed . Th is i s a we ld i n g c r an e th a t i s a b l e to p u t th e

we lding hea d in many d if ferent po si t ions . The w eld-

i n g h ead i s l oca ted a t on e en d o f th e h or i z on t a lb o o m .

The w ire fee d unit c ompr ises a feed ro l l, press ure

rol l a nd wire s t ra ightene r. The fee de r pushes the w ire

th rou gh a 220- 275 m m lon g con t a c t tu be w i th a l a r ge

diam eter. The out le t end of the c onta c t tub e i s

e q u i p p e d w i t h w h a t a r e k n o w n a s c o n t a c t j a w s t h a t

a r e s p r in g p r ess u red , en ab lin g g ood cu r ren t t r an s f e r

to th e w e ld i n g w i re . Th ese jaw s a re w ea r p ar ts a n d

ar e c h an g ed wh en th ey w ea r ou t . Th e f lu x ou t le t n oz -

z l e i s a l s o a t t a c h e d t o t h e e n d o f t h e c o n t a c t t u b e .

To rec yc le unus ed f lux a nd return i t to the f lux hop-

per dur ing w elding, a n a dd it iona l flux rec overy uni t is

a va ila ble . This f lux rec overy unit is p ow ered b y c om-

press ed a ir. The remaining s la g d eta che s i t se lf from

the weld . An automat ic jo in t- t racking device i s a

welcome anci l l ary uni t using which wire s t ick-out

an d j o i n t p os i t i on i n g a r e kep t con s t an t t o th e we l d-

ing jo in t . The mos t s igni f ica nt jo in t- t ra cking e q uip-

ment that i s current ly marketed by ESAB is the ABW

s y s t e m w h i c h u s e s a l a s e r a n d c a m e r a m a t r i x t o

p os it ion th e h ea d an d ca lcu la te th e jo i nt v o l um e.

Points to consider

S om et i m es i t is e ss en t ia l t o m od if y th e des ign o f th ewel d be f o r e m ech an i s i n g w i th a su b- ar c sys tem .

J o i nt s s h ou ld b e ea s i ly ac ces s i b le f o r th e we ld i n g

h e a d . A g r e a t d e a l o f h e a t c a n b e g e n e r a t e d a n d i t

c an th en de f o r m th i n n er p l a te , so i t i s i m p or t an t t o

p la n t h e w e ld s e q u e n c e t o e n s u re t h a t t h e le a s t p o s -

s i b le d e f o r m at ion oc cu r s . Th is is don e by t e s t we ld-

in g to ob t a in th e m os t su i t ab l e we ld i n g p roce du re . I t

is a lso impor ta nt to cho os e the b es t f lux/wire co mbi-

n a t i on to m a tch th e req u irem en ts o f th e a p p lic a t ion .


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22


23/28

23

One o f thes e m ethod s is TIG (Tungs ten Iner t Ga s) . In

mos t ca se s , the TIG w elding of a luminium is p er-

f o rm ed on a lt e r n a t in g cu r ren t . For so m e rea so n , AC

is able to break down the a luminium oxide which i s

a lwa ys pres ent on a luminium ob jec ts . TIG we lding i s

a s l ow p r ocess , bu t i t i s ex t r em el y easy to con t r o l .

H i gh - qu a l i t y we l ds a r e p r odu ced an d th e su r f ace

a f ter the w eld us ual ly req uires no f in ishing. This

m eth od i s u sed a l m os t exc l u s i v e l y f o r th e m os t

dem an di n g we l d i n g j obs .

