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13 Checking the Quality of the Weld
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You don’t need to test all studs.
It is sufficient to carry out stud tests on several production samples that are
picked at random.
Bending Test
Type of fracture
Possible cause
Corrective actions
Tearing of parent material
Correct parameters
none
Fracture above collar after sufficient
deformation
Correct parameters
none
Fracture within the weld.
High porosity
Weld energy too low
Increase current and/or
welding time
Unclean surface
Clean the surface
Material not suitable for stud
welding
Select suitable material
Fracture of weld
Bright appearance
Welding time too low.
Increase welding time
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.
They 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.