Sunday, September 21, 2008

Affordable CNC Plasma & Laser Cutting Machine

The plasma cutting process uses high velocity as well as high temperature ionized gas along with an arc, to cut different types of materials.

Plasma cutting process

The plasma cutter torch has a high velocity ionized gas that conducts electricity, which is used to heat the work piece and eventually melts the material. While the purpose of the arc is to melt the material with its high heat, the function of the gas is to blow the molten material away from the piece and cut the material. Due to the force of the plasma, you get a clean cut with very little or no slag at all. The plasma arc roughly has a speed of up to 20,000 feet per second (that's more than 13,000 miles per hour!) while the temperature is as high as 30,000º F.

Different types of Plasma cutting machines

Plasma cutting machines are available in a variety of types such as plasma torches, plasma torches, and plasma cutters. Compressed air or nitrogen is used as a cutting gas in plasma cutting torches. The torches have a narrow-width kerf along with a water-cooled electrode. Plasma torches use a high temperature gas steam, which is produced by passing the gas through an electric arc discharge. The plasma torch has two electrodes that are metallic and tubular in nature. The electrical arc flows between the negative or positive electrodes. Plasma cutters are specially used for cutting steel and materials that conduct electricity.

Advantages of Plasma cutting machines

- They provide high quality cuts and fast travel speeds.

- It is a low cost process for short runs as no physical tooling is required.

- A cost effective option for thick metal sheets.

- As compared to laser cutting can cut thicker sheets.

- It can be used to cut a wide variety of geometric shapes along with 2D shapes that do not require too much precision.

Specifications

The process can be used on ferrous and non-ferrous metals and requires only software tooling. It helps to reduce cost by reducing total cut length. At times, some warping may occur on complex parts. The cut edge is somewhat roughened and may show the presence of an oxide layer. Further, the plasma cut surface may not be precisely perpendicular to the surface of sheet material.

eMachineShop offers you information about various types of CNC machines along with other cutting techniques such as Plasma cutting and Laser cutting. Visit the site www.eMachineShop.com to design and order custom plasma cut parts today!

George is a well-known author who writes on the topics related with Injection Molding, Free CAD Software and CNC Milling for the site http://www.emachineshop.com

Article Source: http://EzineArticles.com/?expert=George_Ure

Sunday, August 24, 2008

Plasma Cutter Safety - Plasma Cutting Is As Safe As Welding - With A Few Exceptions

Attention Plasma Cutters! General Welding Safety is not enough.

There are a few things about plasma cutting safety that are different from general welding safety tips

This short list of plasma cutter safety tips is geared toward light duty plasma cutting using compressed air not large industrial units that use gas mixtures and water cutting tables.

Electric Shock Can Kill

- Operating a plasma cutter completes an electric circuit between the torch and the workpiece. The workpiece and anything touching the workpiece are part of the electrical circuit.

- Never touch the torch body, workpiece or the water in a water table when the plasma system is operating.

Voltages & Currents

- Plasma cutter output voltages are much greater than welding voltages, usually 100-200 volts.

Precautionary Measures

- Do not pick up the workpiece, including the waste cutoff, while you cut. Leave the workpiece in place on the workbench with the work cable attached during the cutting process.

- During plasma cutting operations do not move the work clamp.

Wear insulated gloves and boots, and keep your body and clothing dry.

- Do not stand, sit or lie on or otherwise touch any wet surface when using the plasma cutter system.

- Insulate yourself from work and ground using dry insulating mats or covers big enough to prevent any physical contact with the work or ground. If you must work in or near a damp area, use extreme caution.

Work Cable

- Ensure metal-to-metal contact between work cable and workpiece or work table.

- Work cable clamp should make contact with clean metal free of rust, dirt, painted surfaces, etc.

- Do not attach work cable to the piece that will fall away when the cut is complete

Plasma cutter Arc Rays

Plasma cutter arc rays produce intense visible and invisible (ultraviolet and infrared) rays that can burn eyes and skin.

Protective Clothing

- Guantlet gloves, safety shoes and hat.

- Flame-retardant clothing to cover all exposed areas.

- Cuffless trousers to prevent entry of sparks and slag.

- Remove combustibles, such as a butane lighter or matches, from your pockets before cutting.

Noise Levels of Plasma Arc Cutting

- Plasma arc cutting systems can generate noise levels in excess of 120 dB during high-amperage cutting operations.

- Ear protection should be used when operating or working near plasma arc cutting operations.

Toxic Fumes & Gases

Plasma arc cutting can produce toxic fumes and gases that deplete oxygen and cause serious injury.

- Keep the cutting area well ventilated or use an approved air-supplied respirator.

