MIG (Metal Inert Gas) welding, also known as Gas Metal Arc Welding (GMAW), uses an inert gas – usually a mix of argon and CO2 – as part of the process.
MIG welding uses consumable electrodes that are delivered from a spool. Pulling the trigger on the spool gun feeds the wire at a preselected speed as a current passes through, melting both the electrode and the base metal.
MIG welding is usually done with a DC (direct current) or reverse polarity, where the electrode is kept positively charged while the base metal is negatively charged. In either case, the base metal and the electrode melt together in a molten metal weld pool, which is protected from outside atmospheric contamination by a shielding gas.
The equipment used by MIG welders is relatively simple and straightforward, with most MIG machines only using three settings for wire speed, polarity and voltage. The welding machine spool gun is also easy to use with a trigger and an on/off switch.
There are a number of advantages with MIG welding, including:
- Precise: MIG welding offers a high level of precision, able to weld metal that is as thin as 24 gauge, as well as create intricate welding designs
- Clean: MIG welding is a clean process with little spatter, allowing for smooth, high quality, slag-free joins with minimal clean-up
- Efficient: Because it is a spooled wire welding process, there is no need to interrupt your welding work to replace the stick rod electrode
- Fast: MIG welding is one of the fastest welding methods, leading to high productivity
- Easy-to-Learn: MIG welding is easy to learn and the machines easy to operate, meaning that even a complete beginner can soon start to create acceptable welds
- Flux Core: MIG welding can also be used on flux cored welding projects
Despite the many advantages, there are also some disadvantages with MIG welding:
- Environment: MIG welding is difficult to perform outdoors as even a slight breeze can disrupt the shielding gas, leading to weak and porous welds
- Contamination: If the metal is contaminated at the weld point, it can lead to a porous weld, meaning that MIG welding is not ideal for metals with rust or paint on them. As a result, the metal surface must be completely cleaned before welding can commence
- Spool Changes: Although the wire spool means that there is rarely a need to change the electrode during welding, the spool will need changing when you weld different metals
MIG welding is a flexible technique that can be used for a range of metals and is easy to learn, allowing it to be used for a wide variety of applications.
Able to join both thin and thick metals, MIG welding can be used in different welding positions and with reactive metals like aluminum, copper, and magnesium as well as stainless steel, carbon steel and nickel.
This versatility means that industries including oil and gas, power, automotive, construction, rail, marine and more use MIG welding.
You can find out more about MIG welding here, but next we will examine stick welding.
Stick welding is an electric arc welding process that uses a metal stick or rod as filler material. These stick are usually covered in a flux material and are available in different diameters and lengths. To achieve high strength welds, it is important to choose the correct type of flux core wire welding rod for your application.
Frequently used to weld steel and iron, stick welding uses a DC or reverse polarity current as with MIG welding. This creates an arc between the welding rod or stick and the base metal. The heat of this arc melts both the base metal and the filler rod, which forms droplets that flow into the workpiece to form beads that fuse the two metal pieces together.
The heat also causes some of the flux to vaporise, creating a shielding gas that helps to stabilise the arc. The rest of the flux forms slag on the molten melt pool to protect the weld from contamination or oxidisation. The use of flux means that there is no need to use an external gas supply as with MIG welding.
The advantages of stick welding include:
- Environment: Stick welding creates a large arc that is not affected by wind, meaning that it can be used effectively both indoors and outdoors. Stick welding can be done in windy conditions and even underwater.
