METALWORKING SCIENCE - Understanding Plasma Cutting

WHAT IS PLASMA CUTTING?

Plasma cutting uses a torch to cut through metal. Unlike common oxyacetylene torches, plasma torches cut more quickly, precisely and efficiently—without the need for bottled gas. Instead, ordinary compressed air is heated into plasma form (the fourth state of matter) by an electric arc running through it. The superheated plasma shoots out the torch nozzle in a fine stream, cutting through the metal in its path.

People often confuse plasma cutting with laser cutting. Lasers can cut many different materials with higher precision, but they normally only cut thin metals. Plasma cutters are much less expensive and complex than laser cutters. They can cut a wider variety of metal thicknesses more quickly and economically than any other technology. For just a few hundred dollars, you could be plasma cutting metal in your garage!

WHAT IS CNC PLASMA CUTTING?

Cutting by hand with a plasma torch is crude and painstaking, limiting the quality of your work. But when a machine holds the torch and carefully controls its position and speed, much higher detail and accuracy is possible. Plus, the machine can quickly and automatically cut the same design many times. While traditional CNC plasma cutting systems were large, complex and expensive, almost anyone can now obtain and use this technology—thanks to a new breed of machines and software. As a result, CNC plasma cutting is revolutionizing metalworking in the same way that printers have revolutionized drawing, coloring, writing and typing.

HOW DO I CHOOSE THE RIGHT MACHINE?

Due to the plasma cutting process, a faster machine cuts better quality parts. So choose a machine that is fast as well as accurate. Check specifications for speed and acceleration, and avoid machines with heavy, slow moving parts. Also choose a machine that uses high-performance servo motors rather than slower and less accurate stepper motors.

A very important factor to consider is how easy the whole system is to use. Avoid machines based on traditional but outdated CNC technology, which are very complicated and difficult to work with. This includes any system where a program (eg. G-Code or HPGL) is created to run the machine, or where you have to transfer files between multiple software packages or programs not designed for plasma cutting. Instead, choose an integrated system where you can draw, customize, position, and cut parts from a single visual program interface (just like you would draw and print something from your computer). Watch a demonstration of the machine and software to make sure you understand how easy or difficult it will be to use.

A new CNC plasma cutting machine with high quality servo motors like this GoTorch model can be purchased for as little as $3,000.