What is Plasma Cutting?


Plasma cutting is a process that is used to   cut steel and other metals of different thicknesses (or sometimes other   materials) using a plasma torch. In this process compressed air is blown at high   speed out of a nozzle; at the same time an electrical arc is formed through that   gas from the nozzle to the surface being cut, turning some of that gas to   plasma. The plasma is sufficiently hot to melt the metal being cut and moves   sufficiently fast to blow molten metal away from the cut. Plasma can also be   used for plasma arc welding and other applications.


The HF Contact type uses a high-frequency,   high-voltage spark to ionise the air through the torch head and initiate an arc.   This requires the torch to be in contact with the job material when starting,   not sp good if you have to penetrate through things like rust or painted   surfaces.

The Pilot Arc type uses a two cycle approach   to producing plasma, avoiding the need for initial contact. First, a   high-voltage, low current circuit is used to initialize a very small   high-intensity spark within the torch body, thereby generating a small pocket of   plasma gas. This is referred to as the pilot arc. The pilot arc has a   return electrical path built into the torch head. The pilot arc will maintain   itself until it is brought into proximity of the workpiece where it ignites the   main plasma cutting arc. Plasma arcs are extremely hot and are in the range of   15,000 degrees Celsius.

Plasma is an effective means of cutting thin   and thick materials alike. Hand-held torches can usually cut up to 2 in (48Â mm)   thick steel plate, and stronger computer-controlled torches can pierce and cut   steel up to 12 inches (300Â mm) thick. Formerly, plasma cutters could only work   on conductive materials; however, new technologies allow the plasma ignition arc   to be enclosed within the nozzle, thus allowing the cutter to be used for   non-conductive workpieces such as glass and plastics. Since plasma cutters   produce a very hot and very localized “cone” to cut with, they are extremely   useful for cutting sheet metal in curved or angled shapes.


Inverter plasma cutters rectify the mains supply to DC, which   is fed into a high-frequency transistor inverter between 10kHz to about 200kHz.   Higher switching frequencies give greater effiencies in the transformer,   allowing its size and weight to be reduced. Today’s power modules are called   IGBT’s (Inter Gate Bipolar Transistors) and are generally found in better   quality machines. IGBT based machines operate more efficiently and   reliably.


The   best way to decide which model is going to be right for you is to consider the   thickness of metal you intend to cut. We are always honest in what we claim our   machines will cut. We quote the clean cut depth as a benchmark for cutting   thickness. This will mean that the maximum, or severance cut, will be 20 -25%   higher then the clean cut measurement. Severance cuts on most machine will   normally require some finishing on the cut edge due to the cutter operating at   the upper most limit of it’s operational envelope.

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