When welding sheet metal, your goal is to prevent distortion, molten seam welds, and excess heat-related zones while ensuring the weld has enough thermal strength for the job. The four basic sheet metal fabrication techniques you use to achieve these effects are discussed below. The first technique involves feeding the material into the welder’s feed plate, which pushes the welding sheet metal into the welder’s gun and feeds the metal to the blank space in the center. The feeding process allows the sheet metal to cool, which fuses the weld to the metal. The second technique uses a tungsten inert gas (TIG welding), which heats up the welding arc while shielding the filler metal from the high heat of the welding process.
TIG welding, or short-circuiting metal arc welding, is a popular technique for welding sheet metal because it is capable of performing at very low amperage with excellent fusion efficiency. To perform this technique properly, you must start by feeding the material in through the side of the weld seam, avoiding the feed plate, and working inside the confines of the welded area. Next, start to feed the metal into the center of the frame, and work outward toward the edges. This produces a variety of different effects, depending on the type of metal and the welding situation. The best way to see these results in practice is by using an electric welding gun, as it allows you to do it right in front of your eyes, and demonstrates the best way to create varying degrees of distortion.
This technique is sometimes called pulse welding because the welder feeds the metal in a very short pulse, producing very strong amperage, but a very low output of heat input. Because the welding sheet metal is fed in a very tight spiral, the welder can get a thin finish on one side of the sheet by feeding the metal in at a fast rate, while not heating the welding sheet metal at all. Because the welder must use more of his/her time on the thinner side, this technique generally produces higher quality welds than the other techniques. If a welder can perfect the pulse pattern, then he/she can produce very thin metal on both sides of the sheet at a high amperage, which is a recipe for sloppy welds and low-quality welds. Because the welder can use the thinner side without any concern for the quality of the weld, this technique can be used to weld aluminum, tin, and stainless steel, as well as most other types of metal.
The next technique that you should know about when you learn how to weld sheet metal is known as a match and slip, or M&S. This is the process of welding two pieces of similar metals together, but in opposite directions, which is why the name match and slip. You use M&S techniques when welding two pieces of metal together that are already hot because the heat of the flame will cause the metal to adhere to each other, creating a tight joint. You can use M&S to weld aluminum and tin because both of these metals will also bond with each other, although the amount of strength given by either of the metal will be lower.
One technique that you should know about when learning how to weld sheet metal is known as the burn-through. When you weld metal using the M&S technique, you have the combination of the slip and match process, where the metal is fed into the welder’s gas port, and the welder continuously feeds metal into the sheet until it becomes hot, which causes the sheet to burn-through. As the metal burns through, it takes the sheet with it, and the sheet is actually pulled through the weld puddle by the pulling force of the metal feed. It is important to understand that the amount of heat produced is directly proportional to the thickness of the material that is being fed because a thicker metal will produce a hotter burn-through.
In the final step of the welding sheet metal welding process, you have to realign the electrode. The purpose of this step is to create an even, smooth, continuous arc that leads to a clean weld. In order to do this, you will need to use wire feeders and a push rod, or if you have a workshop, you can even use hydraulic hammers to do the re-alignment. This is also the stage when the chances of welding sheet metal electrodes coming apart are reduced because they stick together when welding. The welder now has a clean weld, and you can start on your next project.
This article was written by Tyler Duoos, Tyler is the owner of General Saw Company. General Saw Company takes pride in being a leader in sheet metal fabrication services to Central Florida and its surrounding areas. If you are looking for Sheet Metal Companies to get the job done right the first time we got you covered!
