|
|
|
|
| Welding Part 1 |
| Written by David Jackson | |||||
| Wednesday, 09 August 2006 | |||||
|
Burn your retina out
Part 1 - Part 2  Ah, the smell of burning metal, the crackle of the arc... sounds like bacon frying. The MIG hums as it feeds the wire to the torch. A brilliant blue-white light plays on the walls around me. Clad in thick leather gloves, I gently wave the torch back and forth. Watching through my full face mask, I feel like Darth Vader, but without the protective black glass to watch through, one look and it'll burn your retina out. I am talking about gasless MIG welding. Relatively cheap ($175 - $450), efficient and easy, MIG welding is the
best choice for most modders. Think of the possibilities! A custom
steel case, brackets or tubing. All these things are possible, and
more. Welding, while requiring practice, is something anybody can do.
Don't be intimidated by a tool!Ok, now I hear you saying, “but welding is a specialized skill that takes expensive equipment and years of experience.” Well, you are correct... but you are also dead wrong. FCAW or gasless MIG welding is perfect for the modder or the home shop. It uses household current and relatively inexpensive equipment. It's also fairly easy to learn. I would recommend taking a class if possible, or at least having an experienced MIG welder show you the ropes. But, it is entirely possible to read a “how-to” (like the one I'll be presenting to you) and pick up the torch and start welding. At first the welds you run will be pretty ugly, but with practice you will be turning out “fine beads” in no time. 
Traditional MIG welding, or “Metal Inert Gas” welding, uses a wire fed through a hose to a torch. An inert gas flows around the wire and out the torch. A high amperage DC current flows through the wire. When the trigger on the torch is pulled, the wire is pushed out of the nozzle and the gas flows. The wire is touched to the “grounded” metal to be welded. As the high electrical current flows through the wire it “arcs”, or vaporizes, and is sprayed onto the metal. A somewhat newer form of MIG is the gasless, or "flux-core", MIG welder. These welders are not exactly gasless, but they use a wire that contains a flux inside that releases a gas as the wire arcs or vaporizes. Therefore a tank of argon is not required. Wikipedia says, “Flux-cored arc welding (FCAW) is a semi-automatic or automatic arc welding process. FCAW requires a continuously fed consumable tubular electrode containing a flux and a constant voltage or, less commonly, a constant current welding power supply. An externally supplied shielding gas is sometimes supplied, but often the flux itself is relied upon to generate the necessary protection from the atmosphere. The process is widely used in construction because of its high welding speed and portability”. As we discussed in the series on soldering, flux is needed to exclude oxygen during this time of high temperatures. Without some form of flux, the metal will oxidize or rust almost immediately. The inert gas, usually argon, helium or a combination of argon and carbon dioxide, is the flux. It displaces the oxygen at the tip of the torch, allowing a nice weld. A gasless MIG works when a wire fed welder plugs into normal AC household current. In my case, 120 volts 60 hertz, with a standard grounded plug you have in every room in your house. A 220 volt version is also available. In the photo below you can see my welder with the top up showing the wire feed system. 
The flux core welding wire is pulled from the spool by a set of rollers powered by a small motor. The wire is the pushed through a tube that is lined with a flexible metal conductor. This applies the positive DC charge to the wire. The wire then flows to the “torch”. In the top picture in the photo below, you can see the torch includes a trigger for activating the wire feed, and in some cases the current flow. Let's take a closer look at the torch itself. In the second picture below, the tip cover has been removed to show the welding tip and the wire protruding from the tip. The tip cover helps contain and “focus”, the shielding gas produced by the flux core of the welding wire. The tip of the torch is held very close to the weld pool to concentrate the gas, and to allow for control of the short arc the MIG produces. 
I mentioned a few terms in there that may need some explanation. First, the weld pool: when I first heard this term, all I could envision was a bunch of guys in leather aprons and gloves, covered with soot, smoking Camels, standing in line to be picked to weld something. Really, this is a pool of molten metal. This is where the actual bonding of the metal takes place. The two pieces of metal and the wire are heated to the melting point. This occurs at the point of the arc, a spot as bright as the sun at noon, in the desert. Next, is the short arc. MIG or FCAW is considered short arc for various reasons, the easiest and most logical is that if you move the torch away from the grounded work piece, the arc breaks and you stop welding. 
The photo above shows my Mig setup. The additional tools are needed for safe and efficient welding. We will discuss these in greater detail next article where our discussion turns to technique and some important safety issues such as, "How to move the torch properly" and "Don't catch your hair on fire."
Write Comment |
|||||
| < Prev | Next > |
|---|
|
|