NS20A & NS20N Heavy Duty Gun
Page 6
Revision 1.20 2/19/08
WELD INSPECTION
Visual Inspection
A proper relationship between the Lift, Plunge, Time,
and Amperage is needed to obtain good weld results.
The length reduction or burn-off and the weld fillet
appearance are determined by the weld settings. Visual
weld inspection consists of interpreting the appearance
of the weld fillet and is normally very accurate if
certain guidelines are followed.
A good weld is characterized by:
•
Even fillet formation.
•
A shiny, bluish hue to the fillet surface.
•
A slight flow or blend of filler metal into the
base material.
•
Good fillet height.
•
Normal length reduction or burn-off
A cold weld, which requires more time and/or
amperage, is indicated by:
•
Low fillet height.
•
Incomplete fillet formation.
•
A dull gray cast to the fillet surface.
•
Stringers of fillet metal forming spider legs.
•
Inadequate length reduction or burn-off.
•
Fillet sits on top of the base material.
A hot weld made with too much time and/or amperage
is distinguished by:
•
Excessive spatter.
•
A washed-out fillet.
•
Undercutting of the stud.
•
Burn through the base material.
Physical Inspection
If, after visually inspecting the welds, a questionable
weld is evident, the weld should be physically tested.
Initial weld setups should also be physically tested.
Suggested physical tests are as follows:
1. Bend Test - Stud to be tested shall be bent away
from its vertical axis 90º or until failure. Failure
should occur in the stud proper, or, on thin
plate, a full stud diameter plug of base metal
should be torn out.
2. Torque Test - Stud shall be torqued until a pre-
specified loading is attained or until the stud
fails or, on thin plate, a plug of the base
material should tear out.
Normal Stud Weld
Stud hang-up.
Check
setup of gun. Refer to
page 2.
Hot weld.
Check weld
setup. Refer to page 2.
Cold weld.
Check weld
setup. Refer to page 2.
Figure 4: Weld inspection diagrams
