dabotek BS108, Руководство по эксплуатации

Страница: 26 / 41

WELD ASSESSMENT / TESTING
Visual examination of weld quality can, even with limited experience, pro-
vide 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
-
fused area between the stud flange and the parent sheet or plate. In-
correct settings, adverse magnetic effects etc. such as those at edge weld-
ing 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 :
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 the DVS0905 (German Welding So-
ciety Spec') specification .
TORSION.
A torsion test provides useful information for threaded fasteners. This in-
volves tightening a nut on the stud against a spacer, suitably relieved to
cater for the flange and weld spatter. For quantitative assessments a suita-
bly 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 consid-
ered in relation to the thickness of the material to which the stud is weld-
ed. 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.
24