Plasma and Oxy Fuel Cutting are two different processes used for cutting custom shapes out of sheets of metal plate. While Oxy Fuel can only be used to cut ferrous material (material containing iron, such as steel), Plasma Cutting can cut non-ferrous materials such as stainless steel and aluminum. Each method of cutting plate has its benefits, which is why they are often combined on one CNC controlled machine.
Invented in the early 1900’s, Oxy fuel cutting uses a fuel gas, such as acetylene or natural gas, along with an accelerant, typically compressed oxygen, to burn through steel plate. By using pure oxygen instead of air, the temperature of the flame is increased dramatically, which is necessary to bring metals to their kindling temperature. At this point, the oxygen helps to burn the metal rapidly into metal oxide(rust), essentially cutting the part into a desired shape. The benefits of oxy fuel cutting are that the equipment is easy to maintain, and does not require a high power electricity supply. Oxy fuel also can cut very thick steel materials. The negatives of oxy fuel are that it can only cut ferrous material, and it also can overheat small parts due to its slower speed, so it can only cut materials thicker than about ¼” without inducing warpage into the part.
Plasma cutting is a newer technology, invented in the 1950’s that has really come into its own in the manufacturing environment in the last 20 years. Using a high voltage and amperage power supply, plasmas cutting can be used to cut through various thicknesses of any electrically conductive material. The basic plasma cutting process involves creating an electrical channel of superheated, electrically ionized gas i.e. plasma from the plasma cutter itself, through the work piece to be cut, thus forming a completed electric circuit back to the plasma cutter via a grounding clamp. The negatives of plasma cutting are that it can require very expensive and sometimes maintenance intensive equipment, and it cannot cut as thick as the oxy fuel process. The positives, however, are that it can cut a variety of both ferrous and non-ferrous materials, it does not induce large amounts of heat into the part, so parts can be very intricate and be made of very thin materials. Plasma cutting is also a very fast process, so it is desirable for applications requiring high output.