Stud welding or stud arc welding is a special form of the Arc welding procedure and is used to make permanent joins between large workpieces and studs. This procedure is very time-saving, as the arc is ignited directly between the workpiece and the stud and pins, causing the arc inlet and outlet areas to be melted. The two melted metal parts are pressed together with a low pressure and are therefore joined permanently.
Stud arc welding is generally divided into tip ignition and drawn arc stud welding. Basically, both methods are identical, and only differ in the way in which the arc is ignited.
Tip ignition stud welding
In this procedure there must be a small tip on the underside of the stud. The arc ignites at this tip and melts it as well as the whole underside of the stud. The weld pool produced is adequate for joining the stud. The tip ignition procedure is a very quick welding method and is particularly suitable for thinner sheet thicknesses from 0.6 mm. Welding studs size M3 to M8 with a diameter between 2 and 10 mm are used.
This type of stud welding can be used in many and diverse ways. For example, it is used in the electrical industry, for building housings and enclosures, in facade construction and in apparatus construction.
Drawn arc stud welding
In the drawn arc procedure the stud is in direct contact with the workpiece. In this position, the stud is energised and therefore forms a closed electrical circuit with the workpiece. The arc required for the melting is produced by lifting the stud. The stud and workpiece are then joined in exactly the same way as with the tip ignition stud welding procedure.
This procedure is used for greater sheet thicknesses from 2mm. Studs with diameters from 2 to 22 mm (M24) are used. This type of drawn arc stud welding can also be used on many and diverse ways. For example, it is used in structural steelwork, in mechanical engineering, in boiler construction as well as in shipbuilding.
The shapes of the studs are variable. Threaded studs, coarse thread studs, internal thread internal thread bolts and even simple pins can be used for both procedures. Tab connectors, cupped head pins and studs with paint scraping groove are only used for tip ignition stud welding. Collar weld studs, pigtail anchors, earthing weld studs with and without protective cap, concrete anchors and shear connectors on the other hand are only used for drawn arc stud welding.
In stud welding the surface must be electrically conductive. Therefore, it is absolutely necessary for paint, rust or scale, for example, to be removed before welding. If the sheets or plates are zinc-plated, this must be checked beforehand for welding compatibility.
Special forms of stud welding
Another area of use is the magnetic rotating arc. In abbreviated form it is called MARC welding. In this case a magnetically moved arc is used. It is similar to drawn arc stud welding, but a rotating arc is used. A magnetic field transfers the energy, uniformly and concentrated, onto the area to be welded.
Sleeves with a diameter of 30mm (outer diameter) are preferably welded. This is done sputter free and with little distortion. Welds of unperforated and perforated sheet and plate parts are possible and gas and pressure-tight welds are produced. Lower energy requirement, very short welding times coupled with weak thermal stress are guarantees for quality and high efficiency.
Stud welding- the advantages
Leaks that can occur when parts are bolted are not a problem with stud welding. Because of the very short welding times distortion is kept to a minimum. The resulting joint is very strong. As there is no need to rework coated or high-alloy sheets or plates, this welding is very profitable.