- Do not cut in locations near degreasing, cleaning or spraying operations. The vapors from certain chlorinated solvents decompose to form phosgene gas when exposed to ultraviolet radiation.

Pacemakers & Hearing Aids

- Pacemaker and hearing aid operation can be affected by magnetic fields from high currents. Pacemaker and hearing aid wearers should consult a doctor before going near any plasma arc cutting and gouging operations

Overall Plasma Safety

- The plasma arc cutting process can be very safe.

- By paying attention to safety standards and correctly setting up and operating the system, plasma arc cutting poses no more a threat than most welding processes.

For more information on plasma cutting and other welding information, visit http://www.weldingtipsandtricks.com

Article Source: http://EzineArticles.com/?expert=Jody_Collier

Affordable CNC Plasma & Laser Cutting Machine

The plasma cutting process uses high velocity as well as high temperature ionized gas along with an arc, to cut different types of materials.

Plasma cutting process

The plasma cutter torch has a high velocity ionized gas that conducts electricity, which is used to heat the work piece and eventually melts the material. While the purpose of the arc is to melt the material with its high heat, the function of the gas is to blow the molten material away from the piece and cut the material. Due to the force of the plasma, you get a clean cut with very little or no slag at all. The plasma arc roughly has a speed of up to 20,000 feet per second (that's more than 13,000 miles per hour!) while the temperature is as high as 30,000º F.

Different types of Plasma cutting machines

Plasma cutting machines are available in a variety of types such as plasma torches, plasma torches, and plasma cutters. Compressed air or nitrogen is used as a cutting gas in plasma cutting torches. The torches have a narrow-width kerf along with a water-cooled electrode. Plasma torches use a high temperature gas steam, which is produced by passing the gas through an electric arc discharge. The plasma torch has two electrodes that are metallic and tubular in nature. The electrical arc flows between the negative or positive electrodes. Plasma cutters are specially used for cutting steel and materials that conduct electricity.

Advantages of Plasma cutting machines

- They provide high quality cuts and fast travel speeds.

- It is a low cost process for short runs as no physical tooling is required.

- A cost effective option for thick metal sheets.

- As compared to laser cutting can cut thicker sheets.

- It can be used to cut a wide variety of geometric shapes along with 2D shapes that do not require too much precision.

Specifications

The process can be used on ferrous and non-ferrous metals and requires only software tooling. It helps to reduce cost by reducing total cut length. At times, some warping may occur on complex parts. The cut edge is somewhat roughened and may show the presence of an oxide layer. Further, the plasma cut surface may not be precisely perpendicular to the surface of sheet material.

eMachineShop offers you information about various types of CNC machines along with other cutting techniques such as Plasma cutting and Laser cutting. Visit the site www.eMachineShop.com to design and order custom plasma cut parts today!

George is a well-known author who writes on the topics related with Injection Molding, Free CAD Software and CNC Milling for the site http://www.emachineshop.com

Article Source: http://EzineArticles.com/?expert=George_Ure

Friday, August 15, 2008

Jay Leno’s Garage Turns to Hypertherm For Plasma Cutting Needs

Hypertherm plasma cutting brand is the choice for Jay Leno and his professional race team, when it comes to cutting metal during an auto restoration.

The team at Jay Leno's Garage knows that when it comes to fixing up cars-namely Jay's impressive collection of vintage automobiles-there is one plasma cutting brand that rises above the rest: Hypertherm. That is why Jay and the Big Dog Race Team turn to the Hypertherm Powermax30 when cutting metal during an auto restoration.

When it comes to automotive restoration, the team at Jay Leno’s Big Dog Garage looks for the latest in plasma metal cutting technology. Whether it’s to fix an exhaust system on a car, remove a bent or crushed bracket or replace corroded and rusted body panels the team has turned to Hypertherm and the Powermax30 manual plasma system.

Super portable, the Powermax30 can easily cut through metal up to 10 mm thick and sever metal up to 12 mm thick. And all with only 110 or 220 volt power and compressed air.

"The Powermax30 is definitely impressive. I have to admit I was a little skeptical when I first saw it because the unit is so small. I thought there is no way that thing is going to cut through the metal on our cars. But it did with no problem," said Bernard Juchli, head mechanic and race car driver for the Big Dog team. "It didn't even hesitate for a second. It was fast, easy to use, and really produced a nice clean cut."

You can see what Jay and Bernard have to say about the Powermax30 in the garage's latest Under the Hood segment available by clicking here. "The Powermax30 is a great tool," said Juchli. "I would even go as far as saying it is the first tool any auto restoration professional or hobbyist needs for their shop or garage."

Weighing just 9 kg, the Powermax30 is one of the smallest plasma cutters on the market, making it super portable. But don't let the small size fool you. As the old saying goes, "good things come in small packages". The Powermax30 is no exception. Even though it's small, it can easily cut through metal up to 10 mm thick and sever metal up to 12 mm thick. All of that with only 110 or 220 volt power and compressed air.

