MIG-MAG welding

In this process the electric arc is maintained between a solid wire that functions as a continuous electrode and the work piece. The arc and the molten weld are protected by an inert or active gas atmosphere.

Gas shielding ensures a continuous and uniform weld seam, free of impurities and slag.

MIG welding is more productive than MMA, where productivity losses are much more frequent, and more profitable, because for each kg of electrode, around 35% is waste, while in solid wire and flux cored wire only 5% is wasted.

 

Metal Activ Gas (MAG)

  • In this procedure, the gas used is CO2, pure Carbon Dioxide or mixed with Argon in different proportions, which reacts thermo-chemically with the weld.
  • The use of gas heaters in case of using pure CO2 is done to avoid freezing of the pressure reducer.
  • Characteristics of the process: Higher welding speeds and penetrations, with higher heat input, quantity of fumes and spatter, with a worse aesthetic appearance.
  • THIS PROCESS SHALL NEVER BE USED FOR WELDING OF:
    • STAINLESS STEEL.
    • ALUMINIUM.

 

Metal Inert Gas (MIG)

  • In this procedure the supply gas used is inert, ARGON or mixtures of Argon with small contents of CO2, Oxygen, Nitrogen, etc…. Offering a perfect protection and ionization.
  • Process characteristics: Controlled heat input and reduction of fumes and projections, with an excellent aesthetic appearance.

 

Metal Inert GAS-MIG Tubular

Flux cored wire welding is very similar to MIG/MAG welding in terms of handling and equipment. However, the continuous electrode is not solid but consists of a hollow metal tube surrounding the flux-filled core.

The electrode is formed from a metal strip that is formed into a U-shape in a first phase, into which the flux and alloying elements are then deposited, and then closed by a series of forming rollers.

This facilitates the creation of a weld material without causing depletion of metal-chemical alloys in the joint, making this process versatile for almost all base metals.

Types of arches:

  • Short arc.
  • Transition arch.
  • Arc spray.
  • Globular arch.
  • Pulsed arc.

Description Pulsed Arc

What does it consist of?

Spraying of the droplets (spray type) using a lower average current intensity than that used to achieve this type of transfer.

The background intensity serves to preheat and condition the wire while the peak intensity will produce droplet detachment.

The application of the pulsed current allows the heat input to be adapted to the welding requirements of the position, type of joint and thickness of the weld.

What are the advantages of pulsed arc MIG/MAG welding?

  1. Reduction in the number of projections.
  2. Possibility to work with yarns of higher Ø in lower intensity ranges, reducing production costs.
  3. Lower heat input for thin thickness and position welding applications.
  4. More uniform penetration and surface appearance.
  5. Less deformation of the base material.

 

Short circuit Pulsed Arc
Drop transfer on contact with metal. Drop transfer by controlled impulses.
Current: 50 – 150A. Current: 15 – 200A.
Voltage: 16 – 22V. Voltage: 16 – 26V.
Recommended welding PF, PD, PE, H-L 045. Recommended welding in all positions.
Thin welding. Thickness up to 6mm.
Large root gap welding. Inner fillet welds.
Short arc. Medium arch.
Number of projections: medium. Number of projections: low.
Sound: crackling. Sound: buzzing.
Recommended gas:CO2 in high percentages. Recommended gas:CO2 mixtures < 18%.

 

Applications

This welding process can be used on most metals and the range of wires in different alloys. Its flexibility is the most representative characteristic of the MIG / MAG method since it allows welding low alloy steels, stainless steels, aluminum and copper, in thicknesses from 0.5 mm and in all positions.

Its high productivity and ease of automation place it squarely in the automotive sector.

The process is widely used in thin and medium thicknesses, in steel fabrications and aluminum alloy structures, especially where a large percentage of manual work is required. The introduction of flux cored wires is increasingly finding its application in the heavy thicknesses found in heavy steel structures.

Steel structure and building

The carbon steel welding program, with CO2 as shielding gas, is recommended for welding carbon steels in applications with high penetration and high filler speeds.

Metallic carpentry

Carbon Steel (Copper Free) welding presents arc stability and spatter reduction, improves cleanliness and increases the life of consumables and drive systems (up to three times longer), reduces downtime and maintenance and improves productivity.

Especially recommended for automated or robotized processes.

Automotive industry and galvanized fabrication

Soldering with CuSi 3 makes it possible to perform joint soldering on copper alloys, the same or similar. It has good corrosion resistance and is easy to apply.

The energy input in this welding process is 20% less than in MAG welding, which saves energy in manufacturing.

Especially recommended for the manufacture and repair of car bodies, exhaust pipes, water tanks of coffee machines, joints in galvanized installations.

Chemical, dairy, food, pharmaceutical, chemical, paper, oil, steel, biotechnology and architectural industries

Stainless steel welding is used for its corrosion resistance, low temperature hardness and good high temperature properties.

The 308 Lsi stainless steels have cleaner beads, higher application speed and a high degree of resistance to atmospheric corrosion.

While 316 Lsi stainless steel provides greater resistance to corrosion in acidic media and hydrochloric solutions.

Bodywork manufacturing, shipbuilding and railroad industry, automotive industry and paper industry

ALSi 5 is excellent for the repair and construction of valves, pipes and fittings, as well as in the manufacture of heat exchangers, condensers and evaporators.

Ideal for maintenance of pipes and rolls in the paper industry.

However, ALSi 12 provides better corrosion resistance and is specially designed for applications in nozzles, engine heads and covers, tanks, valves, etc.

While ALMg 5 increases corrosion resistance. Applied to the manufacture of metal carpentry, bodywork and automobile manufacturing.

 

Welding execution

The arc length (distance from the base metal to the unmelted end of the filler material) must be controlled at all times.

The greater the electrode extension for a given intensity, the higher the deposition rate and the lower the penetration.

Approximately 90% of the energy is concentrated in the arc and 10% in the wire, therefore, the longer the arc length the higher the stress.

The larger the wire end, the lower the penetration, increasing the occurrence of projections.

We regulate the intensity, the higher the intensity the greater the penetration.

Adjust the intensity according to the welding position, in inner angle it will be 20% higher and in ascending 15% lower.

It is convenient to maintain the same arc length, avoiding oscillations in tension and intensity that generate an uneven penetration.

The travel speed should be adjusted so that the electric arc is slightly ahead of the molten pool.