In th e TIG p roce ss , th e a rc is s t r u ck be twe en a

n o n - c o n s u m a b l e t u n g s t e n e l e c t r o d e o f a c e r t a i n

diam eter . To ob ta in an e lec tr ic a rc , an iner t ga s , no r-

ma lly a rgo n, is req uired . The tungs ten elec trod e i s a

cha nge a ble pa r t o f the TIG torch . The w elding c ur-

rent and iner t ga s a re s uppl ied through the TIG torch

to th e tu n gs ten e l ec t r ode wh i ch i s su r r ou n ded by a

h igh l y h ea t - res is t a n t ce r am ic ga s cu p . Th e h ea t f rom

the arc mel ts the a luminium and a f i l ler wire i s

a p p lied to th e l ead i n g ed ge o f th e m ol ten p oo l m a n -

ua lly or using a wire fee de r.

The o ther metho d is MIG (Meta l Iner t G a s) wheret h e c o n s u m a b le i s u s e d t o p ro d u c e t h e a rc .

Advantages

Th e m eth od wh i ch is m o s t c om m on l y u sed to we ld

aluminium in industry i s the MIG process . I t has fewlim it a t i on s a n d a ll th e w e ld i n g p os it ion s c a n be u sed .

P lent i fu l suppl ies o f a luminium are avai lable a l l

ov er th e wor ld . S c r ap p e d a lu m in iu m is ea sy to recy-

c l e an d a bou t 90-95% ca n be r e-u sed .

P u re a rg o n i s t h e m o s t u s e d g a s b u t a ls o a m ix

be tw een a rgo n a n d h e l iu m ca n be u sed . F in a l ly , on ly

in er t gas es a r e u sed to w e ld a lu m in iu m .

Limitations

This proce ss is s ens it ive be ca use o f the prope r t ies

of aluminium. Aluminium is also highly susceptible to

ex ter n a l con t am i n a t i on , so i t i s i m p or t an t th a t th ejo i nt su rf ac es a re a s c lea n as p os s i b le . J o i nt su r -

f aces m u s t be kep t f r ee f r om ox i de an d con t am i -

n an t s su c h as d i rt , o il an d g r eas e . Th e d i am eter o f

the f i l ler wire i s o f great impor tance when welding

aluminium. As feeding can be sensi t ive , the wire

d i am eter t o l e r an ces a r e v i t a l , a s th e f i t be tween th e

wi r e an d th e f eed r o l l s m u s t be as p r ec i se as p oss i -

ble . Feed ro l lers have grooves through which the

w i r e p a s s e s a n d t h e y m u s t h a v e a d i a m e t e r t h a t i s

exac t l y th e sam e as th a t o f th e w i r e . I f th e d i am eter

of the w ire d iffers, i t w ill be d efo rmed . The e ntire

f eed sequ en ce f r om th e f eeder to th e a r c m u s t bep er f ec t , o r m a l f u n c t i on s an d we l d i n g de f ec t s w i l l

eas i ly occur .

Aluminium

N o slag is produced in aluminium welding.

M IG electrode wire feeder systems.

Tw o m a in m e t h o d s a r e u s ed f o r t h e

p r o d u c t i o n w e ld i n g o f a l um i n i um .

PUSH up to 3,5 m (12 ft)

PULL up to 3,5 m (12 ft)

PUSH-PULL up to 9 m (30 ft)

SPOOLON GUN1000 mm (4 in)

300 mm(12 in)

300 mm(12 in)

300 mm(12 in)


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24

Influencing factors

There are co nside rab le di f ference s in the physica l

proper t ies o f a luminium a nd s te el . Aluminium is c on-

s i der ab l y so f t e r, h a s a low er den s it y, a low er m elt in g

point and the abi l i ty to oxidise much more rapidly in

con tac t w i th oxygen . O x i de occu r s i n f r ac t i on s o f a

second on a pure a luminium sur face . In welding, th is

ab i l i t y c au ses p r ob l em s as th e ox i de coa t i n g h as amuch higher mel t ing point than pure a luminium and

is harder .

