African Fusion’s Peter Middleton talks to country business developer, Eduardo Poblete of Air Liquide Welding France about Oerlikon seamless cored wires for flux-cored (FCAW) and submerged arc (SAW) welding.
Oerlikon first patented seamless cored wire technology back in 1966, a technology that has come to be globally known as tubular flux-cored wire technology. “There are still only two broad groups of flux-cored technologies today, which are all based on either Oerlikon’s seamless patent or Chemetron’s open seam manufacturing technology,” says Poblete, adding that the original patents have now lapsed, so many different cored wire manufacturers use these technologies.
The production of Oerlikon tubular (seamless) flux-cored wires begins with the welding, using an HF process, of tube from flat sheet consumable material. The sealed tube is annealed before the blended, agglomerated and heat treated flux constituents are added. After further annealing, the tube is drawn down to the wire size required, surface coated with copper and then spooled onto reels or drums.
The end result is a damage-resistant cored wire with excellent feedability. “Chemetron’s folded seam technology does not produce wire solid enough to remain round. Our tubular technology produced perfectly round wire that is as robust as solid wire. This results in easy wire feeding with no risk of the drive rollers causing the seam to open,” says Poblete.
In addition, the final mix and the flux constituents are tightly sealed into the wire, making it very similar in terms of physical characteristics to solid wire. The spiralling, bending or torsion effects that can cause seamed wires to open are not a problem. Feeding through extended torch lengths becomes possible and, due to the smooth copper coated surface, the electrical contact and arc stability are much better than seamed cored wires, resulting in a tight arc with excellent metal transfer.
Due to the heat treatment of the final flux mix immediately before filling the tubes, Oerlikon can guarantee low hydrogen levels in the final weld metal and the sealed outer sheath prevents moisture ingress after manufacture. “This means that our tubular technology can be stored and packaged as easily as solid wires. There is no need for baking or wire reconditioning processes to remove moisture before use,” Poblete adds.
From a metallurgical perspective, Oerlikon’s patented high-precision filling process results in good homogeneity and compositional accuracy across the full length of the wire. “Compared to solid wires, tubular technology offers better control of the weld metal composition and up to 30% better deposition rates.
Along with the feeding advantages, these features make tubular technology ideal for automatic welding applications such as those used at car plants and shipyards.
HD flux-cored wires
As well as offering high deposition rates Oerlikon tubular flux-cored wires have long been renowned for their all-positional welding capability ...