To understand the working of a plasma cutter, it is better to start with the understanding of the characteristics of plasma. Plasma is called the fourth state of matter. We all know that there are three states of matter: solid, liquid, and gas. Sometimes matters transfers from one state to the other when energy is introduced. A good example to understand this phenomenon is ice changing to water when heat is supplied to ice. If more heat energy is supplied, the ice is converted to water vapor. If the heat is further increased, the water vapor gets ionized and conductive electrically and becomes the 4th form called plasma. A typical plasma cutter uses a gas to transfer energy from a power supply to the electrically conducive material. This results in a faster, efficient, and cleaner cutting finish when compared to the cutting with the help of an oxyfuel.
A plasma arc can be formed with the help of a gas like oxygen, argon, nitrogen, or sometimes shop air is passed through a tiny nozzle in a torch. The arc generated from an external source is then induced into a high-pressure gas flow, which results in the form of a highly-pressurized plasma jet. The temperature of the plasma jet can reach to temperatures close to 40,000° F and can pierce through any kind of work pieces and blows away all the molten material.
The Different Components of A Plasma System
The different components of a plasma cutting system are-
- Power Supply – The power supply unit has the unique ability to convert a single or three phase AC power into a very efficient DC voltage that ranges from 200 to 400 VDC. This value of the DC voltage is completely responsible for maintaining a plasma arc throughout the cut of the material. This voltage also helps in the regulation of the current output that is required and is based on the type of materials and thickness that is processed.
- Arc Starting Console – The ASC circuit has the potential to create an AC voltage to the range of 5,000 VAC at close to 2MHz and at the same time creates an efficient plasma arc.
- Plasma Torch – The main objective of the plasma torch is to assist in the cooling and the alignment of all kinds of consumables. The primary parts of the consumable parts for the generation of an arc are the electrodes, nozzle, and swirl ring. Sometimes a shielding cap can be used to improve the quality of the cut. Also, all the outer and inner retaining caps are held together.
How to Select the Right Kind of Plasma Cutter?
The initial questions to ask when choosing a plasma cutter depends on the overall cutting capacity:
- How quickly do the end user want to carry out the cut?
- What is the metal thickness that is routinely cut by the user of the plasma cutter?
- The maximum thickness that need to be cut.
- What is the cutting speed for a particular thickness of a type of material?
Very similar to a welding machine, the amperage and the voltage capacities determine the size of the plasma cutter. One important point to remember here is that the process of plasma cutting requires high voltage and low ampere levels. These parameters are just the opposite of the parameters that are required for welding. Some users judge a plasma cutter incorrectly based only on the amperage. These people need to understand that the total power output is the product of amperage and voltage. Hence, both these parameters should be considered while selecting the right kind of plasma cutter.