Although orbital welding technology is not new, it continues to evolve, becoming more powerful and versatile, especially when it comes to pipe welding.An interview with Tom Hammer, a skilled welder of Axenics in Middleton, Massachusetts, reveals the many ways this technique can be used to solve difficult welding problems.Image courtesy of Axenics
Orbital welding has been around for about 60 years, adding automation to the GMAW process.This is a reliable, practical method of performing multiple welds, although some OEMs and manufacturers have not yet used the power of orbital welders, relying on hand welding or other strategies to join metal tubing.
The principles of orbital welding have been around for decades, but the capabilities of the new orbital welders make them a more powerful tool in a welder’s toolkit, as many now have “smart” features to make it easier to program and process prior to actual welding. Start with quick, precise adjustments to ensure consistent, pure and reliable weldments.
Axenics’ team of welders in Middleton, Massachusetts, is a contract component manufacturer that guides many of its customers in orbital welding practices if the right elements exist for the job.
“Where possible, we wanted to eliminate the human element in welding, as orbital welders generally produce higher quality welds,” says Tom Hammer, a skilled welder at Axenics.
Although the earliest welding was performed 2000 years ago, modern welding is an extremely advanced process that is integral to other modern technologies and processes.For example, orbital welding can be used to create the high-purity piping systems used to produce semiconductor wafers that go into basically all electronics today.
One of Axenics’ customers is part of this supply chain.It sought out a contract manufacturer to help expand its production capacity, specifically creating and installing clean stainless steel channels that allow gases to pass through the wafer fabrication process.
While orbital welding units and rotary tables with torch clamps are available for most tubular jobs at Axenics, these do not preclude occasional hand welding.
Hammer and the welding team reviewed the customer’s requirements and asked questions, taking into account cost and time factors:
The rotary enclosed orbital welders used by Hammer are Swagelok M200 and Arc Machines Model 207A.They can hold 1/16 to 4 inch tubing.
“Microheads allow us to get into very tight places,” he said.“One limitation of orbital welding is whether we have a head that fits a specific joint. But today, you can also wrap a chain around the pipe you’re welding. The welder can go over the chain, and there’s basically no limit to the size of welds you can perform. . I’ve seen some setups that do welding on 20″. Pipe. It’s impressive what these machines can do today.”
Considering the purity requirements, the number of welds required, and the thin wall thickness, orbital welding is a smart choice for this type of project.For airflow process control piping work, Hammer frequently welds on 316L stainless steel.
“That’s when it gets really subtle. We’re talking about welding on paper thin metal. With hand welding, the slightest adjustment can break the weld. That’s why we like to use an orbital weld head, where we can Dial in each part of the tube and make it perfect before putting the part in it. We turn down the power to a specific amount so we know when we put the part in there it will be perfect. By hand , the change is done by eye, and if we pedal too much, it can penetrate directly through the material.”
The job consists of hundreds of welds that must be identical.The orbital welder used for this job makes a weld in three minutes; when Hammer is performing at top speed, he can manually weld the same stainless steel tube in about a minute.
“However, the machine isn’t slowing down. You run it at max speed first thing in the morning, and by the end of the day, it’s still running at max speed,” Hammer said. “I run it at max speed first thing in the morning, but In the end, that’s not the case.”
Preventing contaminants from entering stainless steel tubing is critical, which is why high-purity soldering in the semiconductor industry is often performed in a cleanroom, a controlled environment that prevents contaminants from entering the soldered area.
Hammer uses the same pre-sharpened tungsten in his hand torches that he uses in the Orbiter.While pure argon provides external and internal purging in manual and orbital welding, welding by orbital machines also benefits from being performed in an enclosed space.When the tungsten comes out, the shell fills with gas and protects the weld from oxidation.When using a hand torch, the gas is only blown to one side of the tube that is currently being welded.
Orbital welds are generally cleaner because the gas covers the tube longer.Once welding begins, argon provides protection until the welder is sure the weld is cold enough.
Axenics works with a number of alternative energy customers who manufacture the hydrogen fuel cells that power a variety of vehicles.For example, some forklifts built for indoor use rely on hydrogen fuel cells to prevent chemical byproducts from destroying edible stocks.The only by-product of a hydrogen fuel cell is water.
One of the customers had many of the same requirements as a semiconductor manufacturer, such as weld purity and consistency.It wants to use 321 stainless steel for thin wall welding.However, the work was prototyping a manifold with multiple valve banks, each protruding in a different direction, leaving little room for welding.
An orbital welder suitable for the job costs about $2,000, and it can be used to make a small number of parts, with an estimated cost of $250.It doesn’t make sense financially.However, Hammer has a solution that combines manual and orbital welding techniques.
“In this case, I would use a rotary table,” says Hammer.”It’s actually the same action as an orbital welder, but you’re spinning the tube, not the tungsten electrode around the tube. I use my hand torch, but I can hold my torch in place with a vise Positioned so it’s hands-free so the weld won’t be damaged by human hand shaking or shaking. This eliminates a lot of the human error factor. It’s not as perfect as orbital welding because it’s not in an enclosed environment, but this type of The welding can be done in a clean room environment to eliminate contaminants.”
While orbital welding technology offers purity and repeatability, Hammer and his fellow welders know that weld integrity is critical to preventing downtime due to weld failures.The company uses non-destructive testing (NDT), and sometimes destructive testing, for all orbital welds.
“Every weld we make is visually confirmed,” says Hammer.“Afterwards, the welds are tested with a helium spectrometer. Depending on the specification or customer requirements, some welds are radiographically tested. Destructive testing is also an option.”
Destructive testing may include tensile strength testing to determine the ultimate tensile strength of the weld.To measure the maximum stress a weld on a material such as 316L stainless steel can withstand before failure, the test stretches and stretches the metal to its breaking point.
Welds by alternative energy customers are sometimes subjected to ultrasonic nondestructive testing on component weldments of three-channel heat exchanger hydrogen fuel cells used in alternative energy machinery and vehicles.
“This is a critical test because most of the components we ship have potentially hazardous gases passing through them. It’s very important to us and our customers that the stainless steel is flawless, with zero leak points,” says Hammer.
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