ABSTRACT
Gas welding is used mainly in the repair of classic cars and the fabrication of components. It tends not to be used on most current vehicles because heating the steel to high temperature changes the steel structure and can cause defects. Flame cutting, known also as oxygen cutting, is made possible by the fact that oxygen has a marked affinity for ferrous metals which have been previously heated to their ignition temperature. Cutting may be done by means of a simple hand cutting torch or by a more complicated, automatically controlled cutting machine. The plasma cutting process relies on the fact that if a gas or mixture of gases, such as air, is subjected to a very high temperature it becomes ionized: negative electrons are separated from the atom, which is then positively charged. Plasma arc cutting is one of the most effective processes for high-speed cutting of many kinds of ferrous and non-ferrous metals.
