MIG welding is a method of welding whereby an electrode wire and shielding gas are fed continuously through a hand-held torch. A non-consumable tungsten rod is used with a shielding gas applied through a line for TIG welding. A filler rod is provided separately and is manually dipped into the weld pool.
In TIG welding, a foot pedal or a mounted torch control can be used to change the amperage. In general, both types of welding use separate shielding gases.
It is not accurate to compare MIG with TIG and tend towards either being better as both have their advantages and disadvantages depending on the circumstance.
MIG welding is inexpensive, easy to learn, and employs fast welds. This means that novice welders are able to produce decent quality welds. The learning curve for TIG welding is significantly more difficult compared to MIG which also means it’s more time-consuming and costly.
Nonetheless, the level of precision and aesthetic quality produced by TIG welding surpasses that of MIG welding. MIG welding is ideal for thicker materials, while TIG welding is favorable for thinner materials and more delicate tasks.
What is Metal Inert Gas (MIG) Welding?
Metal Inert Gas (MIG) welding is an arc welding technique that employs the continuous contact of a solid wire electrode, which is melted at its tip and pushed into molten metal from a welding gun as it is heated.
In this case, two workpieces are fused together, and the weld junction is formed. It also employs a welding shield, which, in this case, is gas that protects the weld from reaction products resulting from atmospheric contamination.
MIG welding was first patented in the USA for aluminum welding in 1949. In those days, helium gas was available and used to protect the arc and melt bath produced with a bare wire electrode.
The use of argon gas in the UK for aluminum welding and CO2 for welding carbon steels became common from around 1952.
Technologies using CO2 and its mixtures with argon are also known as metal active gas (MAG) processes. The productivity advantages of MIG over MMA are outstanding in terms of deposition rate and overall efficiency of the welder’s work.
What is Tungsten Inert Gas (TIG) Welding?
Tungsten inert (TIG) welding is a highly flexible and accurate technique to achieve complex welds that require precision. It uses a solid, non-consumable tungsten electrode to join two metals while shielding the working area from air using an inert gas like argon.
The most outstanding feature of TIG welding is the precise control that it offers, along with the capability of welding different metals together, for instance, aluminum, copper, and stainless steel.
An electric arc is created between the workpiece and the tungsten electrode which gives off lots of heat. This process melts the metal, the welder pours a filler rod into the molten pool to increase the quantity of material. When it cools, the pool solidifies into a bond.
TIG welding has its advantages, which include sharp control over heat and filler material along with low spillage and aesthetically pleasing welds.
The Key Differences between MIG And Tig Welding
In previous sections, we have briefly described some differences between MIG and TIG welding.
For example, MIG is considered much easier to perform and is quicker along with being able to weld thicker pieces. TIG has superior control, is likely to be used for thinner work pieces, and has less post-weld dressing.
Besides the general differences mentioned, there are still some important differences that can be considered under different heads like properties, cost, ease of learning, and so forth:
#1. Weld Strength
TIG welded joints are usually stronger than the MIG welded ones. This is because with TIG welding, the very narrow and focused region of the welder’s arc penetrates the metal better than any other welding method.
Furthermore, the TIG weld beads, if done correctly, have very little holes and other imperfections which tend to make the weld weaker.
There is some generalization, however, where MIG welds can be done with strong penetration if a groove in the shape of a V is ground or cut into the weld joint before slitting the weld. Also, good travel speed and torch positioning improve the weld strength of MIG welds.
#2. Weld Speed
CO2 welders generally have a higher speed of welding in production when compared to TIG welders.
This is due to the reason that with most MIG and air cooled welders, the filler is automatically fed to the weld pool. Also, these welders have a rounder and broader arc, which helps dissipate heat.
With all this, welders can work faster, and as they make longer runs, they do not easily overheat the welder. This is unlike a TIG welder, whose speed is always limited when set to fill the weld puddle.
Likewise, the air-cooled torches Tungsten Inert Gas welding employs for welding gets extremely hot after prolonged periods of use, necessitating it to be swapped for costlier water-cooled torches or requiring a cooling break.
#3. Shielding Gas
Both TIG and MIG welding processes employ a shielding gas for a quality weld. The shielding gas acts as a barrier for unwanted reactive gases available in the atmosphere that can cause further damage to the weld and increases the quality of the weld.
Argon gas is employed for the shield while performing a TIG weld because the tungsten electrode is highly reactive with gases like oxygen or carbon dioxide and needs protection while welding.
