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Picking the Right Plasma Cutting System

May/June, 2011

When purchasing a plasma system, there can be a considerable amount of confusion as to what a company really needs.

There is the evaluation of what you think you need, taking budgets into consideration, and there’s the concern that if you buy the wrong system, your budget is now spent, and you have to live with your decision. Since options have increased, especially in the past few years, it makes comparison shopping a lot more necessary.

Basic plasma cutting systems range from simple do-it-yourself kits where the motion system, plasma and controls are provided but unassembled, to large, fully automated systems that can even be used for untended production with the right automation package.

However, companies that sell this equipment all agree that a purchase is primarily application driven.

Along with basic bed size of the plasma system and other criteria of how the system is produced, a main consideration for purchasing one is the power unit used for cutting.

For this article, we’ve interviewed three companies that supply power systems: Hypertherm, Thermal Dynamics (Thermadyne) and ESAB, along with three companies that sell the entire plasma system. Power supply companies primarily offer their systems to OEM plasma equipment producers, but also offer them to end users when they want to change out a power supply. This overview will give you a better understanding of what to look for in a plasma system.

Driving a decision

“An important consideration in purchasing a plasma system is the material that’s cut,” says Dirk Ott, plasma product manager, Thermal Dynamics.

“Generally with plasma you’re cutting mild steel, stainless steel and aluminum. A company looking to buy a plasma system has to look at the materials they will be cutting the majority of the time. Then they must look at the thicknesses of material that they’ll be cutting along with the types of part quantities they’ll be expecting from the equipment.”

Jim Colt, Hypertherm’s plasma product manager, mentions, “For a plasma system, it’s not just the torch or the power supply that’s important, but every single component in the system can offer advantages when all the system components work really well together.”

And Ruben Chico, ESAB’s product manager for mechanized plasma systems, says, “We have somewhat of a different sales pitch for our power system depending on who we are talking to. If we’re talking to an OEM, certainly there are certain features and benefits that are important to them such as ease of integration, modularity, etc. However, for the end user, features and benefits will be speed, cut quality and cost of operation.”

Koike

Koike manufactures complete plasma cutting machines and offers their customers a choice of three power supplies: Hypertherm, Kaliburn, and Thermal Dynamics.

Tim Joslin, Koike’s cutting machine product manager remarks, “As far as one being better than the other, one thing that we run into right now is that there is some new technology available that could drive one technology over another.”

Joslin says that if they have a new customer, and he’s just getting into high-definition plasma cutting, they’ll put him into a system based on what he’s cutting. “If the customer requires very accurate holes for instance, such as a ½-in. hole in ½-in.-thick steel plate, using a Hypertherm power supply with its True Hole Technology will allow the customer to cut holes like this with a very minimal bevel angle inside the hole.

“If a job shop is just cutting out a part shape with no holes, then we could talk about conventional plasma, and we could use anybody’s height controller. So really it would depend on the customer, and what they are doing with the system,” he adds.

Integration

There’s also the aspect of integration remarks Rodney Plowe, electrical engineer at Koike. “Some plasma systems integrate with certain CNCs and some don’t. They have software that sets all the process and height control parameters directly to the height control and power supply. But it depends on what controller will communicate with this particular power supply. For instance, Hypertherm controllers communicate directly with Hypertherm power supplies, while Burny controllers communicate with the Kaliburn power supplies. We need to match this equipment. You don’t want to do too much mixing and matching, otherwise they might not communicate properly.”

Joslin says the best idea is to use a suite of equipment. For instance, Hypertherm’s suite would include the Hypertherm CNC controller, high-tech height control for the torch and a high-definition, auto/gas plasma-power unit. This would be considered a suite.

Plowe says for a system using a Burny controller, the plasma equipment would use an Inova height control, and a Kaliburn plasma system. Advanced Command Messaging controller software would be used to allow a company to use an off-line software package to communicate with the system. This would allow a company to set everything automatically without much operator intervention.

