Welding Methods

This welding technology is used in building/composite construction.

In through-deck welding, shear connectors are welded through galvanized trapezoidal plates onto steel girders and all components are joined together.

The resulting combination of composite girder and composite decking provides a range of installation options on the underside for suspended ceilings as well as air conditioning and electrical equipment, and also saves a great deal of time compared to conventional formwork. Through-deck welding is particularly popular in the Anglo-Saxon countries due to the use of uncoated girders as well as the prevalence of the size 19 shear connector, which is easier to machine than the size 22 shear connector traditionally preferred in Germany for composite construction.

Stud welding with an ionized arc works with the brief application of a high DC voltage. When the welding process is triggered, a low current is activated, the stud is raised off the workpiece and an arc skips across. This arc melts the contact points of both materials and the welding stud is then pressed on. When the welding stud comes into contact with the workpiece, the arc disappears and the voltage is switched off. The weld pool cools and hardens. Fusion is complete.

In stud welding with a ceramic ferrule, the welding stud has a small aluminum ball at the bottom. This burns within milliseconds as soon as the welding current is switched on. This converts the oxygen present at the welding site completely into chemically neutral aluminum oxide, which prevents unwanted oxidations at the weld.

Despite the speed of the stud welding process, the maximum duration of a welding process of 1.5 seconds is long enough for the inflowing oxygen from the ambient air to cause unwanted penetrations in the weld zone that negatively impact on the quality. To prevent this, the use of a ceramic ferrule has become standard practice. This is positioned above the weld zone to seal it. The metal vapor generated during the welding process is able to dissipate through gas vents and this prevents the atmosphere from reacting with the melt. The ferrule is struck off after the welding process. And this reveals another function of the ceramic ferrule. The melt pressed away when the stud is plunged in is formed into a defined weld bead. As a secondary function, the ceramic ferrule slows the cooling and protects the operator from radiation and spatter, as stud welding is a very intensive arc welding process.

→ see also shielding gas welding

Despite the speed of the stud welding process, the maximum duration of a welding process of 1.5 seconds is long enough for the inflowing oxygen from the ambient air to cause unwanted penetrations in the weld zone that negatively impact on the quality. Besides welding with a ceramic ferrule, welding with shielding gas is another suitable measure to further optimize the level of deoxidation and prevent the described penetrations. In shielding gas welding, a bell jar is placed over the weld zone during the welding process and then filled with shielding gas. This prevents the atmosphere from reacting with the melt.

Welding with shielding gas is less intensive than welding with a ceramic ferrule, and is primarily used for stud diameters up to 12mm.

→ see also ceramic ferrule

Welding studs are the consumables in stud welding. They need to be geometrically correct for the specific task and, above all, be technically suitable for drawn arc or capacitor discharge welding. The stud material is precisely adapted to the specific application to ensure the best results and protect the equipment.