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Spot
welding
●
×
×
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×
×
×
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●
●
●
×
×
AC
pulse
TIG
2T
●
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●
●
●
●
●
×
●
●
●
●
4T
●
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●
●
●
●
×
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Repeat
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×
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W
el
d
ing
m
ode
T
orch
tr
igg
er
m
ode
P
re
-f
lo
w
ti
m
e
Ini
ti
a
l
curr
ent
Up
-s
lop
e
ti
m
e
P
ea
k
curr
ent
B
as
e
curr
ent
D
o
w
n
-s
lo
pe
ti
m
e
Fi
n
is
h
curr
ent
P
ost
-f
lo
w
t
im
e
S
pot
w
el
di
ng
ti
m
e
A
C
f
req
uen
cy
A
C
b
al
anc
e
M
ixe
d
fr
eque
n
cy
M
ixe
d
dut
y
cyc
le
Mixed
TIG
2T
●
●
●
●
×
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●
●
×
●
●
●
●
4T
●
●
●
●
×
●
●
●
×
●
●
●
●
Repeat
●
●
●
●
×
●
●
●
×
●
●
●
●
7.2. MMA operation
MMA electrode welding process
1. I
h
(hot start current) = I
Δh
(arc starting current) + I
a
(welding current); the hot start time is
fixed at t
h
, which helps the arc start, and reduces the sticking tendency of welding electrode
and workpiece during arc starting. The magnitude of hot start current is generally determined
based on the type, specification, and welding current of the welding electrode. For welding
electrodes with sound arc start performance and small diameter, generally select small hot
start current; large welding current also has little requirement for hot start current. The hot
