Welding Processes — The Definitive Guide

During the beginning stages of learning the welding trade, most novices get overwhelmed by the amount of information available on the topic.

Different processes for joining materials are the most common stumbling point — and for a reason. A seemingly endless list of available methods exists for a new welder to learn about and master.

If you have so many options to choose from, how can you ever be sure you’re making the right call? All processes come with different learning curves, benefits, and drawbacks.

Some are cleaner, while others cater to a more varied range of metals. Some are more straightforward, while others produce more consistent results. The list of considerations goes on and on.

To simplify the matter, today, we’re taking an in-depth look at all the most prominent welding processes. Of course, as so many options exist, you’ll always miss out on a niche option or two.

Still, for newbies, our definitive guide will provide a solid foundation for making a decision.

What is Welding?

Let’s start by overviewing the most prominent terms in the world of welding.

Welding is an operation during which two or more parts get united using heat, pressure, or both. Most often, you’ll use the technique to join pieces of metals or thermoplastics, but it’s possible to weld wood as well.

Certain matters will ask for the use of particular procedures and processes. You’ll even find the term “unweldable” describing some materials, which means a lot in the world of engineering.

Joined parts go under the name of the parent material. The materials you add to form a joint are called consumables or fillers. Most common filler materials include pipes, filler wires, and consumable electrodes.

Most often, consumables are similar in composition to the parent material. That way, a welder can form a homogenous weld.

On some occasions, however, such as when fusing brittle cast iron, a filler is a different material. These welds agree in properties but are otherwise heterogeneous.

Welders call a completed joint a weldment. Next, let’s take a look at the differences that arise when it comes to welding various materials.

Joining Different Materials

Here, we’ll briefly explain how welding works for different types of materials.

Metals

Welding is a process conducted at high heat, melting the base material, usually with the addition of filler material. In that way, it’s different than brazing and soldering.

The high heat creates a weld pool of molten metal. When the melt cools, it forms a joint stronger than the parent material. Welders also use pressure alongside high temperature, or by itself in some cases, to strengthen their welds.

Finally, they might take advantage of shielding gas. It serves to protect melted and filler metals from oxidization and contamination.

Plastics

Plastic welding is, in some ways, the same as the process for metal. It takes advantage of heat to join the materials. In general, there are three stages of plastics welding.

The surface must get prepared before you fuse it, and it takes more time to cool the materials and create a fusion.

The joining methods for plastics tend to get differentiated into external and internal heating. The term used depends on the exact process in question.

Wood

Wood welding doesn’t use electric heat, but that generated from friction to create a weld. The materials are subject to a great deal of pressure and linear friction before joining.

That way, they bond together. Although it sounds complicated, this process is quick and allows for a clean joining without adhesives and nails.

Choosing the Right Welding Process

No welding process fits all applications. What you decide to do depends on your experience, readiness to learn, ability to invest in tools and equipment, as well as the materials you’ll weld.

As a general rule, do your best to match your project needs and current skills with an appropriate process and the right equipment.

The most common welding processes include MIG, TIG, and FCAW. Each comes with a set of inherent characteristics.

Today, we’ll go through them and some other examples and mention their benefits, limitations, and capabilities. Our guide should help you steer towards the right method for your project.

Arc Welding

Arc welding is a common technique among welders. You can start practicing this process at a low cost, using a device that gives off electric current, serving as an electrical power source.

The particulars of the equipment vary significantly from one process to another, but the basics stay the same. The device enables the current to move through generally non-conductive materials.

Once you turn on the machine, all you need to do is tap the electrode against your base material. The heat will melt the metals, and you can proceed to join them with a weld.

The name “arc welding” comes from the fact that the current created between the device and materials looks like an arch. This one is also among the oldest forms of welding, dating back to 1802.

As such, it is also one of the most developed types of welding, with many subcategories. Your choice, again, depends on the metal you use more than anything else.

Flux-Cored Arc Welding (FCAW)

This subtype of the process was first put into use in the early 1950s to give an alternative to traditional “stick welding.” The process is the best for fast-speed projects as it’s close to an automatic form of fusing materials.

Today, construction workers tend to take advantage of flux-cored welding because of its speed and variety.

The flux-cored technique requires an electrode constantly fed by electricity. It also needs a tube-shaped wire which is full of flux. There are two main types of the flux core wire:

• Socially shield wires – an excellent solution for outdoor use, work even in windy situations.
• Will shield wires – use an external shielding gas and flux to guard the weld puddle.

The main selling points of this process include high efficiency for electrodes, reduced waste, and lower hit inputs.

You don’t even need an external shielding gas if you choose the right type of wire, and you’ll see a reduced amount of welding fumes, no matter which material you use. Plus, this process is quite clean, producing a minimal amount of debris.

The negatives of this method include the fact it generates a lot of smoke. Also, the equipment you need for it comes at high prices. Finally, you shouldn’t practice flux-cored welding on thinner materials, as it could create slag and other residues.

Otherwise, the method is cheap to practice and easy to learn. You’ll find many professionals in the welding business preferring it to other, more sophisticated processes.

