DISCUSS THE TYPES OF METAL WELDING PROCESS IN CONSTRUCTION
More than 30 different types of welding exist, and they range from simple oxy-fuel to high-tech processes such as laser beam welding. However, only four welding types are used commonly, and they are MIG, TIG, Stick and Flux- Cored arc welding.
MIG - Gas Metal Arc Welding (GMAW)
This welding process uses a continuously fed electrode through a welding gun and the operator needs to pull a trigger in order to feed the consumable electrode through. Between the base material and the electrode an electric arc forms, heating and melting the materials to join together.
For this type of welding, you need an externally supplied shielding gas, and some of the most common used gases for this purpose are stainless steel, carbon steel, magnesium, copper, nickel, aluminium, and silicon bronze.
The main advantages of choosing the MIG style for welding include the reduction of waste thanks to the higher electrode efficiency, the minimal weld clean up required, lower heat inputs, and reduced welding fumes. Moreover, this is the easiest welding technique to learn, which makes it suitable for beginners and DIY enthusiasts.
Among the disadvantages, we can count the need for external shielding gas, the rather high cost for the best MIG welders and other equipment needed, the limited positions in which you can weld, and that all the materials need to be free of dirt and rust.
MIG welding is very commonly used in the automotive industry, branding, robotics, constructions, and the maritime industry.
TIG - Gas Tungsten Arc Welding (GTAW)
Also known as Heliarc welding, this process utilises a non-consumable tungsten electrode to produce the weld. It requires the use of a filler metal and an inert shielding gas, usually argon or argon/helium mixture, which protects the weld and electrode from atmospheric contamination.
TIG welding is mainly used for piping systems, aerospace welding, as well as vehicles and bicycles.
The main advantage of this technique is the ability to weld very thin materials, as well as a wide range of alloys. The process offers a clean weld with a high degree of purity.
However, TIG welding requires expensive equipment but has lower deposition rates, along with the need for an external shielding gas and high operator skill.
Stick - Shielded Metal Arc Welding (SMAW)
Often referred to as stick welding, it is a manual arc welding process using a consumable electrode that is covered with a flux to make the weld. The molten metal is free of nitrates and oxides in the atmosphere, making it fit for pipeline welding and construction, steel erection, and heavy equipment repair.
The technique requires equipment that is low-cost and portable. Plus, it also works on rusty metals.
The lower consumable efficiency and the high operator skill requirement are two disadvantages of it.
Flux-Cored Arc Welding (FCAW)
In this welding process, a DC electric arc generates heat that fuses the metal in the joint area. The arc is struck between a consumable filler wire that is fed continuously and the workpiece, and a shielding gas protects the weld from atmospheric contamination.
Besides being used for plain carbon, alloy, stainless and duplex steels, FCAW can also be used for surfacing and hard-facing.
The higher electrode efficiency creates less wastes and lower hit inputs, and requires no external gas shield, hence, producing fumes. It is a low-cost, easy-to-learn, and clean welding process. However, the process may produce slag.
Electron Beam Welding (EBW)
This method utilise heat generated by a beam of high energy electrons and can join any metals.
Atomic Hydrogen Welding (AHW)
This welding technique uses an arc between two tungsten electrodes in a shielding atmosphere of hydrogen to create cohesive and strong welds.
Gas Tungsten-Arc Welding
For this process small strips of metal are welded in order to obtain an extremely strong and long-lasting weld. It is a very difficult and time-consuming process, used for bicycle and aircraft manufacturing.
Plasma Arc Welding
This technique is for heating metal very extreme temperatures to create deeper and stronger welds. The method utilises a non-consumable tungsten electrode, and an arc is formed by strengthening the plasma throughout a bore nozzle. This method is useful in aircraft manufacturing industry.