'Sooner or later you'll need to have something welded. Our hobby requires it. As musclecars get older, as parts break or rust out, and as replacement parts vanish, you'll long for welding skills. The good news is that it's easier and cheaper to buy a welder now than it ever has been in the past. All the name brands make quality, entry-level MIG machines that run on household voltage and will meet the demands of the average weekend enthusiast. There's never been a better time to buy a welder and get good at using it.
There's a saying in the industry: "Weld-ing holds the world together." While it seems that everything-every business, institution, city department, you name it-has a slogan, this is one that is absolutely true. Think about it: Nearly everything we use every day is held together by welds. To put a new twist on the old saw: Teach a man to weld and he'll fix things for a lifetime.
Of course, it is possible to teach yourself how to weld, but the process is time-consuming and can be frustrating. It can also be difficult to know if your technique is correct. It's pretty easy to get a decent-looking weld with the newer MIG machines, but just because a weld looks nice doesn't mean that it's structurally sound. As with anything else, it is best to learn from a pro. A person wanting to gain welding skills has many options-learn from a professional welder, take classes at a vo-tech school, or go to one of the manufacturers. Both Lincoln Electric and Hobart offer welding classes in their own dedicated training facilities.
Lincoln Electric has been making welders since the turn of the century (last century, that is) and has been teaching welding classes since 1917. It offers a variety of instruction, from plate and pipe welding for industrial applications to dedicated MIG and TIG classes. The one that appealed most to us was the Basic Motorsports class. It's a five-day intensive course covering MIG and TIG welding, plus a little oxyacetylene and plasma cutting on the last day. There's a lot to learn, from basic metallurgy in the classroom to developing and honing your technique in the workshop. We packed our bags and flew to Lincoln's headquarters in Cleveland, Ohio, ready to burn some metal. Here's what we learned.
GTAW
Gas tungsten arc welding is a process in which a nonconsumable tungsten electrode is used to channel a high-amperage current through the workpiece. It's more commonly known as TIG, or tungsten inert gas welding, and is sometimes called Heliarc welding. Tungsten is used as the electrode because of its high melting point. The arc struck between the electrode and the work is blanketed with an inert, or nonreactive, gas, usually argon, helium (the "heli" in Heliarc), or a mixture of the two. The gas flows through the power cable and exits from a nozzle near the electrode. It shields the arc and weld puddle from contaminants in the atmosphere, specifically oxygen and nitrogen, that would react with the molten metal and possibly weaken the joint. Filler rod is fed manually into the weld puddle to help bridge the gap between the two pieces of metal being joined together.
The TIG welding process was developed in the '30s but became commercially viable during WWII when it was used to join magnesium airplane parts. It produces the best welds both structurally and aesthetically, but the process is very slow and requires a lot of practice to nail down the technique. In contrast to other forms of welding, all types and thicknesses of metal can be welded with the GTA process. The operator has a tremendous amount of control over all aspects of the weld: the amount of current, the rate of travel, and the amount of filler material used. GTA welding can also be performed in any position-vertically or overhead-so it lends itself nicely to structural automotive work such as making rollcages.
Most TIG welding is done with the machine on the DC negative setting. This means that the workpiece is positive and the tungsten electrode is negative. Because of this, about 70 percent of the heat generated by the arc is concentrated on the work rather than at the tungsten. A few metals, particularly aluminum, are welded with the machine in the AC setting. That will be explained later.
TIG welding is both easy to learn and difficult to master. The process itself is simple: Start an arc and aim it at the two pieces being joined together. Increase the heat (amperage) using the foot pedal until a small puddle of molten metal appears, and quickly dab the filler rod into the puddle. Once the filler material wicks into the base metal, move forward with the torch, repeating the process over and over until the joint is fused. It takes a lot of practice to get a weld that looks good, though. The tip of the electrode must stay between 11/416 and 11/48 inch above the puddle. At this distance, it's easy to accidentally touch the tip of the electrode with the filler rod or dip it into the weld puddle. When this happens (and it frequently will), the tungsten becomes contaminated and the arc becomes erratic. You must remove the electrode from the torch and grind the contamination off. Also, if you don't maintain a steady distance above the weld puddle with the torch, your "stack of dimes" weld bead will look more like a stack of dimes, pennies, and quarters. The bead will be uneven.
The great thing is that once you get the technique right, you can make anything. And anything you make, whether it is a rollcage, filler neck, or seat bracket, will look like a work of art. You will know that it is structurally sound, too. Because you have absolute control over the weld process, you are able to see the weld puddle forming on both pieces being joined while you're welding. And you'll see the filler material melt and flow into the joint, leaving no doubt that the weld is sound.
GMAW
As you've probably guessed, GMAW stands for gas metal arc welding. This process is commonly, though not always accurately, referred to as metal inert gas (MIG) welding. Not quite correct, because the shielding gas most frequently used in MIG welding has up to 20 percent carbon dioxide, a reactive gas, in it. So you may run across a smartass who will inform you that the more appropriate moniker is metal active gas (MAG) welding. Silence him by simply referring to it as wire-feed welding, a more general but always appropriate term.
GMA welding differs from GTA welding in several key ways. It operates in DC positive polarity-the electrode is positive, and the work is negative-and no welding rod is used. Instead, the filler material, or welding wire, is the positive electrode. It is wound on a spool inside the body of the welding machine and is fed through the power cable, exiting at the tip of the torch. With GMA welding, the operator does not have as much "real-time" control over the process as in GTA welding. Yes, changes can be made while welding, but to do so the operator may have to look away from the weld to fiddle with the controls, and that can be a risky endeavor. Starts and stops don't blend together in the weld bead with MIG welding as nicely as they do in TIG welding, so to get a smooth weld, it's best to have all the controls properly set ahead of time so you can run a continuous bead.
