Welding is one of the few jobs that have a place in almost every industry. Even in these turbulent times, welding is one of the more solid skills to pick up because you can rest assured that there will always be some demand for it. However, welding is a very complex trade with numerous variables.
One of these variables is the welding process itself. Before learning how to weld, it’s important to understand the caveats of different welding processes and carefully choose one process before mastering. Specialization in the welding industry is very valuable and gives welders many advantages in the job market.
Every welding process has benefits and there is no one welding process that is right for everyone. That said, MIG and TIG are two of the most popular methods of welding in 2020 and worth looking into.
Both welding processes come with their own set of advantages, disadvantages, and use cases. In this guide, we’ll take an in-depth look at both of these techniques and explain all of their differences so that you can choose the right welding process for your next project.
Metal inert gas (MIG) welding, also known as, gas metal arc welding (GMAW) is a popular welding process where a solid wire electrode is placed between the workpiece, both of which are then melted (creating a weld pool) by a high power electric arc.
A shielding gas is also used to ensure that the weld pool does not get contaminated. MIG Welding is also called wire welding because of the solid wire electrode used in the process.
MIG welding started being used in the mid-1900s (developed in the 40s) to weld aluminum together. However, as prices of inert gases became more affordable, the technology proliferated to other areas of metal fabrication and different types of groups (hobbyists to professionals) adopted MIG as their go-to welding process.
One of the main reasons behind this popularity (that still continues today) is speed and efficiency. MIG welding was and still is faster and more efficient than most of the welding processes easily accessible today.
MIG welding also makes for a gateway into welding, especially for beginners with little to no experience in professional welding. The basics are easy to pick up and the learning curve isn’t too steep which allows welders to quickly get to welding without requiring a lot of training.
Combine these benefits with the versatility of MIG welding as well as the low cost of welding, you can understand why MIG welding is so popular in all circles and industries.
Tungsten Inert Gas (TIG), also known as Gas Tungsten-Arc Welding (GTAW), is another very popular welding process used to weld different groups of metals by different types of welders.
While both MIG and TIG welding share a few similarities (for instance, both require a shielding gas to protect the weld pool from contamination), TIG welding has a few key differences that separate it from MIG welding. For instance, TIG welding a non-consumable electrode made out of tungsten unlike a consumable wire electrode used in MIG welding.
This means that in most cases, TIG welding requires a filler metal to join the base metals. This means that TIG welding requires the welder to hold the welding gun in one hand and the filler metal that usually comes in the form of a wire, in the other.
And while the separate filler metal allows an unmatched level of control over the welder, it also means that learning this process can be tricky. In fact, it is one of the most difficult welding processes to master. That said, TIG welding is also one of the most rewarding to learn as it is an extremely versatile welding process than can be used to weld a wide variety of metals.
Overall, TIG welding is a great welding process for workflows that require a greater degree of control. TIG welding is also great for working on thin metal sections as the lower heat input (especially in the DCRP mode) means that the heat-affected zone (HAZ) is inherently less severe.
Most importantly, welders can use TIG welding to create some of the cleanest, strongest, and high-quality welds possible through any welding process (even MIG welding).
The only major drawback with TIG welding is the slow deposition rate which limits how fast and how much welding can be done in an hour (usually only about 1-2 lbs per hour). However, there are ways through which the deposition rate can be increased.
There are quite a few differences between MIG and TIG welding. Following are some of the most important differences:
The strength of any joint is perhaps any welder’s biggest concern. The thought of a weld breaking any time is scary and the last thing you want to choosing the welding process that produces the strongest weld would seem like an obvious choice. However, there are a few things you should know.
First, every welding process that uses fusion process to create joints should be strong enough for daily use. Unless the project is very heavy and the joint undergoes regular pressure, the joint is unlikely to break.
Second, the strength of the joint is highly dependent on the quality of the weld. Skilled welders can generally create welds through TIG welding that are usually stronger than those created with MIG welding.
The other, equally important, side of strength is reliability. Due to the lower heat input, TIG welding results in the less severe heat-affected zone (HAZ) which helps in the long-term reliability of the weld.
Additionally, TIG welding gives the welder greater control so the weld can be more precise and the chances of compromising the integrity of the base materials are reduced.
Since TIG welding requires the welder to physically do more (hold the welding gun as well as a separate electrode), it is considered a more difficult welding process. TIG welding also has a steeper learning curve along with a higher skill ceiling. For these reasons, TIG welding is considered a more difficult welding process to pick up and master.
MIG welding, on the other hand, is considered to be one of the easier welding processes that is more forgiving when learning and easier to control. Therefore, MIG welding is more suitable for beginners and hobbyists.
The deposition rate refers to the amount of wire that actually ends up as weld metal. It is calculated in one hour and depends on two major factors: the wire type and the welding process. Since MIG welding is a more efficient welding process, the deposition rate is much higher (between 10-40 lbs per hour).
TIG welding, on the other hand, is a much slower process with a deposition rate of 1-2 lbs per hour. Due to this big difference, MIG welding is a much better choice if you need to do a lot of welding quickly.
However, the deposition rate in TIG welding can actually be increased to be closer to or even match the deposition rate found in MIG welding through a few workarounds.
