Welding is a fabrication process where two or more parts are fused together by the use 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.
Here we will discuss some of the most common welding techniques used in the industry and where they are used.
Note that the types of welding mentioned here apply only to metals. The following are the most common metalworking weld methods in use today.
1. Arc welding is a very widespread form of welding
As the name suggests, arc welding uses an electric arc to melt materials before joining them together. A power supply is used to create an electric arc is between an electrode (which can be either consumable or non-consumable) and the base metal to melt the metals at the point of contact.
The welding area is usually protected by some type of shielding gas, vapor, or slag. This is because the atmospheric air can interact with the weld pool and cause oxidation.
This electric arc can create temperatures upwards of 6300°F (3500°C), which is high enough to melt metals like carbon steel.
There are different types of arc welding, such as shielded metal arc welding (SMAW), flux-cored arc welding (FCAW), submerged arc welding (SAW), plasma arc welding (PAW) to exemplify.
Applications of arc welding:
- Automotive industries
- Construction industries
- Mechanical industries
Advantages of Arc welding:
- Suitable for high-speed welds
- Simple welding apparatus
- Portability as a result of the simple equipment
- Can work on AC or DC
- Superior temperatures
Disadvantages of arc welding:
- Not suitable for welding thin metals
- Requires skilled welders
- Cannot be used for reactive metals like Aluminum or Titanium
2. MIG (metal inert gas) welding has many applications
MIG or metal inert gas welding is another welding method that uses an electric arc to create welds. However, MIG uses a continuous solid wire electrode, which is heated and fed into the weld pool from a welding gun. The two base materials are melted together, forming a join.
In MIG welding, the melted electrode facilitates the joining of the two metals. Hence, MIG is ideal for joining dissimilar metals. Shielding gas is also supplied through the weld gun to ensure that the weld pool does not interact with the air, oxidizing the weld area.
Some of the popular applications of MIG welding:
- Used for most types of sheet metal welding
- Fabrication of pressure vessels and steel structures
- Automotive industry and home improvement industry
Advantages of MIG welding:
- Creates high-quality welds
- Minor weld splatter
- Can be used to join dissimilar metals
- Can be fully or semi-automatic
- Good weld speed
Disadvantages of MIG welding:
- Unsuitable for outside welding
- Unsuitable for thick metals
- Needs metal preparation
3. Another important welding technique is TIG (tungsten inert gas) welding
Tungsten inert gas welding (TIG) uses a non-consumable tungsten electrode to create an arc between the metals. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas, such as argon or helium. A filler metal is also sometimes used.
TIG welding can work on both AC and DC power sources. One of the greatest strengths of TIG welding is that it can be used for welding non-ferrous metals like aluminum, copper, magnesium, copper, nickel, titanium, etc.
Some of the popular applications of TIG welding include:
- Aerospace and aircraft construction
- Automotive industry
- Auto body repairs
Advantages of TIG welding:
- Very clean welds
- Offers a high degree of control to the welder
- Can be used with or without filler material
- Can be done in manual or automatic methods
- Creates strong welds
Disadvantages of TIG Welding:
- Needs skilled welders
- Cannot be used for thicker metal joints
4. Flux-cored arc welding (FCAW) is pretty cool
Flux-cored arc welding (FCAW) uses a continuous wire fed electrode, a constant-voltage welding power supply, and similar equipment to MAG welding. There are two types of flux cored arc welding — Self-Shielded and Gas-Shielded Flux-Cored welding.
The FCAW process can be divided into two types depending on the shielding method; one that uses an external shielding gas and one that solely relies on the flux core itself for protecting the weld area.
The shielding gas, where used, protects the weld pool from oxidation and is usually provided externally from a high-pressure gas cylinder. Weld metal is also shielded by the slag formation from flux melting.
Where an external shielding gas is not used, the process relies instead on the protection offered by the flux-cored electrode itself. This electrode provides gaseous protection and also forms a slag that covers and protects the molten metal in the weld.
Some of the popular applications of flux cored arc welding are:
- Manufacturing plants
- Industrial piping
- Maintenance and repair
Advantages of flux cored arc welding:
- Excellent weld penetration
- Suitable for thicker joints
- Flexibility in terms of torch movement and orientation
- The highest metal deposition rate
Disadvantages of flux cored arc welding:
- Can result in slag inclusion
- Flux-cored wires are more expensive
- Weld is often not aesthetically pleasing
5. Gas welding (oxyacetylene welding)
Gas welding uses the heat from a concentrated flame to melt metals and then join them. Gas welding is possible with or without filler metal.
The flame is controlled using a welding torch. An oxygen gas canister and a fuel gas canister is connected to the welding torch. The welder can control the flame by controlling the number of gases fed to the torch using a pressure regulator.
Most commonly, we see a gas combination of oxygen and acetylene, which is capable of producing 3200°C (5792 oF). Other fuel gases that are also seen in gas welding are hydrogen, butane, and propane.
Some of the popular applications of gas welding are:
- Fabrication of sheet metal
- Automobile and aircraft industries
- Joining ferrous and non-ferrous metals
- Joining thin metals
Advantages of gas welding:
- Easily portable equipment
- Superior flame control
- Low cost and maintenance
- Can also be used for Gas Cutting
- Cheaper equipment cost
Disadvantages of gas welding:
- Not suitable for very thin sections
- Lower temperatures than arc welding
- Harder to flux shield
- No suitable for reactive metals
If this article has piqued your interest, then remember that welding is a vast field where new material joining techniques are consistently being developed. This is not only interesting in its own right, but welding is a vitally important field as much of the machinery that we use to create complex and common items require some form of welding.
For this reason, welding will likely remain an important part of various industries for many years to come.