MIG or Metal Inert Gas welding is the process of welding pieces of metal together using a current of electricity . It is usually considered the easiest type of welding for one to start out engaging in only because of the somewhat straightforward nature of the machine’s functionality.
What’s the history of MIG welding?
MIG welding otherwise known as GMAW welding was first developed in the early 1940’s. As mentioned in the above section it is the process of using an arc of electricity between a positive and negative (anode and cathode) to form a weld. The heat necessary to weld the metals together is produced by both the arc and inert gas involved in the process.
MIG welding in the 19th century
The principles of MIG welding were first developed at the beginning of the 19th century when Humphry Davy first discovered the electric arc. While MIG welding first used carbon electrodes, it was then found that metal electrodes are better for them by C.L. Coffin and N.G. Slavianoff.
MIG welding in the 20th Century
By the year 1920 the early predecessor of GMAW was first invented by P.O. Nobel of General Electric. It used a direct current and a bare electrode wire, as well as an arc voltage to regulate the feed rate. However, it did not use a shielding gas to protect the weld since the developments in welding atmospheres didn’t take place till further down the line. While it still wasn’t suitable for practical use, the forerunner of GMAW was released in 1926.
MIG Welding was officially developed by the Batelle Memorial Institute in 1948. This MIG welding process used a smaller diameter electrode and constant voltage power source. It also relied on an aluminum continuous fed electrode and an argon gas shielding gas.
The short arc variation of MIG / GMAW welding was released between the years of 1958 – 59 and increased welding versatility while making thin material welds possible. It also became the most popular MIG variation. One year after the short arc variation was developed the spray arc variation was developed. Spray arc variation was developed when experimenters added small quantities of oxygen to inert gasses.
In the 1970s additional development for MIG welding were found which allowed or improvements in both the GMAW – P and GMAW processes.
Now, however, MIG welding (or GMAW as it’s more widely known) is used widely by the sheet welding and automobile industries. Within these industries it’s used to perform arc spot welding, which allows it to replace resistance spot welding and riveting. It is also popular in robot welding, where robots handle the work-pieces as well as the welding gun to quicken the manufacturing process.
It is, however, unsuitable for outdoor welding since the movement of the surrounding atmosphere causes dissipation of the shielding gas, which makes welding with it difficult.
What are the advantages of MIG welding?
MIG / GMAW / MAG does yield a few advantages to those who use it. Below are a few examples of benefits offered by MIG welding.
- Works with a wide range of different metal types
- It makes producing high quality welds much easier (and a much faster process)
- Because MIG welding uses shielding gasses the arc is protected which means there is very little loss of alloying elements.
- This helps prevents excessive spatter
- There is no slag to clean off
- Easy to learn and can be done using both a semi-auto and fully-auto process
- MIG welding doesn’t use a flux so there is very little chance for the entrapment of slag in the weld metal; this results in the production of very high quality welds.
What are the disadvantages of MIG welding?
- Doesn’t work very well with thick metals because it doesn’t provide enough penetration for them.
- Less portable than welding types that don’t require an external shielding gas.
- Not to mention that since it uses a shielding gas it can take a little more time to change which results in welds taking more time to complete.
- Less controlled than TIG welding
- It takes a while to clean metals well enough for them to be MIG welded. This is necessary to make sure that you’re safe when using a MIG welder as well as for making sure you get a good weld.
- MIG welding a bit more expensive than other methods of welding as well as more complex to perform.
- MIG welding has limited positions. The viscousity of the MIG welding metal puddle and the heat input of the MIG welder means that it can’t be used for either overhead or vertical welding.
What are the components of a MIG welding machine?
The great thing about the whole MIG welding process is that it is fairly simple. The part that makes it so simple is that it doesn’t require very many parts-there’s just 4.
Welding Machine
First you have the actual welding machine. The welder carries with it a spool of wire (consumables) and a variety of rollers which puch the wire out of the welding gun. Before you begin welding it helps to actually go through your machine and make sure you have a solid understanding of it’s inner workings. The type of wire loaded into the welder depends on the type of material that will be welded. For instance, if you’re trying to weld aluminum, then you will load aluminum wire into the machine.
This is what the actual MIG welding machine looks like
Gas Tank
Next we have the gas tank. The tank will be filled with either entirely Argon or will contain a mix of C02 and Argon. The purpose of this mixture is pretty straightforward-it’s meant to protect your weld from the harmful contaminants in the environment. Before you begin to weld it’s important that you open up the machine and check that there is some actual gas in the tank. It’s a good rule of thumb to make sure that your gauges are reading somewhere between 0 and 2500 PSI and that your regulator reads between 15 and 25 PSI.