Whether you need to fix an exhaust system on your car, remove a bent or crushed bracket, replace corroded and rusted body panels, or fix up a floor or frame, a plasma cutter like the Hypertherm Powermax30 is indispensable. First, it is more versatile than any other metal cutting method out there, especially since you can cut both mild steel and aluminum; even if it's rusted, painted or dirty. In addition, patented Hypertherm technology and simple controls make it easy to drag cut with your Powermax system. You can also cut with a standoff (great for odd-shaped pieces or when trying to access a tight location) or make high quality, very narrow cuts on thin material with virtually no warping and a very small heat affected zone.

In addition to cutting, plasma can be used in place of carbon arc gouging to remove metal for weld preparation or for gouging out worn or cracked parts for repair or replacement. Plasma is also great for piercing.

Not only is plasma fast-in fact, much faster than oxyfuel, saws, and shears-it makes nice clean cuts so very little time is wasted on cleaning up cut parts. The combination of speed, superior cut quality, and low cost of operation makes it very popular in auto shops: it saves time which ultimately makes the shops more productive and profitable.

Jay Leno's Big Dog Garage is home to one of the world's great car collections and one of the world's best equipped garages. The 5,181.6 square meters facility was custom-built from the ground up and is run by a team of mechanical wizards adept at fixing, restoring, and customizing just about every type of vehicle imaginable. Since you can't exactly go down to the local auto shop for parts from pre-teen cars, the garage is geared up to fabricate parts and do just about all required work in house: a CNC Mill, a water jet cutter, sheet metal equipment, a lathe, a regular mill, welding equipment and a Hypertherm Powermax30 are among the shop highlights.

Plasma-arc unit offers high cutting

Kjellberg Finsterwalde will be demonstrating at EuroBLECH its HiFocus 440i plasma-arc cutting unit, which offers highest cutting precision across material thicknesses from 1mm up to 100mm.

Kjellberg Finsterwalde will be showing its latest developments in plasma-arc cutting technology and high efficiency arc welding at the EuroBLECH 2008 sheet metal working exhibition The company's HiFocus plasma-arc technology will be represented by a demonstration of the HiFocus 440i plasma-arc cutting unit Kjellberg claimed that the system offers the highest cutting precision across a full range of material thickness from 1mm up to 100mm.

The new PerCut 450M plasma-arc torch completes the unmatched process flexibility of the system, said Kjellberg to manufacturingtalk.

The torch has dimensions reduced by 15%, which with a reduction of weight and enhanced performance capacities, this plasma-arc torch is the latest swirl-gas design.
A new plasma-arc automatic head change unit, the BWE, is a turret system for profile cutting machines.

By integrating now the ignition boxes for the HiFocus 130 and HiFocus 160i into the plasmatorch connection unit PBA-160 the units will be more compact.

In addition to the increase of ignition reliability the investment costs will be reduced.

This logical step was taken after the successful experiences with the more powerful HiFocus units, which were furnished before with similar combined plasmatorch connection units.

As a novelty for the consumable system, YellowXLife the Cathode T012Y is now available.

Constructed for oxygen cutting Kjellberg Finsterwalde offers a cathode which is suitable up to 360A cutting current.

YellowXLife offers a significant extended life time for nozzles and cathodes.

* Arc welding - welding tractors of the KA-series are the basis for various customised automatic welding systems.

They will be shown first time with a cross-slide for positioning the welding head.

This ensures high stiffness for rugged industrial applications.

A special column and boom device for welding longitudinal and circumferential seams on, for example, wind towers, tanks and tubes, will be exhibited.

It features 3-axis drive and adapters for various welding heads, including power sources, to ensure highest flexibility and productivity.

* Strip cladding - the range of equipment for the high performance welding technologies will be enlarged by strip cladding.

Especially for the submerged-arc welding and the electro-slag welding, the highest melting down rates and enormous cost reductions can be obtained, said Kjellberg.

* Kjellberg Finsterwalde at EuroBLECH 2008, Hannover, Germany, October 21-25, Hall 13, Stand D40.

Plasma Cutting System features heavy-duty welded steel frame

Featuring uniframe design, tru-kut heavy-duty 5 x 10 ft system offers single set-up machining of frame and mounting surfaces. It utilizes Edge Ti CNC which includes touchscreen graphics display, on-board true shape nesting, and remote diagnostics/help capability. Air down draft cutting table includes 3 clean out doors on each side and parts catcher collects smaller parts falling through cutting slats. It also has digitally controlled brushless servo motors and high-precision motion system.


