Welding Techniques - New Tricks

Racers tend to be prepared. That means they try to plan for the worst-case scenario. If a part breaks, they either carry enough spares to replace what they have found to be consumables or they try to have enough tools to be able to fix the broken part on the car.

In the past, only the most resource-rich teams would carry welders to fix damaged cars. The cost was just too high. Not only did you have to have an expensive welder, but you also needed a fairly large generator. Not to mention that the weight of the machine and power supply might require a larger tow vehicle. But today is a dawn of a new age. Welders from many manufacturers are available at very reasonable costs, and due to inverter technologies, you do not have to have a killer generator to run the machines. For the most part, a low-cost 2500W generator makes enough power to run an inverter-type TIG or MIG machine. Miller and Lincoln make a portable TIG machine that is about the size of a large kitchen toaster, and I don't mean one of those fancy four-slice models.

The problem with the TIG machines is that you still need an argon bottle and a method to hold all of the various component parts together. While this is not a real packaging challenge, it requires some effort by the racer. Even the compact models require some infrastructure to support the machine. If you decide to use a MIG welder, there are machines that are completely self-contained in one small, suitcase-sized package. The gas bottle is the same size as the C02 bottle that is used in a paintball gun. It will allow you to weld for about 20 minutes. A real positive is that you can purchase a bottle at Wal-Mart if you happen to run out while you are on the road.

The prices for these machines vary from maker to maker. It will require some shopping, but you can probably be set up to weld at the track for less than $1,500 if you already have a generator. The price of being prepared just got a whole lot more reasonable.

There always seems to be controversy about MIG (metal inert gas) versus TIG (tungsten inert gas) welding. According to the welding experts I have conferred with-and I have conferred with many, mostly in the Aerospace industry-the general consensus is the difference in strength is mostly academic. The main points of discussion centered on the material being welded and the complexity of the weld joint. If we focus on steel and the types of joints used in race cars, in a correctly performed weld, the difference between a MIG and a TIG weld is almost nonexistent from a strength perspective. The same can be said for aluminum in a race car context.

In the TIG process, the amount of control you have when it comes to heat input and adding filler material is much greater, as the inputs are instant due to TIG welding being a much more manually controlled process. The operator is in control of the heat input via a foot control, and adding weld material is also a completely manual process and can be adjusted instantly.

With the MIG process, the heat levels are preset prior to starting the weld, as is the amount of filler material added. In fact, you can't MIG weld without the addition of weld material. With a TIG weld, you can fuse metal without the addition of any filler material. The MIG process is more automated than the TIG process at the level of welding that racers will be operating.

The amount of metal fitment precision required is much greater with TIG welding than with MIG. With MIG welding, you can get by with a bit more misalignment and the weld can still be accomplished. TIG welds are much prettier than even a perfect MIG weld. There is almost no spatter or slag associated with a TIG weld. The TIG process is much slower than the MIG process due to the fact that the operator has to feed the weld rod into the weld puddle versus the MIG welder, which feeds the wire into the weld zone automatically.

TIG machines require a greater amount of infrastructure support (they cost more to outfit) than a MIG welder, and they generally cost more than a MIG welder with a similar power level. Once you balance the positives, negatives, and the cost difference, you still have to decide what you want. The individual racer needs to ask some questions, gather data, and let the numbers help make the decision.