Metal inert gas (MIG) welding is also known as gas metal arc welding (GMAW). It uses a semi-automatic or fully automatic arc to create the weld with a consumable wire electrode as the filler material and a shielding gas to protect the weld, promote weld penetration and reduce weld bead porosity.
The electrode and the shielding gas are both fed through the welding gun (or torch). The shielding gas is usually a mix of 75% argon and 25% CO2, although other mixtures are also used depending on materials being welded and other variables.
It also uses a continuous, consumable wire electrode and a shielding gas, which are fed through a lead to a welding gun (sometimes called a torch). The composition and diameter of the wire electrode also varies according to the types of metal being joined, the part thickness and the joint configuration. The pace at which the electrode is fed into the weld is determined by the wire feed speed (WFS) settings, which needs to provide enough weld metal fir the join.
Tungsten inert gas (TIG) welding is also known as gas tungsten arc welding (GTAW). As with MIG, this welding process also uses an arc but, unlike with MIG, the electrode is a non-consumable tungsten electrode that is used alongside a separate consumable filler material. This filler is usually a rod that is manually fed into the weld pool, meaning that both hands are used for TIG welding – one for the tungsten electrode and the other for the filler rod.
The composition and size of the filler rod varies according to the weld being made. TIG welding also uses a shielding gas, although this is typically 100% argon as CO2, as used with MIG, promotes tungsten oxide formation that can prematurely wear your electrode and contaminate the weld.
TIG welding also uses a foot pedal so the welder can control the amperage, adjusting the heat during welding and allowing for precise control over the heat introduced to the metal.
MIG Advantages and Disadvantages
MIG, or metal inert gas, welding tends to be used to join large and thick materials, using a consumable wire that is both the electrode and filler material.
MIG welding is faster than TIG welding, creating shorter production times for welds and, subsequently, lower costs. MIG welding is also easier to learn, making it easier to produce welds that require little or no cleaning and finishing.
However, MIG welds are not as precise, strong or aesthetically pleasing as those produced by a skilled TIG welder.
TIG Advantages and Disadvantages
TIG, or tungsten inert gas, welding is a versatile technique that is capable of joining a wide range of small and thin materials, using a non-consumable tungsten electrode alongside an optional, separate filler rod.
TIG welding is slower than MIG welding, which increases production times and, subsequently, leads to increased costs. TIG welding is also harder to learn and requires skilled practitioners to deliver the correct weld precision and accuracy.
However, because TIG provides greater control over the welding operation, TIG welds are stronger, more precise, and more aesthetically pleasing than MIG welds.
|
Benefit
|
MIG
|
TIG
|
|
Welding Speed
|
√
|
X
|
|
Welding Costs
|
√
|
X
|
|
Ease of Welding
|
√
|
X
|
|
Strength of Welds
|
X
|
√
|
|
Weld Precision
|
X
|
√
|
|
Weld Aesthetics
|
X
|
√
|
|
Thick Materials
|
√
|
X
|
|
Thin Materials
|
X
|
√
|
MIG Applications
Because MIG welding is easy to learn, relatively simple to perform and able to join materials such as aluminium, mild steel and stainless steel, it is suitable for a range of applications.
MIG is particularly effective for thicker metals and typically used where weld aesthetics are not a priority.
TIG Applications
TIG welding is more difficult to learn, but offers more precise results than MIG welding. TIG is also better for joining thinner materials and can be used to weld aluminium, copper, steel, titanium and more.
As such, TIG welding is widely used jobs where precision is required, such as for aerospace, motorsport, industrial structures, production line manufacture, and more.
We have already mentioned some of the differences between MIG and TIG welding processes.
MIG is generally seen as being easier to learn and perform as well as being faster and better for welding thick materials. However, TIG welding offers greater control and precision, is better for thinner materials and offers neater welds with little finishing required.
Aside from these general differences, there are a number of key differences that can be categorised according to different properties, cost, ease of learning, and more:
1. Weld Strength
TIG welded joins are typically stronger than those produced by MIG welding. This is because the narrow, focused arc created by TIG welders offers better penetration of the metal. In addition, the TIG weld beads, when applied correctly, contain few holes and other defects that can weaken the weld. Despite this generalisation, MIG welds can still produce strong welds with good penetration by grinding or cutting a V-shaped groove into the joint before starting to weld to increase penetration. Good travel speed and torch positioning will also improve the weld strength of MIG welds.
2. Weld Speed
MIG welders typically provide faster welding speeds in a production setting.This is because air-cooled MIG welders auomatically feed filler material into the weld pool and have a rounder and broader arc that dissipates heat better. This allows welders to move the weld puddle faster and make longer runs without overheating.By contrast, TIG welders cannot move the weld puddle as fast or supply enough filler rod to compete with MIG welding speeds. In addition, the air-cooled torches used in TIG welding get too hot during lengthy welding runs, meaning they need to cool or be swapped for more expensive water-cooled torches.
