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August 01, 2019

How a CNC plasma works

By scribe


CNC plasma cutting machines provide numerous benefits for fabrication shops, autobody shops, industrial construction applications, and more by delivering increased precision and efficiency. These benefits are fairly easily understood by both hobbyists and professionals who have worked with CNC plasmas before, but it’s not quite as easy to understand the technical intricacies of specifically how these machines work in order to achieve said benefits.

Here is a breakdown of how CNC plasmas work and how they go about streamlining the production process of shops both big and small.

What is a CNC plasma?

Before we dive into how a CNC plasma works, we’ll first touch on what a CNC plasma is. A CNC plasma is a table with a plasma torch positioned above it that moves along three axes – x, y, and z – to perform cuts through metal.

The torch is programmed via computer to move in precise sequences above the table in order to cut the metal placed on the table, such as steel, aluminum, or brass – just to name a few. Metalworkers use CNC plasma tables to perform precise and efficient cutting jobs on an accelerated timeline.

CNC plasma machines also allow users to perform repeated jobs quickly without having to reconfigure the machine between each cut.

But how?

What’s just been given is a high-level explanation of CNC plasma – the cut is programmed into a computer and then performed by the torch along three axes to cut a piece of metal. But there’s much, much more to it than that.

What is plasma?

Plasma is often referred to as the fourth state of matter, preceded by solid, liquid, and gas. As heat is applied to matter, it turns from a solid to a liquid to a gas. We’re all familiar with that.

But when enough energy is applied, gas turns into plasma capable of carrying its own electrical current. Lightning is the best example of naturally occurring plasma.

Creating plasma in the shop

Since waiting for lightning to strike your work piece in the right spot might take a while, we need to be able to create plasma on-command in the shop. Here’s how.

The heat and energy exacted upon gas by the plasma torch is what allows the cut through conductive metals to take place so quickly and cleanly. The plasma cutter sends an electric arc through a gas (e.g. oxygen, nitrogen, argon, compressed air, etc.) as it is passing through a constricted opening inside the torch. This increases the temperature of the gas to the point that it becomes plasma and is directed out of the torch.

The cut

As it’s directed out of the torch, the electrical conductivity of the plasma interacts with the metal on the table to produce the cut. The plasma arc is directed through the restricted opening, or nozzle, at an incredibly high speed, reaching a temperature of up to 40,000°F and immediately cutting through the work piece.

The gas is also directed around the perimeter of the cut, shielding it to help create clean edges.

Note: In many modern CNC plasmas, a pilot arc between the electrode and the nozzle ionizes the gas to generate the plasma prior to the arc transfer.

The CNC advantage

Not all plasma cutters include the CNC system capability, with many being operated by hand or by other means. The inclusion of the CNC table allows computers to control the torch to produce clean, high-quality cuts. It also allows for multi-axis cutting to perform complex jobs not possible otherwise.

Streamline your shop’s production with ShopSabre

ShopSabre delivers the best CNC routers and plasmas in the industry at the best value. Our products are proudly made in the USA and built with top-rated technology to provide a lasting edge in the shop. Get a quote today to start making the most of your operation.

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