S u rf ac e a p p ea ra n ce i s a lso v ery im p or t an t . Wh en

a p o l ish ed m eta l su r fac e i s s tu d i ed th r ou gh a m ic r o-

scop e , i t i s n o t a s f i n e as i t ap p ear s , a s i t ac tu a l l y

co n s i s t s o f a n u m be r o f p eaks a n d v a lleys . Th e su r -

f ace f i n i sh i s a m easu r e o f th e d i f f e r en ce be tween

th e h igh es t p ea ks an d th e low es t v a l leys an d th is d if -

f e r en ce m u s t n o t be too g r ea t , a s th e su r f ace f i n i sh

should be rela t ively h igh . For th is reason, many wire

m an u f ac tu r er s m ach i n e th e w i r e w i th a cu t t i n g too l

th a t r o t a tes a r ou n d th e w i r e an d cu t s o f f m a ter i a l ,result ing in a ve ry f ine f inis h. The s urfac e res ult ing

f r om a cu t i s con s i der ab l y f i n er th an th a t ob t a i n ed

w hen the w ire i s d raw n. Tight er dimension to leran-

ces c an a l so be m a i n t a i n ed . H i gh - qu a l i t y w i r es a r e

gen er a l l y a l ways m ach i n ed . C l ean l i n ess i n th e f eed-

er and in product ion i s very impor tant . I f d i r t gets

in to the feeder around the feed ro l lers through which

th e w i r e p asses f eed p r ob l em s can eas i l y occu r ,

thereby in ter rupt ing welding. D ir t causes porosi ty in

th e we l d .

Applications

Welding w ith a luminium is o f ten pra c t i se d in s hip-

bu ild i n g . Man y m o der n h igh - sp eed f e rr ies a r e m a de

ent i rely o f a luminium. The me thod is a lso use d in the

automot ive industry , where a luminium is becoming

increasingly common. Audi , for example, produce a

chassis which i s made ent i rely o f a luminium. Alu-

m in iu m wel d in g i s bo th m ech a n ised a n d r obo t i sed .

Aluminium has a much lower mel t ing point and

higher thermal and elec tr ica l conduct iv i ty than s teel .

For th is reason, the heat suppl ied dur ing welding

must be rela t ively h igh , to keep the temperaturea bov e m el tin g p o i nt .

Th is a l so req u ires a v ery a cc u ra te we l d in g s p eed .

If th e sp e ed is t oo low , th er e is a co n s i der ab l e r isk o f

System for classifying consumables for aluminium welding.

ELEMENTS ALLOY FAMILY PROPERTY WIRE ALLOYS

C u

Mg

Zn

Mn

S i

99.xxPure

Al

Al Cu 2xxx

Al Cu Mg 2xxx

Al Mg Si 6xxx

Al Zn Mg 7xxx

Al Zn Mg Cu 7xxx

Al Mg 5xxx

Al Mn 3xxx

Al Si 4xxx

Al 1xxx

HE ATABL E

WORKING HARDENING

MELTING TEMP. &FLU IDITY

HIGH P URITY


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25

burning holes through the mater ia l . As the welding

sp eed i s h i gh an d th e op er a to r m ov es qu i ck l y i n

m an u a l we l d i n g , th e r i sk o f de f ec t s i n c r eases . For

th i s r eason , MIG we l d i n g i s f r equ en t l y au tom ateda n d w a l l t h i c k n e s s e s o f 1 . 5 m m a n d a b o v e c a n b e

w e l d e d .

Productivity

The p roduc tivity o f MIG w elding in aluminium is

en t ire l y dep en de n t on th e w e l d in g c u rren t . J u s t a s

wi th o ther methods o f welding, where f i l ler wire i s

used to t r anspor t the current f rom the posi t ive pole

to th e n ega t i v e , th e dep os i t i on r a te dep en ds on th e

a m ou n t o f cu rren t p a ss in g th r ough th e a rc .

Th e s h ie l d in g g a s an d it s f l ow r a te a r e a lso v ery

im p or t an t . As a ligh t , i n ert g a s is u sed , th e m e th od issen s i t i v e to d r au gh t s an d we l d i n g sh ou l d th er e f o r e

b e d o n e i nd o o r s .


