Amac Engineering

Welding Processes

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TIG Welding
 
 
TIG Welding Schematic
 
 
TIG Welding

Gas Tungsten Arc Welding (GTAW) is frequently referred to as TIG welding. It is a commonly used high quality welding process. TIG welding has become a popular choice of welding processes when high quality, precision welding is required.
In TIG welding an arc is formed between a non-consumable tungsten electrode and the metal being welded. Gas is fed through the torch to shield the electrode and molten weld pool. Filler wire is then added to the weld pool separately


TIG Welding Benefits
· Superior quality welds
· Welds can be made with or without filler metal
· Precise control of welding variables (heat)
· Free of spatter
· Low distortion


Shielding Gases
· Argon
· Argon + Hydrogen
· Argon/Helium


Helium is generally added to increase heat input (increase welding speed or weld penetration). Hydrogen will result in cleaner looking welds and also increase heat input, however Hydrogen may promote porosity or hydrogen cracking.

TIG Welding Limitations
· Requires greater welder dexterity than MIG or stick welding
· Lower deposition rates
· More costly for welding thick sections


 
     
 
MIG Welding
 
 
MIG Welding Schematic
 
 

MIG Welding


Gas Metal Arc Welding (GMAW) is frequently referred to as MIG welding. MIG welding is a commonly used high deposition rate welding process. Wire is continuously fed from a spool. MIG welding is therefore referred to as a semiautomatic welding process.


MIG Welding Benefits
· All position capability
· Higher deposition rates than SMAW
· Less operator skill required
· Long welds can be made without starts and stops
· Minimal post weld cleaning is required


MIG Welding Shielding Gas

The shielding gas forms the arc plasma, stabilizes the arc on the metal being welded, shields the arc and molten weld pool, and allows smooth transfer of metal from the weld wire to the molten weld pool.


The primary shielding gasses used are:
· Argon
· Argon - 1 to 5% Oxygen
· Argon - 3 to 25% CO2
· Argon/Helium
CO2 is also used in its pure form in some MIG welding processes. However, in some applications the presence of CO2 in the shielding gas may adversely affect the mechanical properties of the weld.

 
     
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