Thermal Arc POWERMASTER 400SP, Руководство по обслуживанию

Страница: 59 / 110

POWERMASTER 400SP, 500SP AUTOMATION
Octobe r 30, 2008 6-1
SECTION 6:
MANUAL GMAW WELDING
6.01 Types of Weld Transfer Modes
A. Dip transfer mode (short circuit arc)
This type of a r c is especially suitable fo r thin mate r ials
and positional welding due to a r elative cool welding
pool welded with ve r y sho r t a r c, low a r c voltage and
low cu rr ent. The su r face tension of the welding pool
helps to d r aw the d r op into the bath and to r eignite
the a r c. This cycle is r epeated again and again so the
sho r t ci r cuit and the a r cing pe r iod a r e constantly
alte r nating.
NOTE
The t r ansition f r om the sho r t ci r cuit to
sp r ay a r c depends on the wi r e diamete r
and the gas mixtu r e.
B. Transitional arc
The t r ansitional a r c is especially suitable fo r medium
thickness sheet metals and fo r ve r tical-down welding.
The t r ansfe r of the elect r ode to the wo r kpiece takes
place pa r tly in sho r t ci r cuit and in f r ee flight. Due to
fewe r sho r t ci r cuits, the welding pool is hotte r than
at the sho r t ci r cuit a r c. Welding with t r ansitional a r c
p r ovides highe r elect r ode melt r ate and is mo r e
economic than welding at sho r t ci r cuit a r c.
C. Long arc
Long a r cs a r e typically at a highe r ampe r e r ange unde r
ca r bon dioxide and gases with a high CO2 content. It
is not pa r ticula r ly suitable fo r positional welding. In
this type of a r c la r ge d r ops a r e fo r med which falls
into the welding pool mainly by fo r ce of g r avity. This
r esults in occasionally sho r t ci r cuits occu rr ing, which
inc r eases the cu rr ent at the moment of the sho r t
ci r cuit and high spatte r levels when the a r c is r eignited.
D. Spray arc
The sp r ay a r c is not suitable fo r positional welding,
due to the ext r emely liquid natu r e of the welding pool.
The sp r aying a r c fo r ms by welding at the highe r r ange
of ampe r e using ine r t gas o r mixtu r es with high a r gon
content. The most typical cha r acte r istic of the sp r ay
a r c is the t r ansfe r of ext r emely fine molten metal
d r oplets ac r oss the a r c.
E. Working range at GMAW welding
Wire
diameter
inches A V A V A
V
.030
140…
180
23…
28
110…
150
18…
22
50…
130
14…
18
.035
180…
250
24…
30
130…
200
18…
24
70…
160
16…
19
.045 o r 3/64
220…
320
25…
32
170…
250
19…
26
120…
200
17…
20
1/16
260…
320
26…
34
200…
300
22…
28
150…
200
18…
21
Long arc /
Spray arc Transitional
arc
Short circuit
arc
Favo r able welding cha r acte r istics a r e only possible if voltage
and cu rr ent a r e co rr ectly adjusted.
CO2 r equi r es an a r c voltage app r oximately 3 V highe r than gas
mixtu r es with a high a r gon content.