MIG welding is a welding technique that has the electrode wire and shielding gas supplied to a hand-held torch in a continuous manner. In the case of TIG welding the electrode is a non-consumable tungsten rod, there is still shielding gas that is supplied to lines and a filler rod that is separate from the torch and is being manually dipped into the weld pool.
In TIG welding a foot pedal can control the amperage or a control on the torch mounted to a welding head can change the amperage. In general, for both welding approaches a shielding gas is supplied separately from each welding process.
It is neither correct to compare MIG with TIG leaning towards one of the processes is better since both processes have pros and cons that are situational based.
MIG welding is inexpensive, very easy to pickup, and fast when it comes to welding processes. Therefore, new welders can produce welds of decent quality because of the shear ease of learning MIG as compared to TIG welding by far.
The learning curve for TIG welding is significantly tougher than MIG welding therefore it takes longer to learn as well as cost more.
In some ways that may be a disadvantage of MIG welding since the beauty and precision of a weld made by a TIG welder cant be matched by MIG welding. MIG welding is ideal for thicker materials but TIG welding is ideal for thinner materials or other fragile applications.
What is Metal Inert Gas (MIG) Welding?
Metal Inert Gas (MIG) welding is an arc welding approach that uses continuous contact between a solid wire electrode that is melted at the tip and pushed into molten metal of a welding gun under heat.
In this case, two workpieces connect joint, and produce a weld junction.In this context, a welding shield- which is gas that protects features shielding the weld to prevent contamination from air reactive products – is also used.
MIG welding was patented in the USA for aluminum welding in 1949. At that time, helium gas was available and used to shield the arc and melting bath with a bare wire electrode.
From around 1952, it became common practice in the UK to use argon gas for welding aluminum and CO2 for welding carbon steels. Processes that use CO2 and mixture gases with argon are termed as metal active gas (MAG) processes.
The productivity advantages of MIG versus metal manual arc (MMA) as a process are outstanding in aspect of metal deposition rate and are of productivity overall to the welder.
What is Tungsten Inert Gas (TIG) Welding?
Tungsten inert (TIG) welding is an extremely versatile and precise process used to produce very intricate welds where accuracy is critical. It uses a solid, non-consumable tungsten electrode, which is used to join two metals well, while inert gas, such as argon, shields the heated area from air.
The most distinguishing feature of TIG welding is the precision of the process; it is possible to weld dissimilar metals – for example aluminum, copper, and stainless steel.
An electric arc is struck between the workpiece and the tungsten electrode resulting in considerable heat. The workpiece melts and once there is enough molten metal in the pool, the welder can push a filler rod into the pool to increase the volume of material.
When the pool cools, the metal solidifies and creates a bond.TIG welding has its share of benefits, such as fine control of heat and filler material, and only a low amount of slag left in the weld, and has beautiful welds.
The Key Differences between MIG And Tig Welding
In the previous section we have briefly outlined some differences between Mig and Tig welding.
For example, Mig is thought to be much easier to do, has faster speed and it is capable of welding a much thicker workpiece. Tig is superior when it comes to control, will likely be used for thinner workpieces, and has minimal post-weld dressing.
There are also differences apart from the above general ones, which further can be grouped under headings like properties, cost, ease of learning, etc.
#1. Weld Strength
TIG welded joints tend to be stronger than MIG welded joints. This is mostly due to the very narrow and focused area of the welder’s arc, which yields better penetration than any other method of welding.
In addition, the Tig weld beads to be almost free of holes and other problems that cause lower strength in the weld.
It is important to mention some generalization that the MIG welds can have strong penetration, if the groove in a V shape is ground or cut in the weld joint before welding. For example, if a good travel speed is used, and torch positioning is consistent, it will also increase the strength of MIG welds.
#2. Weld Speed
In production welding, CO2 welders do tend to have a much faster speed of welding, compared to tig welders. Most MIG and air cooled welders automatically feed the filler into the weld pool. These welders provide a rounder and broader arc.
This faster feed makes it easier to maintain a longer run time without overheating the welder, which is what happens with most TIG welders, as there is always speed limit when set to fill the weld puddle.
Similarly, the air cooled TIG welding torches get very hot and prolonged use will either require you buy more expensive water-cooled torches or require a cooling period now and then.
#3. Shielding Gas
The TIG process and MIG process both use shielding gas to produce a quality weld. The shielding gas acts as a barrier to protect the weld from unintended reactive gases, that are available in the atmosphere, from causing further harm to the weld quality.
The shielding gas is argon gas for the shield when performing a TIG weld because the tungsten electrode reacts readily with gases like oxygen or carbon dioxide and needs protection from them while welding.
