Mitsubishi Galant (2004+). Manual - part 31

WELDING

TSB Revision

BASE OF BODY REPAIR

9-3

PROCEDURE
There are three basic stages in electric resistance spot weld-
ing.
1. Initial pressure application stage

This stage precedes the current application. Applying
pressure to the steel panels through the electrode tips
ensures a uniform contact resistance and a smoother
current flow.

2. Current application stage

While an ample amount of pressure is being applied, the
current is sent through the electrode tips. The contact
resistance causes the contact surfaces of the steel panels to
heat up and fuse together.

3. Holding stage

When the current application is finished and a nugget (a
solidified piece of molten metal) forms at the weld, the
pressure application is continued in order to strengthen the
weld. This is the most important stage of electric resistance
spot welding in ensuring the strength of the weld.

AB200026

AB200027

AB200028

WELDING

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BASE OF BODY REPAIR

9-4

NUGGET FORMATION

Generally speaking, the size of the nugget will
increase as the welding current increases, and as
the size of the nugget increases, the strength of the
weld will also increase.
Nugget formation will not begin until the current level
reaches a certain point; however, once this welding
current level is passed, the strength will increase rap-
idly (between points A and B).

As the current level increases further, the weld
strength for thick panels [more than 1.6 mm (0.06
inch)] continues to increase proportionately (between
points B and C); however, for thin panels [1.6 mm
(0.06 inch) or less], the weld strength reaches a peak
very quickly and will increase only slightly, even if the
current level increases (between points B' and C').
Then, for both thick panels and thin panels, the mol-
ten metal will scatter if the current level increases
past a certain point.

AB301468

SMALL

←

WELDING CURRENT

→

LARGE

WEAK

←

SHEAR STRENG

TH PER POINT

→

STRONG

COOLING WATER

ELECT-
RODE

NUGGET

STEEL
PANEL

WATER
TEMPERATURE

540

(1,000)

1,095

(2,000)

1,650˚C

(3,000)˚F

MAX. HEATING TEMPERATURE

MELTING
POINT

1.6 mm (0.06 in)
OR LESS

MORE THAN
1.6 mm
(0.06 in)

C IS THE SCATTER POINT

WELDING

TSB Revision

BASE OF BODY REPAIR

9-5

NOTES REGARDING WELDING

1. Selection of the electrode tips

•

Select the electrode tips according to the
thickness of the panels to be welded.
D = 2t + 3 mm (D = 2t + 0.1 inch)

•

The angle of the tip should be between 90
degree angle and 120 degree angle.

•

To always keep the end of tip in the correct
shape, use a tip cutter, file or similar tool to
shape it if it becomes worn.

2. Alignment of the electrode tips

•

Adjust the arms so that the upper and lower
electrode tips are in a straight line.

3. Alignment and length of the arms

•

Adjust the electrode tips so that the upper and
lower arms are parallel.

•

Select an appropriate arm length. Note, how-
ever, that the arm length should not be more
than 350 mm (13.8 inches) in order to ensure
nugget strength.

4. The weld points

•

The overall strength will increase as the pitch
decreases; however, if the pitch decreases
too much, the current will be short-circuit
diverted to the previous weld point and the
strength of the individual nuggets will be insuf-
ficient.

•

Make the spot welds at the center of the
flanges to provide sufficient adhesion. When
welding at an edge, make the spot welds at
least 5 mm (0.2 inch) from the edge of the
flange.

•

The number of spot weld points should be the
same as, or slightly more than the number of
original repair welds.

•

When spot welding three or more panels
together, if painted surfaces cause a loss of
conductivity, make the welds at the same
places as the factory welds. If this is done,
extra welds will not be necessary, but if extra
welds are necessary, switch to plug welding.

AB301455AB

90 – 120˚

D
t

:
:

DIAMETER OF THE ELECTRODE TIP
THICKNESS OF THE PANEL

WELDING

TSB Revision

BASE OF BODY REPAIR

9-6

WELDING REQUIREMENTS
Standard steel plate (SPCC, etc.)

CAUTION

If the total thickness of the plates at the weld
places is 3 mm (0.12 inch) or more, use plug
welding, because spot welding will not provide
sufficient welded strength.

Example

•

Center pillar (outer): plate thickness 1.4 mm (0.06
inch), material SPCC

•

Center pillar (inner): plate thickness 1.5 mm (0.06
inch), material SPCC

The number of weld points are as below when the
outer and inner center pillars are repaired by weld-
ing.

*: For welding steel plates of different thickness, con-
form to the welding conditions for the thinner plate.

AB200031AB

FACTORY WELDS (F)

8 POINTS

11 POINTS

REPAIR WELDS (R)

As shown by the Welding Requirements table, the number of repair welds is as follows.
8 (points)

130 (%) = 10.4 (points)

The number of weld points should, therefore, be ten or eleven.
If, however, a pitch of 26 mm (1.0 inch) or more cannot be maintained, the plug
welding method (eight weld points) should be used.

PANEL
THICKNESS*
[mm (in)]

NUMBER OF REPAIR WELD (PERCENTAGE OF FACTORY WELD)

SAFETY
EQUIPMENT
AREA

1.0 (0.04) or
less

100% Same number as factory welds

1.2 (0.05)

150% Maintain pitch of at least 22 mm (0.9 inch); if not possible, plug weld.

1.4 (0.06) or
more

100% Same number as factory welds; plug welding

OTHER
AREA

1.2 (0.05) or
less

100% Same number as factory welds

1.4 (0.06)

130% Maintain pitch of at least 26 mm (1.0 inch); if not possible, plug weld.

1.6 (0.06) or
more

100% Same number as factory welds; plug welding

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