Welding Studs from KÖCO

KÖCO provides a comprehensive range of welding studs for various applications. These include SD headed studs for composite steel construction, different threaded stud variants such as RD, PD, FD, and MD studs, as well as ID internally threaded sleeves. In addition, we manufacture special materials and coatings according to individual requirements.

Shear connectors are the proven solution for creating permanent connections between steel and concrete in composite steel construction. Their characteristic mushroom-shaped head ensures optimal force transfer and secure anchoring of steel beams in concrete.

These studs are typically manufactured from structural steels that achieve higher strength through cold forming during production. To maintain this increased strength and prevent “soft annealing” of the stud, these studs must be welded exclusively using drawn arc stud welding. Other welding methods such as MAG, TIG, or MMA are not permitted, as they lead to a loss of strength. For this reason, the executing company must hold an appropriate welding certificate in accordance with EN 1090, and the operating personnel must have a valid operator qualification according to ISO 14732.

At KÖCO, shear connectors are available in diameters of 6, 10, 13, 16, 19, 22, and 25 mm, with lengths ranging from 25 to 525 mm depending on the diameter.

Note: The length specifications always refer to the welded stud, since the fusion projection is already included. For example, a 13 mm stud with a finished length of 100 mm measures 103 mm before welding, while a 25 mm stud with the same finished length measures 105.5 mm.

The RD stud is the most common threaded welding stud for drawn arc stud welding in accordance with DIN EN ISO 13918. The designation RD stands for “reduced shank,” meaning that the weld collar corresponds approximately to the external thread diameter. This design is particularly widespread and has proven itself in practice.

When setting the parameters, it is important to note that the welding parameters are not based on the nominal diameter of the stud but on the actual shank diameter. For example, an M8 RD stud is not set to 8 mm, but to 7.1 mm. For an M20 RD stud, the setting is 16.5 mm instead of 20 mm. For all calculations, the reference dimension of RD studs is the diameter in the welding area, i.e., the smallest cross-section.

MD studs are classified in accordance with DIN EN ISO 13918 as studs with an almost continuous thread. The shank diameter corresponds to the nominal diameter minus the thread depth, resulting in a weld collar larger than the external thread diameter. This design combines the advantages of an almost continuous thread with optimal welding properties.

When setting the parameters, it is important not to select them according to the external thread diameter of the stud. Instead, they must be set according to the actual welding diameter. This correct adjustment is essential for successful welding and the desired connection quality.

KÖCO drawn arc internally threaded sleeves are the ideal solution wherever a weldable internal thread is required. These sleeves are available with internal threads from M5 to M12 in various lengths with corresponding thread depths. They provide maximum flexibility in designs where external threads are not practical.

A technical limitation arises with larger dimensions: since the M12 threaded sleeve already has an external diameter of 18.2 mm, larger sleeves can no longer be processed using drawn arc stud welding. Within these limits, however, ID sleeves offer a very practical and reliable fastening solution.