MIG, also known as Metal Inert Gas welding is a welding technique that employs the use of a consumable thin wire electrode, an addition of filler metal that’s added automatically and a shielding gas.
The electrode, a thin wire is fed from a reel that’s mounted on the welding machine through a flexible tube called a conduit liner and finally on a welding gun. The wire electrode is fed continuously when the trigger is pulled. The welding gun’s nozzle consists of a contact tip which electrically charges the wire and a gas diffuser which releases the shielding gas.
The Welding Gun
The welding gun’s trigger has three roles: to continuously feed the thin electrode, to switch on the welding current and a shielding gas. The electric current heats both the wire and the base metal above melting point in an electric arc; which explains why MIG welding is also referred to as Gas Metal Arch Welding (GMAW). The two coalesce and solidify into a single piece. The shielding gas protects the molten metal from reacting with oxygen and water vapor.
The Shielding Gas
The shielding gas contains three parts of Argon to one part of carbon dioxide. As you would expect, the gas is stored in high-pressure cylinders and regulated to usable levels. MIG welding uses a direct current. The MIG welding machine controls voltage, wire speed and polarity, all of which are set on it. The wire electrode is positive while the base metal, negative. A handle attaches the latter to the welding machine.
The MIG welding machine is set to different heat setting to ensure adequate penetration while at the same time avoid overheating the base metal. Test your weld setting on a piece of scrap metal to check whether they are the required ones is good practice and helps you avoid wasting material and ruining your project.
Top 6 MIG welders
Vulcan Migmax 140
The Millermattic 211 is a MIG welder that is suitable for steel and aluminum metals. It has been ranked one of the best welders for small weld works by a significant number of users. This is because of its amazing features. The Advanced Auto-set feature makes it extremely easy to adjust the welder to the right parameters.
Hobart Handler 140
The Handler 140 is one of the best welders for DIY’ers who are involved in a wide range of welding tasks. It is simple to setup and can be used by someone with less welding experience without experiencing major difficulties. Also, the Hobart Handler’s reasonable price does not at all compromise the expected quality of service.
The Forney 29801 100 ST is yet another one of the most reasonably priced yet high-quality welders on the market. This welder was designed with the needs of DIY’ers and hobbyists in mind as it comes with everything that you need. It also has economic and convenient power ratings and is fairly easy to set up.
Hobart Handler 190
The Hobart Handler 190 is a 68-pound welder that is suitable for 24 gauge to 5/16” metal thickness. This welder is one of the few in the market that comes with a built-in gas cylinder and a SpoolRunner feature that regulates the electrode. With the easy to manipulate controls, this welder is pretty simple to use even for an unskilled person.
The PowerMIG 210MP is a MIG welder from Lincoln Electric that is designed to serve quite a number of purposes. It is primarily designed to solve the day to day needs of educators, contractors, and do-it-yourselfers who are constantly in need of welding equipment. It has an adjustable power input of between 120V and 230V.
Why a MIG welder is a must-have tool?
A plethora of metals with various degrees of thickness can be welded using MIG welding. Stainless steel, aluminium, copper, silicon bronze, nickel and carbon steel are but a few commercially available metals and alloys in this list. These wide ranges of metals are most commonly used in day-to-day welding activities meaning it covers all the needs of most fabricators. Although it can only weld to a certain degree of thickness when done correctly, it can deliver a structurally sound weld on thin joints; 0.5 mm to be precise. The structural integrity of such welds in different industries makes it a flexible welding option.
For hobbyists, manufacturing experts and tinkerers of technology, MIG welding creates possibilities that were, before its inception, not possible. MIG welding machines can be integrated in robotics, a process known as automatic or mechanized MIG welding. Automatic MIG welding offers ensures accuracy and timeliness in the production process. The importance of the two cannot be understated. It speeds up experimentation procedures and saves time, making it more economical than any other welding technique.
Advantages of MIG Welding
MIG welding is perfect for multi-pass welding, particularly with suitable electrode selection. It also offers a wide array of electrode materials of different diameters to attain different weld thickness. This makes weld penetration viable at equal strength.
MIG welding has little or no waste. First, not as much fumes and gases are churned out as is the case with other types of welding, notably stick and flux cored welding. Since no covering slag is deposited, it also ensures minimal clean-up after welding. Electrode deposition is better than FCAW and stick welding.
Due to high visibility when welding, increased welding speeds, and affordable costs of the machine’s components, mostly the electrode, and the welding process this is the easiest way to learn how to weld. Welding in many positions is also possible.
Choosing a MIG welder
First, you need to consider the power output of the welding machine. This is dictated by the different use-cases of your machine. Different power outputs are ideal for different thickness of welding. A 30A machine would suffice for thin materials, e.g. car body panels. For steel and stainless steel, a minimum of 30A per millimetre is sufficient. This, however, can be counterproductive depending on the machine’s duty cycle. A safe choice would be to buy one that produces a 30% higher output than what you need to avoid overheating. The MIG welder also needs to have at least four power output settings especially those with 200A.
Second thing is the type of torch. Fixed torches which are more common for domestic use get the job done but easily break and are quite pricey when replacing them. A Euro-fitting torch is used by most professionals and has a build quality that matches and is, therefore, long-lasting.
The size of the spool of wire is also an essential factor to consider. Larger spools are cheaper than smaller ones. Most machines accept at least two different sizes of spools: maxi and midi spools or midi and maxi ones. A mini spool has a four-inch diameter while the midi is an eight-inch diameter spool. The two are commonly used domestically. The maxi, a twelve-inch diameter spool is preferred in industries.
Cylinders and Wire Feed Units
Small machines use disposable gas supply cylinders which have low upfront costs and are used domestically. Welders who will be handling a lot of welding need to go for the large cylinders, which are higher in upfront costs but cheaper in the long-run.
Finally, the number of wire feeds units. Most have two or four roll feeders. Two roll feeds are better for solid wires, but the latter is better for flux-cored and aluminium wire.
Whether you are a hobbyist who’s just toying around with metal work, a mechanic, a seasoned steel fabricator or a maintenance chap who works with steel, MIG welding is a welding technique you need to seriously consider. Not only for it’s wide array of uses, but also because it’s easy to learn in a short period of time. While most MIG machines are costly and getting familiar with the complexity of the machine is quite difficult at first, they are easier to maintain over time and you’ll soon overcome the expected learning curve, and getting a hang of it in no time.
It efficient, clean, delivers higher productivity that other methods and is versatile to different use cases. That faster welding speeds can be achieved through it only adds to the long list of advantages of using this type of welding technique. This article details all the information you need regarding the basic of MIG welding. With it, it is much easier to know what to look for when shopping for a MIG welding machine, the steps involved and why you need it.