How does a stud welder work?
In stud welding, pin-shaped components are attached to sheet metal parts. The pin-shaped components are usually fastening elements such as threaded bolts or threaded bushes. In stud welding, devices, machines or entire plants are used. Stud welding is essentially divided into two processes. On the one hand, there is drawn arc stud welding and capacitor discharge stud welding.
Principle of a drawn arc stud welder
A drawn arc stud welder first places the stud with its end face on the sheet metal. When the welding current is switched on, the stud is slightly lifted and an electric arc is generated. This melts the stud sufficiently and the stud is pressed onto the sheet metal by the welding head. As soon as this happens, the arc goes out and the degree of melting solidifies.
A ceramic ring or inert gas is used as weld pool protection. A weld pool protection is not required for the short-time stroke ignition process with welding times of less than 0.1 seconds. A controlled rectifier is usually used as welding power source.
Principle of a capacitor discharge stud welder
The capacitor discharge stud welder uses a stud which is provided with a tip on the welding surface during production. This attached tip is melted off after switching on the welding current and thus the light current is ignited. It is not necessary to lift the stud when using a stud welder with tip ignition. When sufficient melting has been achieved, the stud is pressed onto the sheet metal and thus fused with it.
The quality characteristics
In order to ensure high welding quality, the stud welding equipment must be set up correctly and work stably. In this way, the current and voltage curves will differ only minimally from weld to weld.
However, the welding quality also depends on the following:
- from the electrical adjustment of the welding equipment from the mechanical adjustment of the welding head or the welding gun from the geometry of the used studs from the individual materials from the surface condition
With weld quality monitoring, it is possible to react to gradual changes in the electrical or mechanical settings before these changes cause major damage.
Fields of application of the stud welding units
The range of application of stud welding units is wide. They can be found in the electrical industry for the production of appliance chassis, in the manufacture of household appliances or for the production of fittings as well as in the automotive industry.
Steel construction, process engineering apparatus engineering, shipbuilding and civil engineering are also important sectors for stud welding. They are used to fasten fasten fasteners to sheet metal both for manual construction site production and for large series production.