V
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21A
WELD TESTING
14
Visual examination of weld quality can, even with limited experience, provide a useful
quality assessment. In such a check the presence of a small even witness of weld material
around the base of the stud flange after welding should be ensured. Poor welds are
indicated by excess metal on one side of the welded flange and / or the presence of an
undercut or non
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fused area between the stud flange and the parent sheet or plate.
Incorrect settings, adverse magnetic effects etc. such as those at edge welding positions or
with unbalanced earths and studs welded to the work piece at an angle, the controller and
pistol should be examined with a view to correcting such defects.
MECHANICAL TESTS :
1. BENDING.
The most easily applied method of testing the quality of welded fasteners considered here,
involves the use of a bending bar. This bending bar (available from your supplier, see the
accessories section of this manual) fitted with the correct size of nozzle for the stud to be
tested is used to bend over the stud in accordance with BS EN ISO 14555:2006
specification.
2. TORSION.
A torsion test provides useful information for threaded fasteners. This involves tightening a
nut on the stud against a spacer, suitably relieved to cater for the flange and weld spatter.
For quantitative assessments a suitably calibrated torque wrench may be used, but at its
simplest, a spanner will suffice.
In the above tests the performance of the welded joint should be considered in relation to
the thickness of the material to which the stud is welded. On thicker materials, a full
strength weld is denoted by deformation or failure of the stud shank. On lighter gauge
material, severe "dimpling" or "dishing" at the reverse to the weld side normally indicates
sufficient strength, whilst in most cases, the tearing of a slug of material from the parent
sheet will occur.
