Welding is of two types in case of arc welding; these are MIG or Metal Inert Gas welding and TIG or Tungsten Inert Gas welding.
The MIG is also called the wire welding that is because the wire is fed by a spool that comes via the electrode of the welding machine. This wire, in this case, is the filler material.
However, stick electrodes can also be used as filler material, but this article is solely based on wire welding.
Basic MIG welding techniques require a lot of in-depth knowledge on the welding machine itself, so let’s have a clear concept on that at first.
The MIG Welding Machine
The welding machine consists of a welding gun, a power source, which is usually a DC supply, shielding gas supply, and wire feed. This welding gun has a torch shaped tubular body and a trigger. Upon pulling the trigger, the wire comes out via the contact tip through the nozzle onto the base metal.
Now, the shielding gas is also released simultaneously when the trigger is pulled, and this helps in protecting the molten material from atmospheric contamination like oxygen or water vapor. The gas comprises of argon and CO2 and is stored in high-pressure cylinders.
In the MIG welding machine, the current has to flow in a complete circle, so a work lead is clamped to the work surface to ensure a complete circuit. The closer the lead is connected, the smoother the welding is.
Things You Need to Know Before Using a Mig Welding Machine
For customization of a metallic tool, knowledge of welding is a must-have. By reading books, seeing videos, or attending seminars, one cannot learn everything about welding. For this practice and only practice is a necessary thing. But even before that, comes safety.
Protective helmets gloves jackets are a must, although you will see most people just close their eyes during welding. This will only make the welding look bad as well as some serious long term effects on the nervous system.
The welding produces rays that are more powerful than the sun, so helmet should always be worn. Welding fumes are hazardous to health, so the person must work in a well-ventilated room.
Before starting the welding, make sure there is a clean working surface possibly made of metal. The working surface must not be cleaned with any chemical cleaners, as they can break into harmful gases during welding. Again, the working lead or the ground lead must be attached.
Then the welding machine is set up, check the gas flow, electrode polarity, and cables.
In the case of working with steel, ER70S-3, and ER70S-6 wire are more used. The latter is used in case of rusty tools.
Basic gas is argon and CO2. 75/25 ratio is best for carbon steel, whereas 100% CO2 will cause deeper penetration but lead to an uneven surface.
Voltage and Amperage
this should be set correctly according to metal thickness, type of metal and type of shielding gas used.
Wire Stick Out
The appropriate length is 3/8 inch, which, when kept long, results in uneven welding. This is a common mistake made by beginners.
Mig Welding Techniques for Beginners
Here are three basic techniques for beginners.
The first step before starting the welding gun is to tune it. If it is not tuned properly once the trigger is pulled, it will produce a bizarre loop and only stab on the metal. In this case, the wire will feed out fast. So tuning is important.
- Getting the Technique Right
Hold the MIG welding gun at a 15-degree angle (travel angle), so shielding gas can cover the surface then pull the trigger. Go in a forehand or backhand technique.
The forehand or pushing technique produces lesser penetration, but the backhand or pulling technique creates a better weld. You should go slowly at first but don’t burn the metal itself. For beginners, it is easier to go in ‘e’ or ‘u’ shapes and then move on to loops to create an even weld.
The welding bead depends on the amount of penetration. At first, start working in a small metal piece and see the depth of the bead. The size of the bead determines whether you are moving too fast or slow.
For instance, if the bead is a snake-like and thin, it means you are moving too fast. The beginners mostly make the same mistake. They hold the gun too far away, some keep the wire stick out too long, and some go so slow that they burn down the entire metal.
The key to success is practice, start by practicing in a small metal piece and then later work on the actual metal after you have enough confidence.
Basic Weld Joints
Here are some basic weld joints you need to know.
- Butt Joint
This is produced by sealing two metal pieces together. The beading can be seen under the surface.
- T Joint
The name comes from the obvious shape of the metal after welding them at right angles.
- Lap Joint
This is done by welding the edge after two pieces of metal are laid on top of another.
MIG Welding Tips for Beginners
- Protective helmet, gloves, the jacket should be worn by the person who is welding to prevent any health hazard.
- To fill in deep space, hold the gun at a 90-degree angle so that penetration is most and space is easily filled.
- In high voltage, the weld will be very hot, so tune the voltage according to metal type.
- A cleaner work surface provides better welding.
- The working lead should always be connected to the work surface.
- Right shielding gas should be used.
- If there is a little or no shielding gas present, the weld will be porous.
- Use a DC electrode — positive or reverse polarity for MIG welding.
- Keep some extra contact tips at hand if they are rusty or old.
- If the feeding wire is rusty, use a new wire.
- If the machine is too hot or wire speed is slow, the weld will burn through the metal.
- The sizzling bacon sound during welding represents that the wire speed is optimum; if the wire speed is too high, it will produce a popcorn popping sound.
- The uphill welding method is better for thick metal penetration.
- Smaller wires should be used according to the rule of thumb for thick metal welding.