The process „drawn arc stud welding with shielding gas“ is used for welding studs of a diameter of 3 to 12 mm ( 16mm).
In general, the positive pole of the power-source is connected to the workpiece.
The stud will be inserted into the chuck of the stud welding gun and positioned onto the workpiece, possibly by adding a ceramic ferrule.
Initiating the welding process: by means of a lifting mechanism, the stud will be lifted and at first an auxiliary arc (pilot arc) of a low current will be drawn. Then the main arc will be drawn between the tip of the stud and the workpiece.
The main arc of a high amperage must be adjusted to the diameter of the stud.
The cross sectional area of the stud and the opposite workpiece a partially melting.
After the lapse of the adjusted welding time, the stud is moved towards the work piece and both melting zones join tightly.
The power-source turns off, the melting zone solidifies and cools down.
In order to obtain a good gas-protection, an adequate appliance is indispensable. At the upper part of the chuck, the gas chamber should be sealed by means of a rubber sleeve.
Down at the workpiece, lateral slotts are required to allow the gas to escape.
The use of appropriate shielding gas is of great importance: mild steel and stainless steel: 82% Ar and 18% Co2, for aluminium; pure Argon or Ar and He.
The stud is placed against the workpiece.
The stud is lifted off, while current is flowing, thus creating an arc.
The arc melts the surfaces of stud and workpiece.
The stud is plunged into the weld pool.
A cross-sectional joint is achived.
|Process||Stud welding with shielding gas|
|Minimum sheet thickness t||1/8 d|
|Maximum stud diameter d for welding from different positions||12(16) ↓|
|Suitable surface conditions¹)||bright metal, rolling skin, primer suitable for welding, surface rust, thin layer of oil, zinc coating|
|Unsuitable surface conditions¹)||loose layers of scaling, heavily corroded, protective coating|
|Common applications||studs from M 6 to M 12 in downhand position, especially with automatic feeding of studs|
|¹) Here, we can give only general hints without any commitment or warranty on our part. The conditions must be tested in each individual case. Basically, a higher degree of surface cleanliness is required for shorter welding times. The best results are always achieved on bright metal surfaces.|