Welders wear helmets to protect their eyes.
Welding is the process of joining two pieces of similar metal together with enough heat that the mating surfaces melt together and become one. It is part skill, part science but mostly an art form. Due to imperfections in the surfaces to be joined, a filler is generally required. The common filler for the hobbyist is wire. Dispensed from a specially designed wire feed welder, wire welding forms a strong, long lasting joint. While there are dozens of formulations of welding wire there are only a few basic types that will join most metals: solid, flux-core and alloy. The welding arc produced can be as hot as 7,000 degrees and will quickly blind you if you are not wearing the proper eye protection. A shielding helmet, apron and gloves are the minimum safety equipment required for welding.
Solid Wire
Welder wearing full protective clothing
Solid wire is the most basic type used in welding. It comes in many sizes and lengths and is compatible with the widest range of steel types. Special formulations are available for specific applications. This wire requires the use of a shielding gas to prevent contamination during the heating and initial cooling process. Most often this gas is carbon dioxide (CO2), as it gives the best penetration. Some operators use a mix of CO2 and Argon because they can work faster with that combination.
Flux Core
Flux core wire produces its own cloud
Flux is a chemical additive that burns so hot that it consumes all contaminants in the area around a weld. The wire itself is hollow and the flux is carried as the core. As the wire melts, the flux creates its own cloud around the weld. Using this type of wire eliminates the need for a shielding gas, so the equipment is cheaper and you do not have to worry about running out of gas. The wire composition is useful for most general-purpose welding. Flux core wire is also excellent for use on a windy day because there is no danger that an errant gust will blow away the shielding gas. The downside is that there may be a residue on the cooled weld that should be removed by chipping or grinding.
Aluminum
Tanks of welding gas on the job
Aluminum welding wire is used to weld aluminum and aluminum alloys. It is used with Argon gas as a shield and requires adjustments to equipment due to its delicate nature. This wire is available in many thicknesses to suit the requirements of the job.
Stainless Steel
Note the brightness of the arc.
Welding stainless steel requires a special wire as well as a special gas mix for shielding. At a minimum, an Argon/CO2 mix is used. Some add Helium to the mix to control slag and penetration in the weld.
