Plasma, an Efficient Way to Cut Tube, Pipe or Structural Components

May/June, 2011

YOU CAN ALSO LISTEN TO THIS ARTICLE

When square tubes, I-beams, round tubes or even oddly-shaped structural steels need to be cut fast, precisely and efficiently, most companies have two choices: either a laser or plasma cutter.

Each of these machines has its benefits, but for a lower cost solution, the plasma tube/pipe-cutting machine could be the best one for flexibility and productivity.

Controlled Automation’s Revolution Coper offers a unique design and some interesting features. “We are a bit different than a lot of the other manufacturers out there,” says Kris Sikes, sales manager for the company.

“First off, we design and build these machines ourselves. Our design uses a mechanical six-axis robot to handle the plasma torch and for axial movement. However, it’s not a robot from a vendor such as MotoMan or ABB,but it does compete against plasma tube/pipe equipment that also uses robots.

“Ours also has a unique feature: a tool changer. It can automatically pick a cutting head. For instance it can select a plasma head, or it can pick another tool such as an oxy/acetylene cutting head. Or you can even pick up an ink jet marker to write instructions on the part that’s being cut. You can do all these operations using just one machine.”

Controlled Automation’s Revolution Coper uses an automated material feed where the material isn’t pinched. Material is brought in on a powered roller conveyor, stops in position and is clamped. It isn’t shuttled back and forth for the cutting operation.
Once the material is clamped, it’s measured using a laser. Then the robot will contact the material to sense its position, eliminating touching it every time it cuts a feature.

With this setup and tool change capability, Sikes says, “You’re looking at a machine that is twice as fast as a robotic plasma cutting machine, as most robotic plasma cutters have to use either arc voltage to find the cutting stand-off or actually touch the material every time it starts a cut. We eliminate this process altogether.”

Cut sizes

The Revolution Coper will process cut tube or pipe, structural I-beams, flat bar or angled material up to 48 in. wide. On the minimum size, “We could probably go down to a 3-in. diameter or width, but most people that use our equipment don’t need that small of a cutting capability. Our smallest machine will go down to a 1.25-in. diameter or width,” remarks Sikes.

Sikes notes that material cut length is “as long as you want to go. And we say the accuracy of this machine is +/- 1/32 of an inch over about 80 ft.”

The coper uses a probe system that is basically like a rack and pinion he mentions. It follows the end of the material. When a tube, pipe or other structure is loaded onto the roller conveyor, a probe comes into contact with the end of the material.

Therefore the machine knows where the end of the material is at all times while it pushes against its back to move it. Once the material enters the machine, it passes by the laser measuring system, so it knows where the material begins.

“In the future, we’ll be adding more tools to the tool changer. Last year we introduced an ink jet marker for it, and this year we’ll be adding another style of marking system. We can also do marking on whatever we’re cutting to indicate where stiffeners need to be welded to the material, which helps for layouts for downstream welding,” he remarks.

Another benefit of the Revolution Coper is the ability to change tools to get into tight cutting areas. If a plasma cutting head is being used, often the barrel of the plasma torch is very thick and can’t get into some types of I-beams or oddball structural members remarks Sikes. “In this situation, the machine can change heads to an oxy/acetylene one to get the job done, since it’s smaller in size.

“The big difference with our equipment is that everything that’s used to build it comes from off-the-shelf parts. And it’s all from one vendor. We supply the controls and the software and the machine manufacturing is all done in-house. Our customer doesn’t have to rely on a robot manufacturer along with a different software vendor and computer vendor. If a customer has a problem with our system, we take care of everything. He won’t have a controller manufacturer saying there’s a problem with the robot and vice versa.”

Controlled Automation’s computers are off-the-shelf PC controllers using Windows 7 software. “Any local computer shop will have the parts to fix the machine. We’ve also designed the equipment that if parts are needed, they’re very simple to replace.”

The Revolution Coper has a 48-in. by 24-in.-material cutting window. It uses both plasma and oxy-fuel for cutting. The maximum plate thickness it can cut using plasma is 2 inches and 6 inches with oxy-fuel. The maximum material weight it can handle is 1,000 lb. per ft.

2D to 3D

MultiCam

Take MultiCam’s standard plasma 2-D cutting system, add a rotary axis, and you have a versatile machine for cutting tube, pipe or any material that the chucks can hold.

“What we have is the capability to handle a 24-in. maximum diameter by using the Y-axis on our standard plasma machine,” says Craig Brooks, MultiCam plasma product manager. “We can go to a minimum diameter of 5 in. or even less and can cut a thickness of up to 1/2 in. to cut square tube; it’s just positioned on the bed, and the Z-axis height control will allow the cutting head to elevate to cut the features on the pipe and along its length.”

With the addition of an optional rotary axis, a tube or pipe can be placed in the chucks along the Y axis. Then the cutting torch will move along its Z axis to position itself over the tube or pipe. The part will rotate and also move along the Y axis so that the torch can cut whatever features are needed.