A gr ea t dea l o f wor k is p u t in to th e d ev e lop m en t o f

welding procedures . As the method is sensi t ive , i t i s

essent ia l to mainta in smal l to lerances for a l l the

p ar am eter s , su ch as cu r r en t , a r c v o l t age , s t i ck- ou t ,

sh i e l d i n g gas f l ow , we l d i n g sp eed an d gu n an g l e .

Wel d in g is com m o n ly d on e m an u a lly , bu t m ec h an i sa -

t i on i s be i n g u sed to an i n c r eas i n g degr ee to ob t a i n

improved control o f a l l parameters .Friction Stir Welding (FSW) is another welding

metho d in w hich no f iller ma ter ia l is use d. A rota t ing

tool i s pressed in to the a luminium to sof ten i t wi th

f r i c t i on a l h ea t . FSW i s m ech an i sed an d i s u sed i n

sh i p bu i l d i n g an d i n th e au tom ot i v e an d aer osp ace

industr ies .In th e au tom o t iv e i n du s t ry , on ly r obo t s a r e u se d .

An assem bl y l i n e con s i s t s o f sev er a l we l d i n g s t a-

t ion s . P rod u c t ion i s s e t u p i n a f a s h ion s im ila r t o th a t

u sed i n th e wh i te goods i n du s t r y . Mech an i sa t i on i s

widely used in shipbui lding, where an operator-con-

trolled Rail trac o r Mig g y t ra c c a n b e u s e d .

Equipment

I t i s i m p or t an t t o p ay g r ea t a t t en t i on to th e equ i p -

ment w hen w elding a luminium. It is d es irab le to ha ve

th e sm al l es t n u m ber o f s top p ages f o r w i r e ch an ges .

Aluminium wire cannot be s tored in drums as i t i sso f t . It is i n s tead wo u n d on to la rge s p oo l s w h ich a re

m ou n ted h or i z on t a l l y on a s t an d an d th er e i s a l so a

d i s c , k n o w n a s a d a n c e r o n a n a r m f i x e d t o t h e

s t a n d . Th is d an c er is c on n ec ted to a m o tor wh ich

p u l l s th e w i r e a t th e sam e t i m e as i t sen ses th e

r e s i s t a n c e i n t h e d a n c e r . W h e n t h e r e s i s t a n c e

in c r eas es , th e m otor a l so i n c rea se s i t s s p eed . Th is

permits f r ic t ion- f ree feed f rom the large drum to the

feed er. The d es ign i s l inked to the w elding g un and

f eeder. Th e sp oo l s u sed a t r obo t s t a t ion s h o ld a

g r e a t d e a l o f w ire a n d a r e e a s y t o c h a n g e .

There a re a la rge numbe r o f d i fferent we ldinggu n s f o r a l um in iu m . In s om e ca ses a p u sh - p u ll feed

sy ste m is used . The w ire i s pushe d f rom the w ire

P roduction of aluminium high-speed ferries.


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26

feed er in to the feed unit in the g un. This sy ste m

al low s u n if o rm , s t ab le w ire f eed to b e a ch i ev ed . Th e

feed er in the g un is dr iven b y ei ther e lec tr ic or pneu-

m at i c m o to rs a n d th er e a r e sev er a l d i ff e ren t t yp es o f

f eed sys tem . O n e sys tem con s i s t s o f two r o l l e r s

wh i ch p r ess aga i n s t each o th er wh i l e th e w i r e p ass-

es i n be tween . An o th er sys tem h as an g l ed r o l l e r s

wh i ch a r e con cen t r i c a l l y a r r an ged a r ou n d th e w i r e ,so - ca l led p la n e t a r y f eed . A p la n e t a r y f eed er is re l a-

tively s ma ll a nd rel ia ble. Teflon is us ed a s a l iner in

the w ire g uide to red uce f ric t ion . Tef lon res is ts bo th

h e a t a n d f r i c t i o n a n d i s u s e d i n a s m a n y p l a c e s a s

p oss i b l e wh er e th e w i r e p asses th r ou gh th e f eeder .