“There are software packages that will also dictate what plasma equipment the buyer should be looking at,” says Plowe. “For instance, if a company is already running one software suite, which could’ve cost them $22,000, he doesn’t want to buy another one to use a particular plasma system. Also, a customer could have a software suite for a laser that could be used for a plasma system. This would save them money for the software.”

Joslin mentions another thing that’s important is the equipment interfacing: “How to control the process as easily as possible for the operator. This really drives a lot of what is being purchased.”

Plowe also adds that local representation available for each power supply and the consumables used on the system is another important consideration. “If there’s no Hypertherm distributor in the area, but there’s a Thermadyne distributor, they might want to go with a Thermadyne power supply because it’s easier to get the consumables and service if needed.”

Power supplies

Hypertherm’s power supplies and systems for OEM plasma manufacturers are well known. Colt says what differentiates them from other companies is their “technology and engineering prowess that have really made a difference for us through the years. It has allowed us to design products that the market wants and needs.”

Hypertherm has a line of CNC-mechanized-plasma cutting systems called HPR. These are their high-definition plasma systems. They offer four different electrical current levels that match up with four different power supplies. They offer 130, 260, 400 and 800 amp units. However, all the control circuitry, the torches and the consumables are all shared between the systems.

“Today, if somebody wants to just cut ½-in. thick steel, they can use our smallest power supply,” says Colt. “Then if they need to cut 2-in.-thick steel, they could just buy the upgraded power supply and use all the rest of the equipment that wouldn’t have to be changed out. It’s a modular approach to the best technology and plasma.

“We have two lines of plasma cutting equipment. We have manual systems for mechanized plasma cutting, or they can be used with a hand torch. These systems are lower duty cycle. But for our industrial plasma system products, everything that is 130 amps and above are 100 percent duty cycle under the worst-case conditions.”

Colt mentions that a reduction of a plasma system’s complexity is very important. “Some years ago an operator for one of these systems had to really know what they were doing to get a proper cut. There were as many as 25 different settings that the operator had to make correctly for cutting. All the settings were different for every thickness and type of material that was being cut and the power level being used.

“Today an operator doesn’t have to be an expert anymore. All the settings are refined and canned into the software with the Hypertherm system. And the canned software takes control using a large database that tells the CNC control how to set up the system automatically.”

Thermal Dynamics

Thermal Dynamics offers three different styles of plasma cutting systems. The CUTMASTER line uses shop air for the plasma gas to cut steel, stainless steel and aluminum, providing good quality. Systems of up to 120 amps are available that can provide production cutting of up to 5/8-in. thick material.

The Auto-Cut line of water-cooled systems uses mainly shop air for cutting all kind of materials, but also can use argon/hydrogen or nitrogen for cutting non-ferrous materials. It can do production cutting of up to 1-1/4-in. thick material. The O2 version of the AutoCut Series can be used for high speed cutting of mild steel using oxygen. It also offers industry leading parts life and cut quality.

For the best weld-ready cut surface, Ott recommends their Ultra-Cut systems that use oxygen for high definition cutting on mild steel. “These units also offer very good consumable parts life,” he notes. “The cut has minimal bevel, a smooth surface and minimal dross that requires no secondary operations.”

For stainless and aluminum materials, the Auto-Cut and Ultra-Cut Systems use a very unique process called Water Mist Secondary, says Ott. “We use nitrogen as the plasma gas and water as a secondary gas. It can be used for thin-gauged as well as thick materials. It offers outstanding cut quality, very good angles and up to 50 percent higher cut speeds. And because of the nitrogen plasma gas, compared to argon/hydrogen mixes that competitors use, the cost per foot are considerably lower. This is a unique and beneficial feature of our machines when cutting stainless steel and aluminum.”

ESAB

ESAB offers several different lines of mechanized plasma systems to fit a customer’s specific needs.

Ruben mentions that one of the differences between ESAB and the other plasma power-supply companies is that its system is modular. “We use the same gas controls and arc starter and the same torch design across a wide range of cutting. This modularity makes changing plasma power levels easy, as well. The smallest power supply for our M3 Power Supply m3 Plasma System is 200 amps. The largest we offer is 720 amps along with 360, 450 and 600 amp solutions.

