Overview of welding processes
The most common processes are MIG, TIG and stick. Each has benefits and limitations for certain applications. There’s no one-size-fits-all approach.
MIG/gas metal arc welding (GMAW) — MIG welders use a wire welding electrode on a spool fed automatically at a constant pre-selected speed. The arc, created by an electrical current between the base metal and the wire, melts the wire and joins it with the base, producing a high-strength weld with great appearance and little need for cleaning. MIG is an easy process to learn and can be used on thin or thick metals. It can also create extremely clean welds on steel, aluminum and stainless steel.
Benefits of MIG welding:
- Easiest to learn
- High welding speeds
- Better control on thinner metals
- Clean welds with no slag
- Same equipment can be used for flux-cored welding
Flux-cored arc welding (FCAW)* — Similar to MIG, this is a wire-feed process but differs in that self-shielded FCAW does not require shielding gas. Instead, flux-cored wire shields the arc from contamination. This is a simple and efficient approach, especially when working outdoors, in windy conditions or on dirty materials. FCAW is widely used in construction because of its high speed and portability.
Both MIG and flux-cored have the capability to join materials as thin as 26 gauge.
Benefits of flux-cored welding:
- More forgiving on dirty/rusty material (similar to stick)
- Suitable for out-of-position welding
- Deep penetration for thick sections
- High metal deposition rate
*The FCAW process is available through Miller® MIG machines.
TIG/gas tungsten arc welding (GTAW) — This process uses a non-consumable tungsten electrode to produce the welding arc. The weld area is protected from atmospheric contamination by a shielding gas (usually argon), and filler metal is added to the puddle for strength, though some welds, known as autogenous welds, do not require it. A constant-current power supply produces energy that is conducted across the arc through a column of highly ionized gas and metal vapors known as plasma.
TIG welding is most commonly used to join thin sections of alloy steel, stainless steel and nonferrous metals such as aluminum, magnesium and copper alloys. The process grants the operator greater control over the arc, allowing for strong, high-quality welds. TIG is comparatively more complex and difficult to master than other processes and is significantly slower.
Benefits of TIG welding:
- Highest quality, precise welds
- More aesthetic weld beads
- Adjustable heat input with remote foot or hand controls
Stick/shielded metal arc welding (SMAW) — Stick, for many years, has been the most popular method for most garage work. This process uses an electric current flowing from a gap between the metal and the arc-welding electrode. Stick is effective for welding most alloys or joints and can be used indoors and outdoors or in drafty areas. It’s also the most economical method and provides the ability to create a good bond on rusty or dirty metals.
However, it is limited to metals no thinner than 18 gauge, requires frequent rod changing, emits significant spatter and requires that finished welds be cleaned. Stick is also more difficult to learn and use, particularly the ability to strike and maintain an arc. Arc welders are available in AC, DC or AC/DC, with AC being the most economical. It’s used for joining thicker metals of 1/16 inch or greater. Consequently, these machines are a good choice for farmers, hobbyists and home maintenance chores.
Benefits of stick welding:
- Better suited for windy, outdoor conditions
- Forgiving on dirty/rusty metal
- Works well on thicker materials