An arc-voltage system is used at the cutting area to maintain the proper torch height over the material. It does this by monitoring the voltage being used to measure its standoff.

“We also have a five-axis system that will allow the rotation of the torch itself,” says Brooks. This will allow the torch to do bevel cuts. Our rotating tube/pipe option can be purchased on our medium to larger plasma 3000 to 6000 series machines.”

When a standard plasma machine can’t cut it

North American Cutting Systems Inc.

North American Cutting Systems Inc. (NACS) in association with strategic partners, offers several standard plasma cutting systems for both 2-D and 3-D work, but it also specializes in custom cutting systems for non-standard shapes not found in round-pipe systems.

“Even though there are exceptions to this rule, most pipe machines are designed for cutting large round pipe with generous tolerances, “says John E Zuehlke, president. “Many of these will not do thin-wall, small-diameter tubing. They really aren’t tube machines. They are plasma/oxyfuel pipe cutting machines. They weren’t designed for extreme accuracy that’s often needed for tube.”

NACS supplies equipment that can cut round, square, rectangular pipe or tube, or any shape that can be imagined. “We even delivered a machine to cut a very difficult airfoil shape used in the aviation industry,” notes Zuehlke.

“On small aircraft you have a strut that goes from the wing down to the lower body to support the wing. This strut has the shape of an airfoil like the wing. When this airfoil shape is being cut and rotates around, you come to a point where you have to instantly reverse direction with your plasma cutter which is difficult to do. A specialty machine we designed can easily cut this airfoil shape along with any other type of shape.”

To move the material through the plasma cutting process it’s pushed from the rear. This was because of its oddball shape. A custom chuck was designed that could handle any shape up to 4-in. by 6-in. The user would just take a block of aluminum and have the shape cut out using a wire EDM machine.

Then the aluminum block is split in half and clamps around the part using an air cylinder. This gives the user a custom set of jaws that are inexpensive and would grab the shape precisely says Zuehlke.

The plasma’s torch head follows the part’s shape at a controlled distance through the use of an arc-voltage control. However an arc-voltage control would not work very well for an airfoil when it’s flipped over to cut the opposite side. To accomplish this Zuehlke added a Renishaw probe to the machine. Then the operator would place the airfoil or part in the chuck, slowly rotate it, and the probe would be used to program the CNC control for cutting. When the arc-voltage control is turned off, the Z axis would then be controlled by the CNC programmed by the probe. This machine can handle a tube with a minimum ½ in. diameter.

Dual or single-head systems

Vernon Tool

Vernon Tool develops and manufactures both oxy/acetylene and plasma tube and pipe profiling equipment. They’ve even built dual-head machines. “With a dual-head attachment, pipe fabricators can perform both straight cutting and beveling work at the same time,” says Jeff Bennett, managing director.

“The dual-head attachment allows end users to cut the end of the first pipe and the beginning of a second pipe simultaneously, essentially doubling productivity.”

What’s unique about Vernon Tool’s MPM Pipe Cutting and Profiling Models is that they are a roller-bed style machine with built-in conveyors for material handling. This means that Vernon machines do not require cranes and fork lifts for loading and unloading.

“Any fabricator who processes pipe knows that handling 20-ft. and 40-ft. pipe accounts for the majority of a cutting operation,” notes Bennett. “From the operating panel, a single operator can load the machine, perform the cut and unload the machine. The next pipe is loaded in the machine in seconds.”

Cutting capability ranges from a 1-in. diameter pipe to 84-in. Material thickness is virtually unlimited, as it’s based more on the part’s weight. With a modular design that can accommodate increased lengths, Vernon Tool’s machines are available from a 10-ft. length up to 60-ft. in 10-ft. increments.

“Our combination roller-bed/conveyor design provides integrated material handling, and this is key to efficient pipe cutting operations,” Bennett remarks. “Our end users report productivity increases of up to 300 percent.”

Vernon machines range from cost-effective 1-axis mechanized machines to more sophisticated 2-, 4- and 5-axes CNC controlled machines. These allow fabricators to process complex bevels, miters, saddles, multiple intersections and mid-section holes.

Another important feature Bennett mentions is the equipment’s ease of use. Another key feature is their software WinMPM. It’s a Windows-based, menu-driven operating system that is simple to use and doesn’t require highly trained individuals for programming or operating.

“In a matter of hours we can be up and running with a brand-new operator,” says Bennett. “Our interface software does all the calculations for the pipe cutting in the background. The operator just has to input the pipe size and dimensional data and select the type of cut. The software does the rest.”

Because their equipment is modular, the end user can put any type of power supplies on it, but primarily they offer Hypertherm. “We offer a range of plasma cutting solutions from entry level models to more capable, high-definition ones,” notes Bennett.
The equipment also offers plasma marking that can add serial numbers, labels, centerlines or dimensional marks on the pipe. “Marking hardware and software are seamlessly integrated into our equipment.” concludes Bennett.

Controlled Automation
MultiCam
North American Cutting Systems Inc.
Vernon Tool

Get industry news first
Subscribe to our magazines