Today, metal fabrication frequently includes assembly processes. Welding permits a manufacturer to attach metal components to one another more securely. Welded assembly plays a vital role in parts fabrication.
"Welding" typically refers to the union of pieces of metal. While this process may occur through forging or compression, the term today in a manufacturing context generally connotes the selective application of high temperatures which cause pieces of metal to melt and fuse indelibly. Manufacturers utilize welding to promote assembly during parts fabrication, and also as a way to cut through metal. Welders usually add metal to the area of joinder between metal components during welding.
Welding fabrication refers to the assembly process occurs either manually or with automation. It facilitates the fusion of pieces of metal into secure joints. The term "weldment" describes the joinder of two metal surfaces into a single unit during the assembly process.
A Brief History of Welding
While forge welding has occurred for centuries, modern welding did not become a significant industry until an electrical infrastructure developed. Inventors marketed the first oxyacetylene welding torches in 1900. Oscar Kjellberg invented a shielded metal arc electrode used in welding in 1904. Both the spread of mass-produced automotive technology and two World Wars intensified the demand for welded equipment during the Twentieth Century.
Shielded Metal Arc Welding
This basic form of welding, sometimes called "stick welding" or "manual metal arc welding", has historically played an important role in the construction and heavy equipment industries. It permits the joinder of pieces of steel or iron, but can also work on some other metals, such as nickel and copper. A welder uses a coated manually held stick electrode to generate an open electric arc between the electrode and a metal surface. The high temperature causes the metal in the electrode to melt and travel via the electric arc onto the work surface, where the heat melts metal contacted by the arc. Gases released from the metal surface shield both the arc and the surface. Upon cooling, the weld solidifies. This welding process can occur outdoors, but won't work well to join very thin materials. It requires a skilled operator.
Flux Cored Arc Welding ("FCA")
This newer form of welding offers an automated, somewhat safer, alternative to shielded metal arc welding during construction. It does not involve the use of a coated stick electrode. Instead, an automated or partially automated welding machine provides a continuously consumed electrode with a flux at a controlled rate of voltage. This type of welding requires less expertise than shielded metal arc welding, but does typically generate more gas fumes; it may lack the portability of the older shielded metal arc welding method. It is used widely in construction projects to weld thick pieces of metal, and also works to weld heavy machinery.
Gas Metal Arc Welding ("MIG" or "GMAW")
In this form of welding, the welder utilizes a flow of externally supplied inert gas (usually carbon dioxide or argon and carbon dioxide) to shield the work area from room air. An electrical arc forms between a consumable electrode in a welding "gun" and the work piece. This method of welding has become the most widely utilized in fabrication shops today because it will weld steel more rapidly than other methods. It also permits the welding of many other metals (including aluminum, a very challenging metal to weld). It does not join thick materials effectively.
Gas Tungsten Arc Welding ("TIG" or "Heliarc")
Welders with specialized training can perform TIG welding in order to join particularly thick or thin pieces of steel or iron together. They employ a hard, tungsten electrode for this purpose shielded by an external supply of argon or a combination of argon and helium. This form of welding will join thin metals together, but usually requires longer periods of time to complete.
Electric Resistance Welding
This type of welding sometimes occurs in a completely automated form today. It permits spot and seam welding of very lightweight metals during manufacturing. A machine compresses the metal into alignment, then sends electricity through a resistant electrode to generate heat, which in turn causes contact surfaces to melt in spots or along designated seams.
Materials And Applications
Welding typically occurs with the assistance of welding machines and external sources of inert shielding gases, such as argon or carbon dioxide tanks. People who work as welders require specialized training in order to learn metal welding skills and safety protocols. Operators must wear eye protection and extensive safety gear due to the high temperatures. Today some manufacturers utilize sophisticated welding machines relying on lasers.
Welding applications impact every sector of the economy, including agriculture, transportation, aerospace, energy, construction and manufacturing industries. The joinder of metal components proves essential in numerous situations. Welders learn to identify different metals and match the correct welding techniques and tools with specific metals and alloys.
Advantages of Welding
Welding offers many advantages. First, the use of parts with weldments greatly expedites final assembly operation. Instead of relying upon a multitude of components, weldments permit fabricators to secure some pieces permanently to one another, reducing the steps involved during final assembly. Second, welding helps insure some key parts in an assembly will remain in correct alignment. A weldment in a specific location may prevent a component from slipping out of place. Third, welding may help discourage some forms of product tampering, ensuring certain components will remain associated with others.