If you need to cut metal plates on an industrial scale a CNC plasma cutter may be the machine to use. Plasma cutters can slice through metal up to 6” thick and CNC control enables the cutting of complex 2D shapes. Here’s an introduction to the machines and some tips for choosing the right one.
What is a Plasma Cutting Machine?
Plasma is created by directing a high-velocity gas jet over and around an electric arc essentially the same as that used for arc welding. The arc heats the gas enough to vaporize metal, with kinetic energy blowing it out of the cutting path.
Hand-held plasma cutters have a role in construction and fabrication but more often the cutting head is mounted on a gantry-style machine. This moves the head over the work table which holds the plate or sheet being cut. (Sheet becomes plate when the thickness exceeds ¼”.)
Plasma and laser cutting machines are very similar and both are used for cutting 2D contoured shapes. However, plasma machines are generally used for plates while lasers are at their best on sheets.
Plasma Machine Types and Options
Plasma cutting technology has evolved rapidly since it emerged in the mid-twentieth century. The major points of differentiation are:
- Type of torch used
- Torch power, measured in amps
- Table size and arrangement
- Fume and debris capture system
Types of Plasma Torch
The four main types are:
- Air – uses compressed air, relatively slow and results in poor edge quality, best in low volume applications
- Conventional/oxygen – uses a gas, typically oxygen although other gases may be used, to create the plasma and eject material. Better edge quality than air and faster cutting.
- High-definition – a special nozzle narrows the arc for higher accuracy and superior edge quality
- Ultra-high definition – a refinement of the high-definition plasma, cuts fast and clean, parts need little-to-no secondary edge finishing
More amps equal a stronger arc. A unit providing 125 amps will cut steel up to 1½” thick while one of 800 amps can slice through 6” of stainless.
Table Size & Arrangement
A bigger table holds a bigger plate. In addition, a long table can hold two or more plates, allowing loading and unloading at one end while cutting takes place at the other. The potential productivity gain must however be set against the additional square footage needed.
Fume & Debris Capture
The two options are water tables and downdraft tables. A water table machine has the table carrying the plate filled with several inches of water. This captures the debris but water will splash up on the plate being cut, making it somewhat messy.
A downdraft table extracts fumes and debris with airflow under the plate. The table shuts off areas away from the cutting zone to maximize extraction. Downdraft tables need an additional dust and fume collector with filters that need periodic replacement. This makes them more expensive than water tables, but they are also more effective.
Talk to Us About Your Machinery Needs
A CNC plasma cutting machine is a tremendous asset for any fabrication shop, but there’s much to consider when selecting a machine. Specialists at The Equipment Hub can help.
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