Top quality, shorter production times and reliable documentation
Orbital welding is gaining importance in modern production
Orbital welding is a fully mechanical protective gas welding process where electrodes – including the arc – are passed 360 degrees around tubular workpieces. The advantages of this are obvious: high process reliability and reproducibility, short production times, consistently high weld seam quality, easy handling of the process and comprehensive documentation.
It’s in industries where thin-walled tubes are welded with consistently high quality that the advantages of orbital welding are best utilized. This includes semi-conductor production, food technology, aerospace, pharmaceuticals and the chemical industry, as well as heat exchanger production – in other words, wherever aggressive and corrosive media or high process pressures require leak-free piping and a high level of hygiene.
Due to more stringent requirements, an increase in quality awareness and a shortage of skilled workers, the demand for orbital welding systems has been growing continuously for years. An increasing duty to provide documentation is also playing its part, as this process meets international requirements thanks to intelligent welding power supplies and defined processes.
An orbital welding system is comprised of a power supply with a controller, a cooling unit and a weld head with a hose assembly for supplying the control signals, protective gas, cooling medium and weld current. A differentiation is made between closed and open weld head types.
Orbital weld head types
For thin-walled tubes – e.g. those made of stainless steel or titanium – up to about 170 mm (6.693”) in diameter and with wall thicknesses of 0.3 to approx. 3.5 mm (0.012” - 0.138”), closed heads and the tungsten inert gas welding process (TIG) are used.
The welding process is carried out under consistent conditions in the orbital weld head here, which completely surrounds the tube. In a constant protective gas atmosphere, a TIG electrode is passed around the tube by the weld head rotor in a defined way. The tubes to be welded are welded together bluntly (no gap or offset) with an arc. This requires good seam preparation: tubes cut at a right angle, a consistently planar bevel and a metallically clean and burr-free surface can be achieved using state-of-the-art pipe cutting and beveling machines.
The dimensions of the weld heads became more and more compact over the course of development to the point where welding can even be carried out in restricted assembly conditions today. Closed weld heads are currently available for tube diameters from 3 to 170 mm (0.118” - 6.693”).
For thicker walls and pipe diameters up to 270 mm (10.63”), open orbital weld tongs are frequently used. Thanks to the open arc, it is possible to feed consumables to the weld pool in the form of cold wire, which is not the case with closed systems. Multi-layer welding for thicker walls is also possible.
Easy operation and fatigue-free working
Handling of the welding process is easy, as seen in this example with closed weld heads: The head is hinged open, and the two tubes to be welded are placed inside with no gap between them. The tube joint is aligned with the electrode. After closing the head and starting the process, the liquid-cooled head is reliably flooded with argon gas. Once the arc is ignited, the electrode cleanly passes around the workpiece. Discoloration is avoided thanks to the constant protective gas cover. Consistently high-quality welding is carried out automatically with no offset or gap.
Intelligent power supplies enable access to projects and parameters
Intelligent welding power supplies guarantee a high level of operating reliability during the process. By entering workpiece-dependent parameters like the material, diameter and wall thickness, the power supply automatically determines the suitable currents, pulse times, welding speeds and, in the case of open weld heads, the required wire quantity. The connected head type is detected automatically so that the operator only has to call up the corresponding welding program and then start the welding process. Working with this system is so easy and reliable that even less-qualified operators can achieve optimum welding results in batch production under consistent general conditions.
Naturally, seamless data re¬cording and backup in the customer’s LAN is possible with modern welding power supplies. Using the integrated LAN interface, it’s possible to incorporate the Orbimat 180 SW into the customer’s network, for example. Interface communication with various different customer systems is possible using the IoT/Industry 4.0-compliant MQTT protocol. Operators, planning engineers and QA experts have access to projects and data at all times, making it possible to keep track of the entire welding process directly. All welding data and programs for each individual welding process can be called up and documented in full, analyzed and used & optimized for future welding processes. This way, production sequences can be planned better and are also safer and less time-consuming.
All data can also be saved in the internal system memory or on an external USB data medium. In addition to data such as tube diameters, material quality and wall thickness, the customer can also specify additional parameters, such as the operator name, workpiece batch numbers, the position number of the weld seam, the pipeline isometry number etc.