HBS Pegasar 500 accu Insulation Operating Manual page 29

– The weld pool solidifies and the welding element is physically connected to the
workpiece.
– The time period between ignition of the arc and solidification of the weld pool is
about 3 ms.
– The use of contact welding for rapidly oxidising materials like aluminium and
aluminium alloys is not recommended because the arcing period with contact
welding is longer than with gap stud welding.
Contact stud welding - application for insulation
– The welding gun with the put-on welding element is placed onto the insulating
mat and the welding element is pressed through the mat up to the workpiece (see
figure, position 1). With ongoing pressure, the pressure spring is tensioned until
its stop.
– Then the pressure to the welding gun and/or the workpiece is gently released in
such a way that the welding piston of the welding gun lifts by approx. 2 to 5 mm.
The tip of the welding element sufficiently remains under pressure and touches
the workpiece. The current circuit is closed. The operator presses the welding
gun trigger and starts the welding process.
– Capacitors of the stud welding unit are discharged.
– Caused by the high discharge current, the tip of the welding element evaporates
explosionlike. In this way, a gap is developed between welding element and
workpiece, a light arc will be ignited.
– In the ionized gap, a light arc ignites between welding element and workpiece
(see figure, position 2).
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9 Welding Process
29