Plasma is the 4th state of matter. Before digging deep about the working of plasma cutters, let us know its basic types and details about them.
Basic categories of plasma cutters
Most of the plasma cutters are grouped into two categories, namely conventional and precision ones. The conventional cutters generally use shop air as plasma gas. The shape of plasma arc is generally defined by orifice of nozzle.
You can find one as well including handheld systems that use conventional plasma. It is even used in the mechanized applications.
The precision plasma systems are specifically designed to generate highest and sharpest quality cuts. The extra pieces are specially included to constrict as well as shape the arc. The multiple gases including nitrogen, oxygen, etc are used as plasma gas for the best results.
Plasma cutter actually works by sending the electric arc via gas that passes through the constricted opening. The gas can include nitrogen, oxygen, argon, etc. This increases the gas temperature to the level that makes it to enter fourth state of the matter.
The gas that passes through the constrained nozzle causes it to squeeze by at high speed, like the air that passes through venture in carburettor. This gas cuts through molten metal. In order to protect the cut, this high speed gas is directed around perimeter of cutting area.
The metal that is cut is itself a part of circuit. So, the electrical conductivity of plasma makes the arc to transfer to work. In handheld plasma cutter, nozzle and the electrode are in contact with one another in the torch when it is in OFF state.
Once trigger is squeezed, power supply generates DC current flowing through the same connection. It even initiates the flow of plasma gas. This current flow switches from the electrode to the nozzle. This airflow and current continues till trigger is released.
In most of the plasma cutter systems available today, the pilot arc is between nozzle and electrode is normally used to ionize gas and produce plasma before the arc transfer. Some of the other methods that are used include touching torch trip to create spark, use of high frequency circuit just like spark plug, etc. However, these methods are not compatible with the automated cutting.
When it comes to CNC (Computer Numerically Controlled) cutting, the shapes are arranged on computer screen and even cut them automatically within seconds. These systems completely automate the entire process of shape production.