A conventional MIG weld is done with a mixture of argon and carbon dioxide (usually 75% argon with 25 % carbon dioxide) because the small addition of CO2 makes the arc stable and helps it to penetrate. These general rules of shielding gases can be broken based on the requirement
Argon is sometimes blended with helium, dihydrogen, or dinitrogen for use in TIG welding. On the other hand, MIG welding can be performed with pure argon when welding aluminum and with pure carbon dioxide to reduce costs and increase weld penetration.
Both techniques apply different flow rates, as MIG welding uses between 35 and 50 cubic feet per hour, while TIG welding operates at a shielding gas flow rate of 15 to 25 cubic feet per hour.
#4. Weld Aesthetics
TIG Welds usually show finer aesthetic features than MIG welds. With very little to no spatter, TIG welds only needs light polishing to finish and remove any discolorations.
TIG Welds on the stack of ‘coins’ are often considered the most beautiful welds and serve to make unpainted welds (in steel or aluminum, for example) look their best.
On the other hand, some MIG welds are visually obnoxious, even though a competent grinder can make some visually appealing MIG weld beads.
In spite of the appearance issue, some MIG welds are often good for applications where the aesthetic part does not matter much or where the welds will be painted, covering the joint’s appearance.
#5. Process Difficulty
It is easier to learn and master MIG welding than TIG welding. TIG welding, for example, uses both hands, one for moving the torch and the other for feeding the filler rod into the weld pool. A foot pedal that controls amperage can also be used at the same time.
These movements offer greater flexibility, but they are difficult to master. TIG welds, for example, require proper cleaning and preparation of the metals to be joined, which is why many welders consider TIG welding as advanced. TIG welding can be quite intensive.
In contrast, MIG welding takes little time to learn. There is no foot pedal to control it, and both arms are free since the filler material is fed automatically through the welding gun.
#6. Cost
Compared to MIG welding, TIG welding has a more expensive cost per foot of bead. This is because of the lower deposition rates associated with TIG, and the fact that it is operated by a more skilled and therefore expensive welder.
There is also the cost addition in the prep work required for the TIG welding technique. Lastly, both supplies and machinery for MIG welding are cheaper than those for TIG. These reasons are why MIG welding is more economical than TIG welding.
When To Use MIG vs. TIG Welding
The truth is that there does not seem to be a clear winner on the divide between MIG vs. TIG. These methods of welding have some level of interchangeability, and like all systems, each has its pros and cons.
Familiarity with the advantages and disadvantages is what will help one decide the most efficient welding technique. These guidelines will most often be applicable, but there are always some variances that can change everything:
#1. Heavy-duty jobs.
For large-scale projects, standard MIG and gasless (flux-core) welding can be single handedly the most effective option. In comparison to other procedures, they can deposit large amounts of filler and weld substantial thicknesses within one single attempt.
While TIG welding can attain the same results, it takes multiple passes. It is rarely a practical option, and applying weld on weld utilizing TIG consumes too much time.
#2. Precision jobs.
Stainless steel, mild steel, and aluminum TIG welding is possible. It is, however, easy to lose control, especially with thin sheet metal. It is quite common for the rookies to put holes in the workpiece due to overheating.
TIG welding has a fine degree of precision because the welder has better control, unlike in other welding in which the welding machine provides control
#3. Long-run vs. small jobs.
TIG welding rods have a length of about three feet; therefore, there is a lot of pausing in the process. However, a MIG welding spool has hundreds of feet of wire on it.
Since MIG wire is automatically fed through the welding gun, MIG welding is ideal for long runs. Although TIG welding is great for small, intricate pieces, it is also very difficult to perform on large projects.
#4. One- two-handed operation.
MIG welding is a one handed operation, unlike TIG welding, which is a two handed operation. In a workshop, this difference is hardly felt, but one-handed operation can aid in stabilizing a workpiece.
With awkward welding positions, having an additional hand can assist in maintaining stability, which might change the work from being unsafe to safe. An uncontrolled welding torch can pose a serious risk and danger.
In this section, it is pertinent to discuss safety measures along with personal protective equipment (PPE) for welding. To prevent flame and eye injuries, like welder’s flash or arc eye, it is necessary to use a welding helmet, gloves, sturdy welding gloves, a jacket or apron, and preferably a hood.
Luckily, the same top-notch welding PPE applies to all types of welding processes.” Fortunately, the same high-quality welding PPE can be used for all forms of welding.