Mig Welding ( Metal Inert Gas Welding ), AWS American Welding Society called this welding process Gas Metal Arc Welding or GMAW. MIG welding is easy to learn and fun to do. As soon as you pull and hold down the trigger you are welding. You just need to learn to control what you are doing.
There are several different methods of welding. Today, the most common welding process is electrode arc welding. There are three types, or systems, of arc welding in this family: stick, MIG, and TIG. All three types of arc welding use the same three components. The electricity, which creates the arc. Filler material and the third component is flux or shielding gas. Each type of welding has a different method of execution.
MIG Welding wire
Mig vs Tig Welding
Gas Tungsten Arc Welding (GTAW), or what is commonly referred to as Tungsten Inert Gas (TIG) Welding, which is a manual feed process: the operator is feeding the filler metal into the molten metal puddle. But in the TIG process, the filler metal is not the electrode. TIG welding is clean and smooth but can be difficult to master. It’s a good idea to learn MIG welding first and go for MIG welding which is much easier to learn because of the automated process. TIG welding does not produce a spatter during welding, which makes it cleaner and more appealing to the automotive and motorcycle industries and to artists who would like their welds to be a part of the overall look of the piece. The operator has much more control over all the components than other systems.
MIG Welding Machine
The basic GMAW Mig welding machine consists of the gun; electrode (wire) feed unit; electrode (wire) supply; power source; shielding gas supply with flowmeter/regulator; control circuit; and related hoses, liners, and cables, Larger, more complex systems may have water for cooling, solenoids for controlling gas flow, and carriages for moving the work or the gun or both, The system may be stationary or portable. In most cases, the system is meant to be used for only one process. Some manufacturers, however, do make power sources that can be switched over for other uses.
There are plenty of MIG welding machines in the market. if you want to buy a good MIG welding machine you have to know these tips.
To perform gas metal arc welding, the basic necessary equipment is a welding gun, a wire feed unit or Mig welding machine, a welding power supply, an electrode wire, and a shielding gas supply.
GMAW torch nozzle cutaway image. (1) Torch handle, (2) Molded phenolic dielectric (shown in white) and threaded metal nut insert (yellow), (3) Shielding gas nozzle, (4) Contact tip, (5) Nozzle output face.
MIG Welding Techniques
The basic technique for GMAW is quite simple since the electrode is fed automatically through the torch. In gas tungsten arc welding, the welder must handle a welding torch in one hand and a separate filler wire in the other, and in shielded metal arc welding, the operator must frequently chip off slag and change welding electrodes. GMAW, on the other hand, requires only that the operator guide the welding gun with proper position and orientation along the area being welded. Keeping a consistent contact tip-to-work distance (the stick out distance) is important because a long stick outdistance can cause the electrode to overheat and will also waste shielding gas. The orientation of the gun is also important—it should be held so as to bisect the angle between the workpieces; that is, at 45 degrees for a fillet weld and 90 degrees for welding a flat surface. The travel angle or lead angle is the angle of the torch with respect to the direction of travel, and it should generally remain approximately vertical. However, the desirable angle changes somewhat depending on the type of shielding gas used—with pure inert gases, the bottom of the torch is out often slightly in front of the upper section, while the opposite is true when the welding atmosphere is carbon dioxide.
The best choice for welding aluminum is always tig welding. You need to use alternating current (AC) with continuous high frequency to get the best results. Since Aluminum is getting more and more important even for welding applications and metal inert gas (MIG) welding (also known as Gas Metal Arc Welding, GMAW) is one of the main processes for joining aluminum and aluminum alloys. Aluminum can take a long time to weld if you’re working with thick pieces, and MIG welding makes the process go faster. Be sure to keep your electrode wire clean, use a 30-degree leading travel angle, and go with pure argon for your shielding gas.
MIG welding stainless steel
Stainless steels have a chromium content of more than 12%. A thin, tenacious oxide layer is formed on the surface, which prevents the material from further corrosion and oxidation. MIG welding of stainless steel is used frequently. To achieve the right microstructure a filler material of the same composition as the base material is normally used.
MIG welding cast iron
If you want to weld stainless steel, your three best options (by a mile) are stick welding, tig welding, and MIG welding. Generally speaking, stainless steel is slightly more difficult to weld than carbon steels. That’s because stainless steels have lower melting temperatures and more thermal expansion
The gasses used in MIG/MAG welding can be either 100% CO2 or Argon + CO2 mixes.
- 100% CO2: Can not sustain true spray transfer, but gives excellent penetration. The arc is unstable, which produces a lot of spatter and a coarse weld profile.
- Argon + CO2 mixes: Argon can sustain spray transfer above 24 volts, and gives a very stable arc with a reduction in spatter. Argon being a cooler gas produces less penetration than CO2. Argon is normally mixed with CO2 at a mixture of between 5-25%
Inert Gas is required for all non-ferrous alloys (Al, Cu, Ni)
- Most common inert gas for Mig welding is Argon
- Argon + Helium used to give a ‘hotter’ arc – better for thicker joints and alloys with higher thermal conductivity.
MIG welding gloves
There is more than one type of welding glove. The two main types are TIG and general-purpose welding gloves which are more suitable for stick and MIG welding. Both types will protect your hands from ultra-violet rays and a moderate amount of heat. TIG welding gloves are designed to be thinner so that you can feel your filler wire and have greater control of it when welding very fine tool work.
MIG welding tips
- Make sure to wear proper safety gear while MIG welding. Skin left exposed to the arc light can get a pretty bad sunburn.
- Most welding imperfections in MIG/MAG are caused by lack of welder skill or incorrect settings of the equipment
- Worn contact tips will cause poor power to pick up, or transfer
- Bad power connections will cause a loss of voltage in the arc
- Silica inclusions (in Fe steels) due to poor inter-run cleaning
- Lack of fusion (primarily with dip transfer)
- Porosity (from loss of gas shield on site etc)
- Solidification problems (cracking, centerline pipes, crater pipes) especially on deep narrow welds