DINAMITEK PRESENTS A SIMPLE GUIDE TO MIG MAG WIRE WELDING
Wire welding with Dinamitek
Dinamitek presents a simple guide to MIG MAG wire welding.
In this article, you'll find basic information and some in-depth insights into the wire welding technique. Reading this article will help you understand how to perform excellent wire welding work.
The wire welding system consists of:
- Torch with dual function: to strike the arc between the wire and the piece and to bring the shielding gas to the welding pool
- Mass
- Arc current generator (in modern machines the control of the arc characteristic is carried out electronically)
- Wire feed and control mechanism
- Wire winding reel
- Shielding gas cylinder
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Essentially, the continuous wire welding process works like this: a contact nozzle supplies current to the filler wire arriving from the spool; at the same time, gas is released from the wire, protecting the weld pool from oxidation. The use of well-sized cables ensures the current output from the mains supply to the welding machine at a constant voltage.
The continuous wire process is a highly productive process. The gas allows for slag-free operation. This method is derived from the submerged arc, but has the advantage of allowing the operator to directly observe the arc, as occurs in coated electrode and TIG welding. An additional advantage is the ability to weld in non-flat positions.
The Technomig welders on sale here are self-adjusting; the only parameter the user needs to adjust (welding power) allows the machine to adapt to all types of jobs.
When using machines that require manual parameter adjustment, there are some precautions that the user must take depending on the type of work being performed.
Being able to modify the current curve, for example, allows you to adapt your welding processes to different conditions. This can be managed directly from the welder.
When working on thin layers, it's best to use a decreasing voltage because the electric arc is less violent, penetrates less, and doesn't break through the base metal. To set this, you can use the SLOPE on the welding machine. If you need a cold weld to prevent breaking through, with the SLOPE engaged, you can adjust the inductance to stabilize the arc and reduce spatter.
The parameters that must be manually set for the use of a "non-automatic" wire welder are:
- Welding voltage - voltage that you can adjust both roughly and finely. This is the parameter that affects the fusion of the base material. At the same amperage, a higher voltage produces a wider and more aesthetically pleasing weld bead, a warmer weld pool, and less spatter.
- Current intensity – amperage – is related to the wire feed speed. At the same voltage, more wire results in a thicker bead, a colder and less aesthetically pleasing weld pool, and less deformation of the workpiece.
The transfer of the filler material, with wire welding, can be achieved in three ways:
1. SHORT BOW
it is used for sheet metal
“cold” welding, low heat input to the piece
large drops that detach due to a short circuit
obtained with low currents
cord that is not flat and not well connected
2. LONG BOW
it is used for thick sheets of metal
very hot bath
cord with excellent aesthetics
3. INTERMEDIATE ARCH
The welding system is identified by the type of gas contained in the cylinder.
The function of the gas is to protect the weld pool from atmospheric oxidation.
To choose the gas, compare the following tables
Metal | Gas | Advantages |
Carbon steel Thickness < 3 mm | 75% Argon 25% CO² | High welding speed, perfect penetration few splashes and minimal heat input |
Carbon steel Thickness > 3 mm | 75% Argon 25% CO² | Easy control of the melt pool both vertically and overhead. Good |
CO² | High penetration, constant and high welding speed | |
Stainless Steel | Argon + 1÷3% O² | Universal use mixture |
90% helium + 7.5% Argon + 2.5% CO² | No negative effect on corrosion resistance, narrows the heat-affected zone , minimal distortion of parts and absence of microcracks | |
Low alloy steels | 60÷70% Helium + 25÷35% Argon + 4÷5% CO² | Excellent joint toughness and arch stability. Regular lines, minimal splashes |
75% Argon + 25% CO² | Fair toughness, good arc stability , fair welds, little spatter | |
Copper, Magnesium, Nickel and their alloys | Argon + Helium Argon | Argon gives satisfactory results on thin thicknesses.
|
Aluminum Thickness < 25 mm | Argon | Stable arc, good fusion and negligible spatter |
Aluminum Thickness < 25mm | 65% Helium + 35% Argon | It provides greater heat than pure argon, improving melting especially with aluminum-magnesium alloys. Lower risk of porosity |
Magnesium | Argon | Excellent scouring action |
Carbon steel | Argon + 3.5% Oxygen | Improves arc stability, allowing for good and stable wire fusion, the edges of the welding bead They are regular, have minimal penetration, and are faster to weld than pure argon. |
CO² | It further increases the welding speed, especially in automatic mode. Low manual welding costs | |
Low alloy steels | Argon + 1% Oxygen | Promotes toughness and reduces marginal incisions |
Stainless Steel | Argon + 1% Oxygen | Improves arch stability, allows for smooth wire melting , and creates beads without marginal incisions. Eliminates or minimizes microcracks especially on thicknesses |
Argon + 2% Oxygen | It further improves arc stability and bead regularity compared to the 1% oxygen mixture. Very suitable for thin thicknesses. | |
Copper, Nickel and their leagues | Argon | It reduces the fluidity of the bath while maintaining good fusion on thicknesses up to 3mm |
Argon + Helium | A percentage between 50% and 75% helium will favor a warm bath, compensating for the significant heat loss, especially on large thicknesses | |
Titanium | Argon | It allows for good arc stability and prevents contamination of the bath. Gas protection is also essential. on the reverse to avoid pollution |
The welding systems are:
- MIG WELDING WITH METAL INSERT GAS uses an inert gas . This promotes the formation of a very hot weld pool, which is why it's advisable to use sturdy torches and large contact tips to prevent the wire from expanding due to overheating and jamming it inside the copper contact tip. The ratio is one contact tip larger than the wire diameter. The gas preheater, if present, must be turned off when using inert gas. To weld stainless steel, use a long arc, even on thin sheets.
- MAG METAL ACTIVE GAS WELDING uses active gas. Active gas promotes the formation of a cool weld pool, which extends the life of the torches. Using a preheater is recommended. Mixing gases can improve the appearance of the weld bead obtained with this type of welding.
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