CNC plasma cutting uses high velocity high temperature ionized gas along with an arc, to cut different types of materials under computer control.
The plasma cutter torch has a high velocity ionized gas that conducts electricity, which is used to heat the work piece to the melting point at the kerf. The purpose of the arc is to melt the material and the purpose of the gas is to blow the molten material away from the piece. Plasma cutters are specially used for cutting steel and materials that conduct electricity.
Plasma cutting has unique advantages over other processes. It provides lower cost than laser and waterjet and can cut thicker material.
The process can be used on ferrous and non-ferrous metals. The cut edge may be relatively rough and may exhibit an oxide layer. The plasma cut surface may not be precisely perpendicular to the surface of the sheet being cut.
It is the process of cutting electrically conductive materials with an accelerated jet of hot plasma. Steel, brass, copper, and aluminum are some of the materials that can be cut with a plasma torch. CNC plasma cutter finds application in automotive repair, fabrication units, salvage and scrapping operations, and industrial construction. The combination of high speed and precision cuts with low cost makes the CNC plasma cutter widely used equipment.
What is a CNC Plasma Cutter?
A plasma cutting torch is a commonly used tool for cutting metals for a wide variety of purposes. A hand-held plasma torch is an excellent tool for quickly cutting through sheet metal, metal plates, straps, bolts, pipes, etc. Hand-held plasma torches also make an excellent gouging tool, for back-gouging weld joints or removing defective welds. A hand torch can be used for cutting small shapes from steel plates, but it is impossible to get good enough part accuracy or edge quality for most metal fabrication. That is why a CNC plasma is necessary.
A “CNC plasma” system is a machine that carries a plasma torch and can move that torch in a path directed by a computer. The term “CNC” refers to “Computer Numerical Control”, which means that a computer is used to direct the machine’s motion based on numerical codes in a program.
Hand-Held vs. Mechanized Plasma
CNC plasma cutting machines usually use a different type of plasma system than hand-held cutting applications, one specifically designed for “mechanized” cutting instead of hand-held cutting. Mechanized plasma systems use a straight barreled torch which can be carried by a machine and have some type of interface that can be controlled automatically by the CNC. Some entry-level machines can carry a torch designed for hand-held cutting processes, such as the PlasmaCAM machines. But any machine designed for serious manufacturing or fabrication will use a mechanized torch and plasma system.
Parts of the CNC Plasma
The CNC machine may be an actual controller designed for machine tools, with a proprietary interface panel and a specially designed control console, such as a Fanuc, Allen-Bradley, or Siemens’s controller. Or it could be as simple as a Windows-based laptop computer running a special software program and communicating with the machine drives through the Ethernet port. Many entry-level machines, HVAC machines, and even some precision unitized machines use a laptop or desktop computer as the controller.
To cut parts from steel plates, the motion of the torch is controlled by the CNC. The part program, usually just a text file with “M-codes” and “G-codes”, describes the contours of the part and when to turn the torch on and off. Part programs are usually created by a piece of software called a “post-processor”, which can take a part geometry from a CAD file and translate it into M-codes and G-codes that the CNC can read.
A CNC plasma machine also requires a drive system, consisting of drive amplifiers, motors, encoders, and cables. There will be at least two motors, one for the X-axis and one for the Y-axis. There is a drive amplifier for each motor, which takes a low-power signal from the CNC and turns it into a higher-powered signal to move the motor. Each axis has a feedback mechanism, usually an encoder, which creates a digital signal indicating how far the axis has moved. Cables take the power from the amplifier to the motor and carry the position signals from the encoder back to the CNC.
The CNC reads the part program and then outputs signals to the machine’s drive system which moves the torch in the desired direction at the programmed speed. The CNC reads the encoder feedback and makes corrections to the drive signals as required to keep the torch motion on the programmed path. All the electronics in the CNC and drive system work and communicate very quickly, often measuring and updating position information every few milliseconds. This allows the machine motion to be smooth and accurate enough to produce plasma cut parts with a smooth, straight, consistent edge quality, and precise part dimensions.
Finally, a CNC plasma system will have some sort of “I/O system”, an electrical system that handles Inputs and Outputs. This is how the CNC turns on the plasma at the appropriate time, by turning on an output that closes a relay, for example. The CNC uses inputs to know when the plasma arc has started and is ready to move. Those are the most basic Inputs and Outputs required, but obviously, there can be many more.
Many other sub-systems and features can be added, such as arc voltage height control systems, plasma bevel systems, integrated plasma control systems, and so on. But the basics of a CNC plasma cutter described above will be common to all such machines, from the simplest to the most complex.
What Is CNC Plasma Cutting?
It is the process of cutting electrically conductive materials with an accelerated jet of hot plasma. Steel, brass, copper, and aluminum are some of the materials that can be cut with a plasma torch. CNC plasma cutter finds application in automotive repair, fabrication units, salvage and scrapping operations, and industrial construction. The combination of high speed and precision cuts with low cost makes the CNC plasma cutter widely used equipment.
What is a CNC Plasma Cutter?
