What Is Welding
Different Types of Welding Processes
What Is Welding? It is the process of fusing various materials, usually metals or thermoplastics to join them seamlessly.
Table of Contents
Introduction
Unlike other metal joining techniques, welding does not merely join the pieces together. It applies high heat and pressure to melt the parts together, allowing them to cool and form a strong joint.
Apart from melting the base metal. It also involves the addition of filler material to the joint to form a weld pool (molten material). The weld pool then cools down to form a joint. Depending on the nature of the weld, it can be firmer than the parent metal.
Importance Of Welding Gas
Welding also requires some form of protection in the form of a shielding gas to protect the weld area, and the filler metals from external contaminants or oxidation. The process you use will determine the type of gas you apply. Some of which are:
- Argon
- Helium
- Nitrogren
- Carbon Dioxide
- Oxygen
Traditionally welding is regarded as an industrial process, but with the advent of technology, it has evolved day after day. As such, it can be performed in different setups, including in outer space and underwater.
Welding is a hazardous process, and proper welding safety gear should be worn to prevent eye injuries, burns, electric shock, exposure to UV radiation and inhalation of dangerous gases and fumes.
There are different welding techniques, and it is important to understand how each differs. For you to make an informed decision when choosing the right welding process for the job.
Some processes require professional intervention, while others can be done by automated equipment. Welding is an art and requires a lot of practice. It is best learned with the assistance of experienced metal fabricators.
Major Types of Welding Processes
MIG (Metal Inert Gas) Welding
MIG welding uses the concept of joining two pieces of metal together using an electrode that is connected to a wire. The electrode holds all the material that is required for welding, and this process makes use of a shielding gas along with the electrode to heat up the pieces to be fused. The shielding gas protects the welding metal, arc, or even the electrode from atmospheric contaminants such as Nitrogen and Oxygen.
MIG welder systems require direct current and a constant voltage, and it is suitable for fusing aluminum, stainless steel, and mild steel.
What makes MIG welding stand out from other techniques is the ease of use and its wide application. Also, the operator requires a lower degree of precision to obtain aesthetically appealing welds, which saves on time. Also, this technique allows you to work on thin metals, which can be difficult with other processes without running the risk of burning through the materials.
The MIG process has a wide application in automotive repairs as it capable of producing a strong weld. When performed correctly, it can withstand extreme forces, offering the level of versatility required in such applications;
- Plumbing
- Maritime industry
- Construction and;
- Robotics
On the downside, this process tends to be more sensitive to wind, rain, and other external factors. Also, critical settings such as wire speed and voltage need to be fine-tuned by the operator which can prove to be tricky. This process is also associated with porosity and dross, which might result in structurally weak welds.
Shielded Metal Arc or Stick Welding
Shielded Metal Arc is a manual welding technique that uses a consumable electrode which is coated with flux to lay the weld. This welding technique uses sticks/rods that are made up of filler material hence the name stick welding.
The filler is used to join two pieces of metal together while flux is used to protect the molten metal of the weld area.
The weld area is protected from oxides and nitrates in the atmosphere by the flux coat. This implies that there is no need for shielding gas, as is the case with other welding processes. Also, it works perfectly on thick materials such as cast iron that might prove hard with MIG or TIG welding processes. Some of the fields that heavily rely on stick welding include automotive, plumbing, construction, and repair work.
Most stick welders work with all current type depending on the nature of the weld. Also, this technique can be used on projects that involve dirty and rusty metals where TIG or MIG techniques cannot be used.
While stick welding offers a modest solution that requires minimal expertise and equipment, the final weld is not always the best. Too often the weld area is susceptible to;
- Shallow penetration.
- Porosity and;
- Cracking
In addition, the final weld is generally less durable, and it is highly vulnerable to certain weather conditions. There is also a lower consumable efficiency because the technique produces a lot of waste. Also, it is not appropriate for thin materials as the high amount of heat generated can result in a burn-through. Also, because this is primarily a manual process, high operator skill is needed to master the art.
TIG (Tungsten Inert Gas) / Gas Tungsten Arc Welding (GTAW)
TIG welding is a process that uses a non-consumable tungsten electrode which works along with inert gas, usually argon or helium, to heat the filler material resulting in a weld. Tungsten is a high-quality element, and it offers high purity welds.
The heat in TIG welding is generated by running an electric current, either AC or DC through the tungsten electrode. Subsequently, the metal wire is melted, creating the weld pool. The shielding gas is used to keep the weld area free from contaminants, but in some cases, a filler metal is used in place of the gas.
Common applications of TIG welding include;
- Piping systems
- Automotive projects
- Aerospace welding
The main benefits of using the TIG process include the ability to produce high-quality and clean welds, ability to weld fragile metals, and a high degree of precision. Also, since the electrode is non-consumable, no feeding is required, and you do not need to replace the electrode.
However, this technique tends to have lower deposition rates because of the complexity of the process involved. You will also have to put up with the high cost of the equipment. Besides, you will require external shielding gas to achieve the desired results. High operator skill is needed, especially on welds that demand a high degree of precision.
Flux-Cored Arc Welding (FCAW)
Flux-Cored Arc Welder machines employs the same technique as MIG welding only that it uses a tube-shaped wire that is filled with flux instead of a solid wire. The shielding gas is not always needed, but this depends on the filler.
It is best known for its high electrode efficiency that creates less debris and reduced welding fumes irrespective of welding material.
Benefits Of Flux Core
- Less debris and reduced welding fumes
Flux-Cored Arc Welding generates a lot of heat, and it is majorly used for heavy repairs and construction that involves thick materials.
FCAW is easy to learn, and it is a rather clean process as it does not create a lot of spatter. It is also an excellent solution to outdoor use even under windy situations. With this technique, you will have the advantage of a double shield by using the flux and additional external shielding gas to guard the weld puddle.
Although this is one of the cleanest processes, it may still create slag, and it is not recommended for thin materials, not forgetting the high cost of the equipment. Also, the weld is not as aesthetically pleasing, but the process remains popular due to its ease of use.
The final word
No matter what welding technique you choose, remember to choose one that fits your needs. The efficiency of the process may influence the final decision in terms of deposition rates, productivity, the level of clean-up required, and the general outlook of the final weld. The most important thing is to understand what unfolds in each welding process so that you can establish if it is up to the task.
Guest Post By: William Phillips
William has been welding practically for the last one decade. He is an expert in all forms of welding and he loves doing it in the right way. His passion for welding prompted him to start blogging with the objective of sharing his real experiences. He offers practical solutions in well-researched and professionally-written articles to ensure that his readers get the best from the content he creates in his website Tools Haunt.