Th e m otor s i n th e f eeder h av e v er y ac cu r a te s p eed

control as i t i s very impor tant that feed i s uni form

wh en we ld i n g a lu m in iu m . More s op h is t i c a te d sp e ed

control i s used in the feeder , which quickly reac ts i f

a n y c h a n g e s o c c u r in s p e e d o r m o t o r re s i s t a n c e a n d

i m m edi a te l y com p en sa tes f o r th em .

Power supplies

The po we r suppl ies use d for a luminium w elding di f -

fer f rom those used for welding ordinary fer r i t ic

s tee l .

In MIG w elding, pulse d a rc i s o f ten use d. This

m ea n s th a t low n om in a l D C is s u p erim p os ed o n h igh

Choice of fillers for MIG and TIG welding of aluminium alloys.

Basematerial

SwedishStandard

InternationalStandard

ESABname

4244 4425 4104

4107 4163 4140 4120 4106 4054 4007

4010

SS ISO OK SHFK SHFK SHFK SHFK SHFK SHFK SHFK SHFK SHFK

Al

AlMn

AlMg

AlMgSi

AlZn

AlSi

4007

4010

4054

4106

4120

4140

4163

4104

4107

4212

4425

4244

Al-99.5

Al-99.0

Al-Mn 1

Al-Mg 1

Al-Mg 1.5

Al-Mg5Si G

Al-Mg Si

Al-SiMgMn

18.01

18.11

18.04

18.15

18.01

18.11

18.04

18.15

18.01

18.11

18.04

18.15

18.04

18.15

18.04

18.15

18.10

18.04

18.15

18.16

18.04

18.15

18.04

18.15

18.04

18.15

18.04

AAAB

AAAB

AAAC

ABAC

AAAC

ABBC

AAAC

ABBC

AAAC

ABAB

ABAB

ABBA

AAAB

ABAA

BAAB

ABBB

BBAA

AABA

ABBB

BBAB

BBAA

BBAA

BBAA

ABBB

ABAB

ABBB

BBAB

ACBC

SHFK

4212

AABB

BAAB

ABBB

BAAB

ABBB

BAAB

ABBB

BBAB

ABAB

ABBB

BBAB

BBAB

ABBB

BBAB

BBAB

BABB

AABB

BAAB

ABBB

BAAB

ABBB

BAAB

ABBB

BBAB

ABBB

ABAB

ABBB

BBAB

ABBB

BBAB

AABB

BAAB

AABB

BAAB

AABB

BAAB

AAAA

ABAA

AABA

ABAA

AABA

AABC

AAAB

ABBC

AAAA

ABBC

AAAA

AAAA

ABAA

AABA

AABC

AAAB

AABD

BAAB

AABB

AAAA

AAAA

ABBC

ABAB

AACB

BABB

BBAA

ABAA

AABB

AABA

BBAA

ABAA

AABB

AABA

BBAA

ABAA

AABB

BBAA

ABAA

AABB

BBAA

ABAA

AABB

Al-Mg 4,5 Mn

Al-Zn5Mg

Al-Si7Mg G

SHFK clarification. S = ease of welding, H = strenght, F = ductility, K = corrosion resistance

D espooling machine for pay-off packs.


