Mig Welding - Alfa Romeo alfa 33 Workshop Manual

1
It must form an opening of
about 3 mm dia., when stressing
(2) Test to be carried out after welding, by means of
chisel and hammer.
.
Insert tip of a chisel between the welded sheets and
slightly tap on chisel until, between sheets, it is
obtained a 3 to 4 mm clearance (0.12 to 0.16 in); if,
on the welded part, no strain is present, test result is
then positive.
.
If sheets thickness is not equal, clearance between
sheets must be limited to 1.5 to 2 (0.059 to 0.079
in).
Take into account that the above value is only a
reference one.
.
The mentioned clearance changes according ta
position of welding spots, flange length, welding
inclination and other factors.
never exceed this limits in order not to cause
D
O
detachment of welding points.
.
After test,
make sure that the strained part is
Reference value: 3 to 4 mm
(0.12 to 0.16 in)
Reference value:
BODY - SHEET METAL PANELS
CORRECT
INCORRECT
Slightly tap by means
of a hammer
1.5 to 2.0 mm
(0.059 to 0.079 in)
Slightly tap by means
of a hammer

MIG welding

1. Conditions of panel to be welded.
By means of belt sander or wire brush, remove any
foreign matter from surface.
Paint films, rust or oils present on sheet surface, causes
decrease of welding strength, thus generating blow holes.
2. Cautions during welding operations.
welding (of
a) Make a hole, having 6 to 6 mm diameter (0.20
to 0.24 in) on one of the two sheets to be welded,
then match the two sheets and clamp them.
b) Position the torch at right angle with respect to
sheet, then fill metal into the hole.
Each time welding is stopped, on the surface an
oxide film generates which causes blow holes. If this
occurs, remove oxide by means of a wire brush.
sheet is perfect.
Part around the hole
Plug welding
(2) Butt welding.
a) By means of intermittent weld, tack the two surfaces
to be welded in order to prevent strains and align the
two surfaces, then, fill in the spaces by placing small
welding beads.
established holes)
pre
Panel edge
Butt weldiirg
SEC. A-A