A typical MIG weld is performed using a mixture of argon and carbon dioxide (75% Argon mixture & 25% carbon dioxide) because the small amount of CO2 provides stable arc and aids penetration. General shielding gas rules can be disregarded based on job requirements.
In addition to argon, helium, dihydrogen, or dinitrogen may be mixed with argon for TIG welding purposes. MIG welding can use pure argon when welding aluminum, and pure carbon dioxide to save on cost and promote penetration.
MIG and TIG welding processes do apply different flow rates. For example, MIG welding may use tank gas at rates of 35 – 50 cubic feet per hour while TIG welding uses shielding gas at around 15 – 25 cubic feet per hour.
#4. Weld Aesthetics
TIG welds usually have finer beauty features than MIG welds. Because there is, and usually very little spatter from the TIG process, a TIG weld usually only needs light polishing to finish and to remove any discoloration.
It is an accepted best practice that TIG welds on a stack of ‘coins’ are the most beautiful and serve to make unpainted welds (steel or aluminum) look their best. On the other hand, some MIG welds are ugly enough that a qualified grinder could only make some visually desirable MIG welded beads.
Be that as it may, some MIG welds are usually adequate for projects where the aesthetic or beauty of the weld does not matter much or when the welds will be coated or painted, which will cover the joint’s beauty.
#5. Process Difficulty
It is easier to learn and perfect the process of MIG welding than it is to learn and perfect the process of TIG welding. With TIG welding, for example, you have to use both your hands to hold the torch and position the filler rod in the weld pool at the same time.
When using a foot pedal to control amperage simultaneous with torch and filler rod movement adds another variable. While controlling the torch, the flow and fill offers more flexibility, but it is not easy to learn and master.
TIG welding for instance requires proper cleaning of the metals to be welded and preparation which is one reason a lot of welders consider TIG welding to be advanced. TIG welding can be somewhat labor-intensive.
MIG welding takes little time at all to learn, as there is no foot pedal for you to control it and your two arms are free because your filler material is fully wired into the welding gun.
#6. Cost
TIG welding has a more expensive cost per foot of bead than MIG welding, because of the low deposition rates of TIG and the fact that it requires a more skilled and therefore expensive welder.
Also, the prep needed for the TIG welding technique adds a cost factor. In general, MIG welding supplies and machines are less expensive than TIG. These are some of the reasons why MIG is more affordable than TIG.
When To Use MIG vs. TIG Welding
The bottom line is that there does not seem to be a definitive line on which is better MIG vs. TIG. Both have some interchangeability and on the surface there are pros and cons to both methods.
Having an idea of the pros and cons will help someone give consideration to what is the most efficient method of welding. Often the guidelines will apply, but there will also be variances, which can change everything:
#1. Heavy-duty jobs.
In heavy duty jobs, usually on larger jobs, standard MIG or gasless (flux-core) welding can be just more effective than other processes. They can put lots of filler and weld large thicknesses, all in one pass.
While TIG welding can do it all too; it uses multiple passes, which is usually impractical, because weld on weld makes TIG taking too long.
#2. Precision jobs.
With TIG welding, you can weld stainless steel, mild steel, and aluminum. It is easy to lose control, particularly with thin sheet steel. In practice, it is very easy for people to burn holes on the workpiece when overheating.
TIG welding, although capable of doing similar controlled things to other welding processes, has a level of control and precision, because the welder provides control and not the welding machine.
#3. Long-run vs. small jobs.
With TIG welding, you’ll use a stick that is maybe three feet in length, so there will be quite a bit of stopping. With MIG welding, if the spool is long, you’ll have hundreds of feet of wire at your disposal.
MIG is fed at a set rate through the welding gun, which makes it best for long runs. While it is awesome for smaller, intricate pieces, the physical properties of TIG, makes it difficult to do on anything large.
#4. One- two-handed operation.
Unlike TIG which is a two-handed operation, MIG is a one handed operation. It matters in a workshop; but one-handed operation is even more useful when you need to stabilize a workpiece in an awkward shop position.
In awkward odd welding positions, one additional hand is all that is needed to stabilize that piece of work. It including might change whatever your doing from danger to not danger. An out of control welding torch is dangerous.
In this section it is significant to discuss safety along with Personal Protective Equipment (PPE) as related to welding. Protecting oneself from flame injuries and injuries to the eyes, specifically welder’s flash, and arc eye, and the reasons for having a welding helmet, gloves, strong welding gloves, jacket or apron, and ideally a hood.
The good news is that the same high quality welding PPE can be used for all types of welding.