Welding Processes Procedure For Arc Welding MIG/MAG
1. Process Description
The electric arc welding with protective gas welding is a process in which the necessary heat is generated by an arc established between a consumable electrode and the metal to be welded.
A solid wire, bare, which is fed continuously and automatically becomes the metal deposited as consuming, do the work electrode.
The electrode, arc, molten metal and base metal adjacent areas, are protected from contamination of atmospheric gases through a gas stream that is provided through the nozzle of the gun, concentrically to the wire / electrode.
2. Applications
The process MIG / MAG can be used for welding of all materials (carbon steels, stainless steel, aluminum …..)
The electrode is continuous, increasing productivity by not having to change the electrode and the deposition rate is high. It can achieve speeds much higher welding with coated electrodes.
It is easy to implement a process that allows welding in any position. You can make long welds without joints between cords. Not required to remove any scum as it does not exist.
Furthermore, a computer is more expensive, larger and requires installation of gas which makes their use is restricted to indoor industrial spaces.
3. Team MIG / MAG:
3.1. Power source: The energy source must be capable of operating at high currents and provide a constant current so that it can melt the filler wire as this flows continuously.
This power source will require single phase power (1ph) or phase (3ph) as its power consumption or so.
3.2. Wire feeding system: The wire feed unit is the device that causes the wire to pass through the contact tube of the gun to melt in the arc. Teams MIG / MAG have a system to vary the speed of the wire and a solenoid valve for the passage of gas.
A motor transmits power to the drive rollers so that they displace des coil wire to the contact tip of the torch. The rollers in contact are usually one flat and one with bevel. The bezel is V-shaped for hard materials such as steel and stainless steel U-shaped and for soft materials such as aluminum. It is imperative to select the roll under the wire diameter.
3.3. Torch: The welding guns for filament yarn have to allow the wire to move through them at a predetermined rate and, secondly, to transmit the welding current to the wire and direct the shielding gas.
The torch is connected to the computer mostly via SCART which facilitates the exchange of the same if necessary. The recommended maximum length for welding of carbon and stainless steels is 4m. In such cases tow (tube through which the wire along the torch) is steel. During the welding of aluminum using MIG process, the recommended length is about 3 m in which the towpath in this case of softer material such as Teflon.
3.4. Mass Tweezers: The correct connection of the clamp of mass is an important consideration. The situation of the cable is especially important in welding. A bad guy cable will not provide consistent electrical contact and the connection is heated and can result in a disruption in the circuit and the disappearance of the arc. The contact zone of the clamp of mass must be totally clean without substances that may hinder their correct contact as paints, varnishes, oils ….

4. Welding parameters
4.1. Materials input: The string or wire performs the function of electrode during the welding process and provides the necessary material for the union.
The wires are usually employees of the diameters 0.6, 0.8, 1.0, 1.2, … and are supplied in coils that are placed directly on feed systems. To achieve a smooth, even feeding the wire layer wound must be perfectly flat and is not necessary during this tight supply.
The steel wires are often a copper coating improves electrical contact, wing corrosion resistance and reduce friction with the different feeding systems and antorcha.El filler material must be similar in chemical composition of base metal. when varying the diameter of the wire used should change the guide tube. The contact tube and adjust the rollers to wire the new measure.
4.1.1. Welding WIRE WITHOUT GAS: There is a type of wire called “lively thread” or “tubular thread” that allows welding without the need to provide shielding gas. This makes it ideal for welding outdoors or in environments with large drafts. To this type of welding wire is necessary to have equipment that allow us to reverse the polarity.; Torch to the negative (-) and ground clamp to the positive (+).
4.2. Wire speed: The speed of the wire should be regulated in accordance with the intensity of welding so that the wire is grounded evenly. If the power is varied to suit welding a new material or a new measure of wire, it must simultaneously modify the wire speed.
+ Current-speed = + = intensity – speed
4.3. Welding current: This parameter is selected based on the material to weld, thickness and diameter of the wire. The selected intensity condition the wire speed.
4.3. Shielding gases: The main purpose of shielding gas is to protect the molten metal contamination surrounding atmosphere. Many other factors affect the choice of shielding gas. Some of these include a welding material, metal transfer mode of input desired, penetration and bead shape, welding speed and of course gas prices.
Generalized, the gases most commonly used are:
MATERIAL
PROTECTIVE GAS
STEEL
Argon 8Argón 85% + CO2 15% 5% + CO2 15%
STAINLESS STEEL
ALUMINUM
Argon 100%
The flow of gas you use depends on the conditions under which we work, but usually we can calculate a basis of 10 times the diameter of hilo.Ej. Wire of 0.8 mm x 10 = 8 L / min.