Blog 35: Welding its Types

Introduction:

By using heat at high temperatures, the fabrication technique of welding enables you to combine materials such as metals. While soldering and brazing do not enable the base metal to melt, welding employs high temperatures to unite the components. The base metal and the filler metal get joined after cooling.

While looking for a method to form iron into useful shapes, the welding process was discovered. In the early years of welding, the first product was welded blades because hard steel that was too brittle for use was generated when iron was carbonised. Later, hammer forging and interlacing the rigid and soft iron with high-carbon material produced a robust and resilient blade.

The filler material is used during the welding process. The pool of molten substances that helps build a solid bond between the base metal is known as the filler material. Following the welding of the metals, the shielding procedure prevents oxidation of the base and filler components.

Metalworking is thrilling and empowering. Welders are able to shape some of the strongest materials in the world into the goods they imagine while the heat and sparks fly.

There are numerous welding techniques, some of which you might not be familiar with.

Electromagnets, lasers, and microwaves are all used in several high-tech processes.

Low-tech techniques include forging or melting metal with a flame, and then forging two pieces together with a hammer.

What Is Welding?

In the production process of welding, two or more components are fused together to form a junction while they cool. Although welding is frequently done on metals and thermoplastics, it can also be done on wood. Weldment is the name for the finished welded junction.

Certain materials demand the employment of unique procedures and methods. Some are regarded as being “non-weldable.” This phrase is helpful and descriptive in engineering but is uncommon in dictionaries.

The base material is the component that needs to be bonded. Fillers or consumables are materials that are applied to create a junction. These materials can be referred to as substrates, tubes, flux-cored wires, consumable electrodes (for arc welding), etc. depending on their shape.

Consumables are typically chosen to have a composition that is comparable to the base metal so that they make a homogenous weld, however, there are instances where fillers with extremely different compositions are employed, and as a result, the properties are very different, such as when welding brittle cast iron. Dissimilar welding is what these joints have.

Sometimes referred to as a weldment, a finished welded junction.

Common Joint Configurations

Butt Joint

A connection between the ends or edges of two parts making an angle to one another of 135-180° inclusive in the region of the joint.

T Joint

A connection between the end or edge of one part and the face of the other part, the parts making an angle to one another of more than 5 up to and including 90° in the region of the joint.

Corner Joint

A connection between the ends or edges of two parts making an angle to one another of more than 30 but less than 135° in the region of the joint.

Edge Joint

A connection between the edges of two parts makes an angle to one another of 0 to 30° inclusive in the region of the joint.

Cruciform Joint

A connection in which two flat plates or two bars are welded to another flat plate at right angles and on the same axis.

Lap Joint

A connection between two overlapping parts making an angle to one another of 0-5° inclusive in the region of the weld or welds.

Types of Welding:

1. MIG – Gas Metal Arc Welding (GMAW)

A beginner can simply operate and master the art of MIG welding because it is a common and basic method of welding.

Metal Inert Gas (MIG) welding is sometimes known as gas metal arc welding (GMAW). Filler wire is fed through the gun semi-automatically, while shielding gas is released all around to shield it from outside contaminants. The filler wire that was fed onto a spool also served as an electrode.

To form the arc with base metal, which melts as filler material to create the weld, the wire’s tip serves as an electrode. The continuous process necessitates presetting the parameters in accordance with the welding need. The adaptable method for joining a wide variety of metals that results in a neat, smooth, and aesthetically pleasing weld bead.

These welding processes are not recommended for outdoor use since they are sensitive to environmental elements like rain, wind, and dust. Dross and porosity are two issues with MIG welding’s quality that contribute to the structure’s weakness.

The MIG welding technology is most frequently used in the nautical, construction, plumbing, and automobile repair industries. The supplied welding is robust, powerful, and able to endure great force.

2. Stick – Shielded Metal Arc Welding (SMAW)

These welding techniques have been around for 100 years and continue to advance. Because of its low cost, ease of use, and simplicity of operation, welding is popular. The technique involves spattering welding, which must be cleaned up.

A replaceable stick electrode serves as the filler material in this instance. When the stick’s tip comes into contact with the base metals, an arc is created. The electrodes’ filler metal melts in the arc’s heat, creating the weld. In order to shield the weld zone from oxidation, it coats the stick electrode with a flux that produces a shielding cloud. As the flux cools, it transforms into slag, which must be chipped off.

The process’s positive aspect is that stick welding may be done outside in bad weather conditions like wind and rain. It is helpful in equipment repair since it is feasible to weld on rusty, painted, and unclean metals. There are many different electrodes on the market, but none of them works with thin metals. Before you master stick welding, you must put in a lot of practice.

3. TIG – Gas Tungsten Arc Welding (GTAW)

There is no need for filler material with TIG welding. When the non-consumable tungsten electrode comes into contact with the base metal, an arc is produced. The two metals are melted and joined by the powerful arc. If necessary, you may use filler wire. Shielding gas is required continuously to protect welding from environmental contaminants. It functions better inside, away from the elements.

Although it is a powerful weld, it is challenging to learn. Only a skilled welder can master this art since they utilise both hands simultaneously to do the welding. The results of the welding are exact, powerful, and beautiful, and cleanup is not necessary. It is used to easily weld copper, aluminium, magnesium, nickel, and stainless steel. The procedure is particularly widespread in nonferrous metal-using companies, such as those that manufacture bicycles, vehicles, and tubing. Tools constructed of aluminium, magnesium, and stainless steel can be repaired.

