WELDING PROCESS AND TECHNOLOGY

Commonly referred to as the MIG process, GMAW is an arc welding process that incorporates the automatic feeding of a continuous, solid consumable electrode that is shielded by an externally supplied gas. The process is used to weld most commercial metals including steel, aluminum, stainless steel and copper and can be used to weld in any position when appropriate welding parameters and equipment are selected. GMAW uses direct current electrode positive (DCEP) polarity, and because the equipment offers automatic arc control, the only manual controls required by the welder are gun positioning, guiding and travel speed.

FCAW is an electric arc welding process designed for carbon steel, stainless steel and low-alloy steels. It uses an electric arc to produce coalescence between a continuous tubular filler metal electrode and the base material, and can be done with or without a shield gas. With gas shielded flux-cored wire, shielding agents are provided by a flux contained within the tubular electrode. An externally supplied gas augments the core elements of the electrode to prevent atmospheric contamination of the molten metal. When a shielding gas is used, the process equipment is virtually the same used in Gas Metal Arc Welding (GMAW).

With special voltage sensing feeders it is possible to do high-quality flux-cored welding with a constant current welding power supply. The process is suitable for all position welding with the correct filler metal and parameters selection.

Commonly referred to as Tungsten Inert Gas (TIG),  GTAW produces coalescence of metals by heating them with an electric arc between a tungsten electrode and the work-piece. Pressure and filler metal may or may not be used and shielding is obtained through the welding torch.

The use of a non-consumable tungsten electrode and inert shielding gas produces the highest quality welds of any open arc welding process. Welds are bright and shiny, with no slag or spatter, and require little to no post-weld cleaning. GTAW can be used in all welding positions but requires a high level of operator skill, especially on thin and intricate parts. It has been used extensively in the aerospace & aircraft, energy, chemicals and oil & gas industries.

PAW is a variation of Gas Tungsten Arc Welding (GTAW). The process uses a restricted arc that is squeezed through a copper nozzle to create a longer, narrower and more focused arc than is obtained with GTAW. The constriction process greatly increases arc voltage and the amount of ionization that takes place.

In addition to raising arc temperature, the hottest area of the plasma is extended outside of the nozzle down toward the work surface. The overall result is a more concentrated heat source at a higher temperature that greatly increases the heat transfer efficiency, allowing faster travel speeds. When used manually, a high level of operator skill is required.

LBW is an automated process that utilizes the heat from a concentrated beam of coherent light to join two materials. The process is used to weld all commercial metals including steel, stainless steel, aluminum, titanium, nickel and copper, and delivers high mechanical properties and travel speeds, with low distortion and no slag or spatter. Welds may be fabricated with or without filler metal and in many applications, a shielding gas is used to protect the molten pool. The equipment used requires a significant capital investment and high level of operator skill due to the very high welding speeds and small area affected by the laser beam.

Commonly referred to as stick welding, SMAW produces heat from an electric arc that is maintained between the tip of a flux-covered electrode and the surface of the base metal. The electrode consists of a solid metal core covered by a mixture of mineral and metallic compounds. The composition of the coating is dependent on the type of electrode and welding polarity. Among its functions are shielding the weld pool, providing a fluxing action to remove impurities from the weld deposit and by controlling the weld deposit chemistry, providing the desired weld mechanical properties. 

SMAW can be performed in areas of limited access and in all positions. It is a viable process for joining most metals and alloys, and the equipment needed is both portable and low in cost.

SAW heats metals using an electric arc between a bare electrode and the base material, beneath a blanket of flux material. This process uses a continuous, solid wire electrode shielded by the flux. The flux acts to stabilize the arc during welding, shielding the molten pool from the atmosphere. It also covers and protects the weld during cooling and can affect weld composition and its properties.

SAW is most commonly automated, but semi-automated systems are also available. The current can be either AC or DC and for automated systems, the electrodes can be a single wire or multiple solid or tubular wires, or strips. Welding can only be done in a flat or horizontal position due to the use of granular flux and the fluidity of the molten weld pool. High deposition rates can be achieved and very thick and thin materials can be welded with this process.

Compared to a conventional GMAW system, tandem welding uses two in-line wires, one behind the other. The welding wires are fed simultaneously and melted using independent contact tips mounted in the same torch. The result is excellent weld quality with little spatter and up to three times the deposition rates and travel speeds of conventional systems — ideal characteristics for automated applications.