Undertaking the challenge of tube fabrication

A company specializing in aircraft tube fabricating reaches a whole new stratosphere

The FABRICATOR July 2012
July 16, 2012
By: Dan Davis

The field of aerospace tube fabricating is one marked by difficult-to-form materials and very tight tolerances. As a result, not too many shops are involved in the business. Tube Specialties, Tempe, Ariz., however, has emerged as a go-to shop for this type of challenging work.

Undertaking the challenge of tube fabrication - TheFabricator.com

Figure 1: Tube Specialties Inc. has the capabilities to bend tube from 0.03125 in. to 5 in. OD. For the large orders, it relies on six CNC tube benders.

Tube Specialties Inc., Tempe, Ariz., is a manufacturer of custom tube assemblies and part of a small, talented fraternity—suppliers to aerospace companies.

These tube fabricators are the survivors of several economic downturns and the OEMs’ desires to create a smaller, more manageable supply base. Owner John Costabile, who has run a tube business since 1973, said he knows of similar shops in California and a handful of others on the East Coast, but for the most part it’s not a large subset of the metal manufacturing economy.

When you consider what it takes to become a certified supplier for the large aerospace OEMs, you understand why these types of shops aren’t found in every industrial park in the U.S. It’s a complicated business.

Jumping Into the Tube Business

“Everything that I know about tube fabricating I taught myself. I had an advantage because I was a designer, an engineer, a tool- and diemaker, a machinist, and an inventor. I found ways to do things, and even to this day, there are some things I do that nobody knows. They are trade secrets,” Costabile said.

He and his brothers, Ben and Ernst, started in metal manufacturing not with tube, but with stampings. They opened Precision Die and Stamping in 1963, in the years before Phoenix became the sprawling metropolis it is today.

Costabile began his tube education about the same time as the company was being asked to quote jobs for tube assemblies. He couldn’t find anyone to outsource the tube fabrication work to, so he decided to build the machines to do the work himself.

When the company received a RFQ for machined fittings on the ends of tubes, Costabile purchased machinery to create those end forms. As a result of this focus on specialized fabrication, Costabile’s tube fabricating business was growing rapidly.

Ten years after starting the stamping business, Costabile took control of all the tube-related work and launched Tube Specialties. The business moved to Tempe in 1976 and now resides in a modern facility following a move in 2008. Following an expansion, the building is now 65,000 square feet.

The company, which employs 96, tackles nearly all aspects of tube fabricating and assembly. It bends, end-forms, heat-treats, machines, welds, brazes, swages, and pressure-tests tubes and tube assemblies. About the only manufacturing operations the company can’t perform in-house are activities like anodizing and plating.

A one-stop shop is hardly unique in metal fabricating, but a shop that focuses primarily on aerospace work is. This isn’t a typical job shop.

Undertaking the challenge of tube fabrication - TheFabricator.com

Figure 2: An extensive collection of machining tools gives the fabricator flexibility. For example, a trimming job can be done on an EDM machine, with an abrasive cutoff wheel, or possibly with a specialty machine that has been built just for the job.

Making the Intricate Bends

Most of the tube bending jobs for aerospace customers are highly specialized. People aren’t throwing tubes into clamps and applying pressure until they think the bend is complete.

So just how does a fabricator describe working on aerospace jobs? Concerning bending, for example, Costabile said several factors have to be addressed:

  • Minimizing wall thinning Avoiding wrinkles
  • Bending tight radii, such as a 0.50-in. bend on a 0.50-in. centerline radius in a 0.50-in. tube
  • Working with a tube that requires multiple bends

Surprisingly, most of these complex jobs aren’t headed for a CNC machine, which is just the opposite of what would happen in the 2-D sheet metal world. Because many of these jobs are low-volume, Tube Specialties simply can’t afford the time to build the special fixturing that would be necessary to accommodate tubes that might have multiple bends and radii.

“You don’t want to spend three or four hours to set up a bender to do a short run of tubing,” Costabile said.

That’s where the years of experience come into play. These complex jobs are done on manual and powered bending units using tooling built in-house. The only items not made regularly by the company’s tooling department are ball mandrels and wiper dies.

To illustrate the point of why a complex part needs to be hand-bent, Costabile described one of his company’s more complicated parts: a flattened tube with nine bends, a rounded edge, and a couple of fittings attached to it. This part has to be exact because it holds a computing device and has to accommodate coolant flow. Also, the tube assembly is cast in aluminum and ultimately placed in the nose cone of a missile. Let’s just say there is no room for error.

To make those multiple bends, the fixturing has to be stacked. When the first bend is made, the fixture holds the part precisely to allow the next bend to be made. Each spec-replicating bend can take place only if the clamp is placed on the previous perfect radius.

