Palli Plasma

We bought this plasma cutter on ebay for $1,150 US, it was already 5 years old but had never been used and was still crated! We purchased a SureLok hand torch for $500 which replaced the PCM-52 machine torch. The model is Signature PAK 1000XR, it has a power output of 35/45/80 Amps and can cut up to 25mm (1") thick steel. We saved ourselves around 2000$ US by using ebay instead of buying it new. Total cost with shipping and taxes came to 170.000isk (2800$ US).

The plasma cutter is great for anyone cutting plates, it can cut any metal faster, cheaper and with more accuracy than any other manual tool*. The oxy-acetyline torch will still have a place for cutting very thick sections (above 25mm/1") but the plasma cutter is far superior in any other scenario.

A plasma**cutter works by means of two non-consumable electrodes inside the plasma torch, these are seperated by a narrow gap of air. When the button is pressed current flows from one electrode to the other through the air, this turns the air into superheated plasma** (an arc is formed). A constant flow of air is required to cool the electrodes, the plasma** escaping from the torch is directed in a stream towards the workpiece. This stream and the workpiece are protected by a secondary flow of air surrounding the plasma** column.

Plasma cutters work with relativly low voltage (30-50v DC), the problem is that as voltage is reduced so is the tendancy of electricity to "jump" across the electrodes and form an arc.*** Modern plasma cutters are equipped with high frequency starting, where a 20.000v current is momentarily superimposed on the circuit and starting the arc.

A plasma cutter has two modes of operation, gauging is when you "punch" a hole in the workpiece, cutting is when you drag the torch along the material to sever the work piece. This distinction is important because there are different sets of consumables**** because cutting tips have a tendancy to clog when molten metal is blow back towards the torch.

Gauging is done by tilting the torch 35° sideways before pressing the trigger, this ensures the metal is blow away from the torch. The torch is then slowly tilted back to face the work surface.

How cutting is performed depends on the material and thickness of the work piece, this controls the amperage by which the tips are selected. When cutting thin materials (1-5mm, 4gauge-18gauge) a drag tip can be used, with a drag tip you can rest the torch tip on the material. For thicker sections the torch needs to stand clear (1-3mm, 0.040"-0.120") from the surface and a tip matching the amperage is used. Try to start the cut on the edge of the material, if this is no possible you can "punch" your way through when dealing with thin sections (up to 3mm, 18gauge). Thicker materials need to be drilled or gauged and the cut started from the hole.

Always make sure that the gas/air supply is connected and fully functional before cutting, if current is passed through the electrode without a gas flow the consumables will literally burn away.

For most cutting applications shop air is perfectly acceptable as the cutting plasma and the shielding gas. More advanced systems used to cut high strenght alloys can use a mixture of inert gases and seperate supply of shielding/plasma gas.

*There are two automatic methods which produce better results than plasma with less distortion, the first is laser cutting and the second is hydro cutting.

** All material has four states, solid, liquid, air and the forth is plasma. The state depends on the heat of the material. Air conducts electricity poorly in a gas state but when it is superheated into plasma it becomes a superconductor and breaks Ohm's law (the more current it conducts the less the resistance is)

*** Higher voltage causes less resistance and is therefor more likely to use poor conductors such as air.

**** The entire front (white part) of the torch is made out of replacable consumables. These include electrode, cutting tip and shield cup, there are different cutting tips for each amperage.