MIG welding is a specialized type of welding that utilizes heated wire or small metal beads to generate a molten metal which is passed through a welding gun to glue two pieces of metal together. MIG simply means Metal Inert Gas Welding and is also referred to as Gas Metal Arc Welding (GMAW).
It is commonly used for joining pieces of low-alloy steels together in home repair projects and in the automobile industry. The process is easy to learn. It’s not surprising, then, that it is the preferred choice of hobbyist mig welders. In this guide, you’ll learn how the process works, the benefits, its uses, and drawbacks.
Let’s quickly begin with the MIG welding process.
MIG Welding Working Process
MIG welding process involves using an arc formed by a molten heated electrical wire electrode to join two pieces of metals together. Besides, the electrical power, the heat is commonly supplied by a shielding gas from an external source.
The process works through the basic theory of heat generation of an electric arc. The generated heat from the arc helps to melt the pieces of metal and the wire electrode which mixes up and solidifies to create a well-built joint.
Using the MIG gun, the electrical wire used as the electrode is linked up with a MIG welder and heated into a molten pool of metal. The shielding gas is also discharged through the MIG gun to avoid any atmospheric gas contaminating the arc and the molten metal. Clean and contamination-free weld results in high-quality surface finish and a stronger joint
A constant voltage DC machine is commonly used in the process while the shielding gas used is primarily carbon dioxide. Sometimes, argon or a mixture of argon and helium are used. Each of these gases has advantages and disadvantages. The amount of electric current passed through the wire varies from 100 Amperes to 400 Amperes. This depends on the thickness of the wire which is usually low steel coated with copper material.
How to use Mig Welders?
MIG Welding is used for different types of metals of varying thicknesses. For success, you need to get the following right:
- Proper type and diameter of the electrode
- The right type of shielding Gas, suitable flow rate and purity level.
- The required processes including the right amount of current, the method of metal transfer and the right speed rate.
- Suitable welding gear including the source of power, welding gun, and wire feeder.
Also, ensure you put on suitable welding safety clothes and eliminate possible fire hazards out of the welding location.
1. Carefully Prepare the metal for welding
With a metal brush, clean the metal part to expose the metal before hitting the arc. Also, ensure your work clamp links up to clean metal to avoid electrical impedance affecting the proper functioning of the wire feed. While welding metal with a larger diameter, bevel the connection point between the metal pieces to make the weld strong.
2. Properly set up your gear
For each weld project, do the following:
- Ensure all wire connections of your welding gear are in good condition before you strike the arc.
- You need a direct current electrode positive or polarity reversal to MIG weld.
- Switch the shielding gas on and ensure your flow rate setting is between 20 – 25 cubic ft/hr. Never use leaking hose.
- You need to get the tension of the speed rolls and molten wire right to ensure good wire supply performance.
- Eliminate surplus spatter from contact hoses, change damaged contact angles and liners and avoid using rusted wire.
3. Get the welding travel speed right
How the weld bead is shaped and the overall quality depends on the way your welding gun travels through the metal piece. You need a bit of practice to estimate the right molten metal for each joint thickness. As a rule, the weld bead ought to be smaller than the slenderest part of the metal you’re welding.
There are currently many MIG welding equipment that makes it easy for you to get the power settings which ensure you get a suitable wire speed for the voltage applied.
Uses of MIG Welding
MIG welding is a much more technologically advanced type of welding compared to other types of welding. Due to its efficient welding process, it has immense application in the automobile manufacturing and in the bridge construction industry. MIG welding is especially useful in the automobile industry because it is suitable for welding different projects and provides strong welds equal to 0.5mm.
The major uses of MIG Welding include the following:
- Repair of automobiles including large, small, medium, light and heavy-duty vehicles.
- Reconstruction of equipment like old car
- Deposition of wear resistant covering including soft and hard bearing surfaces, abrasion-resistant and erosion-resistant covering.
- It is used in Pipe-welding. While MIG welding pipe, you save costs and time
- For strengthening the surface of a washed-out rail track.
PROS & CONS
- Cost effective and very economical process
- High welding speed resulting in faster welding
- High productivity and higher profits
- Efficient and good quality welding results due to lack of flux
- User-friendly and easy setup.
- Minimal operation skill required. It’s easy to learn and this makes it great for house and hobby welding.
- Versatility and wide varieties of applications in welding metals of varying thickness including mild and stainless steel, aluminum and nickel.
- Safe welding process due to gas shield and little weld spatter.
- Allows different welding position with proper gear and settings
- Eliminates flaws caused by occasional stoppage due to the constantly-fed electrode.
- Allows deep weld infiltration and better deposition rate
- Easy to clean up after welding
- Minimal fume discharge compared to Stick Welding and Flux Cored Welding
- Little or no slag and Minimal weld defects
- The process can readily be automated
Despite the numerous benefits of MIG welding, there are a few hitches you need to know. These include the following:
- Not suitable for welding metals in tight corners
- High initial overhead cost
- Bulky and less portable welding gear
- Only suitable for indoors to avoid wind damaging the gas shield.
- Requires high-temperature welding and, thus, not suitable for vertical welding or welding metals above your head.
- Complex equipment requirement and setup- the shielded gas supply system, regular supply of power, the wire feeding process, the welding gun and the supply of cooling water.
- Discomfort as a result of high heat discharge
- There may be burn-through issues while welding very thin metals less than 16”
- Contamination of base metal may ruin the process.
- An incorrect setting may result in fusion defects particularly while welding base metals with a thickness of over 1/4”
The efficiency of MIG Welding and its high productivity yield makes it a preferred welding choice for the production and repair of automobile, mending of broken pipes and in bridge construction. Besides the high yield and clean weld results, it is relatively easy to learn and is more user-friendly than other types of welding.
Although you can easily learn the process, you do need a collection of complex gears that require some time of practice to learn the suitable welding arrangements. However, these basics will make your journey and task easier. With, the right type of MIG welding gear and proper information guide, there is no reason you can’t become a skilled MIG welder!
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