Here's a little guide on choosing the correct wire for your welding needs. The criteria of choice would differ with the type of welding machine used, type of metal, size of metal, weld strength and of course the cost of the wire itself are factors. Since were all handyman per se, I would concentrate on the types of wire's that are "commonly available" in the market and those that a diy would normally use. So we start with the basics:

Types Of Mig Wire : There are several types of wires but in general there are only 2 types. A GAS SHIELDED wire and a SELF-SHIELDED wire or commonly know as the gasless wire.

A Gas Shielded wire requires Inert Gases like CO2,Argon or a Mixture of both. The Gas is used to shield of the weld to remove impurities and O2 from weakening the weld by introducing airholes commonly known as POROSITY. The gas also improves the welding process for a better weld finish.

POROSITY (Welding with Gas and No Gas)

A Self Shielded wire on the other hand do not require gas to attain the same effect on the weld. It does this by combining the metal wire with a flux compound which burns together with the material and thus shielding the weld on the process.

So what are the advantage and dis-advantage? Gas wires like Copper Coated Mild Steel or Solid Steel wires are cheap and very common. They produce nice and strong welds, however, they require large industrial welders, costly gas setup like tanks and regulators and stable air environment. Welding with gas outside a windy place would hardly be possible. But the outcome of gas wires are always superb in terms of cleanliness and strength. Self-Shielded wires or the FLUX CORED wires require a minimum type welder, it does'nt even have to be D.C. to burn correctly. But I always re-iterate that it's best on D.C. machines as wires are polarized. Gas wires are straight and Flux cores are reversed. Gasless wires don't come cheap but if your going to add it up with the gas wires, you'll surely realize they are not that far away from each with regards to cost. In summary, gasless wires are for general purpose. it can be used on anything and anywhere.

Gasless Weld Finish (Slag not removed)

Gas Weld Finish

What's with the sizes? Wire sizes start from 0.6mm up to 2.5mm. The choice of size would depend on the welding requirement. Thicker materials, bigger size. The type of machine your using greatly affects the use of wire. A 90amp AC welder would not have any problem burning a 0.8mm flux cored self-sheilded wire but burning a same size copper coated mild steel wire is hardly possible. it could melt but not burn, stainless and aluminum on-the-other-hand is definitely impossible. As a general rule for gas wires your machine should be twice the amps required to burn the wire, 0.1mm = 10 amps. So for a 0.8mm gas wire to burn nicely you need a welder that is 0.8mm x 10amps = 80amps x 2 = 160amps.

What Spool? Spools sizes vary from 0.5kg up to 100kg. But the most common sizes are 1kg to 15kg. Most sub-compact machines can handle spools from 1kg to 5kg provided you have the necessary adapter to match. Some portable mig machines spool bays are located on-top of the machine which prohibits them from using 5kg spools which are very common here in the philippines. So be sure to put that on list when choosing which wire to choose.

So what are the wires to choose from? For Gas wires you have all kinds and sizes, mild steels, solid steels, stainless and aluminum and alloys. For Gasless you have Flux Cored Self Shielding Mild Steel. Special wires like Flux Cored Steel, Flux Cored Stainless and Flux Cored Aluminum requires both shielding, meaning gas and gasless at the same time. Remember to check their polarities if their D.C or A.C use.

So there you are, hopefully you have something here to start with. Comments, Suggestions and Corrections are always welcome! Cheers PHM! 😎