The success of MIG welding projects depends on picking the right wire electrode for the job. While you’ll first need to choose between solid core wire that is protected with shielding gas or a flux core wire that shields itself, the width of your wire determines the appearance and strength of your weld.
You may think that a thick wire will give you more penetration, but that isn’t always the case. A lot can hinge on the amperage, metal thickness, the width of the weld joint, and the material itself. Here’s an overview of some factors to consider when choosing a wire for your next MIG welding project.
Referencing A Wire Thickness Chart
If you’re MIG welding with solid wire and use a shielding gas, then you can typically opt for a thinner wire compared to flux cored wire that tends to be thicker. For instance, 22 Gauge metal can be welded effectively with .024 thick solid wire, but when it comes to flux core wire, you’ll use .030 flux core wire. This trend holds true throughout a typical wire thickness chart.
In addition, metal that is 3/16 inch thick or more may require several passes in order to completely fill the weld joint and to achieve sufficient penetration.
Welding with Smaller Wires
A wire with a small diameter will leave less filler in the weld joint, but that doesn’t necessarily mean it won’t give you good penetration. In fact, a narrow wire will concentrate current right into the joint. While the final weld will be rather narrow and won’t fill a large joint with material, it will tend to provide a deeper weld than a wider wire under the right conditions.
The quality of your penetration and the strength of your weld will also change based on your technique, angle, and material. However, before picking a wire, consider the depth and the width of the weld joint together.
Smaller wires also require a faster wire speed in order to reach an optimal deposition rate while welding. Thicker wires can often feed at much slower speeds.
If you increase your amperage too much, then the arc will become erratic and leave spatter along the weld. When you need to increase your power, then your best bet is to use a thicker wire.
Welding with Thicker Wires
Welding with a thicker wire means you may not get the same amount of penetration compared to a thin wire. However, the advantage is that you can weld with a slower wire speed and fill a wide opening.
You’ll improve your penetration by paying attention to your technique and matching your amperage to the thickness of the metal and the depth of the weld joint. The wider your weld joint, the more likely you’ll still need to consider making multiple passes.
If you start to have problems with burn through, then consider switching to a thinner wire that won’t deposit as much material into the weld joint.
Wire Options for Aluminum Vs. Steel
Aluminum and steel are two of the most common materials that welders work with. In the case of a MIG welder that is adapted with a wire feeding spool for aluminum, you’ll want to pick a wire that is a bit stiffer in order to make it feed easier.
Generally speaking, MIG welding aluminum is very different from working with steel, as the metal tends to be thinner and heats up very quickly. Most times you’ll want to use a thin wire, such as 0.035 inch diameter, and use a pulse welding procedure so that you don’t burn through. You can usually complete most aluminum welding jobs with a wire that is 3/64- or 1/16- inch diameter.
Steel tends to be thicker and does not heat up as fast, so your wire options tend to be on the thicker side. This is especially true since you would only use a thinner solid core MIG wire on aluminum with shielding gas, while steel can use either flux core MIG wire or a solid core wire with shielding gas.