4. Flux-cored arc welding (FCAW)

Due to the power source’s ability to execute both types of welding, FCAW is comparable to MIG welding. The filler wire must function as an electrode fed constantly from the gun during MIG welding. In contrast, FCAW generates a gas shielding zone around the weld by using a wire with flux as its core. With this technique of welding, no additional shielding gas is required. The method is flexible and effective with thick metals.

High-heat welding is an effective procedure that works well for heavy metals. Because no external gas is required, welding is a less expensive option. It is helpful for thicker metal and is utilised in the repair of large machinery. You must clean off the flux slag before you can have a lovely clean weld. Since a shielding gas is not needed, it can be carried out easily outside.

5. Submerged Arc Welding (SAW)

Different types of welding require covering the welding joint, arc, welding wire, and metal components with flux. As there are no welding fumes, powerful arc lights, or flying slags, the technique is safe. Whether a human or a robot is doing the welding, they are both protected by the flux barrier. The high-production industry can go through the procedure more quickly.

Rapidly and effectively, SAW generates strong welds with deep penetration and little preparation. Due to the flux layer, it shields the welder from UV and infrared rays.

6. Gas Welding/Oxyacetylene Welding

3500 degrees Celsius makes this one of the hottest welding techniques. Here, the welding environment is seven times hotter than the largest, hottest pizza oven. When fuel gases and oxygen are circulated in a torch, heat is produced. Three different flame types—the neutral flame, the carburizing flame, and the oxidising flame—are used in the process.

The welding process has various benefits. Because pressurised gas is contained in a convenient steel cylinder, it is portable. It is adaptable to different metal diameters and rather simple to operate. It is a very cost-effective and safe alternative that even a beginner can use.

7. Thermit Welding

Thermit, a compound made of aluminium powder and iron oxide, produces a non-violent exothermic reaction when it is ignited. The metal is melted by the intense heat and then poured onto the necessary joint surfaces. After cooling, the liquid metal solidifies to form a strong welding junction.

It is an easy and quick way to combine metal that is similar and different. Thermite must be heated to a temperature of 1300 degrees Celsius for this welding procedure to work.

8. Forge Welding

The earliest method of welding used back when we didn’t know what welding was. This method has been used for millennia. Here, the metal was heated to a pliable state, which allowed it to be shaped by hammering, and then it was allowed to cool to solidify the shape.

The method was thought of while a blacksmith was working on some metal. Forge welding is an option in the aircraft industry, yet it is not just confined to these specialists. Since there is no need for filler metal, the procedure is popular but requires a trained user.

9. Electron Beam Welding

Firing the ray of high-velocity electrons at the welding metal involves this type of welding. The energy from the electron transfers to the sheets to melt the welding metals, which can be joined and fused.  

The type of welding is employed in multiple industries like automated automotive parts, and high-end aircraft engine industries. This can be a useful tool in aerospace components, bimetal saw blades, and transmission assemblies. It is a perfect choice to seal electrical components. The technique is good for dissimilar metals of various melting points and thermal conductivities. This welding method is good for thin and thick metal.

10. Atomic Hydrogen Welding

The welding process is replaced now by the MIG welding now in most indications. It is still a perfect choice for tungsten welding. This metal is heat resistant, but by this method, you can fuse without altering the metal when joining and welding them. They place the two metal tungsten electrodes in a hydrogen atmosphere. The hydrogen molecules in explosive heat can produce heat up to 3000 degrees celsius. The proper safety precautions like welder gloves, suits, goggles, helmets are essential.

11. Plasma Arc Welding

A newer technique developed in 1954 and similar to TIG welding. They pass the electrical current through an orifice of the nozzle protected by gases for the ultimate accuracy to weld a small area.It produces a narrow bead, pleasing weld, strong, and speedy welding. 

The method used an extremely high temperature for a deep and stronger weld. The aircraft industry uses this technique, but not of any use for hobbyists and DIY users.

12. Resistance Welding

This is a thermoelectric process where electric resistance is employed to create heat, leading to a molten state of material to be joined. The efficient welding process which is pollution-free with minimum electricity consumption as well. It uses two electrodes in Spot Welding where the tip of the electrode produces heat and fusion on cooling. The following are the different types of welding.

  • Spot welding
  • Seam welding
  • Projection Welding
  • Flash butt welding

Advantages Of Welding

  • Welded joints are strong and may be stronger than the base metal.
  • Can weld different materials.
  • Welding can be done anywhere and does not require a long distance.
  • Offers a sleek look and simplicity of design.
  • They can be done in any shape, any direction.
  • Can be automatic.
  • Provides a perfectly rigid joint.
  • Easy addition and modification of existing structures.

Disadvantages Of Welding

  • Members may be distorted during welding due to uneven heating and cooling.
  • They are permanent joints, so welds must be cut to separate them.
  • High initial investment.

Application Of Welding

Welding is commonly used in pressure vessels, bridges, buildings, aircraft and spacecraft, rail vehicle and shipbuilding, automotive, electrical, electronics and defense industries, pipelines and railways, and nuclear power plants. Installation.

  • Fabrication of sheet metal.
  • Automotive and aerospace industries.
  • Connecting ferrous and Non-ferrous metals
  • Joining of thin metals.

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