AN EXPLANATION OF THE PROCESS
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. This is
sufficiently hot to melt the metal being cut and moves sufficiently fast to blow
molten metal away from the cut..
HOW IT WORKS?
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 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 cutting
arc. These 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 (48 mm) thick
steel plate, and stronger computer-controlled torches can pierce and cut steel
up to 12 inches (300 mm) thick. Formerly, these 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.
WHAT IS AN INVERTER CUTTER?
Inverter 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
efficiencies 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.
CHOOSING THE RIGHT ONE?
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.