A plasma cutting torch is a commonly used tool for cutting metals for a wide variety of purposes. A hand-held plasma torch is an excellent tool for quickly cutting through sheet metal, metal plates, straps, bolts, pipes, etc. Hand-held plasma torches also make an excellent gouging tool, for back-gouging weld joints or removing defective welds. A hand torch can be used for cutting small shapes from steel plates, but it is impossible to get good enough part accuracy or edge quality for most metal fabrication. That is why a CNC plasma is necessary.
The impressive cutting power of plasma cutters comes from their ability to harness and direct the fourth state of matter, plasma. Barring the surface of the sun or lightning strikes, one doesn’t often stumble upon plasma in the day-to-day. That’s because it’s a very high energy, forming when a gas is heated so much that it becomes electrically conductive.
The operation principle of a plasma cutter is actually pretty straightforward. Pressurized gas gets forced through a copper nozzle. The nozzle is part of a carefully designed electrical circuit that can carry the high current required for ionization. As the gas exits the nozzle, it must pass through an arc of electricity. The arc is so powerful that it ionizes the gas and transforms it into plasma.
Air pressure from the nozzle forces the plasma downwards to the surface of the sheet. Plasma melts through the metal, pushing the molten material out of its way. This means that a cut from a plasma machine won’t be as clean as one from milling or laser cutting.
CNC plasma cutters can vary greatly in size, price, and functionality. There are vast machines that cut huge industrial components, but also 4-foot by 4-foot machines that can fit into almost any workshop. As a whole, the machines are generally accurate but not as precise as a milling machine. Their strong point is speed; cutting through metals at speeds of up to 500 inches per minute is possible with plasma cutting.
Of course, those specs are reflective of commercial devices. There are instructions available online for building a DIY CNC plasma cutter, Keep in mind, though, that the ability of your cutter will depend on the amount of power it can generate.
The amperage of the arc largely determines how thick the sheet metal can be, along with the compressor force. A larger amperage will allow for a more powerful plasma arc to be created, which means you can cut a thicker piece of metal.
The type of metal that can be cut depends on the type of gas used to create the plasma. So next, let’s take a look at the options and what they’re capable of!
There are several technologies that can be used to cut sheet metal, including CNC milling, laser cutting, and CNC plasma cutting. Where CNC milling machines use a tool end for cutting, plasma cutters use a high-temperature plasma torch to blast through the metal. The process appears comparable to laser cutting, as they’re both non-contact. However, plasma operates at much hotter temperatures and therefore can cut through thicker materials.
Similar to the way FDM 3D printers interpret printing instructions in G-code, CNC plasma cutters use G-code as instructions for cutting. And when we say cutting, we mean it. The plasma is too strong to carve a nice design in the metal; that job should be saved for the CNC mill. Plasma cutting is primarily used to cut large gauge sheet metal for welding purposes.
Plasma cutting is a good option for those who often have metal cutting needs because it’s relatively easy to operate once you have it set up. The limiting factor is often the required workshop space needed for both safety and the equipment.
So if you have the need for some heavier-duty metal cutting, read on to find out how plasma cutting works and what you’ll need to get cutting in your own workshop. First, let’s take a look at how the process actually works.
Computer numerical control (CNC) has been incorporated into a wide range of different machines and technologies, including plasma cutters, in order to provide greater control for more technical cuts. If you are wondering what a CNC plasma cutter is and how it works, consulting an expert, such as the ones from LWS Manufacturing & Welding, will provide you with a greater depth of knowledge and will make it easier for you to determine if CNC plasma cutting is the best option for your specific project requirements.
WHAT IS A CNC PLASMA CUTTER?
A CNC plasma cutter is a machine that is specifically designed to cut through electrically conductive materials by using a computer to control and direct an accelerated jet of hot plasma at the material being cut. CNC plasma cutters can cut through a wide range of different materials, including steel, aluminum, brass, and copper, and can be used for a selection of different industries like fabrication and welding shops, auto repair and restoration shops, industrial construction sites, and salvage operation sites.
HOW DOES A CNC PLASMA CUTTER WORK?
CNC plasma cutting machines are computer-run systems that have the ability to move a high-definition plasma torch in various directions by using the numerical coding that has been programmed into the computer. The high-definition plasma cutter itself operates by forcing a gas or compressed air through a nozzle at high speeds. An electric arc is then introduced to the gas, creating plasma which is able to cut through metal.
CNC plasma cutters are available in a range of different sizes, prices, and functionalities. These machines are highly accurate and can slice through metals at speeds of up to 500 inches per minute. While high-definition plasma cutters require a plasma gas and an assist gas to function, the type of gas will vary depending on the material being cut. Some of the gases that can be used in plasma cutting include:
Oxygen—can be used to cut mild steel up to 1 1/4 inches thick but causes rough-looking cuts in stainless steel and aluminum.
Argon and hydrogen mix—provides high-quality, smooth cuts in stainless steel and aluminum.
Compressed air—works well for low current cutting applications in metals up to 1 inch thick.
Nitrogen—can be used to cut thin stainless steel.
Methane—can be used to cut thin stainless steel.