AKS Cutting systems introduces the new tru-kut heavy-duty 5' x 10' plasma cutting system. The rigid heavy-duty fully welded steel frame provides a stable platform for high precision plasma cutting.

Single set-up machining of the frame and mounting surfaces builds accuracy into the system and the heavy-duty design withstands rigorous usage requirements. The uni-frame design provides a compact footprint and allows for quick installation without any special floor preparation.

AKS tru-kut utilizes the easy to learn and use Edge Ti CNC which is specifically designed for plasma cutting applications and includes touch screen graphics display, on board true shape nesting and remote diagnostics/help capability and many more plasma application specific features.

Air down draft cutting table includes three clean out doors on each side for quick and efficient cleaning and a parts catcher to catch smaller parts falling through the cutting slats.

Latest technology digitally controlled brushless servo motors and high precision motion system with helical precision ground rack and pinions and linear guides provide quick acceleration, motion smoothness and accuracy.

http://findarticles.com/p/articles/mi_m0PIL/is_2008_May_7/ai_n25385978

Tuesday, February 12, 2008

Hypertherm simplified plasma cutting system

Hypertherm has simplified mechanized plasma cutting system integration with the introduction of Hypertherm PowermaxEDGE. The 'bundled' solution integrates a patented Powermax G3 Series plasma system with either a standalone Sensor PHC, Plasma Height Control, or the EDGE Ti CNC with integrated torch height control.

Metal fabricators can configure the PowermaxEDGE for their specific requirements starting with one of three Powermax G3 plasma systems - the Powermax1000, Powermax1250 or Powermax1650 - depending on cutting requirements. Each model features patented Coaxial-assist technology as well as advanced torch and power supply designs to cut thicker plates, at faster speeds, with better overall cut quality and consumable life. The PowermaxEDGE with a Powermax1650 cuts up to 88" per minute on ½" thick plate.

Sensor PHC is an easy-to-use automatic plasma height control that maximizes cut quality. Designed for easy integration to CNC tables, it features simple operational controls and fault indicators. The PowermaxEDGE provides easy integration for small- to mid-range table applications, including original equipment manufacturers building light to medium gantry cutting tables, light duty cycle needs such as HVAC or custom fabricators, and for retrofit of existing oxy-fuel or plasma tables.


http://home.nestor.minsk.by/build/news/2007/04/2408.html

CAD/CAM supports ZUND cutting technologies

An agreement between JETCAM International and ZUND Systemtechnik will ensure hat current and future ZUND cutting technologies are supported by JETCAM CAD/CAM productsCAD/CAM and Nesting specialists JETCAM International has announced an agreement with ZUND Systemtechnik, based in Switzerland whereby JETCAM Expert will be offered with the ZUND range of flatbed cutting machines. The agreement will ensure that current and future ZUND cutting technologies are supported by JETCAM products, with closer co-operation between sales, marketing, technical and development staff of both companies.
Mike Weber, managing director for JETCAM International said: 'With composite prices only increasing, and machine throughput becoming ever more important, we feel that the combination of ZUND and JETCAM technologies complement each other very well'.

'Customers now have a complete end-to-end solution which provides interaction and automation at every stage of the manufacturing workflow.' Mike Zuend from ZUND Systemtechnik added: 'This partnership cements a relationship that has already proven successful for some time.

Customers appreciate that they can receive a proven solution from a single vendor rather than a fragmented offering.
We can now combine the productivity and versatility of the ZUND cutters with JETCAM's automation and efficiency.' ZUND and JETCAM have already completed several successful installations for tier 1 and 2 companies in the aerospace and motorsport industries including several Formula 1 manufacturers.

JETCAM software is available either from JETCAM International and its worldwide network of distributors, or through selected Zund partners.

* About JETCAM International - JETCAM International has been developing and distributing its JETCAM Expert range of CADCAM software since 1986.

In use in over 70 countries worldwide, JETCAM Expert software supports virtually every CNC punching, laser, plasma, routing, waterjet and flatbed cutting machine available today, allowing users to program any combination of CNC machines with a single CAM system.

* About ZUND Systemtechnik AG - ZUND is recognized worldwide as the leading manufacturer of multifunctional, digital flatbed cutting and printing systems.

For over 20 years, ZUND has been spearheading the development of Swiss flatbed cutting technology, setting standards for precision, quality, and versatility while producing systems and tools for knife-cutting, laser-cutting, creasing, routing, etc.



http://www.manufacturingtalk.com/news/jea/jea165.html

Plasma cutting CNC runs Windows XP Embedded

Hypertherm of Hanover, NH recently introduced a plasma cutting system with an optional CNC (computer numerical control) unit that runs Windows XP Embedded. The PowerEDGE system offers metal fabricators a "complete entry-level mechanized plasma cutting system with outstanding performance and value," the company claims.

