The role of the welding wire consists on the one hand of bringing the metal responsible for ensuring the connection between the two parts to be welded and filling the joint to obtain a rigid assembly; and on the other hand to ensure the passage of current by serving as a welding electrode .
If it is often possible to fuse thin pieces without using a filler rod, the filler metal is essential for welding thick pieces.
There are two main categories in the welding wire:
- solid (or solid) wire which is simply a filler metal and an electrode
- the cored wire which is a filler metal, and an electrode plus a protective powder
The solid wire can be used without special precautions while the cored welding wire can be either basic (B) or Rutile (R).
- The wire diameter is expressed in mm:
- Depending on the diameter of the wire, the welding current intensity must be higher or lower.
- There are wires from 0.6 mm in diameter to 3.2 mm (cored or solid).
- The composition of the wire according to the metal to be welded:
- pure copper wire,
- silicon wire,
- manganese thread.
- The characteristic: solid wire or cored wire.
- G for solid wire.
- T for the cored wire.
- The type of protective flux required according to the chemical nature of the substances constituting the fodder (cored wire only):
- basic fodder,
- need for gas.
CodedTypeRRutile, slow hardening of the slag, protective gas requiredPRutile, rapid hardening of the slag, protective gas requiredBBasic, protective gas requiredMMetal powder, protective gas requiredVRutile or basic / fluoride, protective gas requiredWBasic / fluoride, slow hardening of the slag, protective gas requiredYBasic / fluoride, rapid hardening of the slag, protective gas requiredSOther typesZOther typesUWithout protective gas
The possible welding position:
SymbolPosition1All positions2All positions except the vertical position for the top-down method3Flat, gutter, flat angle4Flat, in gutter5Descending
The usefulness of cored wire
In MAG welding only (inert gas), the welding area must be protected against ambient oxidation either:
- by an inert protective gas and a solid wire is then used;
- by the powder contained in the cored wire which evaporates in the flame to produce the inert gas and avoids vaporizing bottled gases on the welding area.
What to choose solid wire or cored wire?
The advantages are cored wire are:
- increasing productivity by increasing the deposition rate and by reducing handling (no gas bottle),
- comfort of use thanks to wide ranges of usable parameters
- increasing the quality of appearance of welds
- appreciable reduction in weld spatter and improvement in the hygienic conditions of the welder by reducing the volume and harmfulness of the fumes.
Example of comparison between the different processes:
TypeCoated electrodeSolid wireCored wireDiameter4 mm1.2mm1.2mmIntensity165 A140 A250 AInstant deposit rate1.7 kg / h1.7 kg / h3.5 kg / hActual deposit rate0.6 kg / h0.75 kg / h1.6 kg / h
For the same weld, it will be necessary to take a coated electrode 4 mm in diameter which will deliver only 1.7 kg of filler metal per hour. The cored wire of 1.2 mm will deposit twice as much for a diameter of only 1.2 mm.
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