One method is to use larger, water-cooled electrodes instead of traditional electrodes s these larger electrodes can be used with much higher current, more than a thousand amperes (compared to just a hundred amperes in normal electrodes).
MIG welding machines usually run off a DC power source with constant voltage, whereas TIG welding machines are more likely to work with either current. Some machines will also have a switch to convert AC current to DC as different currents have different effects on the welding. For instance, DC produces a strong arc whereas AC is better when working on aluminum.
Although MIG welding machines usually require a bit more maintenance than their TIG counterparts, the common consensus among welding circles is that TIG welding is the more expensive out of the two welding processes.
Some of the things that make TIG welding more expensive to operate include lower efficiency and lower deposition rate (less work done). Conversely, TIG welding results in an overall higher quality and cleaner weld that decrease the amount of time and money required for additional finishing. Spare parts for TIG welding machines are also more expensive.
MIG welding is the more cost-effective alternative and its low cost of operations is part of the reason why its so popular in the manufacturing sector. The only downside to MIG welding is that the power supply typically required are expensive.
Even though the welding arc produced in both MIG welding and TIG welding is extremely pinpoint, welders have more control, and thus can be more precise with TIG welding machine, compared to MIG welding machines. The extra control is granted by the separate electrode used in TIG welding which is extremely valuable when making intricate welds.
Another benefit of the separate electrode in TIG welding is a better finish. If you care about aesthetics and do not want to spend a lot of time removing bumps or jagged edges from your workpiece, TIG welding is the way to go.
However, note that both welding processes can lead to bumps and jagged edges (from the solidified weld pool), it’s just that the end result is usually more pronounced in MIG welding).
If you need to get through a lot of workpieces quickly and are willing to give up on quality for better speed and efficiency, then MIG welding is the better alternative out of the two.
Partly due to the significantly higher deposition rate out of the box (over 10 times more) and partly due to the lower barrier to entry. MIG welding is easier to get started with which means welders can quickly begin welding.
Both TIG and MIG welding requires the use of gases known as shielding gases. In fact, this is one of the key characteristics of both of these welding processes as they are one of the only welding processes that require shielding gasses.
Since gasses will likely be a major factor in choosing one process over the other, it’s a good idea to understand what shielding gasses are and what kind of different gasses are used for MIG and TIG welding.
MIG and TIG welding processes both use shielding gases to protect the weld pool from contamination from oxygen and water vapor in the atmosphere. Shielding gases are generally heavier than air and thus create a layer of protection around the weld as it is fed through the welding gun. Without this protection, welding can become more difficult and also reduce the overall quality.
Following are some of the advantages of using a shielding gas:
Tungsten Inert Gas (TIG) and metal inert gas (MIG) both use different inert gases (also known as noble gases). Although, there are also semi-inert gases or active gases. TIG uses purely inert gases and mixing in any non-inert gases (oxygen and carbon dioxide) can compromise the weld. On the other hand, MIG welding can and very often does use semi-inert gases which is usually a mixture of inert gas and a non-inert gas.
Some of the common shielding gases used for welding include:
MIG welding is more tolerant of different gases and thus welders have a wider range of options to choose from when it comes to shielding gases. MIG welders can use several inert gases as well as combinations of inert and non-inert gases.
More often than not, welders will choose different types of welding gases for different base metals. For instance, when MIG welding carbon steel, many welders use a C25 mixture which is 25 percent carbon dioxide and 75% argon gas for the best quality. However, it is possible to just use CO2 for carbon steel as it is cheaper.
For stainless steel, welders choose a mixture of argon (98%), carbon dioxide (2%) or helium (90%), argon 7%), and carbon dioxide (2%).
Since aluminum is more prone to contamination (relative to other metals), pure argon is used by many welders to achieve the best welds. However, sometime welders will create a mixture of argon (75%) and helium (25%) when the aluminum is thicker. A similar argon and helium mixture can also be used for copper allows when MIG welding.
As we mentioned, TIG welding only works well with pure inert gases and there are two popular options most welders choose from: argon and helium.
Argon is one of the more popular shielding gases for TIG welding and can be used to weld all metals including aluminum without having to mix it with any other gases. Argon is very stable and delivers a clean and precise weld with little bead rollover.
Helium is another shielding gas used for TIG welding however unlike argon, helium is more often used in combination with argon. For thicker metals, a 50-50 mixture of argon and helium is used. In certain cases, helium can be increased to 90% when used with DCEN (Direct Current Electrode Negative).
MIG welding is a faster welding process (compared to TIG welding) and thus is used in a large number of industries worldwide. The shorter lead time and reduced production costs are additional benefits of employing MIG welding in a manufacturing setting.
Following are some of the common applications of MIG welding:
TIG is also highly versatile and offers superior weld quality and strength. However, it requires greater skill and is much slower which reduces its use cases in manufacturing industries. TIG welding is usually found in more specialized industries including the aerospace industry.
Following are some of the common applications of TIG welding:
MIG and TIG welding processes are incredibly useful to learn, both for hobbyists and professionals with applications spanning many industries. However, each comes with its own set of advantages and disadvantages that make them better for some and worse for others. In a nutshell,
MIG welding offers:
On the other hand, TIG welding offers:
And with that, this ultimate guide on the differences between TIG and MIG welding comes to an end. If you have any questions about these (or any other) welding process, feel free to reach out to us or leave a comment below.