Mitsubishi Outlander XL. Manual — part 36

PROCEDURE
There are three basic stages in electric resistance spot welding.

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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.

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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.

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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.

BASE OF BODY REPAIR

9-3

WELDING

NUGGET FORMATION

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Small

←

Welding current

→

Large

W

eak

←

Shear strength per point

→

Strong

Cooling water

Cooling water

Elect-
rode

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

A'

B'

D

B

D'

C'

1.6 mm (0.06 in)
or less

More than
1.6 mm
(0.06 in)

C

A

C is the scatter point

0000

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
rapidly (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 molten
metal will scatter if the current level increases past a
certain point.

9-4

BASE OF BODY REPAIR

WELDING

NOTES REGARDING WELDING

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90 – 120°

D
t

:
:

Diameter of the electrode tip
Thickness of the panel

t

D

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,
however, 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 insufficient.

｠

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.

WELDING REQUIREMENTS
Standard steel plate (SPCC, etc.)

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

BASE OF BODY REPAIR

9-5

WELDING

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

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Factory welds (F)

8 points

8 points

11 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
equipme
nt 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

NOTE:

*: For welding steel plates of different

thickness, conform to the welding conditions for
the thinner plate.

9-6

BASE OF BODY REPAIR

WELDING