WELDING
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.
.
AB200029AB200029
SMALL ← WELDING CURRENT → LARGE
WEAK ← 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
AB
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