MIG Welding vs Arc Welding: What’s The Difference?

MIG vs Arc Welding, what’s the difference? Arc welding creates an electric arc to melt two metals and join them together. MIG welding uses an automatic wire feed which melts an electrode and adds a filler metal to weld two pieces together.

Both methods work very well and both create an arc to shield the weld. The difference is in how the arc is made, and so how the weld is formed.

MIG Welding

For MIG welding you need a MIG welder. The cost of these will vary, but there will be one for all budgets. MIG welding stands for Metal Inert Gas, and it uses gas as part of the process. Some MIG welders still require a separate gas bottle, but more modern machines incorporate the gas in to the welder.

MIG welders use a gun which feeds wire through automatically. The wire, or electrode, melts and joins with the base metals. For MIG welders which don’t have a separate gas tank, you will need wire which is covered in flux. As this flux melts, it creates an arc which protects your weld.

Setting up a MIG welder is relatively easy, but will take practice. MIG welders allow you to set:

• The speed of the wire.
• The thickness of the wire.
• The voltage.

The wire is placed in a spool inside the machine, then fed through the electrode holder. This is shaped like a gun and has a trigger to begin the feeding process. As the wire feeds through, it creates an arc. The electrode and metal are both heated to create a weld pool, while the gas shields the weld pool from external gases.

MIG welders work well on both thick and thin metals as the power can be adjusted.

Advantages

• MIG welders are easy to use.
• They require minimal setting up so are good for beginners.
• Can create horizontal, vertical and flat welds.
• There is minimal slag and spatter.
• Controlling the weld is easy, as settings can be altered depending on the metal being welded.
• Automatic wire feed means you don’t have to keep stopping to replace the electrode. The trigger also has the option to stop / start as you need to.
• Can weld a variety of metals, including carbon steel, stainless steel, aluminum, magnesium, copper, nickel and alloys.

Disadvantages

• Although MIG welding can handle a variety of metals, it works best with thin to medium thick metals.
• MIG welders can be less portable, due to the need to carry a separate supply of gas.
• They are also not a good choice if working outside, as the weld can be affected by wind or rain.
• The materials being welded do need to be thoroughly cleaned first.

Arc Welding

There are several methods of arc welding, but not all arc welders work the same way. Arc welding machines have an electrode holder but these do not always have a trigger and they do not all have automatic line feed.

Arc welding creates an arc using a power supply. This produces heat of up to 6500 degrees Fahrenheit, and this melts the 2 metals to be joined. The electrode in an arc welder is used to carry or conduct the current. It melts in to the weld pool together with the two metals to create the join.

The arc acts in the same was as a shielding gas, in that it protects the weld from atmospheric gases. Molten metals can react with nitrogen or oxygen, so protecting them will create a better weld.

Arc Welding: 8 Main Methods

Most welding methods will create an arc in some way, and these include:

• MIG / MAG (Metal Active Gas) welding
• SMAW (Shielded Metal Arc Welding
• FCAW (Flux Cored Arc Welding)
• SAW (Submerged Arc Welding)
• ESW (Electro-Slag Welding)
• SW (Arc Stud Welding)
• TIG (Tungsten Inert Gas Welding)
• PAW (Plasma Arc Welding)

Advantages

• Arc welders are cheaper to purchase and use.
• Can be used with thicker and heavier materials.
• Easier to transport, as there is no gas to carry
• The metals do not have to be cleaned before welding
• Arc welding can be done outside, as it is less prone to the effects of the weather.
• As it creates a lot of heat, it works very well with base metals with a high melting point, such as heavy steel construction
• Creates less smoke and sparks
• It doesn’t use a separate gas supply to create the shield
• You don’t need a consumable electrode.

Disadvantages

• Not a good choice for beginners
• Produces a lot of waste
• Arc welding is not good for thinner materials and cannot be used on aluminum or titanium
• It does leave slag so there will be some cleaning required after the weld.

Frequently Asked Questions:

What type of gas is used in a MIG welder?

MIG welders use argon, carbon dioxide or a mix of the two. The gas and percentage will depend on what it is you are trying to weld.

Is MIG or Arc stronger?

If used correctly, they will both produce a strong weld. Arc welding is used on larger projects such as building and ship building, while MIG is better for thinner metals.

I work on different sites. Which is the best to use?

If you want something you can carry easily, then Arc welding is more portable. It also works outside in all weathers, where MIG welding cannot be used in adverse weather conditions.

Conclusion

While MIG welding does create an arc, it is not the same as Arc welding and is better for those new to welding. The need for additional gas in MIG welders can be very off putting, but many welders have now been adapted so you no longer need additional gas.

Arc welding will require some welding experience and is often used in large jobs, and is excellent for larger joins and heavier metals. It does create a lot of heat though, so extra care should always be taken.

As with all welding, the best method is the one you feel comfortable using and the one which will create the right join for your project.