Welding Gun
The most important part of the welding machine isn’t the machine itself it’s the gun – this is where the business actually starts. The welding gun is made of a trigger that handles both the wire feed and the current of electricity. Make sure that the outside of your gun is covered by either a ceramic or metal cup which will protect the electrode and direct the flow of gas out of the gun.
Ground Clamp
Lastly we have the ground clamp. The purpose of the ground clamp is to provide a negative charge (cathode)( to the welding project. This item should be clipped onto either the project or directly on a welding table- just be sure that it maintains some kind of connection with your work.
This is what a ground clamp looks like
How to stay safe when MIG welding
One of the outstanding myths that surround the MIG welding professions is that it’s extremely dangerous. Yes, that can be true, if you don’t have the proper safety gear when you participate in the activity. That brings us to the next part of the guide, ensuring that you have the correctly MIG welding safety gear.
1. Wear Safety Gear
Since MIG welding is a light intensive activity it can be incredibly harmful to one’s eyes and skin if they are not properly protected. The first piece of gear that every welder should have (regardless of the activity) is a welding helmet. The most effective type of welding helmet is the Auto Darkening welding helmet because of it’s ability to automatically adjust to the bright flares of light that will likely occur when you begin welding.
Here are a few good welding helmets
Next we have the welding gloves. These are important because of the splattering that will occur when you begin welding. The thickness of the gloves is entirely up to you but, it’s important that your gloves are made from some type of leather material.
Here are a few examples of feasible welding gloves
As for body gear it doesn’t matter if you wear leathers or not – just make sure that whatever clothes you do wear are flame retardant. At the very least wear clothing that is made from some type of cotton material.
2. How to prep for MIG welding?
As for footwear all I can say is make sure it’s made from a leather material and is thoroughly layered. Shoes that are made from a synthetic material or contain a mesh of some type will likely be destroyed as splatter falls on them.
3. Don’t weld galvanized steel
Long story short, galvanized steel has properties that develop into carcinogenics once heated. Don’t weld this material if you want to stay relatively healthy while you weld.
4. Beware of fire
Welding produces splatter that can land relatively far from the weld itself. Make sure that there are no nearby materials that could easily catch if the splatter were to land on it.
How do you lay a bead in MIG welding?
The most important piece of knowledge you can have as a MIG welder is the ability to actually lay a bead. Make sure that you have a solid understanding of the power settings on your welder so that you can easily weld a proper bead on your machine. Too much power and the bead won’t look right =. Too little power and the bead won’t look right =. Practice laying the bead before you actually try and weld anything of value.
Video credits to Weldingtipsandtricks. It goes over a MIG welding technique.
The easiest way to do this is by practicing laying relatively short beads, about 1 to 3 inches thick. Doing this a few times allows you to get your bearings on the machine and to also preserve consumables.
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This is something that you get entirely by feel. If your welding activities are causing your workstation or metal to have holes formed inside of it then it is very likely that the machine is set too high. If you’re welding in spurts then the machine isn’t set high enough. Just keep adjusting it until you get the right settings. Once your welds start coming out nice and smooth you know that you have the correct settings.
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With any activity you are likely to run into some type of problem. The same goes for MIG welding.
What are common issues of MIG welding?
Not enough gas in the machine: you can tell this is happening when the weld begins to turn brown or some other darkish color.
Weld isn’t penetrating: when the weld is weak and the metals aren’t fully joining this is the common issue.
Holes appear in the weld: When you are welding with much power this is likely to occur
There is too much metal in the weld: This typically only happens when there is too much wire coming out of the gun. AN easy fix would be slowing down your wire speed.
Wire is fused to the tip: A common problem is that the wire in a gun fuses to it’s tip. This typically happens when you are A. welding to close to the material or B. are allowing too much heat to build up in the tip of your welding gun.
The steps to fix this problem are listed below:
- Unscrew the cup of the welding shield
- Unscrew the tip
- Replace the tip
- Screw the tip on
- Replace the welding cup
- Voila, it’s fixed
Replace the wire feed to gun
Another common issue that you will likely face is getting the wire stuck in the machine. This can be avoided by checking the spool and the rollers because this is generally where the material will get stuck.
If in fact the material does get stuck in the gun, you can do this to fix it
- Power off and unplug the machine
- Find the jam
- Cut the material out with a pair of wire cutters
- Pull out the wire from the hose with a pair of pliers
- Replacve the tension bolt
- Turn the machine on and depress the trigger. This is how you know if you fixed the gun or not. Once the wire comes out you know the gun is fixed.
