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Electrode expertise

In orbital welding, the quality of the tungsten electrode directly impacts the quality of the weld

Dairy products and aerospace components aren’t often placed in the same category, but when it comes to manufacturing them, they have a fair amount in common. They both rely on orbital welding and, therefore, both require similar welding consumables. In dairies around the world, orbital welding is required in the installation of cooling and heating pipes, and in the aerospace sector, orbital welding is required for producing fuel lines and other parts.

In both manufacturing environments, special emphasis is placed on the high quality and reproducibility of the welding seams to avoid deficiencies in the end product, which can carry consequential costs for rework or scrapped parts. The reproducibility of welding seams is also key for manufacturers in the interest of occupational health and safety.

To achieve a highly repeatable process, the workpieces and welding equipment have to be considered, but so do the characteristics of the electrode itself. Its quality is decisive in the production of flawless welding seams.

The quality of welding electrodes depends on the consistency of their makeup as well as the way in which they are resharpened and reconditioned throughout their use.

In orbital welding, the welding head using arc welding technology is moved on a circular path around the round workpiece.

Orbital know-how

In orbital welding, a welding head using arc welding technology is moved on a circular path around a round or tubular workpiece. In this process, the operating point is protected against external influences by inert protective gases.

“Commonly, orbital welding is one of the final process steps in the assembly or welding of components,” says Dirk Kunze, CEO of Orbitalservice GmbH. “The welding equipment and processes have been continuously improved over the past 50 years. Yet there has been no further development of knowledge regarding the influence on the process caused by the electrodes that are used. But truly, the only way to attain a satisfactory result is to optimize the tungsten electrode.”

Orbitalservice, a producer of orbital welding products, works in partnership with Wolfram Industrie GmbH, a producer of tungsten electrodes. Orbitalservice has worked with Wolfram since the company was founded in 2008. Thanks to their collaboration, orbital welding customers can obtain qualified know-how regarding the handling of one of the most important TIG welding components: the tungsten electrode.

The advice the companies offer on tungsten electrodes applies to anyone that does orbital welding. Any experienced tungsten electrode manufacturer would provide similar services and advice.

Evaluate to optimize

While tungsten electrodes are frequently used in welding, their structure, sharpening and alloy have a previously underestimated influence on consistent results in TIG welding. A reproducible welding seam is only possible if the electrode quality and geometry are outstanding.

Therefore, equipment users should follow a service program like the one offered by Wolfram that includes an evaluation of the process steps and the material to be welded to guarantee that a tungsten electrode is suitable for the respective requirements. The analysis is done through metallurgical investigations and process diagnoses using spectral analyses and measuring equipment, such as a scanning electron microscope.

Wolfram also makes recommendations for aspects of the welding process that may create a secondary impact on the electrode, such as proper ergonomics for cleanroom applications or use on construction sites. Unsurprisingly, the challenges vary widely depending on the user. In some cases, possibilities for process optimization are relatively low in the case of customers with tight, established processes.

In orbital welding, the operating point is protected against external influences by inert protective gases.

“When a structural component for aircraft is fabricated, its electrode geometry is a fixed parameter that cannot change,” explains Matthias Schaffitz, application engineer for welding processes at Wolfram. “But, for newly developed production processes, we can provide customers with an electrode that meets their requirements in the initial delivery. Here, the sharpening, alloy and tip geometry are tailored precisely to the application.”

Reconditioning issues

Electrodes are always subject to wear in the welding process over time and, therefore, require reconditioning. To ensure optimum results, after-sales service for electrode users is recommended.

“Welding is highly complex work and demands great concentration,” Schaffitz says. “The welder is often under quality and time pressure. That is why resharpening the electrode is a particularly unpopular ancillary task. It requires the welder to interrupt the production process and leave the workstation.”

In order to continue using the electrode for TIG welding, the tip of the tungsten electrode first has to be cut off with a diamond saw, and then, the region that is free of contamination must be freshly sharpened. Small and mid-size companies often lack the corresponding special equipment for resharpening the electrodes to high quality.

Thus, welding operations can significantly reduce strain on their personnel by outsourcing resharpening to the specialists. Product quality is improved at the same time because the welder can focus on their core task.

Orbitalservice GmbH manufactures orbital welding equipment for various industries, such as automotive and aerospace sectors.

R&D

To continue to drive their research and development efforts, Wolfram and Orbitalservice collaborate with the University of Bern. They have jointly investigated the behavior of tungsten electrodes with various gas mixtures and alloys. This wealth of experience also benefits customers in the long term because it is incorporated directly into service and support.

Additionally, Wolfram builds awareness by sharing the company’s accumulated knowledge about tungsten electrodes and their benefits. In training, the experts use sample electrodes to illustrate the differences in quality of industrially sharpened tungsten electrodes versus supposedly more cost-effective versions.

“Our goal is to place a greater emphasis on electrode quality and for the welder to find the optimum tool for his work,” Schaffitz says. “That is a gain for everyone – for us as the electrode manufacturer, but also for the user whose products can be delivered in perfect condition, and at the end of the supply chain naturally also for the end customer.”

Orbitalservice GmbH
Wolfram Industrie GmbH

 

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