Mitsubishi MOTORS Lancer Evolution 2008, Body Repair Manual

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WELDING
TSB Revision
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 (0.063
inch)] continues to increase proportionately (between
points B and C); however, for thin panels [1.6 mm
(0.063 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
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 (0.063 in)
or less
More than
1.6 mm
(0.063 in)
C
A
C Is The Scatter Point
AD