What Is Welding?- Definition | Types of Welding

What is Welding?

Welding is a fabrication process that uses heat, pressure, or both to fuse two or more parts together, forming a joint as the parts cool. Welding is typically used on metals and thermoplastics, but can also be used on wood. The completed welded joint can be referred to as a weldment.

Some materials require the use of specific processes and techniques. Some are considered “unweldable,” a term not typically found in dictionaries but useful and descriptive in engineering.

The parts that are joined are known as base material. The material that is added to form the joint is called a filler or consumable. Because of the shape of these materials, they can be referred to as a base plate or tube, flux-cored wire, consumable electrode (for arc welding), etc.

Consumables are usually chosen to be similar in composition to the base material, thus forming a homogenous weld, but there are occasions, such as when welding brittle cast irons, when a filler with a very different composition and, therefore, properties are used. These welds are called heterogeneous.

The completed welded joint may be referred to as a weldment.

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Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure, or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

Definition of welding

Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure, or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

How Does Welding Work?

Welding works by joining two materials together without a separate binder material. Unlike brazing and soldering, which use a binder that has a lower melting point, welding joins the two workpieces directly together.

Most welding done today falls into one of two categories: arc welding­ and torch welding.

Arc welding use­s an electrical arc to melt the work materials as well as a filler material (sometimes called the welding rod) for welding joints. Arc welding involves attaching a grounding wire to the welding material or other metal surface.

Another wire known as an electrode lead is placed on the material to be welded. Once that lead is pulled away from the material, an electric arc is generated. It’s a little like the sparks you see when pulling jumper cables off a car battery. The arc then melts the workpieces along with the filler material that helps to join the pieces.

Feeding the filler into the welding joint takes steady hands and an eye for detail. As the rod melts, the welder must continuously feed the filler into the joint using small, steady, back-and-forth motions. These motions are what give welds their distinctive appearance. Going too fast or slow, or holding the arc too close or far away from the material can create poor welds.

Shielded metal arc welding (SMAW or stick welding), gas metal arc welding (more commonly known as a metal inert gas, or MIG welding), and gas tungsten arc welding (frequently called tungsten inert gas, or TIG, welding) all exemplify arc welding.

These three common methods each offer unique advantages and drawbacks. Stick welding, for instance, is inexpensive and easy to learn. It’s also slower and less versatile than some other methods. Oppositely, TIG welding is difficult to learn and requires an elaborate welding rig. TIG welding produces high-quality welds, however, and can weld materials that other methods can’t.

Torch welding represents another popular welding method. This process typically uses an oxyacetylene torch to melt the working material and welding rod. The welder controls the torch and rod simultaneously, giving him or her a lot of control over the weld. While torch welding has become less common industrially, it’s still frequently used for maintenance and repair work, as well as in sculptures.

Types of Welding

There are four main types of welding. MIG – Gas Metal Arc Welding (GMAW), TIG – Gas Tungsten Arc Welding (GTAW), Stick – Shielded Metal Arc Welding (SMAW), and Flux-cored – Flux-cored Arc Welding (FCAW). We dive deeper into each type of welding here.

#1. MIG – GAS METAL ARC WELDING (GMAW)

MIG welding is one of the most common types of welding that beginners need to learn. MIG welding is used in the auto industry to repair vehicle exhaust and also in the construction of houses and buildings. This is a type of arc welding that uses a continuous wire called an electrode. You also use a shielding gas that flows through the welding gun and protects against contamination.

MIG welding is actually two different types of welding. The first use bare wire and the second uses flux core. Bare wire MIG welding can be used to join thin pieces of metal together. Flux core MIG welding can be used outdoors as it does not require a flow meter or gas supply. MIG welding is usually the welding of choice for DIY and amateur welders who don’t have the cash to spend on expensive equipment.

#2. TIG – GAS TUNGSTEN ARC WELDING (GTAW)

Like MIG, TIG welding also uses the arc, but it is also one of the more difficult welding techniques to learn. TIG welding uses a tungsten electrode. Tungsten is one of the hardest metal materials. It does not dissolve or burn off.

Tig welding can be done by a process known as fusion, which may or may not use a filler metal. TIG also uses an external gas supply such as argon or helium.

Two hands are required for TIG welding. One hand guides the rod while the other holds a TIG torch. This torch produces the heat and arc used to weld most common metals including aluminum, steel, nickel alloys, copper alloys, cobalt, and titanium.

TIG welders can be used to weld steel, stainless steel, chromoly, aluminum, nickel alloys, magnesium, copper, brass, bronze, and even gold. TIG is a useful welding process for bike frames, lawnmowers, door handles, fenders, and more.

The aerospace and automotive industries use TIG welding as do other industrial markets. This is also a great type of welding for Iowa as it can be very useful for farmers to weld wagon frames, fenders, and other vital equipment.

