Plasma cutting utilises plasma i.e. the fourth state of matter for the process of cutting electrically conductive metals. As we know, plasma cutting was developed in the early 50s and was used to cut metals like copper, steel and aluminium.
The process of plasma cutting is where compressed air, oxygen or inert gases such as nitrogen, argon or hydrogen is passed through a tiny opening in a copper nozzle. An electric current is also passed through the gas. The gas moves at a very high speed and is under great pressure; it turns into plasma which is essentially ionised gas that is electrically conductive. The plasma jet contains energy that is so highly concentrated, that it can melt metals and cut through them.
The plasma used in the process of plasma cutting is of 4 types: conventional single flow plasma, dual flow unshielded plasma, dual flow shielded plasma and high definition plasma.
Conventional Single Flow Plasma
In this process, usually a single gas i.e. nitrogen or air is used that produces the plasma which is used in the cutting process. This gas is also used to cool the plasma.
Dual Flow Plasma or Unshielded Plasma
In this process, two gases are used. One gas is used to produce the plasma and the other is used as the shield gas. In smaller cutting systems that are under 125 amps, compressed air is commonly used as the plasma as well as the shield gas. Dual gas systems that are unshielded usually have a nozzle that is exposed and must not be used for the process of drag cutting.
Dual Flow Plasma or Shielded Plasma
In this process also, two gases are used – a shield gas and a plasma gas. Air is used as both the shield as well as plasma gas for systems that are less than 125 amps. The shield technology electrically protects the nozzle from the blowback of the metal that occurs due to piercing. In hand-cutting applications, the shield technology also allows the drag cutting process.
High Definition Plasma
In the process of high definition plasma cutting, the nozzle has a specialised design that narrows the arc and increases the energy focus. Due to the higher energy of the plasma arc, you can achieve high quality, precision cuts. You can obtain a superior edge of the cut, high cut speeds, and narrower kerf than the conventional plasma cutting process.
These days, high definition plasma cutting systems permit high levels of automation and are aimed purely at automated applications. In very advanced cutting systems, all the experience required by the operator to achieve superior, precise cuts are contained in the CAM software that manages the cutting operations. With high definition plasma, you can achieve holes that are round and have no taper. You can get square edges with no dross. The cycle times allow greater levels of productivity.
Today, plasma cutting technology has come a long way and has become more advanced and sophisticated. From conventional plasma cutting to high definition plasma cutting, one is spoilt for choices and one can select the technology that suits their cutting requirements the best.