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D C an d each p u l se m el t s away on e dr op l e t . In th i s

way i t i s p oss i b l e to con t r o l d r op l e t t r an s f e r by

ch a n g i n g p u lse f req u en cy a n d du r a t ion . As a lu m in i-

u m h as an ox ide coa t in g w ith a h igh er m el tin g p o in t

a cu r r en t h i gh en ou gh to m el t th e ox i de coa t i n g i s

req u ired . A m ore s t a b l e a r c is a ch i ev ed by m ea n s o f

puls ing, as the var ia t ion in current values provides

gr ea te r con t r o l o f th e dr op l e t t r an s f e r . P ower su p -

p l i es a r e sop h i s t i c a ted an d sev er a l d i f f e r en t t yp es

a re a vai la ble . Va rying me thod s o f current c ontro l a re

a l so av a i l ab l e ; on e v ar i an t i n v o l v es se t t i n g bo th th e

bas i c an d p eak cu r r en t , a s we l l a s p u l se w i d th an d

f requency , manual ly .U s i n g th i s m eth od , m an y se t t i n gs h av e to be

ch ecked , bu t th er e a r e a l so p r e- p r ogr am m ed p ower

so urce s . They ha ve just o ne c ontro l a nd a ll the input

p a r a m e t e r s a r e a d j u s t e d a u t o m a t i c a l l y i n a c c o r -

da n ce w i th p re- se t w e l d in g p rog r am s . All the o p er a-

to r n eeds to do i s se l ec t th e t yp e o f sh i e l d i n g gas ,

wire diameter , a l loy composi t ion of the wire and

p la te th ickn ess . Th e p ow er sou rce th en ch oos es a

p r ogr am wh i ch su i t s th e ap p l i c a t i on . Som e p ar am e-

ter s c a n a lso be p rec i s i on -ad ju s ted m an u a lly , bu t th e

m ach i n e gen er a l l y wor ks o f i t s own accor d . Nowa-

days , i t i s re la t ively easy to re-program weldinge q u i p m e n t u s i n g a P C a n d u p g r a d e s c a n b e t r a n s -

f e rred b y m ode m .

Points to considerTo s um up, the di f ficul t ies a ss oc ia ted w ith a luminium

we ld i n g a r e re l a ted to m e ch a n ica l f ac to r s wh er e f eed

a n d p o w e r s u p p l i e s a r e t h e m o s t c o m p l i c a t e d

iss ues . There a re a la rge numbe r o f d i fferent a lumini-

u m a l l oys . S i l i con , m agn es i u m an d m an gan ese a r e

u sed to p r odu ce v ar i ou s des i r ab l e p r op er t i es i n th e

f in ished mater ia l . Ship construct ion requires an a lu-

m i n i u m wh i ch r es i s t s s a l twa te r co r r os i on an d , i n

other appl icat ions , an a luminium al loy which can

res is t h ea v y loa ds a t low tem p er a tu res (a irc r a f t a lu -

minium) is req uired .

Th e we l d in g p roce ss c a u ses n eg a t i v e ch a n ges inaluminium. For th is reason, the product designers

m u s t en su r e th a t we l ded j o i n t s a r e p l aced i n a r eas

w i th th e ligh tes t lo a ds .

I t i s easy to ch oose con su m abl es f o r d i f f e r en t

t yp es o f a l u m i n i u m an d th e ch o i ce i s based on a

numbe r o f cr iter ia . I t is e a sy to f ind the var ious type s

of a luminium in char ts descr ibing the ways in which

c o n s u m a b l e s c a n b e s e l e c t e d a n d c o m b i n e d . F o r

exam p l e , th er e a r e v er y com p l i ca ted a l u m i n i u m

al l oys wh i ch h av e been g i v en g r ea te r s t r en g th by

age i n g th e m a ter i a l a t t em p er a tu r es h i gh er th an

room temperature . I t i s d i f f icul t to weld these kindsof a luminium and a i rcraf t a luminium cannot be weld-

ed a t a l l, so th ey a re r iv e ted i n s tead .

Seam welding equipment for the butt welding of aluminium.


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E S AB ABH erkules ga t an 72 , B o x 8004

S- 402 77 G o th en bu r g , Sweden

Tuvemark/SG

id&tryckab,Gteborg122000/15225

Mechanizing Welding Process

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