Plasma cutting utilizes a high-velocity jet of ionized gas that flows from a constricted orifice. The gas, or plasma, conducts electricity from the torch of the cutter to the material to be cut, melting material and blowing it away. It is ideal for cutting steel and non-ferrous material (material without iron), less than one inch thick.



Hypertherm's PowermaxEDGE system comprises a Powermax G3 Series plasma system along with either a standalone Sensor PHC (plasma height control) unit or an EDGE Ti CNC unit. The latter unit provides integrated height control. It is that component of the PowermaxEDGE system -- the EDGE Ti CNC, when it is present -- that runs Windows XP Embedded.

The EDGE Ti CNC is used for shape-cutting control. It features, according to the company, a proprietary GUI (graphical user interface) and "SoftMotion Technology." The device includes a 15-inch touchscreen LCD and provides integrated servo control for up to four axes of motion.

The EDGE Ti CNC's embedded computer is based on an "industrial motherboard" equipped with a 1.2 GHz or higher Intel processor along with 512MB of DRAM. The device also provides at least a 60GB hard drive for control program and data storage, and includes two RS232 or RS422 serial ports, two USB 2.0 ports, and PS2 keyboard and mouse ports for connection of external peripherals.

The PowermaxEDGE system and EDGE Ti CNC are currently available. Pricing was not disclosed.


http://www.windowsfordevices.com/news/NS2818333901.html

CNC software targets plasma arc cutting equipment

Designed for HyPerformance(TM) Plasma systems and FASTLaser(TM) processes, Automation CNC v6.0 provides HPR interface with full-screen diagnostics, configurable Watch Windows, and ability to create custom cut chart databases. HPR130 auto gas console features allow users to setup plasma supply operations. Along with facility for determining focal position, software offers Dynamic Pierce Control, auto process control, and laser marking capabilities.

Hanover, NH, USA - Automation CNC v6.0 software from Hypertherm, Inc. is now available for metal fabricators seeking greater productivity from mechanized HyPerformance(TM) Plasma systems and FASTLaser(TM) processes. CNC v6.0 is especially designed for applications of HyPerformance Plasma.

Newly released by Hypertherm Automation, CNC v6.0 is a performance upgrade that will be standard on all future shipments of Hypertherm CNC controllers including all EDGE[R], MicroEDGE(TM), Voyager(TM) and Mariner(TM) models. The company recommends that current CNC users contact their Hypertherm representative for specific information about system compatibility and available software upgrades to CNC v6.0.

The CNC v6.0 HPR (HyPerformance) interface is the most complete ever offered by Hypertherm Automation. It features full-screen diagnostics, configurable HPR Watch Windows, and the ability to create custom cut chart databases. HPR130 auto gas console features allow users to setup plasma supply operations by selecting material type, material thickness, process current and process gases.

The new CNC release also enhances FASTLaser software tools. Using Hypertherm's patent-pending process monitoring, it provides an automatic adjustment feature for determining focal position. The new automated focal position calibration routine simplifies the process of finding the spot where the laser focal position meets the material surface. It can be used whenever a shift in focal position occurs as with lens installation or resonator maintenance. Additional laser enhancements in CNC v6.0 include time saving Dynamic Pierce Control (DPC), auto process control and laser marking.

"Hypertherm is committed to being the supplier of choice for all our customers' thermal cutting needs," wrote Tate Picard of Hypertherm Automation in a recent Field Facts newsletter. "By actively soliciting feedback from our customers about software enhancements they'd like to see, we've been able to dramatically improve CNC v6.0 user interface screens and functionality. Additional requests from our customers promise to make CNC v7.0, already underway, even better."

Since 1968, Hypertherm has been the industry leader in plasma arc cutting equipment and service. Now, with its entry into the plate-laser cutting market, Hypertherm expands its technology leadership commitment. By continually delivering breakthrough advances in metal-cutting productivity and precision - first in plasma, now also in laser - Hypertherm reaffirms and extends its position as the world's leading supplier of advanced high temperature metal cutting technology. Hypertherm serves a wide range of industrial metal cutting needs from its headquarters in Hanover, New Hampshire, with subsidiaries, sales offices and partner representation worldwide.

Hypertherm, HyPerformance, FASTLaser, EDGE II, MicroEDGE, Voyager and Mariner are registered trademarks of Hypertherm, Inc. and may be registered in the United States and/or other countries.


http://www.cnc-info.blogspot.com/

CNC PLASMA CUTTING

CNC (computer numerically controlled) plasma cutters fully automate the shape production process. Early cnc machines used a tape with small holes punched through to provide instructions to a primitive (by today's standards) computer.

