Welding, the ability to transform metals into a myriad of different shapes and designs, can be a rewarding enterprise. However, when performed incorrectly, welding can be hazardous, which is why it is so important to know the basics before starting off.
There are more than 30 different welding techniques out there, ranging from the simplest oxyfuel to high-tech laser beam welding. However, there are only four types of welding that are commonly used today, each coming with their own advantages and disadvantages, needing the right equipment and techniques.
What is Welding?
Welding is the process of fusing materials, usually metals, by melting them at high temperatures. Unlike brazing and soldering, which operate at a much lower temperature, welding doesn’t simply bond two pieces of metal together. The use of extreme heat and occasionally other metals or gases, causes the metallic structures of the two pieces to join together becoming one.
The welding process often involves the use of a ‘filler material’ which is used to create a molten pool of material, encouraging a strong formation between the base metals. Most welding methods will need a form of shielding gas, which protects the main components and fillers from being oxidized during the process.
Different welding forms use different energy sources, ranging from a gas flame to an electric arc, to a laser, an electron beam, friction, and ultrasound. It is an ultra-versatile technique and can be used in a variety of locations, such as the open-air or even underwater. Welding gear includes thick gloves, jackets, and specialist helmets. Arc Helmets offer good reviews on welding gear if you’re looking to get started.
Gas Metal Arc Welding (GMAW)
This welding process is achieved through the use of a welding gun. The welder pulls the trigger, which allows the consumable electrode to pass through. The welding process is achieved when the bases of the material and the electrode form an electric arc, heating the material until it reaches the melting point. This process is most commonly used for stainless steel, magnesium, copper, nickel, aluminum, and silicon bronze.
There are many benefits to using this welding style; it produces the least waste, requires lower heat inputs, and lowers welding fumes. It is also the easiest form of welding to learn, making it a perfect choice for beginners.
Tungsten Inert Gas (TIG) Welding or GTAW
This welding technique was created in the 1940s and is one of the most complex and time-consuming, requiring a high level of skill and focus. It uses a tungsten electrode to heat the base metal, creating a molten pool and resulting in high quality, splatter-free welds of various alloys. While the technique can produce very precise, thin outcomes, it requires a highly trained operator and eternal shielding gas, and it will not work on rusty or dirty materials. It is the most commonly used welding for vehicle manufacturing, aerospace welding, and high precision welds.
Shielded Metal Arc Welding (SMAW)
This common welding method involves the use of a consumable electrode with a flux-coated core wire that provides an electric current. An electric arc is created when the tip of the electrode is in contact with the metal being welded, generating high temperatures of up to 6500 degrees. It is this heat that melts the electrode and the metal, creating a weld.
This method does not require shielding gas and can be used on rusting metals. It has great money-saving benefits, and it is also very portable. However, it is best used on metals of 4mm and above, as this welding form can only be used on thin metals when performed by a very skilled operator. It is often used in repairing heavy equipment, in the manufacturing and construction industries.
Flux-Cored Arc Welding
Similar to SMAW, expect that a tubular wire-filled flux is used rather than solid wire. It can either be a self-shielded or dual shield and used with external gas. It is often used to weld thick metals, great for construction or repairing heavy equipment.
Material Differences
Welding does not only differ technique to technique, but the metal being worked with can have a significant impact. For example, stainless steel does not transfer heat quite as well as other metals do, making it easy to build up too much heat in the weld area, which results in a steel warm and a reduction in corrosion resistance. Learning to weld stainless steel involves reducing the current and speeding up the movement of the torch.
Unlike steel, aluminum has a much higher thermal conductivity, along with a much lower melting point. It is also highly reactive to air, leading to an oxidation layer on the surface. This oxidation has a much higher melting point than the aluminum below, meaning it has to be removed with a wire brush or chemical solvent for welding to be possible. Working with aluminum requires an even faster welding speed than with steel since it is possible to burn through the base mental, creating a hole. Both TIG and MIC methods can be used with aluminum, but TIG is preferable since the aluminum filler wire can become tangled in the wire feeder of the MIC gun.
Welding Methods
Over time, every welder will establish their own style, which they find most comfortable and effective. Beginning with the welding arc, which liquefies into a small pool of metal, the welder will push this pool with the electrode, using fluid motions, which can look like a figure of eight or a half-moon. It is important to remember that the key is to work evenly, back, and forth across the two pieces of metal so that both are welded.
When it comes to MIG welding, the operator can either push or pull the metal pool along, depending on preference. However, when it comes to TIG, the welder must push the pedal along the seam, while dipping the end of the rod in the puddle. When it comes to the stick and flux-cored welding method, a pulling motion is required. This is necessary to make sure that the melt flux slag is not welded over.
