The process “Drawn arc stud welding” is used for studs of an approximate diameter of 3 to 25 mm, welding current up to 3.000 A and welding times up to 3.000 ms.
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.
If a ceramic ferrules was used, it will be removed afterwords.
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.
|Operation||Stud welding with ceramic ferrule|
|Minimum sheet thickness t||1/4 d|
|Maximum stud diameter d for welding from different positions||25 ↓|
|Suitable surface conditions¹)||bright metal, rolling skin, primer suitable for welding, surface rust, thin layer of oil|
|Unsuitable surface conditions¹)||hot-dip galvanising, loose layers of scaling, heavily corroded, protective coating|
|Common applications||studs with more than 8 mm ø in steel and boiler construction, and shipbuilding, on surfaces only coarsely cleaned, deep penetration, suitable for field welding|
|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.|