New to welding? Consider this.
According to Lincoln Tech:
Working with metal is both exciting and empowering. As the sparks fly and the heat turns up, welders are able to transform some of the world’s strongest materials into the shapes and products they envision. This skill requires work and practice to acquire, and it’s best learned with the assistance and guidance of industry professionals.
Learning the ropes of a new trade can be time consuming. You need to become familiar with the entire working process from start to finish and master each level before moving on. This attention to detail is what makes a great welder and a more versatile potential employee. There are four major types of welding procedures that students at Lincoln Tech must learn in order to become successful welders working in the field. Lincoln students have the unique opportunity to get comprehensive hands-on training from field-experienced instructors. With guidance from some of the best in the industry, students will master the four most popular types of welding procedures.
4 Types of Welding Processes
Gas Metal Arc Welding (GMAW/MIG)
This style of welding is also referred to as Metal Inert Gas (MIG). It uses a shielding gas along the wire electrode, which heats up the two metals to be joined. This method requires a constant voltage and direct-current power source, and is the most common industrial welding process which includes plate and large bore pipe.
The GMAW/MIG welding process uses four primary methods of metal transfer:
- Globular transfer produces a rougher weld bead due to metal droplet size and the propensity for spattering. This method is useful for welding thick metal plates in horizontal positions.
- Short-circuiting works as the name implies – the welding wire contacts the base metal in a quickly repeated tapping method many times per second. Because little spattering is produced in the process, this method can be used in any welding position.
- Spray Transfer transmits tiny droplets of molten metal in such a steady fashion that it maintains a steady-contact arc weld during the process. Even though this method produces little splatter, it is best to use on horizontal pieces that are thick and flat.
- Pulsed-spray is very similar to Spray Transfer, but uses a high-low current pulse to allow micro-cooling periods. Because of this type of delivery, this process can be used on a wide variety of metal plate thicknesses, and in almost all welding positions. Note that when we use the term “cooling” when describing pulsed-spray, the moments of lower voltage that provide a cooler weld are still several thousand degrees Fahrenheit. It is only considered cooler relative to the high-voltage portion of the cycle. All welding uses extreme temperatures.
Gas Tungsten Arc Welding (GTAW/TIG)
Welding together thick sections of stainless steel or non-ferrous metals is the most common use for this method. It is an arc-welding process that uses a fixed consumable tungsten electrode to produce the weld. This process is much more time consuming than MIG, Stick or Flux Cored Arc Welding.
The melting point of non-ferrous metals vary considerably, so care must be taken in identifying the composition of the base metal. Stainless Steel and Steel both contain Iron, however, to be considered Stainless Steel, the metal must contain at least 11% Chromium. Carbon Steel melts in the 2,600 to 2,800-degree F range.
The presence of 11% chromium in stainless steel narrows that temperature range to the 2,750+/- degree F mark. But nothing shows welding skills more than the intricate ability to TIG weld aluminum. This skill takes a steady hand, trained eye, and an artistic touch to create a smooth, amazing weld.
Shielded Metal Arc Welding (SMAW)
With this particular type of welding, the welder follows a manual process of stick welding. The stick uses an electric current to form an arc between the stick and the metals to be joined.
This is often used in the construction of steel structures and in industrial fabrication to weld iron, steel and using the open V-Groove when welding with mild steel pipe.
It is vital that the welder must be able to weld to a level in which their work can pass a destructive type of bend test. While shielded metal arc welding is used to join carbon steel, alloyed steels, stainless steel, cast iron, and ductile iron, it can also be used for some non-ferrous metal applications like Nickel and Copper. It is rarely used on Aluminum.
Flux Cored Arc Welding (FCAW)
This was developed as an alternative to shield welding. The semi-automatic arc weld is often used in construction projects, thanks to its high welding speed and portability. This method has many variables making it applicable in a variety of welding projects. Variables often depend on the model of welder being used, and what type of wire was chosen for the application.
The flexibility is broadened by the many operating angles, voltage levels, polarity used, as well as the speed of the wire feed. Due to the potential of faster welding speeds, the newly joined metal cools quicker. If the welding technician is using a flux cored wire, he or she must be on the lookout for porosity in the welded joint.
Flux Cored Arc Welding is best used in either outdoor settings or under industrial ventilation hoods, due to the amount of smoke and fumes created during the welding process.