#3. STICK – SHIELDED METAL ARC WELDING (SMAW)

Want to take your welding to go? A major benefit of stick welding is that it is portable. Stick welding is used in construction, maintenance and repair, underwater pipelines, and industrial manufacturing. For this type of welding, use shielded metal arc welding, better known as stick welding.

Stick welding, also known as arc welding, does it the old-fashioned way. Stick welding is a bit more difficult to master than MIG welding, but you can buy stick welding equipment for very little money if you want to try it at home. Stick welding uses a stick electrode welding rod.

They use a consumable and protected electrode or stick. The stick softens and bonds metals by heating with an electric arc between a covered metal electrode and the base metal workpiece. As the stick melts, its protective cover also melts, shielding the welding area from oxygen and other gases that may be in the air.

#4. FLUX-CORED – FLUX-CORED ARC WELDING (FCAW)

This type of welding is similar to MIG welding. In fact, MIG welders can often double duty as FCAW welders as well. Just like MIG welding, a wire that serves as the electrode and filler metal is passed through your rod. This is where things start to differ. For FCAW, the wire has a flux core that forms a gas shield around the weld. This eliminates the need for an external gas supply.

FCAW is better suited for thicker, heavier metals as it is a high-temperature type of weld. Because of this, it is often used for repairs on heavy equipment. It’s an efficient process that doesn’t generate a lot of waste. Since no external gas is required, it is also cost-effective. There will be some slag left over, however, and it needs a bit of cleaning up to make a nicely finished weld.

#5. PLASMA ARC WELDING

Plasma arc welding is a precision technique and is commonly used in aerospace applications where the metal thickness is 0.015 inches. An example of such an application would be an engine blade or air seal. Plasma arc welding is technically very similar to TIG welding, but the electrode is recessed and the ionizing gases in the arc are used to generate heat.

The usual gas combination is argon as the plasma gas, with argon plus 2 to 5% hydrogen as the shielding gas. Helium can be used for a plasma gas, but as it is hotter this reduces the amperage of the nozzle.

Want to know more about Plasma Welding? Check out this article.

#6. LASER BEAM WELDING

This type of welding can be used on metals or thermoplastics. As the name suggests, a laser is used as a heat source to create the welds. It can be used on carbon steels, stainless steels, HSLA steels, titanium, and aluminum. It can be easily automated with robotics and is therefore widely used in manufacturing, for example in the automotive industry.

#7. ELECTRON-BEAM WELDING

This is a type of welding in which a high-speed electron beam uses kinetic energy to generate heat and weld two materials together. This is a very demanding form of welding that is carried out mechanically, mostly in a vacuum.

#8. GAS WELDING

Gas welding is only rarely used and has been largely superseded by TIG welding. Gas welders require oxygen and acetylene and are very portable. They are still sometimes used to weld parts of car exhaust back together.

#9. ATOMIC HYDROGEN WELDING

Atomic hydrogen welding is a form of extremely high heat welding formerly known as Atomic Arc Welding. In this type of welding, two tungsten electrodes are shielded with hydrogen gas. It can reach temperatures in excess of that of an acetylene torch and can be conducted with or without filler metal. This is an older form of welding that has been replaced by MIG welding in recent years.

#10. ELECTROSLAG

This is an advanced welding process used to join the thin edge of two metal plates together vertically. Instead of the weld being made on the outside of a joint, it takes place between the edges of the two panels.

A copper electrode wire is passed through a consumable metal guide tube that serves as the filler metal. When current is applied, the arc is created and a weld begins at the bottom of the seam and is slowly moved up, creating the weld instead of the seam as it progresses. This is an automated process and is done by machine.

Advantages Of Welding

  • Welded joint has high strength, sometimes more than the parent metal.
  • Different material can be welded.
  • Welding can be performed anyplace, no need enough clearance.
  • They give smooth appearance and simplicity in design.
  • They can be done in any shape and any direction.
  • It can be automated.
  • Provide a complete rigid joint.
  • Addition and modification of existing structures are easy.

Disadvantage of welding

  • Members may become distorted due to uneven heating and cooling during welding.
  • They are permanent joint, to dismantle we have to break the weld.
  • High initial investment.

Application Of Welding

The welding is widely used for the fabrication of pressure vessels, bridges, building structures, aircraft and space crafts, railway coaches, and general applications besides shipbuilding, automobile, electrical, electronic, and defense industries, laying of pipelines and railway tracks, and nuclear installations.

  • Fabrication of sheet metal.
  • Automobile and aircraft industries.
  • Joining ferrous and non-ferrous metals.
  • Joining thin metals.

FAQs.

What is Welding?

Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure, or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

How Does Welding Work?

Welding works by joining two materials together without a separate binder material. Unlike brazing and soldering, which use a binder that has a lower melting point, welding joins the two workpieces directly together.

What are the 4 Types of Welding?

There are four main types of welding. MIG – Gas Metal Arc Welding (GMAW), TIG – Gas Tungsten Arc Welding (GTAW), Stick – Shielded Metal Arc Welding (SMAW) and Flux-cored – Flux-cored Arc Welding (FCAW).