Welding is the most economical and efficient way to join metals permanently. It is the only way of joining two or more pieces of metal to make them act as a single piece,as a monolithic structure. Welding is used to join all of the commercial metals and to join metals of different types and strengths. Welding is vital to our economy. It is often said that over 50 % of the gross national product of the country is related to welding in one way or another.

Welding is a very important manufacturing method. Welding is also a very important construction method. Look around-almost everything made of metal is welded. This includes a stainless steel coffee pot, bicycles and toys, and jet engines for airplanes. The automobile would be much more expensive if it was not for welding. Oceangoing ships, river barges, railroad cars, and the external liquid fuel tanks for the Space Shuttle are all welded. Bulldozers, excavators, farm agricultural equipment, and construction equipment are all welded. Cross-country pipelines that carry oil and gas are welded, as are offshore drilling rigs and platforms, elevated water tanks, and oil storage tanks. Long bridges are welded and the world’s tallest building is welded.

The use of welding is still increasing. Arc welding equipment represent approximately half of total welding equipment, and arc welding is expected to grow at a rate of 6 % annually. Arc welding equipment includes welding machines and components. Resistance welding equipment includes resistance welding machines, transformers, controllers, and accessories as well as resistance welding electrodes. Gas welding and cutting equipment includes carriages, torches, and accessories. Other welding equipment includes stud welding, laser beam welding, friction welding, electron beam welding, ultrasonic welding, and stud welding, as well as components and accessories. Robot welding includes the welding equipment attached to robots. The total is all considered capital equipment. Although stick welding shipments are declining , they are expected to increase by the year 2000. Coiled or spool wire, including flux-cored electrodes and solid electrode wire, is increasing considerably and expected to rise much more by the year 2000.

Welding use is expected to grow due to its economic advantage. Intelligently designed weldments will always be less expensive for similar applications than will products made by other manufacturing methods, such as castings, forgings, and riveted or bolted assemblies. Welding is the only method that allows the designer to use the proper metal where it is required. This allows their properties that may be different to be used for specific needs. Welding is the best way to protect and conserve metals by protecting their surface with special metal overlays. Corrosion and wear account for losses running into billions of dollars annually. losses from both of these destructive forces can be greatly reduced by welding. Special alloys are deposited on base metals to provide corrosion-resistant surfaces or hard surfaces where required. Weld surfacing is widely used to reduce costly abrasive and corrosive wear of metal parts.

Welding ranks high among metalworking processes, including machining, forging, forming, and casting, among others. Welding involves more sciences and variables than those involved in any other industrial process. Welding appears to be very simple, but it is only when it is understood that it becomes the most economical and efficient way to join metals.

There are many ways to make a weld and there are many different kinds of welds. The welder behind the hood, making sparks, is using a very popular welding process:arc welding. Some welding processes do not cause sparks; in some cases electricity is not used, and in some cases there is not even extra heat. Welding has become complex and technical. It requires considerable knowledge to select the proper welding process for our work. Our job is to learn about welding so we can utilize its many advantages. Some of these advantages are :

  • Welding is the lowest-cost permanent joining method.
  • It affords lighter weight through better utilization of materials.
  • It joins all commercial metals.
  • It can be used anywhere.
  • It provides design flexibility.

It also important to know the limitations of welding. The limitation are:

  • Manual welding depends on the human factor.
  • Internal inspection is often required.

The limitations can be overcome by means of nondestructive evaluation, good supervision, qualified procedures, qualified personnel, and by adopting mechanized welding methods.

[ Modern Welding Technology by Howard B. Cary ]