ESAB’s power supply versatility is very important for our customers says Ruben. Also, the same torch is used for all these different power levels, for both wet and dry cutting. For sustainable production of high quality parts in carbon steel, stainless steel, and aluminum, ESAB offers its customers maximum versatility through their modular plasma system platform.

Versatility for its power supplies is very important for ESAB says Chico. For the production of high quality parts in carbon steel, certain parameters in the plasma system must be selected to get quality cut parts.

ESAB also engenders high versatility into its cutting gas controls. “Often high-quality, carbon-steel cutting is using an oxygen plasma gas with an oxygen/nitrogen mixed shield,” he says. “Our m3 Plasma System is capable of producing this type of gas mixture. If a customer wants to cut as fast as possible, he might use an air shield. Another customer might want to produce inexpensive parts and doesn’t care about speed or quality. Then our system is capable of cutting with air.

“So versatility is going to be a major selling point of our mechanized plasma system. Our m3 Plasma System is capable of cutting with any common plasma gas combination. And they are easily selectable by the operator. You can also choose different modes of operation for edge quality or just production cutting. Our versatility is going to remain a major selling point of our mechanized plasma system.”

Plasma Automation

Once a company reviews their plasma cutting needs, there are a number of manufacturers that make this equipment. Plasma equipment ranges from kits to large custom-made machines with extended beds that can even have multiple plasma cutting heads.

One company is Plasma Automation Inc. that offers a number of different plasma systems and has been selling this equipment for over 20 years. The company builds its equipment in Pennsylvania and designs and produces its own software.

“Our most recent addition to our plasma equipment is our Vicon Monarch Plasma Cutting System. This machine uses an innovative I-beam, grid-frame design for its table. It’s able to accommodate multiple processing stations which offers the user the capability to easily handle sheet metal, structural steel, I-beams, angle, channel and applications that need fixtures,” says Walsh.

Features that the Vicon Monarch offers include an electronic torch-height control and collision protection mentions the company’s website. These features enhance the efficiency of each torch system. An electronic torch-height control maintains a precise torch cutting height during piercing and cutting for enhanced cut quality. A collision protection device is also added to protect the torch from damage if a collision occurs.

For efficient removal of plasma fumes, the Monarch uses an automated, multiple-zoned exhaust system that pulls fumes into linear-exhaust plenums exactly where the plasma cut is occurring. This reduces the volume of air that needs cleaning.

Menu-driven and user-friendly software used by the Monarch is written in-house and supported by Plasma Automation’s experienced team of programming engineers.

“These machines can be equipped with plasma torches ranging from 130 amps that have a capacity of cutting 5/8-in. mild steel, up to an 800-amp system that can pierce and cut up to 4-in. steel,” says Walsh.

“With its available precision plasma, oxy/fuel scribing, multiple cutting head options and oversized table, the Monarch expands the user’s working envelope and increases productivity,” concludes Walsh.

SCA Durma

Another manufacturer is SCA Durma. This company, according to its website, offers several different mechanized plasma systems called its PL and PL-C Systems using Hypertherm’s HPR Power Supplies.

For fast cutting, the systems use a Hypertherm torch-height control that is microprocessor-based. It accurately sets the initial piercing height and controls the torch stand-off distance from the workpiece during cutting operations by using the plasma-arc voltage to control this distance. They also use a laser device to automatically locate the exact position of the plate on the table. This allows overall faster cutting, as the software knows where the plate is with respect to the program information and cut parts.

For accurate axes positioning, a combination of rack and pinion, linear guides and planetary gears provide fast acceleration and deceleration speeds.
The PL Series 2D system is currently available in 5-ft. by 10-ft., 6-ft.-6 in. by 13-ft. and 6-ft.-6 in. by 20-ft. models. The heavy-duty machine frame is welded and stress relieved. A synchronized dual-side, backlash-free drive system using high accuracy planetary gears provides for high quality and accurate cutting. Cutting tables include a dust evacuation and optional filter system.

ESAB
Hypertherm
Koike
Plasma Automation Inc.
SCA Durma
Thermal Dynamics