Welding And Soldering: What Is A Mig Welder And What Does It Do?

MIG welding uses a mixture of carbon and argon to protect the work from the corrosive effects of oxygen and constantly feeds the flux.

The fact that many people confuse welding and soldering is not very surprising. After all, both involve heat and metal. Further, most people have neither welded nor soldered. The difference is actually quite simple: soldering adds metal to fuse the work together but welding actually melts the metal to fuse the work into one. By turning two separate pieces of metal into one, we create a much stronger joint than by simply, of you will, gluing pieces together, which is what soldering does. This is why we use soldering for joints that only need protection from minimal stress, like electrical connections, and welding is used for structural purposes. Obviously, structural joints need a much greater strength than does an electrical outlet.

For the sake of simplicity, we will not consider extreme welding, such as that which happens in a zero-g, zero atmosphere environment or underwater as most of us do not need these skills. With that caveat, we can safely say that there are three main style of welding: oxy-acetylene, stick, and MIG/TIG. For our purposes, we will focus on the MIG.

Oxy-Acetylene welding is the first form of modern welding, and it requires a fair deal of practice and skill to utilize. In this method, a mixture of oxygen and acetylene are used in combination with a flux to meld two pieces of metal into one. This is truly the "old-school" style of welding, and is remarkably slow, although, when used by a master, creates uniformly strong joints. Oxy-acetylene is still in use, although more often as a metal cutting tool rather than a welding tool.

Stick welding uses, not surprisingly, a stick where the flux encapsulates the electrode. This method, like MIG welding, uses electricity to create the intense heat necessary to meld two pieces of metal together. Although easier to learn than oxy-acetylene welding, stick requires a good deal of practice to perfect. Striking the initial arc can be a very trying experience for the welding novice because, while wearing the protective helmet that effectively blinds you, you have to pass the rod back and forth across the work and hope something happens where you want it. Slag, metal buildup that is unwanted, is usually quite extensive, often requiring more time than expected to chip and grind it back down. Finally, especially when working with thinner metals, blow through, or punching a hole in the work, is very common and difficult to fix.

MIG, which stands for metal inert gas, gets around most of these problems, including the corrosive aspects of oxygen. The air we breathe is mostly made up of oxygen and nitrogen, and oxygen is very corrosive. Proof that this is true can be seen when an apple is quartered and left on the counter, or silver is left exposed to oxygen - they will discolor. MIG welders use a mixture of carbon and argon to form an "envelope" around the weld, pushing the oxygen out of the way. It is much easier to strike and arc and continue welding, and because the flux is stored on a spool in the welder itself and fed continuously into the work, there is no need to stop every few minutes to change the rod. The slag buildup is much less than with stick welding, and the slag that does happen tends to not fly everywhere. Similarly, blow-throughs still occur, but a skillful welder can much more easily plug the hole by passing the gun around the site of the hole and building up the slag, thereby plugging up the hole.

When first learning to weld, one of the best tricks to learn quickly is how to flip the helmet down without using your hands. This allows the welder to place the gun and his or her hands in the proper position to begin work and easily strike an arc. The helmets are designed so that a quick nod of the head will bring the faceguard into place.

To close, a few words on safety are in order. Remember that welding is actually heating the metal to the point where it melts and runs together, several thousands of degrees. Sometimes this molten metal spatters, so a heavy fireproof jacket and gloves are a must. There are also fireproof caps that can be worn underneath the welding helmet to minimize the chances of hair catching on fire, but even a baseball cap worn backwards will usually suffice. If you are welding underneath the work, or there is any chance sparks or slag can fall on your head, earplugs or other hearing protection can keep these sparks and slag from settling inside your ears - a very unpleasant experience. The blue light emitted from the weld is ultraviolet light, the bad light from the sun that causes sunburns and even blindness, so never look directly into a weld and make sure that any exposed skin is covered. While these precautions may seem extreme or even uncomfortable, especially when outdoors in August, it should be remembered that they are far less uncomfortable than running, screaming, around the workplace, trying to find enough water to put one's hair out.

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