How To Set Up a MIG Welder – A Technical Guide

If you are not a full-time welder, then it can be challenging to know whether your MIG welder is properly set up for maximum performance.

If you have asked yourself questions such as, “Am I at the correct voltage?” or “Did I use too much or too little wire?’ then this article is for you! We will discuss the basics of safely setting up your welder, and then examine what your weld bead is telling you.

How Will I Prepare the Joint?

Machinery set-up only matters if you have a properly set-up joint. We want all rust, paint, oils, dirt and mill scale to be removed from the weld area. There are three reasons why we do this:

• First, a clean joint produces a clean weld.
• Second, the machine settings will be different for dirty joints and clean ones.
• Lastly, the dirty joint will spit and spatter thereby increasing the chances of getting burns or starting a fire.

Do I Have the Right Gas and Electrode/Filler Wire?

An important component of setting up your machine is the right gas and filler wire/electrode. This selection varies depending on all of the above and is dependent on many more factors that I can not name. A few commonly used gas/electrode variations or combinations are as follows:

• Carbon Steel: ER70s Electrode with a C25 gas (75% Argon and 25% Carbon Dioxide).
• Stainless Steel: ER308L with a C2 gas (98% Argon and 2% Carbon Dioxide).
• Aluminum: ER4043 with 100% Argon gas.

How to Set Up a MIG Welder?

There are three settings or controls that set the welder to work with and those three are:

• Voltage
• Wire Feed Speed
• Gas Flow Rate/Gas Type or Mixture

These three settings are what control the heat of the weld and depending on the gasses they also control the transfer type. If you are not familiar with transfer types then you should read up on MIG Welder Transfer Types because they will have a big impact on your settings and how you will be welding.

More recent machines such as the 211 shown below, no longer require you to control wire feed speed or voltage. You simply turn the dial to thickness you want to weld and adjust from there. The machine does everything other than controlling gas flow.

Voltage Settings and Polarity Type

Let’s begin with the type of voltage used, which is usually D/C electrode (+) positive. This means that the handle is the positive side of the circuit, or in short, the electricity flows from the metal to the welding handle. This option rarely changes and if it does, you need to unbolt the internal leads and flop them.

Voltage is the main heat setting that changes with various factors, such as joint, metal thickness, type of gas, and position. It does most of the adjustment, or as it is commonly referred, make changes to the welder’s setting.

The voltage setting is based on what size electrode is used and how thick the metal is (and type of gas used). Since MIG welders are CV or Constant Voltage power sources the voltage does not change too much while we are welding.

Wire Feed Speed

The wire feed speed controls how much, or how fast, the wire is being fed into the weld joint. Wire feed speed is controlled in IPM (Inches Per Minute). The wire feed speed has another purpose in that it also controls amperage.

In Stick or TIG, the main setting is amperage; however it’s the voltage that fluctuates depending on arc length. In MIG it is the voltage setting that is constant but the amperage changes with wire feed speed and electrode stick-out.

Since you do not want to have fluctuating wires, just select one for your most used thicknesses.

30-130 amps: .023 inch
40-145 amps: .030 inch
50-180 amps: .035 inch
75-250 amps: .045 inch

Gas Flow Rate/Gas Type or Mixture

In conclusion, the gas type and flow rate help control transfer type. A high content of Argon mixed will create a hotter arc with a percentage of Helium providing one the same effect. The ultimate goal for the settings with gas is to apply enough volume of gas to shield the weld from the environment.

Gas flow rates are controlled using CFM (Cubic Feet Per Minute). This is an area that often relies on your experience to identify optimal flow rates. In a shop environment, it may be 15 CFM, in a sufficiently windy area it may go up to 50 CFM. One additional observation is if your gas flow rates are too high.

If the rates are too high you can cause air turbulence, causing air to contaminate the weld. Your gas flow rates are trial-and-error, a happy medium of all of your settings applied to your specific welding conditions.

Putting the Voltage, Wire Feed Speed, and Gas Flow/Gas Type Together

Lastly, after putting all these settings together, you have the transfer type requested and enough heat to properly penetrate the metal without burning holes through the joint.

