Metal inert gas (MIG) welding is an easy entry point to the world of welding. It uses a simple machine with a simple mechanism that can do long passes on certain metals and appeals to both the inclined rookie and a skilled professional.
In this article, we're highlighting the MIG process and its benefits. But to properly let this welding process shine, it's important to give the whole picture that is arc welding.
In a Nutshell: Arc Welding Explained
Arc is generated by running a charge on two electrically conductive metallic objects. The electrode of a welding gun is the first half, and it normally has a positive charge. The workpiece metal forms the second half and has a negative charge. These two objects form an Electric Potential Difference—a voltage in which electricity runs in a circular motion.
The voltage and heat produced by the flow of electricity make the gas in the surrounding area between the tip of the welding gun and the workpiece become conducive to producing more heat—in the form of plasma or arc.
Types of Arc Welding
Arc welding is an umbrella term. Under it are different welding processes that use a core feature—the arc, which is essential in joining two metals together. Below are the different types of processes that use arc as their heat source.
Shielded Metal Arc Welding (SMAW)
The SMAW welding process is the most versatile of arc welding processes. Also known as Manual Metal Arc (MMA) welding for welding snobs, this process involves an arc that rises to a temperature of around six 6000 degrees celsius.
SMAW welding uses a consumable electrode. It looks like a stick and is attached to the welding gun and refilled once melted. The electrode serves as a filler that combines with the workpiece and is instrumental in creating the arc necessary to produce a high temperature. The heat produced by the arc, in turn, melts both the workpiece surface and the electrode—both become part of the weld pool.
The electrode is the core of the consumable column. A flux coating surrounds the electrode and forms the outer layer. When the arc heats this flux coating, it produces gas that protects the weld pool from elements in the surrounding atmosphere, which affects the quality of the weld.
Apart from gas, the flux also produces slag. It acts like an outer shell that protects the welded metal underneath it. This shell-like substance doesn't form part of the result. You'll have to scrape or brush it off once everything cools down.
Stick welding is a common welding process. In most households that have their workshop, you'll most likely find a stick welding machine that's been sitting idly in a corner. Average welding enthusiasts find stick welding to be straightforward to use because it doesn't require any gas setup. Just plug it, clamp the workpiece, and pull the trigger.
On the other hand, the strength of the stick welding process is also its weakness—the flux coating. As a result, when the consumable stick is heated up, it produces not only gas but also plenty of fumes. Moreover, the slag can alter the weld quality the wrong way if you're not careful.
Flux Cored Arc Welding (FCAW)
If stick welding has its flux material coated around the electrode, it's opposite for the flux-cored. The electrode is designed to be a tube-shaped wire, and inside it is the flux material.
The flux-cored wire welding is convenient compared to stick welding because of its continuity. You don't have to reload another stick of electrode because the wire spool is fed constantly at the tip of the welding. Combine this with a constant voltage power supplied by a machine, direct current, and electrode positive (DCEP) configuration, and you get a sustained arc on your welding gun. That means longer passes and more time welding.
The flux-cored welding process is usually recognized as a gasless process. The electrode's mechanism works similarly to stick welding because the flux melts along with the electrode to protect the weld pool. This is called the self-shielding variant of the flux-cored welding process (FCAW-S).
But flux-cored welding can also be shielded. The gas-shielded flux-cored arc welding (FCAW-G) uses the same gases employed for other welding processes, such as tungsten inert gas (TIG) or inert metal gas (MIG) welding. FCAW-G mainly uses pure carbon dioxide, while others mix it with argon.
Self-shielded flux-cored welding is the recognized variant of the FCAW process, particularly for those who don't want to assemble gas tanks. It can also function even with strong winds—perfect for outdoor welding projects.
Gas Tungsten Arc Welding (GTAW)
Tungsten is an element that's resistant to intense heat. This non-consumable material is at the core of the GTAW welding process, also commonly called Tungsten Inert Gas (TIG).
The tungsten is used as an electrode and is loaded at the tip of a small welding gun. The tip and the metal workpiece generate the arc, but only the metal workpiece is melted. In effect, the workpiece becomes its pool of liquid metal and can fuse to another piece of metal. This is called fusion welding.
With a TIG welding process, fusing metals together brings a more refined final weld because there are no filler metal beads. It's ideal for joining thicker metals, so you get a substantial metal pool without ruining the quality.
If you're working on thinner metals, the TIG process allows you to introduce a filler metal rod to the welding process. The filler rod is separate from the TIG welding gun. That means you'll be holding the gun in one hand and the filler metal rod in the other. You'll be dipping the filler material into the arc in a controlled fashion.
TIG does need inert gas. The tungsten electrode can oxidize and affect the weld quality, so gas must be fed around the electrode to protect it from the elements. Welding using tungsten takes skill. But with enough practice, this welding process will allow you to join several different metals together.
Submerged Arc Welding (SAW)
Submerged arc welding (SAW) is a type of arc welding that isn't heard a lot. This is because SAW found its niche on certain industrial or heavy-duty applications. Its positioning is also limited to flat and horizontal given the nature of the process, so household welders find this limiting.
