The process of metal fabrication
Fabricators bid on projects provided by contractors and equipment manufacturers. From 3D drawings provided through CAD, the fabricators can determine the type of metal that will be used as well as the bill of materials. The most common raw materials used in metal fabrication of structures are plate metal, pre-formed and expanded metals, welding wires, fittings and castings. A wide variety of tools are used to cut metal into size. Some of the typical processes in cutting metal are shearing or the use of band saws with their hardened steel blades. However, technology has also introduced more modern ways of cutting that include oxy-fuel cutting, plasma cutting and laser cutting with improved accuracy. Metal parts can also be fabricated using tube bending machines and rolling machines to make round sections of metals. After metal has been cut and drilled, they are welded together to match the specifications of the general arrangement.
Different types of welding
In welding, two or more pieces of metal are joined together using heat and pressure. When heat is applied, metal softens which enables it to be affixed together in a joint area wherein an adequate amount of pressure will be applied. When the concept of welding was first developed, flame was used to heat metal at extremely high temperatures. As soon as the two pieces metal softens, they are hammered together until they become one. During the industrial revolution, this forging method of welding was replaced by electric and gas flame heating methods which was safer and faster for welders. Another new method of welding that was later introduced was laser welding. The choice for the welding method is often based on the form and thickness of the metal materials. Welding methods that are currently available include: arc, electroslag, flux-cored, gas metal-arc, gas tungsten-arc, metal inert gas, plasma arc, shielded metal-arc, submerged arc and tungsten inert gas.
Arc welding is the more popular form of welding because of its cost effectiveness. The process differs according to the requirements of the project but it generally makes use of electrical current between the welding devices and the metals that will be joined. Electroslag welding is a faster welding process used on large pieces of metals like thick steel plates. Gas tungsten arc welding is one of the most difficult and time consuming of the welding methods but it produces extremely high quality welds in small areas of space. Plasma welding is similar to gas tungsten arc welding and is typically used in the aerospace industry because of the high precision of the weld. Today, welding methods are consistently being improved to provide welders with more effective choices.