HBS 93-20-290, Operating Manual, Page: 33 / 66

A 22 Order No. BA 93-20-290 Issue 01.03.08 33
5.7.2 Bending Test
You can purchase from HBS a bending device with inserts for various diameters of the
welding elements.
The bending test serves as an easy work sample and as a check for the selected welding
parameters. The welded joint is stressed by bending in a non-defined way.
Bend the welding element with the bending device once by 60°.
Carry out the test in different directions.
The bending test is passed if a crack or a fracture of the welded zone does not occur.
Please note the instructions on fault recognition and corrective actions in
chapter 5.
You don’t need to test all studs. It is sufficient to carry out stud
tests at random.
If the strength of the joint is inadequate, then:
check the setting of the stud welding unit
check whether the surface of welding element and base material are clean and
electrically conductive (must be free from scale, oil, paint, oxide layers)
grind off hardened workpiece surfaces (e.g. roll hardening)
check the piston of the welding gun for ease of movement.