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Metal inert gas (MIG) and tungsten inert gas (TIG) are two versatile welding methods used throughout countless professions. The basic end results are similar, but the machines, setup and processes are vastly different. Most welders can be used on various metals, but there are some things you need to know before getting started. Work environment, materials, supplies on hand and certain restrictions and guidelines will all play a role in which method you use.
TIG Welding Basics
TIG welding utilizes a sharpened electrode inside of a torch. The torch is equipped with a gas lens or nozzle, a gas cup, a collet body and a back cap.
The diameter electrode you use will determine the size of the gas lens and collet body. The back cap compresses the collet down on the tungsten and creates a compression-style hold which keeps the tungsten in place. The welding arc is generally started with a foot pedal and is regulated by a potentiometer inside of the pedal.
A setting on the machine limits maximum voltage. Depending on material and fitment, the metal can be fused to tack pieces in place, but any filler rod must be added to your puddle with a free hand. The most common choice of shielding gas is Argon. Argon will exit through the gas lens or nozzle and is directed at the workpiece by the cup at the end of the torch.
The filler rod and tungsten composition will be based on the welded material. The welders’ voltage capabilities will limit the thickness of metal you can weld. It should be noted that some TIG machines may only weld in DC or direct current, which is unsuitable for aluminum.
MIG Welding Basics
MIG welders use a torch that is controlled by a trigger. The wire is fed through a lined cable off a spool inside the welder, and the welding wire exits through a tip at the end of the torch.
Based on the packaging of MIG welders, working in awkward or tight spaces is generally more accessible with a MIG welder. Shielding gas also flows through the cable and is aimed at the workpiece with a nozzle. Both the tip and nozzle can be removed and changed for different metals. MIG welding aluminum is more effortless when equipped with a spool gun. Aluminum welding wire is very flexible, and feeding it throughout the cable can be difficult.
A spool gun places a 1-pound reel of filler wire inside the gun and drastically decreases the amount of travel and opportunities for the wire to bunch up or become jammed. Shielding gas varies depending on the material.
- For mild steel, the most common is a 75/25% mix of Argon and Co2.
- If you are MIG welding stainless steel, tri-mix is the best bet. Tri-mix is comprised of Argon, Helium and Co2.
- MIG welding aluminum will require 100% Argon, much like TIG. The voltage capacity of your particular machine will also limit welding thickness capabilities.
Similarities of MIG and TIG Welding
- Both MIG and TIG welding requires the use of shielding gas; because of that, external or natural interferences in the workplace must be considered. A gust of wind or a strong fan can easily blow your shielding gas away from your work, causing a weak and porous weld.
- Both practices allow the user to weld different kinds of metals with minimal changes to machine settings and consumables.
- Regardless of what method is used, safety equipment is paramount. A well-functioning, quality welding hood must always be used to protect your vision.
- Welding gloves are also necessary, but TIG welding gloves are generally thinner and allow better dexterity when feeding wire or positioning your torch.
- The arc produced from MIG and TIG welding is extraordinarily bright, and any opportunity to cover the skin should be taken as prolonged exposure to the arc can cause sunburn. Additionally, MIG welding can sometimes cause spatter, which is very hot and can cause burns to exposed skin.
Which Method Should You Use?
In most cases, the choice is up to the welder.
- Location and space will likely require a role in the decision, but if there are no specific requirements, either method will probably work.
- Requirements for either technique are usually due to health regulations or safety standards. For example, if welding a Chromoly roll cage in a vehicle that needs to conform to National Hot Rod Association (NHRA) standards, the roll cage must be TIG welded. Welding in the food service industry also requires the use of a TIG welder as well as various other strict practices pertaining to metal workpiece preparation.
Once the determination has been made for the correct procedure, and you have made sure it abides by any rules set forth, you can get to work!
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