Plasma cutting refers to a metalworking process that involves cutting through materials that are electrically conductive using an accelerated hot plasma jet. When a computer numerical control (CNC) is employed to control the plasma torch, the whole arrangement constitutes a hi-tech machine called a CNC plasma cutter.
Some of the key reasons behind the widespread adoption of this technology are greater accuracy and faster-cutting speed than the appliance that doesn’t use it. A standard CNC plasma cutter slices metals at a maximum of 500 inches per minute (IPM), and therefore is a sure choice for commercial metal fabrication projects.
In this article, we are going to discuss what is a CNC plasma cutter and why they are necessary. Let’s get started!
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Topics Covered in This Article
How Does a CNC Plasma Cutter Function?
A specific type of gas, ideally compressed air, is forced through a consumable (nozzle) at high speeds. As soon as an electric arc contacts the gas, the fourth state of matter known as plasma or ionized gas gets created and ready to cut through the different metals like aluminum, brass, copper, and steel (mild and stainless steel).
A CNC plasma machine is a computer-enabled system including a plasma torch. The system uses numerical coding pre-programmed with the help of CNC to control the torch in different directions. What this machine performs is defined as mechanized cutting through a torch that has a straight barrel and a CNC-controlled interface.
Additional Read: How Does a Plasma Cutter Work
Alternative to a CNC Plasma Machine: A Handheld Machine
An alternative to these machines can be a handheld version, e.g. a plasma CAM machine which uses a torch specifically designed for light-duty metal cutting works.
Ideal applications of a handheld plasma system include cutting through bolts, pipes, metal plates, sheets, straps, etc. When you need a good gouging tool for removing welding defects or back-gouging joints, these plasma torches prove to be useful.
CNC Plasma Machine vs. Handheld CAM
You may cut a very small shape from a metal plate using a handheld machine, but you can ensure neither half accuracy nor perfect edge quality required by some metal fabrication projects.
A handheld model lacks the technological sophistication and precision of a mechanized cutter. Also, the utility of a CNC plasma cutter starts where that of a handheld version ends.
Uses of a CNC Plasma Cutter
The typical advantages of a CNC plasma system make it suitable for a wide variety of household and industrial applications. Designed to be ready for different environments, these machines are ideal for
- Welding and fabrication centers
- Auto restoration and repair shops
- Industrial job sites
- Salvage operation sites
- DIY projects at home
Some of the most familiar creations of these machines are the collective signs and address signs displayed by residential and commercial properties. Decorative metal works performed with the help of the machine include wall art, garden art, and other outdoor arts, etc.
Different Parts of a CNC Plasma System and Setup
The principal parts of CNC plasma machine include an interface panel and a control console. The interface is a proprietary item, and a typical control console can be an Allen-Bradley, Siemens, or Fanuc controller.
A laptop with the assistance of a relevant software program can also communicate with the plasma machine driving through an Ethernet port. A laptop or desktop computer works as a controller for some common appliances.
A text file containing “G-codes” and “M-codes” is a part of the program that describes all the contours along with the direction to the time when the torch will be turned on / off. A “post-processor” is another part that takes up the geometry from a specific CAD file to translate the geometry into “G-codes” and “M-codes” which are readable by the CNC.
Another part is a drive system that consists of cables, drive amplifiers, encoders, and motors (each separate motor for X-axis and Y-axis). Each motor requires a drive amplifier that receives a low-power signal coming from the machine to turn that into a higher-power signal and help move the motor.
Each axis uses an encoder, a feedback mechanism that produces a digital signal to indicate the distance of the axis movement. The components that transfer the power from the amplifier right to the motor are the cables which also send the position signals back to the machine from the encoder.
After reading the program, the CNC outputs signals to its drive system. It’s an action that allows the torch to move as required at a pre-programmed speed. The CNC system reads the feedback from the encoder to correct the drive signals so that the torch motion can be kept right on the programmed path.
Each component of a CNC machine and its drive system perform their designated functions very quickly (every few milliseconds) to keep the motion of the machine accurate and smooth so that plasma cuts can be straight, smooth, and precise with consistent edges.
To control the electrical inputs and/or outputs, a CNC system uses an “I/O system” which is originally an electrical system. Due to this, the machine encounters no issues turning on the plasma just when it’s required. The inputs are in use by the machine to track the starting of the plasma arc and its readiness.
These are the basic parts and features of a CNC plasma machine although other sub-systems or features may come with advanced machines. Some examples include a bevel system, an arc voltage height control system, an integrated control system, etc.
CNC Plasma Cutting Table
CNC plasma cutting requires a special table set up incorporating ventilation systems. In line with this requirement, two types are notable.
A Downdraft Table is known for its built-in ventilation and ability to pull debris/fumes away from the work metal. A working surface with holes is the perfect place for the particulates to get sucked into. An exhaust system (turbine-style preferable) can be attached to the plenum right in the middle of the table.
A Water Table causes the torch to get submerged quickly and resurfaced while allowing the work metal to be worked. The debris is carried away and the parts are kept cool. So, any normal ventilation system should be good.
Most CNC plasma machines provide proprietary software packages which include some version of the CAD platform. Some free CAD choices include DraftSight, Google Sketchup, etc.
DIY CNC Plasma Cutter
So, that’s the sum and substance of a CNC plasma cutter and its usability. Beginners often get confused while differentiating a CNC plasma cutter from a mill/water jet cutter and different other CNC systems. Unlike those machines, this type uses a torch that carries extreme heat.