- Paint and Corrosion Resistance: Stick welding can be used for repairing parts that have paint or corrosion at the welding point
- Easy-to-Learn: Stick welding is easy to learn, meaning that good quality welds can be made by someone with relatively little experience
- Changing Filler Material: It is easy to change filler material when you need to weld different metals such as cast iron or different stainless steels
- Reduce Burn-Through: By using the DC option for the arc, it is possible to alter the polarity of the electrode to reduce the possibility of burn-through when welding thinner metals
- Cost Effective: As there is no need for an inert gas supply, stick welding is an inexpensive option, as well as being easy to use in the field
While there are a number of advantages with stick welding, it also has its drawbacks:
- Slag: Stick welding deposits slag on the metal that needs to be scraped or chipped away before more welding or painting can commence
- Spatter: Stick welding produces spatter, although direct current (DC) welding produces less spatter than alternating current (AC) welding
- Welding Interruptions: There can be interruptions to your welding work when you need to replace the filler rod, which will reduce your productivity
- Welding Thinner Metals: Stick welding is not well suited to welding thinner metals of less than around 1/8” in thickness.
As stick welding doesn’t require a gas nozzle it can be used to weld large materials as well as being able to be used both indoors and out as the electrode flux prevents any contamination.
This means that stick welding is suitable for a wide range of applications including large-scale construction, oil and gas pipelines and other outdoor jobs.
Because the weld surface doesn’t have to be completely free from rust or paint, stick welding is also well suited to repair and maintenance work.
You can find out more about stick welding here, but we will continue by comparing stick welding with MIG welding…
To fully determine the differences between MIG and stick welding, we will compare them over some key parameters:
1. Weld Quality
MIG welds tend to be of a better aesthetic quality than stick welds, since stick welding produces spatter and slag. However, by contrast, when welding thicker metals with MIG, the amperage needs to be turned up high and the surface needs to be completely free of paint and corrosion so as not to affect the weld penetration. When done correctly, stick welding produce stronger joins than MIG welding.
2. Indoor and Outdoor Applications
Because MIG welding involves the use of a shielding gas, it can only be performed indoors since wind or rain can affect the weld. On the other hand, stick welding is wind and water resistant so can be performed outdoors or even underwater. However, the arc with stick welding can produce a lot of fume and smoke, which means good ventilation is required for the safety of the welder.
3. Metal Types and Thicknesses
MIG welding can be performed with different types of metal so long as the surfaces are clean. MIG welds can be used for thin metals including aluminium, brass, carbon steel, copper, magnesium, mild steel and stainless steel. However, MIG welding is not ideal for thicker metals, unlike stick welding, which can fuse thicker metals. By contrast, stick welding is not as effective with thinner metals as it can cause burn-through.
MIG is a clean and fast process, making it suitable to a range of applications from small DIY projects to larger industrial welding tasks. However, MIG is unsuitable to outdoor or more extreme conditions as well as for welding thicker materials. In these instances, stick welding is the preferred option.
5. Ease of Use
Although stick welding isn’t a particularly difficult skill to learn, MIG welding is an easier technique to pick up. MIG welding allows you to operate one element at a time, pressing the trigger to automatically spool the wire to begin welding. Stick welding is slightly more difficult as you need to accurately strike the arc without damaging the weld metal.
Stick welding equipment is more portable than MIG welders, as it does not require an external shielding gas source.
MIG welding equipment is more expensive than stick welders, although when undertaken on an industrial scale, MIG welding becomes more cost-efficient due to factors such as improved productivity.
MIG welding is much easier for a beginner to learn than stick welding. However, setting up MIG welding equipment can be quite complex as there are a number of variables including wire size and type, gas, contact tips and nozzle type. MIG welding also offers cleaner welds that require less post-weld cleaning.
Some argue that stick welding is stronger than MIG welding, since it offers better penetration for thicker materials.
However, MIG welding can provide good welds despite not being as effective on thicker metals, and is better for joining thinner metals with a good finish and less risk of burn-through.
There are a number of key differences between MIG and stick welding, including the ease of the techniques, the thickness of the metals that can be readily joined, and the quality of the welds.
While MIG welding may be easier to learn, stick welding can be performed outdoors, even in adverse conditions. In addition, stick welding is not suited to welding thin materials while MIG welding is not suitable for thick welds.
Each type of welding process has its pros and cons when compared side-by-side, meaning that both are viable when the conditions and applications are suitable.
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