Metals are used to build all sorts of structures, from skyscrapers to robots to automobiles. Before a piece of metal or metal alloy can be used in a building project, it must be cut to the appropriate size and shape. The strength and durability of metal make it an ideal building medium, but also make it difficult to cut and shape. Extreme forces are needed. Plasma cutting is a method of shaping metal using a plasma torch to cut away unwanted parts.
To understand why plasma cutting works, it is important to understand what plasma is. When a gas is heated to extremely high temperatures, its molecules and atoms break apart. Electrons flow freely, disconnected from their nuclei. As the electrons collide, they release huge amounts of energy. It is this energy that makes plasma cutting possible.
Though plasma cutters come in many shapes and sizes, they all function in the same basic manner. A negatively charged electrode is housed inside a tube connected to a nozzle. Pressurized gas is forced through the channel. When the nozzle touches the positively charged metal, it creates a circuit. The resulting sparks heat the gas until it becomes plasma. Meanwhile, channels around the edge of the nozzle allow shielding gas to flow around the plasma beam, controlling its size during cutting.
Plasma cutting became the method of choice in the United States in the 1960s. During World War II, factories started feeding non-reactive gases through an arc of electricity and using the resulting reaction to weld machinery. By the 1960s, they were looking for a way to increase the weld temperature. Engineers sped up the gas and made the release hole larger, allowing more gas to move through the electric arc at a time. The process resulted in a stream of gas so hot that it cut the metal.
The new plasma cutting technology allowed for faster, more precise cuts than ever before. Modern plasma cutting has been made even more precise with the introduction of computers. Instead of guiding the nozzle by hand, an operator programs the desired cut into a computer. Computerized and numerically controlled plasma cutting allows for uniform materials because each piece can be cut in exactly the same way as the one before. The operator can switch between multiple patterns to cut different shapes.
Plasma cutting is still an often used technology in the manufacturing field, and its use has spread to other areas as well. Locksmiths use plasma cutters to open locks and safes that cannot be opened any other way. Demolition specialists also use plasma cutting to remove pieces of metal without explosives.