Wire-feed welding does have a few distinct advantages over GTA welding. One is initial cost. A MIG machine is much less expensive to buy and easier to operate than a TIG machine. Many MIG welders will run on 110V household circuits; you can literally plug them in and run a bead. You don't even need shielding gas if you use flux-cored wire. As with stick welding, the flux inside the wire will shield the weld. Better-looking welds are obtained, however, by using solid wire and an 85 percent argon/15 percent carbon dioxide mix. Undoubtedly, the biggest advantage of GMA welding is speed. In the hands of a professional, MIG welding can be as much as three times faster than TIG welding. In places like collision repair shops where speed is of the essence, you'll trip over MIG machines all day long before you find a TIG machine.
Lincoln Welding School instructor Karl Hoes says MIG welding is the easiest to learn, but may be the most difficult to get right. In theory, it's simple: Since the machine feeds the wire automatically, the operator need only set the proper heat range and wire speed appropriate for the type of materials being welded, and pull the trigger. As long as the operator moves the torch at the same rate as the wire is being fed, it's pretty easy to make a good-looking weld. Problems can arise because of insufficient penetration, though. You may have only laid a good-looking bead on top of the joint being fused. Even with the correct heat setting, MIG welds can often experience insufficient penetration at the start of a bead, a situation called a "cold start." In this case, the weld wire solidifies before the base materials are heated enough to fuse the joint. It takes a lot of practice to get the technique right. In some ways, the benefits MIG welding have over TIG welding (ease of use and speed) can be a disadvantage to a novice welder.
SMAW
Though shielded metal arc welding, or stick welding as it's commonly called, is not normally used in automotive applications, it's worth mentioning here because it's a term you'll hear a lot, and any TIG machine you can currently buy can also be set up to do stick welding. It's an arc-welding process that uses a flux-coated welding rod. The flux is vaporized in the arc and forms a cloud of shielding gas around the weld area. Stick welding is usually done with DC positive current, where the welding rod is positive and the workpiece is negative. Stick welding is the oldest form of electrical arc welding and is usually used on heavy materials in industrial settings like shipyards or construction sites, and for pipefitting.
Materials
Carbon SteelThe most common metal in automotive applications is mild steel, which is good because it's the easiest to weld. Though a full-blown discussion of metallurgy wouldn't be appropriate here, it is crucial to note that different metals must be welded in different ways, and each alloy or blend requires the use of a compatible welding rod or filler wire.
Steel is usually classified according to its carbon content: low-, medium-, or high-carbon. Generally, the greater the carbon content, the harder the steel. However, this is not necessarily a good thing: High-carbon steel can be very brittle and susceptible to cracking under certain forces. Also, steel with higher levels of carbon reacts differently to the heat of welding. Too much heat or improper cooling of the weld can make an already brittle piece even more brittle-a potentially dangerous condition if it is a structural component such as a rollcage or suspension piece. The operator must be aware of this and adjust his technique to suit the composition of the base metal.
Stainless Steel And Aluminum
Stainless steel and aluminum are seeing more use in automotive applications, and they too are welded differently from mild steel. Stainless steel is so named because its high chromium content prevents the formation of iron oxide (rust). When welded, the chromium can react with the carbon in the steel and oxygen present in the atmosphere. The result is called "sugaring," which manifests itself in a scaly, crappy-looking weld. Argon shielding gas will prevent sugaring of the weld bead on the front of the piece, but what about the back? Sugaring can occur on the back of the weld, too, if the penetration was sufficient. As a result, such a weld is structurally unsound and would be prone to cracking or complete failure under high heat or vibration. To avoid this, it is necessary to back-purge the weld-to provide a stream of shielding gas over the back of the joint.
Aluminum is a tricky metal to weld. In its natural state, aluminum is coated with a tough but transparent layer of aluminum oxide. This oxide provides excellent corrosion resistance, but it melts at a higher temperature than pure aluminum. So when welding, the operator must use enough heat to melt the oxide layer, then back off the heat to avoid overheating the aluminum underneath. If using a TIG welder, the machine should be set to run in AC mode. Positive voltage of the AC sine wave will actually clean off the aluminum's oxide layer, while the heat generated during the negative-voltage part of the cycle will melt the aluminum. Again, be sure to use the proper filler rod, compatible with the alloy you're welding, and switch to pure argon gas if using a MIG welder. The 80/20 argon and carbon dioxide mix used for steel will not work when welding aluminum.
Where Do I Sign?
Lincoln offers the Basic Motorsports class 12 times a year, usually around the middle of each month. The course schedule is posted on Lincoln's Web site, and you can register online as well. Sign up early, though-classes are limited to 12 students each and can fill up quickly. It's recommended that you have some welding experience before taking the class. The concentrated nature of this course would likely cause a total novice to get left behind. If you've never welded before, or would just like to spend a week practicing one welding process, Lincoln also offers five-day MIG and TIG classes.
The cost of the Basic Motorsports Welding class was $655. Factor in airfare, hotel, and "entertainment" expenses, and it's possible to ring up a bill over $1,000. Still, we feel it was a bargain based on the amount of stuff we learned. And learning in a concentrated environment with lots of hands-on time really helps hammer the technique home.
We highly recommend that any car guy have basic welding skills. Whether you take classes from Lincoln, Hobart, or your local community college, you'll be learning an invaluable skill that will pay for itself many times over.