3. Shielding Gas
Both MIG and TIG welding use a shielding gas ensure quality welds. The shielding gas protects the weld puddle from reactive gases found in the air that can cause impurities in the weld. TIG welds typically use pure argon gas to protect the weld as the tungsten electrode is more sensitive to reactive gases like oxygen or CO2. MIG welds are typically performed with a blend of argon and CO2 (typically 75/25%), as the small addition of carbon dioxide stabilises the arc and aids penetration. There are exceptions to these general shielding gas rules, depending on the application. TIG welding may sometimes use a blend of argon with helium, hydrogen or nitrogen, while MIG welding is performed with 100% pure argon when welding aluminium and can be performed with pure CO2 to save costs and increase weld penetration. The two techniques also use different shielding gas flow rates, with MIG typically using 35 to 50 cubic feet per hour and TIG welding operating a shielding gas flow of 15 to 25 cubic feet per hour.
4. Weld Aesthetics
TIG welds tend to show better aesthetic qualities than MIG welds. With very little or no spatter, TIG welds usually only require light polishing to finish and remove any discolouration. TIG welded stacks of ‘coins’ are often seen as the most aesthetically-pleasing weld and can serve to make unpainted welds (in steel or aluminium, for example) look their best. By contrast, MIG welds have a less desirable appearance, even though an experienced welder can still create good-looking MIG weld beads. Despite the aesthetic differences, MIG welds are often fine for applications where appearance is less important or where the welds are to be coated, covering the appearance of the joint.
5. Process Difficulty
MIG welding is much easier to learn and master than TIG welding. TIG welding requires the use of two hands, one to move the welding torch and the other to feed the filler rod into the weld pool. Plus, there is often a foot pedal with which you can control the amperage. While these various movements allow for greater control, they can be difficult to master. The metals to be joined must also be cleaned and prepared well for TIG welds and welders tend to consider TIG as a more advanced process. MIG welding, by contrast, is much easier to learn. There is no foot pedal to master and the filler material is automatically fed through the welding gun, meaning that you only need to use one hand to complete the weld.
6. Cost
TIG welding costs more per foot of bead than MIG welding. This is due to the lower deposition rates associated with TIG as well as the need for more experienced, and thereby more expensive, welders. In addition, TIG welding requires more prep work, which also adds to the cost. Finally, MIG welding supplies and machines tend to be less expensive than TIG.All of these factors combine to make TIG welding more expensive than MIG welding.
Is TIG better than MIG?
It is difficult to determine whether TIG is better than MIG, as it depends on a number of factors. TIG offers greater weld strength and better aesthetics if completed properly by a skilled welder but, if the welder is less skilled, MIG welding may be a better option for a quality weld. MIG welding is also a faster process than TIG welding, allowing for longer runs to be completed in less time. So, ultimately, TIG is better in some instances and MIG is better in others.
Is TIG welding harder than MIG?
TIG welding is typically seen as more difficult to master than MIG welding as it is a less automated process that requires greater precision.
Should I learn MIG or TIG welding?
While stick welding is often considered to be the best process for total beginners, MIG welding is a better place to start learning the basics over TIG welding. You should be able to produce acceptable welds much easier with MIG than with TIG.
How to choose the right process for your application?
The differences between the two welding techniques mean that it can be difficult to decide when to use MIG and when to use TIG welding. Each technique has its own advantages, which can act as a guide to which technique to choose…
1. When to use MIG:
- Thicker materials – MIG is better suited for joining thicker stock
- Long runs – The continuous wire feed of MIG welding means that it is better for longer runs, needing to stop and start less often to replace the filler material than with TIG welding, which means less chance of weld defects
- Difficult positions – MIG is easier to use in difficult positions as it only requires the use of one hand
- High productivity – MIG welding is better suited to high levels of productivity than TIG welding, which is a slower process
- Less experienced welders – MIG is easier to learn than TIG, so is better suited to less experienced welders
2. When to use TIG:
- Thinner materials – The precision and accuracy of TIG welding means that it is ideal for joining thin materials that may be susceptible to burn through or warping
- Short runs – TIG welding is best suited to short runs
- Shop or bench work – TIG is not an easy process to manage when out of position, so the best results are achieved in bench or shop work
- Delicate or fine work – TIG welding is preferred when the look of the final weld is important. Visible pieces such as automotive restoration or artwork will look better with TIG welding, while the process also allows for better control to prevent warping or burning
- Non-ferrous metals – Experienced welders will tend to turn to TIG welding for aluminium, copper, stainless steel and other exotic metals
- Experienced welders – All of the advantages of TIG welding depend on having an experienced welder, without which it is better to opt for a simpler method, such as MIG welding
MIG welding uses a continuously-fed electrode wire and shielding gas via a hand-held torch. TIG welding uses a non-consumable tungsten electrode with a shielding gas fed through a supply line and a separate, hand held filler rod that is manually fed into the weld pool. TIG welding also uses a torch mounted control or a foot pedal to change the amperage. Both types of welding typically use different shielding gases too.
Neither MIG or TIG can be deemed ‘better’ than the other as they both have their own advantages and disadvantages depending on the situation.
MIG welding offers low cost, fast welds and is easy to learn, meaning that less experienced welders can put down good quality welds. TIG welding is much more difficult to master as well as being more expensive and slower. However, TIG welding can deliver a level of accuracy and aesthetic quality that can’t be matched by MIG welding. Where MIG welding is better for thicker materials, TIG welding is preferred for thinner materials or more delicate jobs.
Related Frequently Asked Questions (FAQs)