It does come with limitations and doesn’t produce as aesthetically pleasing results as some other methods, but it’s still famous for the sheer ease of use.

Gas Metal Arc Welding (GMAW)

This process is another automatic welding technique that comes to us from the 1940s. It entails using a welding gun, which automatically feeds the filler metal through the gun for creating a weld.

To add to the convenience, the tool distributes a protective gas at the same time to protect the weld from the elements. For these reasons, the process is quite fast, and the best when you need to do a lot of welding at once.

The first uses of gas metal arc welding were for aluminum metals. Today, most welders who use it work in the manufacturing and car repair industries.

The welder using this process needs to pull the trigger, and the welding gun will feed the electrode through the nozzle.

An electric arc forms between the parent material and the wire, thus heating the material until it reaches a melting point. A joint comes to life through this procedure.

The main advantages are similar to the previous type — primarily, the reduction of waste, higher electrode efficiency, minimal clean up required, lower heat input, and reduced fumes.

Plus, this technique is the easiest to learn, which makes it suitable for DIY enthusiasts and beginners.

The drawbacks include the need for external shielding gas and the high costs of the equipment. Plus, you’ll face a limitation in the number of positions from which you can weld — you can’t use the technique for vertical and overhead welding.

It’s also not suitable for thick materials. Finally, for maximum success, you’ll need to ensure all your workpieces are free from any dirt and rust.

Gas Tungsten Arc Welding (GTAW)

Gas tungsten arc welding originated in 1941, but it’s seen almost no development in the previous 80 years. There’s little difference between the process today and in the past.

This process is considered one of the most time consuming, challenging techniques popular today. The main reasons for this widespread opinion include the fact it requires a high level of both skill and focus — you weld a small area between the arc and the welded material.

Most often, welders go for gas tungsten arc welding to join small strips of metal, which contain very little iron.

The process uses a tungsten electrode instead of a regular one. This filler is not consumable by the heat.

Using this method, you can create an autogenous weld without additional materials. If you want to increase the mechanical properties of the metal, though, you can add an external filler.

You’ll also need a supply of external gas. In this case, argon and helium mixtures are the most common.

Although challenging, this method produces super strong, high-quality welds if you do it properly. Welders proficient in the technique often manufacture motorcycles, bicycles, commercial and military aircraft, and piping systems.

The primary benefits of this technique include the ability to weld thin, fragile materials and create clean, high-quality welds. Plus, your results will be beautiful. Tungsten welding also allows you to fuse a range of alloys, spatter-free, and without debris.

The negatives include the expensive equipment, need for a high skill level, and external shielding gas.

Plasma Arc Welding (PAW)

Plasma arc welding is quite similar to the previous type we mentioned. The two processes work in the same fashion, the only difference being that they use a different kind of torch. The plasma arc method comes from 1954, but it’s seeing improvements even today.

Plasma welding requires a lot of concentration, even more than tungsten. Using it, you’ll be operating on an even smaller arc, which asks for a high level of precision.

During the fusion procedure, you pass an electrical current through a small nozzle. The device also gives out shielding gasses, which adds to your accuracy.

Plus, as it creates extreme heat, it can result in deep, strong welds. Welders in the aircraft manufacturing industry most often practice plasma arc welding.

The benefits and drawbacks are the same as with tungsten welding, only amplified. On the one hand, it’s super precise and debris-free, versatile and clean. On the other hand, it’s expensive and a challenge to learn.

Shield Metal Arc Welding (SMAW)

This process was one of the first to rise to popularity among welders. Often called stick welding, the method uses a wire that carries an electric current and thus melts and joins metal.

The electrode, in this case, consists of a coded-influx core. The electric arc shows up when you withdraw the wire from the workpiece while still keeping it in close contact. It can produce extremely high temperatures of up to 6500 degrees Fahrenheit.

During the process, the molten metal has protection from oxides and nitrates in the atmosphere. So, the technique is suitable for construction, heavy equipment repair, pipeline welding, and steel erection.

The main advantages of shield metal arc welding are the low cost and versatility of the method. You won’t need to add shielding gas as you do with some other techniques, which means you can do it outside, even in harsh weather.

Furthermore, the procedure works well, even on dirty, rusted metals. Thus, if you hoped to use TIG or MIG but can’t because of your material quality, this is your best bet.

The procedure doesn’t provide high energy-efficiency of the consumable, though. It also asks for a tremendous level of skill on the side of the operator. You’ll have to tackle a lot of waste, too.

Although it sounds simple, it will take you longer to finish this type of weld than it would with other methods. You can’t use it on thin materials with efficiency, either.

Nowadays, welders tend to consider this method obsolete, mostly because it’s a manual technique. However, it’s good to learn it. It’s not always possible to use more modern methods, in which cases, this is a lifesaver.

Plus, if you’re looking to start welding on a budget, you found your process. The quality of the weld won’t be the highest, but it will work.

Submerged Arc Welding (SAW)

Submerged arc welding is only possible on materials with high contents of iron, such as stainless steel. It’s a relatively fast process, using an automatic or a semi-automatic device.

