Newcomer to Mig Welding?

Starting out with MIG

I was inspired to write a post about getting started with Mig welding, also known as Gas Metal Arc Welding (GMAW), when I was talking with a friend of mine about his welding woes.

My friend just purchased a Lincoln Electric PowerMig 140C and was having problems with the weld being "cold" and getting a "ropey" weld bead. After providing some feedback and insight I figured that more people in the hobby welding segment would benefit from these few points on "Starting out with Mig"

When first purchasing a welder, you need to keep in mind your application. What type of material are you going to be welding on (stainless, mild steel, aluminum)? What is your maximum thickness of material(thin sheetmetal,up to 1")? What is your input power (120V,230V,460V?) Where will you be welding (small garage,outside)? These are important considerations that are easily overlooked when people first purchase a Mig welder.

One of the more popular welding machines on the market right now for hobby welders is Lincoln Electric's Power Mig 140C. The 140 stands for the maximum current output of the machine, and the C stands for a continuous voltage selection. The 140T model is a tapped voltage selection. The advantage of the C model is a user can hone in and fine tune their voltage.

Back to my friend. He was having problems with his bead running "cold". I had a few helpful suggestions for him. First, I asked him what type of circuit he was running on. This is important because most home circuits are 15A 120V. This machine and other small Mig machines may require a higher amperage circuit. The 140C requires a 20A circuit. If you are operating on a lower amperage circuit, be aware that you will not get the full capability of the machine's output.

The second suggestion I had as well was to flip the inside panel up on the machine, preferably with the machine off. Inside the panel is a chart of material thickness corresponding to voltage and wire feed speed (which is synonymous with current). These settings will help the user get a closer "ballpark" setting for their type of weldment.

Next, I asked him what type of consumable he was using. Turns out he was using Lincoln's Innershield 211-MP. It is important to know what type of consumable you are using because polarity is everything! The PowerMig 140C is shipped with its polarity on (DC-) . If you are Mig welding with solid wire and using a shielding gas, then you will need to change the polarity on your machine. This is a detail that is frequently overlooked! See image below to understand a little better.

Lastly, I steered my friend to look at the consumable literature for the type of electrode he was using. I actually sent him the Innershield Welding guide (provided by Lincoln Electric) as well as the literature on Innershield 211-MP. These documents provide vital information on recommended settings and material thickness specifications, code requirements...etc.

In closing, always remember to look through the operator's manual for more detail on the working of the machine. It is also important to always practice safe welding procedures and protocol. For Lincoln machines, you can always find the necessary information at www.lincolnelectric.com

Stick Welding

This process is known as Shielded Metal Arc Welding (SMAW). It consists of Constant Current (CC) Machine, an electrode, electrode holder, and work lead. Stick welding is one of the original forms of welding, it is the most versatile, portable, and least overhead cost of all forms of welding. The use of SMAW as a form of welding has been around for over 100 years. This process is tried and true out in the field. It is used by farmers repairing their old rusty,painted equipment to highly skilled pipeline welders making their root pass on high pressure systems.

SMAW can be welding on multiple polarities. Direct Current Electrode Positive (DCEP) also known as DC+, this is the most popular polarity that welders operate at. The two other polarities are Direct Current Electrode Negative (DCEN) or DC- as well as Alternating Current (AC). One of the major advantages of stick welding is that a welder can

easily change out electrode types and sizes. This gives the welder a wide range of operation and flexibility when welding. SMAW electrodes are identified by their American Welding Society (AWS) Classification. Sample types are E6010, E6011,E7018,E7024..etc.

AWS Classification for SMAW Electrodes

Selecting Polarity:

When stick welding, choosing the correct polarity can be crucial. Wrong polarity may cause lack of fusion, cold lapping, excessive penetration, or burn through. It is imperative a welder read the

manufacturer specifications on which polarity is recommended.

A general rule of thumb for polarity selection is to think "where the heat is." When welding on DC+ polarity, due to the flow of electrons and ions, more heat is generated on the base material. On DC+, since more "heat" is on the base material the welder typically will get more penetration and digging action. Now, on the contrary, DC- polarity will put more "heat" on the electrode. This action will allow a faster melt off rate of the electrode and have a lessened digging action.

This is a great polarity to weld on thin material, such as sheet metal of 10 gauge or thinner.

Lastly, AC gives a good blend of the two polarities. Since an AC output oscillates between positive and negative (typically at 60 Hz in most Transformer-Rectifier machines), the user gets a good mix of penetration and melt off. Take note that not all electrodes are designed to

run on AC polarity. Since AC polarity

oscillates through the zero point electrodes need special chemicals added to keep the arc lit through that zero point. Typically, the addition of potassium helps the arc from being extinguished.

For more detailed information on SMAW check out: http://www.lincolnelectric.com/en-us/education-center/Documents/SMAWFacilitatorGuide.pdf

Always Remember to Practice Safe Welding Procedures and Protocol!

Hausen.