Combining settings to achieve the desired weld is the end result of trial and error and through experimentation, you basically tune the machine just right to achieve the weld we need, want, or hope to have.

None of that makes any difference if a welding engineer or procedure has completed that work for you. If you do have a procedure it’s now time to move on to the next section; MIG Welding Charts, Settings, and Guides.

MIG Welding Settings Chart

To avail exact answers and some guidance, you may want to read! Most manufacturers of welding machines do provide either a MIG welding Settings chart within the machine and/or a guide to their machine settings.

I would like to point out that two identical welding machines made by the same manufacturer at the same time may not ever run the same way. These are only guidelines and will change from machine to machine! Each machine is set differently and this can depend on its use, and who serviced it.

For wire size	Multiply by	Ex. using 1/8 inch (125 amps)
.023 inch	3.5 inches per amp	3.5 x 125 = 437.5 ipm
.030 inch	2 inches per amp	2 x 125 = 250 ipm
.035 inch	1.6 inches per amp	1.6 x 125 = 200 ipm
.045 inch	1 inch per amp	1 x 125 = 125 ipm

What Type of Metal Will I Be Welding?

The type of metal will have a great effect on the machine setting, electrodes and gases that you will be using. Each differnt metal has different melting temperatures, as well as the ability to hold that heat.

When you set up your MIG welder, you will need to know the exact type of metal you are going to weld. There is no such thing as a setting that will work on all types of metal. The three most commonly metal types that are MIG welded are:

• Carbon Steel/Generally designating A 36 Grade
• Stainless Steel/Nickel Based Alloys
• Aluminum/Non-Ferrous Metals

What is the Metal Thickness That I Will Be Welding?

The thickness of the metal plays a significant part in the machine settings. When it comes to other processes like Stick or TIG welding, you can almost use the same setting on various metal thicknesses. For instance, you can weld a ¼ in. thick plate with nearly the same settings you used to weld a 1″-1-inch thick plate, etc.

Now MIG welding, on the other hand, does not operate like this! Depending on the thickness of the metal, the heat settings vary greatly. The most serious threat from a weld quality standpoint is using too low of a heat setting.

So, for example; the Nuclear Power Plant building industry, has all but banned MIG welding. This happened because there were a plethora of welders who in the past were using too little heat when welding, and were welding joints with no penetration at all.

The weld looks great, but a couple of taps with a hammer, and the joint will come apart. Even a proper applied spot weld would be much stronger! MIG welding too cold will put in the weld, but it is only laying on the surface of the joint. A too cold weld is equal to duct taping the joint.

Examining the beads

One way to check your parameters is by examining the weld bead. Its appearance indicates what needs to be adjusted.

• Good weld: An indicator of a good weld involves good penetration into the base metal, a flat bead profile (top and bottom surfaces), bead width appropriate to the base material, and good tie-in at the toes of the cow.
• Voltage too high: Excessive voltage is indicated by poor arc control (e.g., an inconsistent arc), unintentional penetration (e.g., too much, not enough), and a turbulent weld pool (e.g,. not including data to indicate a consistent penetration into the base material).
• Voltage too low: Insufficient voltage results in poor starts, poor arc control, poor penetration, excessive spatter, a significant convex bead profile, and acceptable tie-ins at the toes of the weld.
• Travel speed too fast: Traveling too fast can have undesirable effects of producing a narrow bead with a convex profile, poor tie-ins at the toes of the weld, and insufficient penetration.
• Travel speed too slow: Traveling too slow can contribute to excessive heat contributions, a wide weld profile, and insufficient penetration. Using excessive heat can also be a risk of burn-through due to the inadequate heat-affected zones when working on sheet metal.
• Wire feed speed/amperage too high: If you set your wire speed or amperage too high (based on the type of machine) you may find that it causes poor starts. Inevitably, it will lead to additional wide beads, burn-throughs, more spatter, and poor penetration.
• Wire feed speed/amperage too low: Insufficient amperage can be indicated by the narrow beads with often convex profiles, and poor tie-ins at the toes of the weld.
• No shielding gas: If you have no gas shielding or an inadequate gas shielding, it should be apparent from the porosity and pinholes you’ll find in the weld face and interior of the weld.

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