Today's CNC units use either expensive limited production computers made specifically for running burning machines, or personal computers adapted to run the machines. While the latter group lack some of the refined features of the $100,000 and up machines, such as automatic shape nesting and automatic tip height control, they provide the same cut quality and production speed.

In CNC cutting, you arrange your shapes on the computer screen and cut them automatically, without having to touch the material.

tm2_action_sm.jpg (11620 bytes)

CNC software lets you program pauses for piercing, scale up or down in seconds, set acceleration and deceleration at corners, and other functions not possible with electric eye units.

The above shapes were created in CorelDraw, and then turned and nested together to minimize scrap material. The group of shapes were then exported as a single DXF file. The file was then imported into our Torchmate driver software, which automatically converts it to G-code for cutting.

The shapes are cut in a sequence that minimizes the distance the torch must travel. While cutting speed here is 80 inches per minute (IPM), rapid traverse between cuts is 300 IPM.


http://www.plasma-cutter.com/cnc.htm

SELECTING A PLASMA CUTTER

So you want to purchase a plasma cutter! It's kind of a bewildering prospect to select a piece of equipment that is new to you with so many manufacturers and models to choose from.

Let 's approach the problem logically. To start with, there are a number of questions that you must answer for yourself, before you can go any further:
How many hours a day do you plan to use your plasma cutter? In other words, what kind of duty cycle must it have?

What kind of electrical service do you have where you intend to use the machine? Is it 50 amp 220 volt single phase, or perhaps 30 amp 110 volt single phase? What other equipment will be running simultaneously on the same circuit?

What kind of portability must your plasma cutter have? Will you be using it exclusively in your shop, or will you need to take it to the job? Do you have a means of supplying the machine with compressed air in remote locations? How will you do that, with a portable compressor or an air bottle? How will you supply electric current at the site?

What kind of material do you plan to cut, and how thick is it likely to be?

Will you be doing manual cutting exclusively, or is there a possibility that you may want to use your plasma cutter with a CNC cutting machine?

What are your budget limitations?

Generally speaking, the higher the amperage output of the plasma cutter, the greater the duty cycle is at lesser amperages. In other words, if you plan to use the machine around the clock, you should consider a larger unit than you would need to cut the material you will be working.

If you will be using your machine frequently, but not continuously, consider a unit that is capable of cutting the thickest material you are likely to work. Most manufacturers provide duty cycle information in their literature.

Many people make the mistake of thinking that the greater the capacity of the machine, the better it is. In general, fabricators consider oxy-fuel to be superior to plasma for cutting steel when thicknesses exceed about 1/2 inch. This is because of the slight bevel (4 to 6 degrees) in the cut face that plasma produces. It is not noticeable in thinner materials, but becomes more so as thicknesses increase. Also, at thicknesses above 1/2 inch, plasma has no cutting speed advantage over oxy-fuel.

There is little point in buying a plasma cutter that will cut 1 1/2" plate, if you are going to use acetylene for such work anyway. If you are planning to cut non-ferrous metals such as stainless or aluminum, which cannot be cut by oxy-fuel, consider a 50 to 80 amp. 220 volt plasma cutter.

If you plan to use your plasma cutter outside the shop occasionally, you should consider one of the new breed of semi-portable machines. These units are little powerhouses that weigh less than 100 lbs., yet are capable of cutting 3/4" to 1" in a pinch. You will need a bottle of air or a compressor, and a hefty portable generator.

If you believe that you may automate your plasma cutting at some point, you must select a unit that does not use a high-frequency starting circuit. A high-frequency start acts like a spark plug in a car. Rather than using a relatively lower voltage pilot arc to initiate the plasma process, it uses a high voltage spark. This causes electrical interference such as locking up the computer, destroying files, etc. None of Hypertherm's Powermax units use a high frequency starting circuit.

Like most other things in life, you get what you pay for. Imported plasma cutters can be found on the market for $800 or less. However, that is money that could be put toward a modern inverter type unit costing more initially, but less over time when the cost of replacement parts and consumables is factored in. On that note, it should be pointed out that Hypertherm's Powermax line uses a new, patented air flow system and torch design that actually delivers up to 4 times the consumables life of their other models and competing brands.

Make your selection intelligently, based on the above considerations, and your plasma cutter will give you years of reliable performance. Don't make the mistake of purchasing a unit on the basis of cost. An inexpensive machine that doesn't meet your needs is no bargain.



http://www.plasma-cutter.com/selection.htm

HOW A PLASMA CUTTER WORKS

Plasma cutters work by sending an electric arc through a gas that is passing through a constricted opening. The gas can be shop air, nitrogen, argon, oxygen. etc.

This elevates the temperature of the gas to the point that it enters a 4th state of matter. We all are familiar with the first three: i.e., solid, liquid, and gas. Scientists call this additional state plasma. As the metal being cut is part of the circuit, the electrical conductivity of the plasma causes the arc to transfer to the work.

