Taking automated tube bending to the next level

This all-electric tube bender is configured for left- or right-hand bending of tubes up to 150 mm dia. BLM GROUP USA

Editor’s Note: This article appeared in the February 2023 issue of Canadian Fabricating & Welding.

Today’s tube benders are designed to meet the varying requirements of the many industries that use them. These machines are common across the aerospace, automotive, oil and gas, heating and air conditioning, refrigeration, and furniture manufacturing sectors.

“Most sectors are relatively strong right now, particularly oil and gas, but that may fade as the prices of oil and gas drop,” said Stuart Singleton, vice president, Unison Tube LLC, Danville, Va. “Aerospace is still in recovery mode post-pandemic. We are seeing lower capital investment in automotive due to the transition to electric vehicles and uncertainty around whether hydrogen vehicles will take off.”

There is a push to make things faster and better. With tube bending, like with many other processes, manufacturers are turning to automation.

Simple automation is helping fabricators take the human element and variability out of the process, particularly for loading/unloading. The loading process can be time consuming and requires an operator to orient the tube properly for the bend to be done correctly.

“There is a huge push towards automating various parts of the tube bending process,” said Robert Bowden, North American product manager - bender systems, BLM GROUP USA, Novi, Mich. “An operator responsible for loading a tube into a machine and taking a finished part out may not always work at a constant pace. By automating that process, it becomes more consistent, resulting in higher throughput, which is a huge advantage.”

During the loading process, if an operator is working with a welded tube, the orientation of the tube becomes important. The latest loading/unloading automation automatically detects where the seam is and orients the part for proper bending. This is also true for tube with precut features that need to be placed accurately. Automatically loading tube with these features means that an operator doesn’t need to think about orientation and can focus attention on more important aspects.

“Automation can be as simple as just having a robot that loads and unloads a part,” said Bowden. “Or it could be integrating multiple machines into a common cell. For example, a tube bending machine can be integrated into a larger process, where tubes are loaded into the machine with a robot. After they are bent, the tubes are taken to an inspection station, where the bend angles and lengths are checked for accuracy. From there, the robot offloads the tube to a rack—one rack for good parts and another for bad parts.”

Not all fabricators will have the need or capacity for a larger system. Automation can be used simply to process the tube after it’s bent. Some parts may require end finishing or trimming, which can easily be automated.

“It’s important to think it through, though,” said Singleton. “Fabricators should consider if having a cell produce everything is likely to cost significantly more than focusing on the processes responsible for producing 80% of parts. The 80-20 rule is a good starting point. The biggest error people make is usually around production volumes and the number of variants they want to automate.”

A bending machine is an expensive tool, and fabricators need to make sure they aren’t holding it up for menial tasks. Unison Tube LLC

Getting more done with less is a common trend in today’s manufacturing environment, which is why incorporating multiple processes into a single machine can be quite attractive. With standard-style tube benders, there generally isn’t too much that can be added to make these machines more efficient.

“However, a shear cutoff type system with a shear blade can be added to a tube bender,” said Bowden. “Tubes can often need trimming, and this is a good way to do it. This type of system is popular in the automotive sector with exhaust components.”

Integrating this system into a tube bender will save time, especially in components where there are only a few small bends. For example, an operator can load a standard 20-ft. length of material into the machine and have the machine bend the tube and then cut it off as it’s finished. A shear cutoff system eliminates the need to load and unload the parts.

Another way to incorporate additional features onto a machine is through specialized tooling. For example, with furniture applications, adding a punching process can be extremely helpful. Specialized tooling can apply holes for bolts and screws needed to attach seat, arm, and leg components of a chair.

“A bending machine is an expensive tool, and fabricators need to make sure they aren’t holding it up for menial tasks,” said Singleton. “If a shop has capacity in the machine, is making a limited set of parts, and the operator has other things to do whilst a part is being produced, then there is scope to incorporate multiple processes into a single workflow. But be careful not to tie yourself in knots. Generally, it is much better to complete multiple processes in a cell, with automation taking the parts through the cell, so that every process is done in parallel rather than in sequence.”

