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MIG-MAG Welding machine


MIG/MAG continuous wire welding machines

There are 23 products in category MIG-MAG Welding machine.



CONTINUOUS WIRE WELDING WITH OR WITHOUT GAS

Continuous wire welding is first of all possible without protective gas, with the flux cored wire (NO GAS or FLUX); the ‘gas’ protection is replaced by the core inside the wire. This type of welding is mainly used in outdoor environments in the presence of wind, or for DIY use to avoid buying gas cylinders and relative pressure reducers. However, welding with flux cored wire is not very aesthetically pleasing and, above all, does not allow very thin thicknesses of 0.6 or 0.8 mm to be welded. It is not used, for example, in the repair of sheet metal in body shops where the material is very thin and often dirty with paint or other oxidizing agents. The bead must in fact be hammered and brushed to remove the slag that remains on top. We can say that the aesthetic appearance is very similar to MMA electrode welding with the important advantage that the wire process is much faster and more immediate.

WIRE WELDING MACHINE: THE GENERATOR

The welding generator is a device that has the task of feeding the welding area with the filler material, using a special torch, and maintaining the electric arc that forms between the piece to be welded and the fused wire-electrode. Unlike M.M.A. and T.I.G. welding generators, in which there is only one adjustment parameter (welding current), the wire welding machine has two adjustment devices, one that regulates the intensity of the electric arc (welding voltage), the other that regulates the speed of the welding wire insertion (welding current).

MIG WELDING: THE GASES

The protective gases used in Mig Mag welding processes are essentially of two categories: inert and active. Argon, helium and argon-helium mixtures belong to the first category, while gases such as carbon dioxide, argon mixtures with oxygen or carbon dioxide are defined as active.

Argon (Ar) is an inert gas that is however suitable for almost all welding applications. The use of this gas in MIG wire welding provides good arc stability and easy trigger.

Helium (He) is a rather rare inert gas, which is much more expensive than argon. The characteristics of helium, compared to those of argon, see a lower stability of the arc but greater penetration; its use is predominant in the case of welding on large thicknesses and on materials with high thermal conductivity such as, for example, copper and aluminum. Since helium, unlike argon, is lighter and therefore more volatile, a greater quantity of gas is required to ensure the right protection for the area involved in welding.

Carbon Dioxide (CO2) is an active gas that gives its name to mag wire welding. The most common problem caused by this type of protection is the formation of excessive splashes and an unstable arc; maintaining a fairly short arc of constant length allows to control it well. With CO2 protection you generally get good penetrations.

Active mixtures. It is often possible to exploit the qualities of the single gases, using as one of their mixtures as a gas shield, such as Argon-Oxygen, Argon-Oxygen-CO2, Argon-CO2.

TYPES OF MIG MAG WELDING ARC

In the mig mag wire welding machine , the transfer of the filler metal from the wire-electrode (solid or flux cored) to the melting pool depends not only on the electrical welding parameters, but also on the wire diameter, the type of generator and the gas used. According to these parameters the transfer of the droplets can take place with:

  1. Immersion transfer (short-arc or short-circuit)
  2. Spray-arc transfer
  3. Pulsed-arc transfer

1. Immersion transfer (short-arc or short-circuit)

The filler metal is transferred into the melt pool in the form of droplets that immerse themselves in the pool, creating continuous short circuits.

This short arc transfer is characterized by the presence of currents up to 200 A, the use of thin solid wires, from 0.6 mm to 1.2 mm, making it possible to weld small thicknesses and weld in all positions. It is obtained with direct current generators.

2. spray-arc transfer

In this mode, drops of filler material are not transferred to the melt pool by contact but, due to the high current, are sprayed into the pool itself, creating a continuous flow of material.

This is achieved with DC generators when the currents involved are high, greater than 200 A, and the wire diameter is greater than 1 mm. A fluid and penetrating melt pool is generated, suitable for flat welding especially on medium and thick thicknesses.

3. pulsed-arc transfer

This procedure can only be achieved with pulsed current generators. The pulsations in fact cause the detachment of small droplets, and therefore allow to obtain the characteristic of the spray arc even at low currents. The heat input, pool size and penetration are very similar to the “spray arc” method. This procedure is widely used in materials such as aluminum or stainless steel, where the short arc procedure does not guarantee sufficient quality in the welding results. It is a very special arc dedicated to a professional welding machine.

