Welding sheet metal requires impressive skills that experts and professional artisans obtain after training and practical experience. The welding procedure involves joining metal parts through fusion with extremely high temperatures to melt and fuse the metal joints. This fabrication process may sound simple, but in practice, it is more complicated than it seems. Equivalent to the various metal types available in the market, there is also a wide range of welding methods. If any individual tends to have a sheet metal application that requires custom fabrication, it is essential to understand the project’s welding methods. In this section, three main types of welding fabrication are introduced. These methods include MIG, TIG, and modern laser welding. Each method’s utilization depends on many factors.
MIG (Metal Inert Gas) Welding Sheet Metal
The MIG metal welding, also known as Gas Metal Arc Welding, is an arc method process that utilizes a perpetual solid wire electrode. The process involves feeding the electrode through a welding gun where the contact tip is charged electrically, creates enough heat to melt the material, and produces a weld pool or puddle to join two pieces. In the process, protection is formed on the collection to protect it from environmental contaminants, which could cause defects due to the shielding gas. The MIG process is efficient for projects where weld appearance and cosmetics have minimal importance due to the creation of the spatter during the procedure. The manual weld speeds are generally in 72 centimeters per minute range depending on the size and the procedure’s location. There are modern welding methods that utilize a robotic approach to increase throughput.
Carbon Steels: When it comes to welding carbon steels, the MIG method is superior to the TIG welding system due to its operating speed. It is also practical for joining pieces that do not fit together in close range. A common practice is for creating outside corner that needs dressing.
Stainless Steel Sheet Metal: Welding stainless steel sheet metal is similar to carbon steel. However, for this material, the process utilizes Pulse MIG for reducing the spatter. The Pulse MIG system features no contact between the pool and the electrode. With each pulse between the high and low level, a drop of molten material created from the electrode is applied to the process pool.
Aluminum Plates: Welding aluminum plates with the MIG method is also like carbon steel. A pulse MIG device is suitable for the process. However, the device requires specific gas assist in accomplishing TIG-like characteristics. The spatter and dust issue on aluminum material. Thus, the material involves pre-cleaning before welding for removing the surface scale.
TIG (Tungsten Inert Gas) Method
TIG welding method, which is also called tungsten arc welding, utilizes a non-consumable electrode. Thus, this method is different from the MIG system. The TIG system delivers heat for the process from an arc created from electricity in the electrode. For building up and reinforcement of the weld, filler material is practical. Similar to the MIG welding process, a gas shield protects the pool from contaminants. The operating speed of the TIG system is in the 17 to 39 centimeters per minute range, depending on the fillet size and the application wire.
Carbon Steels: As told, the MIG method is better than the TIG system when welding carbon steel due to the speed. However, the TIG system can be utilized where the MIG gun size obstructs access to the process.
Stainless Steels: Due to the requiring clean appearance in a cosmetic setting, the TIG method is primarily helpful for stainless steels. The heat input and speed require precise control during this welding method due to the physical properties of stainless steel, which is susceptible to warpage from uneven heating. The warpage area of this material is known as a heat-affected zone. Typically, there is no post-process cleanup required unless the specified application calls for the weld to be brushed to match the adjacent substance.
Aluminum: The TIG process is the default welding method for projects that require aluminum as the primary material. However, the Pulse MIG system is making significant progress in competing for the appearance of the TIG system on many projects, including cosmetic purposes. A preheat cycle will be necessary to ensure the perfect welding for thicker materials.
Welding Sheet Metal with Laser Weld
Laser welding is the newest welding method process that utilizes high-energy beams to provide a concentrated heating source to melt the materials. This method requires close part fit-up where the gap between pieces cannot exceed few centimeters. Nowadays, there are fabricating tools and equipment with high precision capable of securing the tolerance required for a uniform laser welding process. In a laser welding system, generally, there is no need for gas shielding. Additionally, the benefits of this method include low thermal distortion and thin weld seams. Unlike the TIG method, there is no filler wire added in this method. This property of the system allows manufacturers to weld smaller parts compared to other processes. There are two primary systems which are cosmetic and keyhole. The first system is perfect for creating smooth and wide weld.
On the other hand, the keyhole burns through the first layer of the sheet metal into the second lap. After the molten material is cooled, the process creates a solid joint, and it is better to use it when a cosmetic weld appearance is not critical. Still, the integrity of an airtight seal is crucial.