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  • How to choose a Welding Method

How to choose a Welding Method

Welding is a method of bonding two pieces of metal together.  In many cases, this bond can be stronger than the base material.  The process of fusing two pieces of metal together requires the base metal to melt and flow together.  Old methods would use a blowtorch to heat metal until the base pieces reached melting temperature.  New methods use electric arcs to generate the required heat.  An electrode—consumable and charged positively or negatively depending on the character of the weld—is passed to a workpiece.  There are many methods to achieve metal fusion via welding; choosing the right method is crucial.

Hybrid Laser Arc Welding

  1. SAW—Submerged Arc Welding welds a joint using an electric arc smothered under a bed of flux. This process, mostly automated, uses a slowly fed filler wire fed along the joint beneath the flux.  High quality welds are yielded thanks to the flux coating the arc and wire; the risk of splatter is negated by the great presence of flux.
    1. Heavy plate fabrication
    2. Pressure vessels and tanks, sub-assemblies, nuclear reactors
  2. GMAW—Gas Metal Arc Welding is more commonly known as MIG Welding. MIG stands for Metal Inert Gas.  A consumable wire is fed automatically through a gun; simultaneous argon gas acts as a shielding agent.
    1. Repairs and rebuilding
    2. Pipes
  3. GTAW—Gas Tungsten Arc Welding is more commonly known as TIG Welding. The most precise and time consuming method, TIG welders feed wire by hand into an arc generated by a non-consumable tungsten electrode housed in an argon dispensing gun, like MIG.  The tungsten allow electrode does not melt under high heat, which facilitates the precision of a handfed wire.  Due to the nature of handfeeding, this method requires a high level of skill and is applied only to special circumstances.
    1. Stainless steel, aluminum, magnesium, copper alloy products
    2. Aerospace industry
    3. Piping applications
  4. SMAW—Shielded Metal Arc Welding is more commonly known as stick welding. SMAW is the most widely used method.  A consumable electrode in the form of a stick is covered in flux to create an arc and melt filler between workpieces; ultimately fusing the two together.
    1. Construction
    2. Pressure vessels, tanks, boilers, ships
  5. FCAW—Flux Core Welding is a variation to MIG welding. FCAW is a wire fed process using a different electrode than MIG.  Of all manual welding processes, FCAW is the most productive.  The process gives welders the ability to perform a single pass on thick steel plate, penetrating both sides.
    1. Ship building
  6. PAW—Plasma Arc Welding is a process using plasma gas heated to extremely high temperature, ionized to become electrically conductive. The plasma transfers an electric arc to the work piece, melting and fusing metals together.  PAW provides a method for welding thin sheet and fine wires without the harshness of a TIG arc.  The arc and tooling are close to the workpiece, reducing arc wander. 
    1. Small components
    2. Pressure and electrical sensors, micro switches, valves, etc.
  7. HLAW—Hybrid Laser Arc Welding is an automated welding process using a laser guided robot. HLAW removes many steps from traditional welding; a need for flux is eliminated, as is the need for weld preparation.  An HLAW machine can weld 300 to 400% faster than traditional SAW welding.  The speed and precision of the weld lowers deformation risks as the heat-affected-zone is significantly smaller than other methods.
    1. Long components
    2. Crane Booms
    3. Bridge decks, Beams, trusses, pilings, etc.

 

Each welding method has its advantages and disadvantages.  The applications of many of the methods overlap—a project involving welding has options and choices to be made.  Ultimately, the designers and engineers of projects must weigh the benefits of possible methods and decide which method best suits the application.