Plasma cutters are precision power tools designed to cut through electrically conductive sheet metals. They are specialised pieces of welding equipment and can be used on varying thicknesses and metal types, with a higher current required in order to cut thicker sheets of metal. Plasma cutters can be hand-held tools, similar to a blow torch in size, or can be larger, automated through a CNC machine (Computer Numerically Controlled) for more controlled and precise cutting.
Plasma is ionized gas and is the fourth state of matter, containing almost equal numbers of positive ions and electrons and exhibiting some properties of gas; it is a very good conductor of electricity. Plasma can also be described as an electrically heated gas stream.
Plasma cutters work by generating a plasma stream which is then guided to cut through the chosen electrically-conductive metal, an important requirement for plasma cutting. The plasma stream is generated when compressed gas is forced through a focused nozzle at high speed, with an electrical arc created within this gas by an electrode either near to or integrated into the cutter nozzle and the workpiece itself. This ionizes the gas, creating an electrically conductive channel of plasma, and completes the electric circuit back to the plasma cutter through a grounding clamp. The heat delivered by this electric current, combined with the high velocity, allows the stream to cut through the chosen material, with the gas also acting to blow the molten metal away, resulting in a cut being left behind.
Plasma cutting is an effective way of cutting both thin and thick electrically conductive materials, even up to 6 inches thick, making them the ideal tool for cutting sheet metal. Due to the cutting method being a stream of ionized gas rather than a blade, plasma cutters can even be used to create cuts in curved and angled shapes. As plasma cutters can only be used on electrically conductive materials, woods and plastics cannot be used with a plasma cutter and only certain metals can. Typical materials cut with plasma cutters therefore include:
Plasma cutters are mostly used in automotive repair, construction, restoration and salvage and scrapping applications due to the ease with which it can cut and shape even larger pieces of metal. They have also been used in metal artwork, either as the main piece or in creating stencils and templates, as they allow for precise shapes to be cut without the need for additional tooling, allowing artists to create sharp, clean lines.
CNC plasma cutters are often used the HVAC industry (heating, ventilation and air conditioning) as the systems can be processed as flat patterns, which are then cut by the plasma torch. CNC plasma is also seen in decorative works, such as domestic and commercial signage, wall art and garden art and furniture.