While quick, it requires a lot of skill, as the arc needs constant protection from the flux to protect the parent material and the weld from outside elements. As an extra benefit, the cover prevents spatter, which makes it safer for welders than other methods.

You won’t need a shielding gas, as the arc submerges beneath a blanket of flux. This feature makes the technique extremely versatile.

It’s most often a mechanized process, as the operator doesn’t get to see the weld pool. So, you’ll need to rely on setting parameters and positioning the filler wire.

Submerged welding is ideal for line pipe and pressure vessel manufacture.

Oxyfuel Gas Welding

Oxyfuel gas welding is one of the oldest, most versatile processes out there. However, in recent years, it’s become less popular in the industry, remaining only in pipe and tube joining and repair work.

In general, the equipment for gas welding is straightforward and inexpensive. It employs the combustion of oxygen to produce a welding temperature. The cooldown time for the weld is more prolonged, though, which leads to more significant distortion.

Let’s take a look at two main types of oxyfuel gas welding.

Metal Inert Gas Welding (MIG)

This process first emerged in the 1940s, but it went through 20 years of extreme improvement until getting to its final form.

It uses a gas to shield the weld metal, keeping it safe from natural elements. So, the process is quite fast, allowing the welder to operate continuously.

The method is also relatively straightforward, not requiring an extreme skill level. Remember, though, that you can only use the equipment indoors, as the gas isn’t appropriate for outdoor use.

Metal inert gas welding is standard in car manufacturing, particularly for replacing parts because it creates strong welds that can withstand high forces. Other uses include branding, construction, maritime industry, and robotics.

The adjustment of your equipment and the speed need to be perfect for good results. So, it asks for some experience before you get it quite right.

Tungsten Inert Gas Welding (TIG)

This process is much like the previous we described. The only difference of massive importance lies in the fact that Tungsten welding, as the name suggests, uses tungsten.

As such, it requires an extra filler inside the device, because tungsten electrodes don’t get consumed during the welding process.

This technique has the upper hand to metal gas welding because it can take higher temperatures. The most common uses are in the stainless steel industries.

Resistance Welding

The resistance welding process involves contact between metal surfaces. The connection produces resistance, from which the name arose.

After the two metals join with pressure, heat passes through it. Subtypes of this method tend to be efficient and cause little pollution. However, the equipment costs are high, and applications limited. Let’s take a look at the most popular kind of resistance welding.

Spot Welding

Spot welding is a popular method used to join sheets up to 3mm thick. Welders use two electrodes to pass currents through the layers. The most common application is in the automotive industry.

The best parts of this method include energy-efficiency, limited deformation of the workpiece, high production rates, lack of requirement for filler materials, and seamless automation. The strength of the weld is much lower than with other methods, though.

Projection Welding

This subtype connects metal sheets with the use of electrodes applied directly to the metal pieces with opposing forces. Welders most often use it in automotive, construction, and electrical manufacture.

The main advantage of this technique is its flexibility. You can weld more than a single spot at a time, and position them more closely than with spot welding for a stronger product.

The results are also neater and less obtrusive. However, you can’t use this method on metals, and it costs more because of the pricey equipment.

Butt Welding

Butt welding entails the connection of workpieces over their entirety instead of small spots. The heat comes from a current passed through the two surfaces facing each other.

The first step in butt welding includes bringing two surfaces together. Then you apply pressure, which combines with heat to create a weld. It’s thus a single-stage operation, quick and productive. The results are smooth and even, most often used for rods and wires.

Energy Beam Welding

The subtypes of this process are relatively new, but they’ve grown in popularity in high-production applications. The two main procedures under the umbrella are laser and electron beam welding.

The two are quite similar, differing only in their power source. The former uses a focused laser beam, while the latter does the same in a vacuum with electrons.

Many industries today take advantage of this process, from automotive production to aircraft engines. Aerospace components, bimetal saw blades, and transmission assemblies are examples of products created by beam welding.

Both kinds produce high energy density, deep welds, and minimal weld areas. They’re also easy to automate and provide productive, constant results.

On the flip side, the equipment is costly, although the prices are decreasing with time. Plus, the welds are susceptible to thermal cracking, at least until it develops even further.

Solid-State Welding

Solid-state welding doesn’t use a filler material, and it produces welds using temperatures below the melting point of the materials.

It relies on time, temperature, and pressure to join materials without melting them too much. Solid-state is one of the oldest forms of welding, but some of the newest, most innovative techniques of today came from it.

Specific advantages of the method arise from the state of the base metal. Chiefly, not melting it allows the material to keep its fundamental properties and not suffer heat-affected problem zones.

Plus, the features of individual metals matter much less with solid-state welding, making it more versatile.

Final Thoughts

As you can see, various welding techniques differ significantly in their applications and processes. Some require professionals and expensive equipment, while others you can master at home and on a budget.

Once you go for a type, get the right equipment, and start practicing.

We hope that our guide helped you understand the basics of different welding processes. Use it as a starting point, pick a method, and develop in-depth knowledge of it. With practice and experience, you’ll start learning more and more. Take your time for the best results.