This is the third and the final part of the series that looks at more plasma cutting related terminology.
Nozzle: The nozzle in the plasma cutter is usually made of copper. It is connected to the high-frequency generator. The pilot arc in the plasma torch is struck between the nozzle and the electrode. When the main plasma arc is produced once the pilot arc is struck, the tiny opening present in the nozzle helps to constrict the plasma arc.
With normal use, the diameter of the orifice in the nozzle increases. Also, if any molten metal that is produced during the process of piercing or cutting blows back into the torch, the shape of the orifice may get distorted. The cut quality produced by the plasma cutter will begin to deteriorate as the size and shape of the orifice of the nozzle changes and when this happens, the nozzle must be replaced.
Shield: The shield is usually fitted onto the front of the plasma torch once all the other parts have been placed inside. The shield protects the nozzle from the metal splatter that is produced during the process of cutting or piercing.
Shield Cap: The shield cap covers the sides of the plasma torch and the nozzle. The shield fits onto the shield cap and protects the nozzle. The shield cap is usually very robust and requires to be replaced only if it becomes burnt or charred.
Water Cutting Table: The water plasma cutting table has a built-in air chamber. When the compartment is filled with air, the water level rises. The water level can be adjusted below, in level with, or above the metal to be cut, as per the cutting requirement. Typically, these kinds of cutting tables are used for plasma cutting underwater or on-water cutting.
Water Shield Cutting: In this kind of cutting process, shield gas is usually substituted by water. This type of cutting is an alternative to the dual gas cutting process. Water shield cutting allows better workpiece and nozzle cooling and the cut quality on stainless steel using this process is also better.
Water Injection Cutting: In this process of plasma cutting, a single gas is used for plasma production and water is swirl-injected into the plasma arc which vastly improves the constriction of the arc. This process is used to cut several types of materials of varied thicknesses and very high-quality cuts are produced by using this cutting process.
Initial Height Sensing or IHS: The plasma torch must be positioned at the correct distance above the workpiece before the arc is struck. This is known as IHS. Usually, inductive sensors are used since they can be used below or above water for cutting.
This article concludes the three part series of most commonly used definitions and terms and is sure to have value-added to your “plasma cutting word repertoire.”