Some tube bending machines are designed to perform in a done-in-one fashion. For the most part, these systems can take material from a coil, straighten it, bend it, and perform trimming and end forming.

“These types of machines are typically used in the heating and air conditioning and refrigeration manufacturing industries,” said Bowden. “They are designed for bending copper or stainless steel tubing, where one or both ends require processing. We also can incorporate drilling, or a flow drill, as an option.”

Having a system with flow drilling is helpful because it basically extrudes the material inward, allowing for threads to be added and screws to be inserted.

“With these types of machines, fabricators are getting close to a completely finished part right off the machine,” said Bowden. “There generally isn’t a lot of secondary operations needed. All that is needed is an operator to manage the machine, with little interact needed. They even allow for one operator to manage multiple machines. It takes the labor required out as well, and with all processes rolled into one, it increases your productivity.”

Beyond the machine itself, there are many opportunities for improving tube bending operations.

While the bending process itself doesn’t change all that much, software can make the entire process more user friendly and ensure it functions properly. BLM GROUP USA

“True automatic setup for those companies wanting right-first-time bending to reduce scrap—especially those bending high-value materials—is something that still hasn’t been appreciated by everyone,” said Singleton. “People still focus on speed rather than the quality of the product—cutting 10 tubes, bending 10 tubes, selling 10 tubes. Imagine the noise that goes on within a business because it has to cut 11 or 12 tubes and it takes one or two tubes to set up. Then, if magically, it can be done in 10 tubes, what do you do with the other two? Or what if it takes 13 tubes in total and you need to issue a request for another tube? Consider how many people are involved in that type of process alone.”

As fabricators look to become more efficient and as flexible as possible, tube bending machine manufacturers have adapted the machines to meet everyday requirements.

Many of the latest machines offer both left-hand and right-hand bending, while some machines can be converted from one to the other.

“Having this feature is important when bending complex geometries,” said Robert Bowden, North American product manager – bender systems, BLM GROUP USA. “There are some parts that if you try to bend it on just a left-hand or right-hand machine, at some point, the tube will interact with the machine or the floor. The machine configuration doesn't allow you to fully bend that part. The left hand and right hand within process allows more complex geometry.”

This is especially important for furniture manufacturers, which make a lot of symmetrical and mirror shapes. For example, if a fabricator is producing a chair, there is often a left-hand side of a chair and a right-hand side of a chair that are basically identical, but mirror image. While fabricators can have no trouble producing one side of the chair, the other side of the chair can be problematic without the ability to switch over from left- to right-hand bending.

Fabricators that are making furniture, like chair frames, tend to bend parts in a kit, making all the components for one chair before moving onto the next rather than batching the same parts. The ability to switch between left- and right-hand bending with the touch of a button during the process eliminates setup changes and downtime.

“Having the ability to switch from the left hand to the right hand within a process is a huge advantage because the time it takes to mechanically change a machine over can sometimes be 45 minutes to an hour,” said Bowden. “This is not time well spent, and fabricators don't want to be doing that on a daily basis.”

The other advantage is that machines with this feature provide more tooling capabilities. Rather than using it for complex or mirror geometries, fabricators can mount multiple sets of tools to the machine. This means that the tools are already set up when needed, and the time needed for changeover is reduced.

“Customers that are more of a job shop, where they don't know what kind of part is going to come across their desk, they want to just have the most flexible machine possible,” said Bowden.

While the bending process itself doesn’t change all that much, software can make the entire process more user friendly and ensure it functions properly. The right software will provide the necessary functions to make an operator’s job that much easier.

“A lot of people think tube bending is like magic,” said Bowden. “But with the advances in software technology, you don’t have to know magic to be able to do it. Also, it does require skill and some background knowledge to get the most out of the process. Today’s machines are a lot more automated. With good software, fabricators can import a 3D file and within a few minutes, the machine will be bending a part. It takes a lot of those steps, like trying to figure out what pressure to use and where to set up the clamp die, out of the equation.”