MIG MAG WELDING OF MATERIALS

1. Soft steels, carbon steels

The applications range from the use of CO2 alone, to Ar-CO2 blends in various percentages (the most common is 80% argon, 20% CO2). The higher the percentage of Argon present in the mixture, the better the characteristics and stability of the arc.

The characteristics of the weld are very good, especially in short arc where you get consistent welding pools that allow applications in all positions.

2. Stainless steels

The shield gas used must be composed of Ar + CO2 or Ar + O mixtures. The percentage of Argon must not be less than 98% to avoid a strong oxidation of the chromium present in the base material. The filler material must be particularly suitable for the quality of the stainless steel to be welded.

3. Aluminum and its alloys

The shield gas used is generally pure Argon. Pure Helium or Ar + He mixture can also be used.

For flat welding, regardless of thickness, the spray-arc and/or pulsed-arc technique is used, while the short-arc technique is used for welding thin thicknesses in vertical and angled positions.

4. Other materials

The MIG MAG wire welding process is also used on materials such as nickel and its alloys, copper and its alloys.

As far as copper welding on thicknesses greater than 5 mm is concerned, it is advisable to use the M.I.G. procedure, considering that the current intensities must be adjusted according to the welding position and the thickness of the joints.

Professional MIG MAG welding machine

On Tuttosaldatura.it we recommend particular Mig welding machine models with an integrated PFC device. These new generation machines allow to weld at very high currents at full power, even in domestic environment where only 3.5 kw are available. They also allow the use of long extensions, even longer than 100 meters and are totally safe to use with motor generators, which often do not guarantee a constant and stable power supply.

HOW A GAS MIG WELDING MACHINE WORKS?

The mig welding machine, used mainly in the industrial sector, is in increasingly high demand also for domestic and DIY use. Compared to coated electrode welding, the wire welding machine uses a reel of wire that is pushed with a drag motor inside a torch until it reaches the piece to be welded; the wire, closing the electrical circuit with the ground clamp, bursts and releases its material in the form of countless drops of molten material and creating the welding bead.

There are two main types of wire welding:

- welding with a gas-free flux-cored wire that contains a material that protects the welding pool from oxygen and external oxidizing agents during fusion. In this case it will not be possible to weld thicknesses less than one and a half millimeters and the bead must be brushed and cleaned to eliminate slag;

- welding with solid wire and gas shield using a wire that varies according to the material to be welded , and a protective gas that allows the welded bead to be ‘finished’ without having to brush or clean it. This type of welding is the same as that found in industrial uses and for bodywork repairs, and allows to weld very thin thicknesses and gives a high production capacity. The aesthetics of the bead is much higher than that of the flux-cored wire without gas.

The operator will therefore have to understand which procedure is the most suitable for his needs: using the flux-cored wire, much more expensive than solid wire, but without having to buy a gas cylinder, or using gas to obtain an excellent bead finish and be able to weld even the thinnest thicknesses up to 6 - 8 tenths of a millimeter.

HOW THE GAS-FREE WIRE WELDING MACHINE WORKS ?

Gas-free wire welding consists of welding iron (mild steel) with a special flux-cored wire that does not require gas shields; therefore no gas cylinder is required to protect the weld bead.

The flux-cored wire is in fact made in a very similar way to an MMA coated electrode and contains the material that by melting will protect the weld bead from the oxygen and external agents present in the air.  However, working as an MMA coated electrode, the operator must then clean and brush the bead to remove the slag deposited on it.

In addition to the advantage of not needing to connect to a cylinder, the no gas flux-cored wire is used for welding outdoors, in the presence of wind, which could create problems for the gas shield in Mig Mag welding.     

When you purchase a wire welding machine, it is important to check whether it is designed for welding with or without gas or one or the other, because it is important to reverse the polarity when switching from one procedure to another. In flux cored wire welding, the torch is connected to the negative, while in welding machines designed for use with gas there is often the possibility of reversing the + and - terminals inside the coil holder compartment or on the front of the welding machine.

However, there are also some negative aspects to the use of a gas-free flux-cored wire welding machine: besides having to clean the bead at the end of welding, it is important to know that with this wire it is not possible to weld very thin thicknesses below a millimeter and a half. Moreover, the aesthetics of the bead are not the best and often there may be projections and pellets that are deposited near the weld bead. For faster and aesthetically better work, it is generally recommended to use a gas shield, i.e. the Argon CO2 mixture for iron welding.


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