What’s The Difference between MIG and Arc Welding?

MIG and arc welding tend to cause much confusion among many aspiring welders because of their similarities, as they who wonder what exactly their differences are and which is preferable over the other.

Below, we will try to answer the questions regarding MIG and arc welding by describing what each is when it is best used, and then finally what differentiates the two welding processes.

Arc Welding

Arc welding, also known as shield metal arc welding (SMAW) on the other hand is a welding process where you join two metals by using electricity.

The electricity creates sufficient heat to melt the metals, which later cool up and bind. An electric arc is formed between a metal and an electrode leading to the formation of a puddle where you add welding filler material.

The heat that concentrates on an electric arc melts an electrode hence fusing the parent metal to a joint.

Electricity from the welder is what passes through a rod and arcs upon contact to create a high temperature that can go up to 7000 degrees F. The rod melts and its flux coating creates a shield against oxygen that would contaminate the weld.

This method can use AC or DC as well as consumable and non-consumable electrodes coated in flux.

When Is Arc Welding Used?

You can use arc welding on metals of different thickness. It is the most common process of welding as it is simple and versatile.

Common projects done with the use of arc welding include gas extraction, digging sand and gravel, shipbuilding, repair work, and pressure vessel fabrication, milling, mining, grinding, drilling, laser cutting, palletizing, and machine tending.

It is also useful in repairing bridges, agricultural equipment, and the like.

MIG Welding

MIG meaning Metal Inert Gas welding is also known as Gas Metal Arc Welding or Metal Active Gas welding. It is a welding process whereby an electric arc forms between a workpiece metal and consumable wire electrode, heating the work metal and causing them to melt and join.

In this case, a continuously fed solid wire electrode is driven through a welding gun to the weld pool where it is melted and deposited in the weld joint where it joins the two base materials.

A shield gas bubble sent through the welding gun protects the weld pool from contamination.

For MIG welding, you, therefore, require electricity for heat production, an electrode to fill up the joint, and a shielding gas that will shield the weld from the air. The welding gun has a trigger that controls the feed of a small electrode.

You feed the electrode from a spool, together with a protective gas. An operator monitors the weld joining the two base metals.

In this case, because you feed wire into the material, pieces that are fed together are not fused, meaning you can weld different kinds of metals together.

MIG welding is mostly done indoors to avoid the effects of wind which could lead to not getting a solid weld.

When Is MIG Welding Used?

You can best use MIG welding when welding thin to medium thick metals. MIG welding is mostly in automotive repair, to weld all manner of vehicles ranging from small to large, and light to heavy ones.

It can also be used in robotics, for welding pipe joints,  hard facing, reinforcing a worn out surface of a rail track, and for building bridges, to mention a few.

Differences Between MIG And Arc Welding

The following are the notable differences between MIG and arc welding to help ease your understanding and differentiate the two almost similar welding processes.

  1. Simplicity of use

MIG welding is simple for a beginner to learn as it only has a single element which a person needs to operate on at any given time.

With the gun, you have the materials you need for welding and all you need to do is press the trigger to start and let it go to stop. Arc welding is harder as it poses the difficulty of striking the arc without causing damage to the material.

  1. The Materials You Can Use

With MIG welding, the materials you can use are limited based on their thinness or thickness.

They should be neither too thin nor too thick. Pushing a MIG welder too hard to weld thicker materials such as cast iron could destroy it. On the other hand, very thin materials such as aluminum will burn under the power of the arc.

Additionally, the material you use for MIG welding must not be dirty or rusty. Arc welding can be used to weld the thickest materials.

  1. Indoor vs. Outdoor Use

MIG welding does not work outdoors because of rain and wind limitations. If air blows on the metals, they will not form a solid weld. Arc welding can be used even in unlikely conditions such as rain or extreme winds.

It is, therefore, best suited for outdoor use.

  1. The Appearance of The Weld

MIG welding makes more aesthetically appealing and hence ideal for making sculptures. Aesthetically, arc welding is less pleasing as it produces a lot of sparks and debris leaving slag all over the place. Finishing touches and some cleanup are therefore inevitable.

  1. Cost And Portability of Equipment

Equipment for MIG welding is quite pricey compared to that of arc welding which is relatively cheap. The apparatus for arc welding is portable as you do not need to feed it with a protective gas and can be kept in a confined place.

  1. Shielding the Weld

MIG welding requires you to supply an external gas to aid in preventing contamination of the weld pool while arc welding uses a wire that has a flux core which generates its own gas shield against around the weld, eliminating the need for an external source.

Frequently Asked Questions

The following frequently asked questions could help answer some of the questions you may have on the differences between MIG and arc welding.

  • What is the best gas for MIG welding shielding?

Argon is the best gas though helium can be added to increase the fluidity of weld pool and penetration.

  • How comes arc welding can be carried out in water?

Arc welding underwater boils down to the principles of underwater welding. It is carried out using manual metal arc electrodes with a waterproof coating over the flux coating. The welder should insulate himself wholly from the welding circuit.

  • Which is the most robust welding process?

Arc welding produces strong welds as compared to MIG welding.

Check out this video about MIG Welding vs. Arc Welding – Which Welder When?

Final Thoughts

Welding is essential in joining metals and carrying out projects of your choice. Hopefully, you can now differentiate between MIG vs arc welding and be able to choose one that best suits your need.

Remember always, to have protective gear to keep your eyes, and hands from harm when welding.

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