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Drawn arc stud welding - efficient and versatile

As specialists in the field of s tud welding, we at KÖCO are very familiar with the various stud welding processes.

Drawn arc stud welding plays a special role, as this welding process for studs with diameters of 3 to 25 mm, amperages of up to 2,600 A and welding times of up to 2,200 ms is used in numerous different industrial applications to weld studs onto metal parts.

Where is drawn arc stud welding used?

Design and manufacture of metal assemblies: Drawn arc stud welding is often used in the metalworking industry to weld studs onto metal parts such as steel beams, sheet metal or profiles. This can occur in the construction industry, in the manufacture of vehicles, in mechanical engineering and in many other areas.

Electrical and electronic applications: In the electrical and electronics industry, drawn arc stud welding is used to weld studs onto electrical housings or other electrical components. This enables a secure connection.

Automotive industry: In automotive production, drawn arc stud welding is used to attach fastening elements such as studs and nuts to body parts or other vehicle components.

Shipbuilding: In the shipbuilding industry, this welding process can be used to attach studs to ship hulls or other metal structures.

General metalworking: Drawn arc stud welding can be used in many other applications where fast and reliable fastening of studs to metal parts is required.

How does the welding process work?

Firstly, the positive pole of the power source is clamped to the workpiece. The stud is inserted into the stud holder of the stud welding gun and, depending on the application, placed on the workpiece with a ceramic ring.

At the start of the welding process, the stud is lifted by a lifting mechanism and first an auxiliary pilot arc of low amperage, then the main arc is ignited between the stud tip and the workpiece. It is important that the main arc of high amperage is matched to the stud diameter.

The stud face and the opposite workpiece now melt.

After the set welding time has elapsed, the stud is moved towards the workpiece and the two melting zones merge.

The power source is then switched off and the melting zone solidifies and cools down.

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The process of drawn arc stud welding

And why the ceramic ring?

The use of a ceramic ring is recommended for welding studs over 10 mm. It supports the desired shape of the welding bead and forms a protective atmosphere in the welding area. The ceramic ring is only used for the respective weld and is then removed from the stud again.

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Illustration of the welding process with and without ceramic ring

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Illustration of the protectice effect of the ceramic ring

How can I recognize a good drawn arc stud weld?

There are different methods for checking the quality of a completed welding job:

Visual inspection: If the welding process is successful, the welding collar or welding bead is closed and has a bright and shiny surface. In addition, the stud has ideally reached its nominal length (L) after welding.

60° bend test: After the welding process, the stud is perpendicular to the base material. Even after a 60° bend test, there is no break or crack in the weld.

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Illustration of the 60° bending test

Tensile test: The occurrence of material failure or breakage does not normally occur within the weld zone. Unbuttoning of the stud from the base material is not an indication of a faulty weld. In fact, it is usually the case that the stud only fails after reaching a tensile strength above the weld. This confirms that the welded joint is generally stable and reliable.

Oops! - Common mistakes in drawn arc stud welding

Nominal length not reached: With a good weld, the defined nominal length of the stud is reached. If this is not the case, the energy used during the process may have been set too high or too low and should be checked.

One-sided fusion due to blowing effect (deflection of the arc): Possibly the earth guidance was unfavourable, the earth clamps should be positioned against the blowing effect. Another reason for one-sided fusion can be the lack of levelling compounds in the edge area. Faults can also occur if welding power cables are routed close to the weld. Welding cables should always be laid away from the weld and the stud welding gun should be rotated with the cable bends on the outside.

Immersion obstruction: If the base plate is not correctly centred or there is heavy weld spatter, this can lead to increased friction of the stud in the ceramic ring. Another potential problem is droplet short circuits between the stud and the base material, which can occur if the stroke of the stud is too short or the blowing effect is too strong. Problems can also occur if the stud welding gun is defective or the damping is set too high. It is therefore crucial to carefully monitor and adjust all welding parameters and components to ensure a reliable and high quality welded joint. This ensures the integrity and strength of the welded joint.

Pore formation: If the welding time is too long or the welding energy too low, pores can form, as can oxidation of the weld pool. A contaminated base material surface or moistened ceramic rings can also contribute to the formation of pores.

Drawn arc stud welding is a common, reliable and versatile process in stud welding technology that creates secure connections and is suitable for many areas of application. Nevertheless, it is important to recognise potential sources of error at an early stage and counteract them in order to prevent unsatisfactory welding work.

Do you have any questions about drawn arc stud welding?

Then contact us, we will be happy to help you and answer your questions!

Published on

Written by

Markus Neuse

Category

welding

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