A CNC plasma cutter is an automated tool that uses the principle of heat cutting, relying on the fourth state of matter called plasma , to cut all types of conductive metals (such as steel, stainless steel, aluminum) quickly and precisely under the control of a computer system.
1. Principles of plasma generation and cutting
The main process of plasma cutting consists of four important steps:
1.1 Gas Flow
The machine injects gas (such as compressed air, nitrogen, oxygen, or an argon/hydrogen mixture) into the plasma torch at high pressure and speed.
1.2 Electric Arc and Plasma Creation
Inside the cutting head are electrodes and nozzles.
When a high voltage current is applied between the electrode and the injector, a spark is created, which ionizes the gas flowing through that area.
The ionized gas becomes a plasma, a very high temperature conductor (up to
to
1.3 Cutting Action
Once plasma is generated, the system transfers the primary current to the metal workpiece (the workpiece acts as the positive terminal in the circuit).
A highly heated plasma jet is forced out at very high speed through a tiny orifice in the nozzle.
The intense heat of the plasma causes the metal in contact to melt instantly .
The pressure and high velocity of the still flowing gas blows away the molten metal from the Kerf, causing the workpiece to continuously break apart.
1.4 CNC control system
The CNC (Computer Numerical Control) system precisely controls the movement of the plasma cutting head along the X, Y, and Z axes according to the shape the user has designed in the computer program.
CNC controls parameters such as cutting speed, amperage, and torch height control (THC) to achieve the best possible cut quality.
2. Working steps of CNC plasma cutting machine
Design: The user creates the shape of the workpiece in a CAD (Computer-Aided Design) program.
G-code Generation: Use Computer-Aided Manufacturing (CAM) software to convert design files into G-code instructions to tell the machine where to move and when to start cutting.
Setup:
Place the metal sheet on the cutting table and connect the ground wire to the workpiece.
Set cutting parameters (current, gas type, pressure) in the CNC system.
Arc Initiation:
The CNC system will command the cutting head to lower to the pierce height.
The machine will start the plasma creation process (Pilot Arc) and send the current to the workpiece.
Piercing:
The high-heat plasma beam penetrates through the thickness of the metal sheet.
Cutting:
Once the cut is made, the CNC system commands the cutting head to start moving along the path specified in the G-code.
The Automatic Cutter Head Height Control (THC) system works to maintain a constant height between the cutter head and the workpiece to produce a consistent quality cut.
Completion: When the workpiece has been cut to the specified shape, the system will stop supplying power and stop the gas flow.
Summary of main components
| component | duty |
| CNC system | The brain controls the movement in the X, Y and Z axes to cut according to the designed shape. |
| Power supply | Converts alternating current (AC) to direct current (DC) and provides the high current required to create the plasma arc. |
| Plasma cutting torch | It is the origin of plasma, consisting of electrodes, nozzles and rotating gas rings. |
| Gas (Gas/Compressed Air) | It is a medium for creating plasma and uses high pressure to blow away the molten metal. |
| Altitude Control (THC) System | Automatically adjusts the distance between the cutting head and the workpiece to maintain the quality of the cut. |
