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Worked Hard, Worn Out Quickly?
Contact tube – the Achilles heel of modern welding technology

Stromkontaktdüse komplett und aufgeschnitten

In MIG, MAG or submerged arc welding systems, one component is subjected to particularly high stresses: the contact tube. Because it must possess high electrical and thermal conductivity, it is usually made of pure copper (electrolytic copper) or electrobronze. Unfortunately, such materials do not exhibit sufficient temperature resistance, although electrobronzes are somewhat more resistant than electrolytic copper. The rapid wear of contact tubes leads to increased downtime, as the parts have to be replaced too often.

What exactly does a contact tip do?

The contact tube is the last part of the welding wire guide system in arc welding equipment (e.g., MAG, MIG or submerged arc welding).

In these high-performance welding processes, the welding wire (i.e., the filler metal) is fed through the contact tube to the workpiece by means of a wire feeder. The contact tube and the wire function as an electrode. In order to produce high-quality weld seams, high electrical conductivity and excellent contact formation are required. In order to keep the contact resistance as small as possible, the bore of the contact tube can therefore only be slightly larger than the diameter of the welding wire.

Rapid wear seems inevitable

In combination with the high temperatures during the welding process, the constant friction of the welding wire causes rapid wear on the bore of the contact tube. When too much play develops between the tube and the wire, the quality of the weld seam decreases. Therefore, the contact tube has to be replaced quite often. Electrolytic copper, which conducts very well, wears out particularly quickly; electrobronzes such as CuCr1Zr last a little longer, but their conductivity is much lower.

Soft shell – hard core: Composite tube reduces wear

As a manufacturer of special copper-based high-temperature materials, CEP Freiberg has developed a composite system called CEP DISCUP®+Cu, which combines the conductivity of electrolytic copper with a wear resistance above that of electrobronzes. A composite tube is created with the help of a special forming process – hydrostatic extrusion: A highly conductive shell made of electrolytic copper, with a wear-resistant core made of CEP DISCUP®. The latter is an ODS copper and a product of powder metallurgy. It obtains its wear resistance through precipitation hardening.

With just a few processing steps, the semi-finished composite tube is turned into finished contact tubes. They can be used in all common MAG, MIG and arc welding systems – i.e., in the Binzel, Cloos, Dinse and Fronius systems – and many more.

The patented contact tubes made of CEP DISCUP®+Cu thus exhibit a combination of properties that typical metals and metal alloys cannot match: conductivity and temperature resistance (‘CT’ properties). They last up to five times longer than those made of electrobronze.

If you would like to order contact tubes made of CEP DISCUP®+Cu or composite tubes as semi-finished products, please send us a message.