Section 10 Auto Body Repair Application - Miller Electric AUTO ARC MW 4150 Owner's Manual

SECTION
10 AUTO BODY REPAIR APPLICATION
CAUTION: WELDING CURRENT
can
dam
age vehicle
computers
and other electronic
components.
Disconnect both
battery
cables before weld
ing
on a
vehicle.
Place
work clamp
as
close
to
the weld
as pos
sible
to
avoid
long
electrical
paths.
Be
sure
gun
to
power source as
well
as
cable
connections
to
work
clamp
are
clean and
tight.
To minimize
risk, disconnect the
computer(s)
from the vehicle.
10-1.
POINTERS
FOR WELDING AUTO
BODY
SHEET METAL
Before
using
this
equipment to weld
on a
finished
piece
of work, make
a
few
practice
welds
on a
sample piece of
material the
same as
that of the finished
workpiece.
Whenever
possible,
weld in the flat
position since this is
the easiest position
to
learn. Be
sure
that the material
to
be welded is clean and free of
paint
and
rust. The work
cable clamp
must
be attached
to
the
parts being welded.
Clean surface
to
ensure
proper
grounding and to
com
plete the
current path.
Use
a
.030
or
.023 in. (0.8
or
0.6 mm) E7OS-6 wire and
argon/carbon dioxide
shielding
gas.
Use direct
current
straight polarity for reduced burn
through.
To obtain
straight polarity (electrode wire to
negative-work lead
to positive), place the Negative/
Positive weld
output
selector plug in the
NEGATIVE
WELD OUTPUT RECEPTACLE and
connect
the work
(ground) lead to the POSITIVE WELD OUTPUT RE-
CE PTACLE.
IMPORTANT: For maximum
penetration
on
thicker
ma
terials such
as
18
gauge
(1.22 mm) and thicker,
recon
nect
for direct
current
reverse
polarity (work lead
to
negative, electrode wire
to positive).
10-2. PROCEDURE FOR WELDING MILD STEELS
The following
are some
basic guidelines that
can
be
used when
using this welding
power source
to weld mild
or
high strength steels:
1. Use
a
power wire brush
or
sander to
remove
paint
to
bare metal in the
area
to
be
repaired.
Two
to
three inches
(51-76mm)
on
either side of the weld
area
should be cleaned for
applying body
filler af
ter
welding is
completed.
2. Remove
damaged
metal
using
hand
cutters,
shears,
or a
power hand grinder equipped with
a
cutting wheel.
3. Fit
a new
piece
of sheet steel
over
the section
which
was
removed. The
new
material should
overlap the
cut
away section
by
one
inch
(25 mm).
4. Clamp
the
new
metal in
place,
and prepare
to
spot
weld.
5.
Rotate the FINE TUNING WIRE SPEED control
to 50%,
the weld timer at 30 to 40
percent, the
burnback at 40 to 50
percent
and the selector
switch
to
the SPOT
position.
6.
Install the
spot
nozzle
on
the
gun.
7.
With the shielding gas and power
source
turned
on,
place
the
spot
nozzle and press
firmly against
the
new
material about 1/2
to
3/4
in. (12-18 mm),
from the
edge.
Fit up
must
be
tight to
assure
good,
repeatable spot
welds.
8. Begin spot welding
from the
center Out
on
each
side. Distortion
may occur
if welding begins
at the
corners.
9. Space spot
welds
1 to 1/2
in.
(25-38
mm) apart
around repair. Spot welds should be about 3/16
in.
(5 mm) in diameter.
IMPORTANT: Do
not
make continuous welds around
the repair
as
this will
promote
distortion and warpage.
10. After welding,
remove
the
clamp and
grind spot
flush
to
surface.
11.
Smooth the
joints
with
body
filler and finish.
10-3.
PROCEDURES FOR WELDING
DOOR PAN
ELS
IMPORTANT: Every experienced autobody
repairman
will
ha
ye
his
own
methodofperforming the following
pro
cedures. However,
this in
formation is
presented to show
how,
in most cases, this welding
powersource can
make
the job
easier and less time
consuming.
If the door is
severely damaged,
but the
damage
is
pri
marily in the outer panel,
or
skin, the door
can
be easily
repaired without necessarily installing
a
whole
new
door.
1.
Remove exterior molding and hardware. It is not
necessary
to
remove
window regulator,
remote
control mechanisms,
lock
or runs.
2.
Remove door assembly, and place
on
flat surface
with edges
of door
extending
over
edges of
sur
face
to
provide
room
to work.
a
Door Skin
Damage
Inner Door
Inner Door
Flange
Figure
10-1. Cutaway
Of
Door Panel Damage
S
.~J4 18
OM-113 336
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