Welding 101

Another feature of today’s best wire-feed welders is an innovative gas shielding process with roots that go back to the Second World War. At that time, factories supplying Allied forces produced planes, tanks, ships and ammunition five times faster than Axis factories. This was partly made possible by an innovation in welding technology that funnelled a stream of inert gas through the tip of the welding electrode, which protected the vulnerable weld area very effectively from the ravages of oxygen while it was still hot. This process–now dubbed metal inert gas (MIG) welding–has become the industry standard for producing clean, fast and strong welds in both steel and aluminum. Move up just a little from the least expensive wire-feed welders, and you’ll find portable machines capable of using the MIG process. The inert gases involved are typically carbon dioxide, or a blend of carbon dioxide and argon. Hook up a cylinder of so-called shielding gas to your wire-feed welder, dial in the correct volume of gas flow, then start welding. The MIG process yields ultraclean welds, without the billows of smoke common with stick welders. Expect to pay about $750 for a MIG-capable wire-feed welder.

So, do all wire-feed welders need compressed shielding gas to operate? No. By using a self-shielding welding wire with a built-in flux core, you eliminate the need for gas, although the appearance of these kind of welds isn’t nearly as clean as MIG welds. Also, self-shielding wire gives off more smoke than gas-shielded welding (although not as much as stick welding). Wire costs about $35 for an 11-lb. roll of MIG wire, and about $25 for a 2-lb. roll of self-shielding flux-core wire. In the photo at right, you can see the difference between a self-shielding wire weld and a gas-shielded MIG process: While strong enough, the messy weld on the left was made with self-shielded welding wire. The cleaner weld on right was made using a gas-shielded MIG?process

Want to build an aluminum dock frame? How about some rustproof outdoor storage racks? Got some aluminum machine parts that need repair? You can tackle all of these things with a wire-feed welder capable of gas-shielded operation. Just rent a tank of carbon dioxide, install a roll of aluminum welding wire in your machine, then get busy.