“So whether we build one or a thousand, they will come out exactly alike,” Costabile said.

For those job volumes that might be closer to 1,000 than one, the CNC tube benders make the most sense (see Figure 1). The company’s six Eaton Leonard CNC tube benders and two Eaton Leonard Laservision Optima XP measurement and inspection devices help to keep these high-volume jobs within expected tolerances.

For instance, if an operator is working with specialty alloys like INCONEL®, he or she can expect major springback. So after the first bend on one of the CNC machines, the operator can take the tube over to one of the measurement devices and use the noncontact laser probe to get an accurate reading of the tube’s dimensions. If the bent part shape deviates from the specs included in the master file, the equipment feeds corrective bend instructions to the CNC tube bender. The operator then places the tube in the equipment and proceeds with another bend. This can result in an in-spec part or more back-and-forth between the tube data center and the tube bender. When the bent tube meets final specs, the CNC bender is then ready to produce quality parts without any further manual intervention. The CNC knows what is necessary to battle any springback issues.

Working With Hard-to-Work-With Tube

Exotic alloys represent just a sample of the material that Tube Specialties works with. It also works with a wide assortment of aluminum and titanium alloys. For the most part, however, stainless steels—primarily 347, 321, and 304—occupy a majority of the company’s time. After all, aerospace companies aren’t interested in materials that are susceptible to corrosion.

Costabile said some of these materials can be especially challenging—particularly some of the titanium alloys.

“If you design everything properly, have the right kind of tools, and have the experience, everything seems to go very well.”

Tube fabricating requires plenty of research and development, and that’s where Costabile likes to spend his time. What’s the best way to bend a tube? What sort of tooling will be necessary? Will the fixture deliver the expected tolerances? If the initial sample lot doesn’t turn out acceptable parts, what needs to be tweaked? Costabile and his team love to figure out how to get the job done.

Finding the Right Talent

Tube Specialties is like every shop in the sense that it also has difficulty finding the right people for the job. However, the tube fabricator is looking for a specific skill set, and not too many community colleges are offering in-depth courses in tube bending theory.

Costabile said it wasn’t that hard to find people in his area comfortable with CNC machines (see Figure 2)—pushing the right buttons and measuring fabrications. It’s locating the personnel who have experience in doing setups for the CNC machines or actually programming the machines that is more difficult. Finding the people with experience in working with complex fabrications and knowing what it takes to hold tolerances on a multibend or -radii part is very difficult.

“We just take young people that have some mechanical aptitude—they usually like to work on cars and have good mathematical experience—and we train them,” Costabile said.

Workers from other facilities sometimes can be hard to retrain, according to Costabile, because they are used to approaching their jobs in a certain way. They aren’t always open to new work processes.

“We like to train our new employees here because then they do things the way we want them done,” he said.

Having to Do Things a Certain Way

Tube Specialties really doesn’t have a lot of leeway in how it approaches quality control. All of its certifications dictate the steps that have to be taken to produce quality parts. Certifications, such as AS9100 Rev C, which is specific to Boeing, encourage organizations to adopt specific kinds of problem-solving methods and collect business and manufacturing statistics to overcome hurdles and improve processes and products.

But certification doesn’t end there. Nadcap, formerly known as the National Aerospace and Defense Contractors Accreditation Program, provides independent certification of manufacturing processes for its member companies. Conducted through the Performance Review Institute in Warrendale, Pa., these certifications give OEMs a level of assurance that companies in the supply chain can deliver on what’s being promised. From Tube Specialties’ perspective, this means brazing and fusion welding, furnace brazing and heat treating, and radiographic and penetrant inspection. The tube fabricator also meets American Welding Society D17.1 standards for fusion welding for aerospace applications and SAE International’s AMS 2664/5 standards for silver brazing through the use of induction or torch.

Of course, you can’t forget about individual company certifications. Tube Specialties is a longtime supplier to Honeywell Aerospace and is certified to gas tungsten arc weld titanium parts and produce orbital-welded parts for the systems provider.

For all of these certifications, the company is audited regularly. Costabile said the effort to stay on top of and update work processes is worth it because quality parts are typically the result. Also, a passing report card from an auditor often means that the next audit might not take place for a year, instead of the traditional six months.

But don’t think that meeting some of these quality demands is just a matter of following procedural steps. For one particular tube fabrication for a defense project, a Tube Specialties quality inspector has to spend about eight hours checking it. Now that part requires 17 welds, and each has to pass an X-ray penetration check. That just happens to be the nature of the work.

Luckily, after almost 50 years in the tube fabricating business, nothing phases Costabile.

“After all these years, I’ve seen just about everything,” he said.

Dan Davis

Dan Davis

FMA Communications Inc.
2135 Point Blvd
Elgin, IL 60123
Phone: 815-227-8281

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The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.

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