Information about Welding

Rarely do we give much thought to welding and its importance. We often tend to limit it to sparks and helmets. Little do we realize that we are constantly surrounded by objects that have undergone the process of welding. Every industry that we can think of is where it is because of this process.

Welding is the process of joining two or more materials, usually metals (also thermoplastics) permanently, to form a continuous material. The ends of the two metals (base metals) that are to be united are subjected to heat, pressure or a combination of both, and are brought to molten state.

A filler (material used to produce a weld) is placed between the two molten metal parts to form a molten pool or weld puddle. On cooling, a strong permanent bond is formed between the two metals, thus forming a joint. Various energy sources can be used for carrying out welding such as gas flame, electric arc, laser, electron beam, ultra sound, friction, etc.

The origin of welding can be traced to the bronze age (more than 2000 years ago), wherein, tiny circular gold boxes were formed by pressure welding the lap joints together. Ancient sealed Egyptian tombs also reveal depictions of welders and tools.

Much later, Sir Humphry Davy's production of an arc between the two carbon electrodes in early 1800s, along with Edmund Davy's discovery of acetylene in 1836, spearheaded the era of modern welding techniques.

Till the 19th century, welding was mostly confined to the blacksmith's shop, where he would unite the metal pieces by a method called forge welding. It involved heating of the two metal pieces and then hammering away until the union took place.

This time-consuming and tedious process was replaced by other quicker techniques, which were made possible due to the introduction of electricity into industrial processes.

Welding processes can be classified into different types depending on the combination of pressure and temperature used for joining the materials. The different types of welding processes are:

Gas welding is also known as Oxy-fuel welding and is the oldest form of welding processes. Over the years, its importance has deteriorated, nevertheless, it is still widely used for repairing hollow items like pipes and tubes. It is also used widely in the jewelry industry and for welding materials that are unable to withstand higher temperatures.

Arc welding is the most inexpensive method and simplest form of welding which uses an electric current to unite the metals.

Resistance welding is a term that refers to a group of welding processes in which the resistance of the metal pieces towards each other caused by the flow of electric charge, produces the heat for joining the metals.

In this type external pressure has to be applied. However, there is no need for any filler or external heat. It is the most environment friendly of all methods as it causes least pollution. However, it is an expensive method.

Solid state welding refers to a group of welding processes, in which the fusion of the metals take place at temperatures which are below their melting points. The base metals do not undergo significant melting and retain their original properties.

Radiant energy welding involves the application of an energy beam on the base metal. It involves the use of electron beam and laser beam for welding. This is one of the most modern techniques of welding, and is fast and accurate.

Thermo-chemical welding refers to a group of welding processes in which the base metals to be united are fused by using heat generated from the chemical reactions (Exothermic reactions).

Friction welding is another type. We often associate welding with sparks flying all across the place. On the contrary, not all forms of welding emit sparks. Friction welding is one type of welding which does not release any sort of sparks, fumes, intense light, and sprays into the air during the welding process.

We may not realize it, but all welding processes involve the emission of hazardous gases. These gases are mostly colorless and odorless and often go unnoticed. The heat from the flame, electric arc, or laser, all result in emission of hazardous gases such as carbon monoxide (toxic), carbon dioxide (non-toxic), oxides of nitrogen and ozone (toxic).

Besides gases, welding processes also give out fumes and vapors which may or may not be visible. The type of process and the amount of gases emitted will determine the type of health hazard.

Irrespective of where the process is carried out, welding is a potentially dangerous process. Various kinds of hazards await the welder during the process, such as damage to the eyes, burns, electric shock, poisonous fumes, overexposure to ultra-violet rays, etc. The well-known saying 'prevention is better than cure' is applicable here.

Wearing appropriate safety gears would minimize the accidents that could occur during the welding process. The different types of safety gears include full face helmets, goggles, heavy duty welding gloves, and heavy soled shoes.

The welding process is highly significant to the economy, as it is used in the fabrication processes of each and every industry. Take for instance a farmer or a doctor.

They have no direct connection with the process; however, they are also indirectly linked and dependent on welding. This is because the tools and equipment that they use on a daily basis have been through welding in their manufacturing stages.

Welding finds its applications in the construction of bridges, pipelines, fuel tanks, tools, etc. The aircraft industry relies on welding for manufacturing airplanes, space crafts, rockets, missiles, etc.

The contribution of welding towards the household sector such as refrigerators and scores of other kitchen appliances is also quite remarkable. Moreover, welding is the most efficient, dependable, and cost-effective means of joining two metals.

Underwater welding refers to the process that takes place underwater, in the ocean. It is used when any pipe, ship, oil platform, etc., need any kind of repair or installation. This type of welding eliminates the need of removing the structure from the water for repair, thereby saving time.

Robot welding is the process that consists of repetitive tasks to be undertaken on similar objects. Robot welding was introduced in the 1970s and its demand has increased considerably over the years. This is because robots can work tirelessly and continuously, giving the same output and quality every single time.

Outer Space welding, a new and promising avenue, is currently under research. This type of welding would make it possible to assemble space stations, etc., in space itself. Even damaged space station parts can be repaired in space itself by this technique.

Welding is crucial to our material existence. Whether we recognize the contributions of welding or not, it will continue to make our world a better place to live in. Welding is a vast and deep concept, and what we have seen here are just a few strands of it. There is so much more to this art of joining metal pieces together!