GMAW (gas metal arc welding) commonly known as MIG (Metal Inert Gas) welding, and less commonly known as MAG (Metal Active Gas) welding, is the dominant welding process for joining metal. This accounts for approximately 70% of all welding, with the remaining 30% split between the other welding processes like SMAW (Stick) & GTAW (TIG) welding).
Gas Metal Arc Welding (GMAW), by definition, is an arc welding process which involves a consumable wire electrode which provides the filler material to the work piece by continuously melting off from the heat of the arc and fusing with the molten base material. The process uses shielding from an externally supplied gas to protect the molten weld pool from the atmosphere. The application of GMAW typically makes use of Direct Current Electrode Positive (DCEP).
The GMAW process is flexible in its ability to provide high quality welds for a very wide base material type and thickness range. The 2 key variables that need understanding are:
- The thickness range of the base material to be welded will decide the wire diameter and the useable current range.
- The shielding gas selection will influence the selection of the mode of metal transfer and will have a definite effect on the finished weld profile.
Most steel and aluminum can be readily welded using GMAW, as well as popular grades of nickel alloy, copper alloy and magnesium alloys to name a few.
The most popular gases used in the GMAW welding processes are 100% CO2 (mild steels in areas in short supply of Argon), and 75% argon/25% CO2 (Mild steel), 98% Argon/ 2% CO2 (stainless steel) and 100% Argon (Aluminium). Gas selection impacts many aspects of welding such as: Arc Stability, penetration depth, toe wetting, mechanical properties (Strength/toughness) and chemical properties (corrosion resistance).
Why Use GMAW?
GMAW is a very user-friendly welding process which allows a large degree of fabrication flexibility through amazingly simple adjustment to machine settings. The process is capable of welding open roots without burning through using short circuiting metal transfer or can be used to deposit substantial amounts of welding metal with great penetration using spray transfer.
Depending upon the mode of metal transfer, GMAW can be done in all welding positions. Welding Fume is less when compared to SMAW & FCAW. Post weld clean-up is minimal provided settings do not generate spatter. There is no slag or flux to clean up, rather only an occasional silicate island (when using a high-quality wire).
The lower-cost welding wire leads to a lower-cost per length of weld metal deposited when compared to other open arc welding processes.
There are limitations to GMAW when compared to other welding processes. These include portability issues compared to SMAW (due to gas bottles); the higher initial cost of the machine & joint preparation; the limitations of welding outside (wind and drafts can cause unacceptable welds) with gas shielded wire. GMAW welding requires some operator skill to ensure that quality welds are made without lack of fusion & undercut. However, it is a straightforward process to learn.
The use of gasless wire will alleviate many of these limitations.
Lincoln Electric has a number of products ideal for the MIG Welding solution in the workshop, on site or at home:
Powercraft 191C 3in1 MIG Welder
Light portable & easy to use 190A 3in1 MIG Welder using a 240V/10amp power supply. A perfect companion for DIY projects, general maintenance & repair & field work. capable of using a 5kg or 1kg wire spool when MIG Welding - (Solid/Cored: 0.8-1.2mm).
Powercraft 200M 4in1 Multi-Process Welder
The only welder you will ever need – 200Amp 240V / 10amp 4in1 Welder. Portable machine Capable of all 4 processes – MIG, flux-cored, stick, pulse AC/DC TIG (including Lift TIG & High Frequency AC/DC TIG) welding. Includes TIG Torch, MIG Gun, Cables, drive rolls & gas regulator. Highly portable welder capable of using a 5kg or 1kg wire spool when MIG Welding using following wire sizes - (Solid/Cored: 0.8-1.2mm).
Powercraft 250M 4in1 Multi-Process Welder:
4-in1 industrial quality inverter-based 250-amp 240V/15amp welder, available in either compact version or with a separate POWERCRAFT® PC4R Wire Feeder. Capable of all 4 processes – MIG, flux-cored, stick, pulse AC/DC TIG (including Lift TIG & High Frequency AC/DC TIG) welding. Includes TIG Torch, MIG Gun, Cables, drive rolls & gas regulator. Capable of using up to a 300mm or 16kg spool size when MIG Welding using following wire sizes: (Solid/Cored: 0.8-1.6mm).
Lincoln Powertec iS Industrial MIG Welder Range:
Suitable for industrial MIG applications. 350A/500A MIG Inverter’s with digital displays. Come “Ready to Weld” – including LF56D Advanced Wire Feeder (with ARCFX™ joint visualization technology), MIG Gun, Cables, Drive Rolls & Gas Regulator
Remember to always weld safely by wearing acceptable eye protection (1/1/1/1 optical clarity) in your Welding Helmet, suitable Welding Jacket & Gloves for the welding process that you are performing.