The restricted opening (nozzle) the gas passes through causes it to sqeeze by at a high speed, like air passing through a venturi in a carburetor. This high speed gas cuts through the molten metal. The gas is also directed around the perimeter of the cutting area to shield the cut.

In many of today's better plasma cutters, a pilot arc between the electrode and nozzle is used to ionize the gas and initially generate the plasma prior to the arc transfer.

Other methods that have been used are touching the torch tip to the work to create a spark, and the use of a high-frequency starting circuit (like a spark plug). Neither of these latter two methods is compatible with CNC (automated) cutting.

The photo at right shows consumables from a Hypertherm Powermax 900 plasma cutter. The electrode is at the center, and the nozzle just below it. The orange piece above the electrode is the swirl ring, which causes the plasma to turn rapidly as it passes.

While these parts are all referred to as consumables, it is the electrode and nozzle that wear and require periodic replacement.


http://www.plasma-cutter.com/technical.htm

Plasma cutters are ideal for accuracy

Plasma cutters are one of the most modern tools for cutting all kinds of metal. A plasma cutter uses electricity to superheat gas to the point where it becomes plasma, which can then be used to cut metal. Because there is no friction between surfaces produced by this process the resulting material will be free of burrs and imperfections. When you combine this technology with CNC (computer numerically controlled) machinery you have a cutting tool that can produce incredibly accurate and detailed patterns even in thick steel and titanium.

Plasma technology

CNC plasma cutting machines use computer programming and precise robotic controls to automate the production of shapes and patterns in metal. With a CNC plasma cutting tool you can produce precisely proportioned metal pieces with a minimum of burrs and imperfections. The accuracy and precision of CNC plasma cutting means that components can often be taken directly from the cutting machine and put into use without further finishing, saving time, effort, and expense.

Principles of operation for a CNC plasma cutter

As mentioned, a CNC plasma cutter uses computer programming to direct the plasma onto the material. This plasma is produced by feeding a gas past an electrode, which superheats this gas (gases used include oxygen, argon, and nitrogen) until it becomes plasma.

Plasma is a fourth state of matter (in addition to solid, liquid, and gas) and this plasma is directed through a restricted opening onto the surface of the metal. Once the plasma contacts the metal the metal is cut using heat. Because the metal is superheated to a molten state there is no messy residue left behind as there is when using friction-based cutting systems (saws).

A CNC plasma table

The best way to direct your plasma cuts is with a CNC plasma table equipped with a gantry that moves the CNC plasma cutter above the work to be cut. Because a CNC plasma cutter is so hot, however, a CNC plasma table does not actually have a table surface. Instead, the metal you are cutting becomes the table surface, and the cut pieces fall through to a holding area beneath the machine. The accuracy and technical sophistication of CNC plasma cutting are the main reasons why many companies that work with metal have switched to plasma cutters.


http://www.insidewoodworking.com/cnc/plasma_cutters.html

Plasma-arc CNC profilers offer high accuracy

Portal cutting machines have been designed for precision plasma-arc cutting, combine high productivity with high accuracy and their advanced process integration ensures high levels of cutting quality.

Esab Automation now has an extended range of Eagle portal cutting machines which have been designed for precision plasma cutting. There are four models in the range which combine high productivity with high accuracy. Advanced process integration ensures consistently high levels of cutting quality.

The four EAGLE machines offer cutting widths from 1500mm, with one torch, up to 3000mm with two torches.

Cutting thickness is up to 30mm with cutting speeds and positioning rates up to 35mm/minute.

The Eagle’s feature automatic switching from cutting to marking.

To promote the highest plasma cutting quality, a number of advanced design features are included.

The voltage related electric arc height regulation ensures optimum cutting quality through the entire cutting process.

The machine’s double side synchronised rack and pinion drive together with an advanced guiding system ensure 100% accuracy over the entire cutting range.

The cutting torch height is exactly pre-set by the Super Rapid Initial Height Sensing System which positions the plasma torch precisely in less than 1.5 seconds, thereby also eliminating unnecessary down time.

Economy, efficiency and flexibility are hallmarks of Esab precision plasma systems they provide exact cutting edges with little slag, minimum material deformation due to a very restricted heat affected zone and no reworking.

By configuring the plasma systems, plate thicknesses up to 30mm can be cut in stainless steel, aluminium or unalloyed steels.

Accompanying the Eagle range are Esab Vision Control Systems.

These provide comprehensive control possibilities with integrated cutting databases and the possibility of implementing fully automated production cycles.