The SAW process involves an arc submerged underneath a pile of granulated flux. This sand-like flux material protects the arc and the weld pool underneath. The arc eventually heats the flux near it to release the shielding gas and create a slag down the line. This slag eventually solidifies and must be scraped off to reveal a nice, clean weld finish.
Despite its limited positions, SAW has its advantages, too. For example, it doesn't produce any fumes. It can also be automated, so you will only have to supervise the welding pass machine. And you can also add several filler wires instead of just one to create the desired welding finish.
Metal Active Gas (MAG)
This Gas Metal Arc Welding (GMAW) process is a subtype that uses active gases to shield the weld pool and the arc. Metal active gas (MAG) uses a mixture of carbon dioxide (CO2) and oxygen (O2) and partners with other gases like nitrogen, helium, or argon.
The resulting concoction of different gases has a beneficial effect on welds. When the arc heats these gases, it changes the weld zone. In a nutshell, you'll get arc stability, a good-quality weld bead, reduced spatter, and an improved welded joint. All of this without having to scrape off slag.
What makes the MAG even better is its affordability. Gas combination for a MAG setup is cheap and accessible. So you'll not only get a good weld, you'll also save up on welding supply expenses. Overall, the MAG process is a terrific GMAW subset that's great to use if you're welding stainless steel or any ferrous metals.
Welding Process Highlight: The Metal Inert Gas (MIG)
The metal inert gas (MIG) welding process is a subcategory of the Gas Metal Arc Welding (GMAW). Unlike with MAG, this welding process predominantly uses argon, which is an inert gas, to shield the weld pool.
Aside from argon, nitrogen and helium are also good alternatives, although argon is the preferred choice in most cases.
This astounding welding process is perfect for regular welding steel, stainless steel, and even aluminum alloys of different thickness profiles. It can yield beautiful weld finishes on your workpiece metal if you know how to capitalize the benefits a MIG welder can give and combine it with your technique.
The Benefits of Using Arc MIG Welder
Getting your own thermal arc MIG welder is a step towards more fulfilling welding efforts. This small machine is loaded with features with the following benefits:
Flexibility — The MIG welder/arc welder is designed to have a wire-feeder mechanism for flux-cored wire welding. You can switch up from MIG to flux just by purchasing a spool of flux-cored wire, detaching the gas hose from the machine, and adjusting the MIG welder's configurations for the flux-cored welding process.
Boosts productivity — Common welding processes such as stick welding can be inefficient. Despite the straightforward use, the stick consumable gets spent and will have to be replaced with another one. MIG welding machines can feed the consumable wire continuously for as long as there's something that's left.
Easy setup — The MIG welder is a user-friendly machine that doesn't take a lot to learn how to use. You can choose to read the manual or use your own intuition to configure the machine. But welding itself is a no-brainer. The MIG process itself only takes less than an hour to learn, and the majority of the time spent learning how to MIG weld is focused on technique.
Efficient — MIG welders have operated with shielding gas mixture. These gases allow MIG welding to retain alloy elements on the weld as the arc does a pass. In addition, MIG machines are also wasted efficiently. It doesn't produce slag and has less spatter than stick welding.
Things You Need to Check for Your MIG Arc Welding Machine
In order to take advantage of your MIG welding machine, you'll need to make sure you've set it up for a successful welding session. Here's a brief list of what you should check before striking an arc.
Wire spool — You'll need to make sure you're using the right wire spool that's MIG specific. If you want something good for all types of MIG applicable metals, get the ER70S-3. The metal workpiece has to be clean. On the other hand, if you're working on rusty steel, you'll be needing an ER70S-6 wire spool.
Gas mixture — The common MIG gas mixture is 75% argon and 25% carbon, as the MIG welding process relies on the inert argon gas to bring the weld finish to a certain quality.
Voltage and amperage settings — Most MIG welding machines are self-adjusting, provided that you give it the correct wire diameter as input. On the other hand, vertical welding for MIG requires a voltage and amperage reduction of about 10% to 15% of the normal flat position setting.
Additional equipment considerations — Inspect the MIG machine's cable integrity. Make sure the cables have not worn out or been damaged. This goes the same for the gas hose and gas regulator. Next, do a quick test on the wire feeder hub and see if the tension is set right. Replace contact tips that are worn out, and be sure your wire consumable is in good condition. If these final checks are done, you can proceed with your MIG welding.
Choose MIG Welding For Steel and Aluminum
If you're a budding welding enthusiast, it's good to get yourself a MIG welding machine as your main welding equipment. Most metals you'll start working on are steel, and you'll most likely be doing joint welds for your first several projects.
MIG welding is a good jump-off point for transitioning to other welding processes such as flux-cored or TIG. Not only is it safer and more efficient, but it's also easier to learn and produces fewer fumes. Try it out and enjoy welding the way it's supposed to be enjoyed.