Full details of the entire Eagle range are provided in new literature available from the company - telephone Esab for details.

http://www.cncmachinesinfo.com/articles/

Making plasma cutting easier Using CNC automation technology

For many people, the world of plasma cutting is a complex and daunting place, with a cryptic set of rules that can be mastered only by highly trained technicians after weeks of training. For every change of material or thickness being cut, a long process ensues of resetting gas mixtures, tweaking pierce heights and pierce delays, and manually calibrating every last parameter to ensure a reliable result.


For many people, the world of plasma cutting is a complex and daunting place, with a cryptic set of rules that can be mastered only by highly trained technicians after weeks of training. For every change of material or thickness being cut, a long process ensues of resetting gas mixtures, tweaking pierce heights and pierce delays, and manually calibrating every last parameter to ensure a reliable result.

However, technological advancements have automated the calibration process and eliminated the guesswork to make highly precise plasma cutting accessible to large and small fabrication shops alike. By working together to develop their technologies, CNC machinery companies and plasma unit manufacturers have optimized machinery control systems to take full advantage of the speed and power of plasma cutting. CNC technology allows systems to communicate to maintain unprecedented levels of control over the quality of plasma cuts.

This level of control is achieved by linking all parameters of a plasma unit to the same CNC unit that instructs the motion of the head, which allows the controller to compute all factors that might affect the quality of a cut. Anytime the material type, thickness, or plasma process is changed, several parameters must be adjusted, such as feed rate, pierce delay, pierce height, and gas mixture. Instead of adjusting dials and making precise measurements before running a job, the operator simply loads the material to be cut and then selects the material type from a menu-driven list on the machine keypad. The controller then automatically configures the machine and the plasma unit. This greatly reduces setup time and nearly eliminates the margin for human error, naturally improving job efficiency, production time, and job quality.

From the User’s Angle

Normally, a user creates a nested sheet of parts in a CAD/CAM system and then saves the machine-ready file on a computer or network server. New systems can have a built-in Ethernet connection and communicate via DNC using standard TCP/IP to the user’s computer or to a network server. At the machine, the user loads the material and selects the material type. The controller prompts the user to insert the appropriate torch consumables.

The user then selects the job and starts the cutting. When equipped with a bar code scanner, the computer can produce a printed work order for all jobs to be cut, allowing the operator to commence jobs simply by scanning the appropriate code on the sheet, prompting the job file to be loaded and executed automatically.

The Cutting Process

The process of cutting with plasma involves an electrical reaction, so unlike other cutting techniques, plasma cutters can cut only materials that conduct electricity. When a job file is started, the machine moves to the first pierce or cut position and the torch moves down toward the material. On the end of the torch is a device called an ohmic sensor. Once the ohmic sensor makes contact with the surface of the material, it closes an electrical circuit, informing the machine that it has reached the surface of the material. The torch then lifts above the material to the pierce height. The pierce height is higher than the cutting height to prevent hot metal from shooting directly back into the torch during the pierce process.

Once the pierce is complete, the torch moves to the cut height and begins to cut. The optimum pierce height, cut height, and feed rate all are based on the consumables and the material being cut. On sophisticated plasma cutting systems, all of these parameters are set automatically.

Once the cutting begins, the distance between the torch and the top of the material is maintained by reading the voltage from the plasma arc, in a process known as automatic torch height control (ATHC). Generally, sheets of material do not lie completely flat, especially thin-gauge material. To ensure a high-quality cut, it is important to maintain a constant distance between the torch and the material surface. Maintaining a constant height requires a responsive ATHC system. On some systems, the arc voltage is checked at a rate of 500 times per second, and the readings are used to adjust the Z axis up or down accordingly. The result is a quality cut that does not require user intervention.

Improvements and Advancements

The process described seems simple, but actually it is a result of extensive developments in modern technology. Older plasma systems, as well as many modern ones, do not take advantage of these new developments and require painstaking manual adjustments to produce parts that remain inferior in edge quality and efficiency. As further technological developments are made, the quality gap between less advanced systems and modern ones is widening at a fast pace.

One of the latest advancements in plasma cutting technology is 200-amp fine plasma cutting. This process produces a more constricted plasma jet for a higher arc density and more accurate cutting. The result is a smooth, precise cut that is almost dross-free.

The condition of the plate with regard to rust or reflectivity does not affect the cutting process. A high-quality fine plasma cutting system allows the cutting of holes with diameters nearly equivalent to the thickness of the material being cut. For example, good-quality 0.35-in.-diameter holes can be cut accurately in 0.25-in.-thick material.

Moving Forward

Many companies today are committed to moving this technology forward. In the future, leading companies will continue to work closely together to push the technological envelope, making plasma technology faster, more accurate, and easier to use.


http://www.thefabricator.com/PlasmaCutting/PlasmaCutting_Article.cfm?ID=675