Welding work can be either automatic or semi-automatic and carried out with a variety of materials. In order for the result of the process to be successful, it makes sense to use a special welding wire.
What is it and what is it for?
Welding wire is a metal thread, most often wound on a spool. The definition of this element suggests that it mainly contributes to the creation of more durable seams, devoid of pores and irregularities. The use of yarn ensures production with a minimum amount of scrap, as well as with a low level of slag formation.
The device is fixed in the feed mechanism, after which the wire is supplied to the welding zone in either automatic or semi-automatic mode. In principle, it can also be fed manually by simply rolling the coil.
The requirements for filler material are related not only to the quality, but also to the suitability of the workpiece.
The classification of the welding wire is carried out depending on the characteristics, properties and tasks performed.
In addition to general-purpose wires, there are also varieties for welding under special conditions. Alternatively, the metal thread may be intended for the procedure with the forced formation of the weld, for work under water or using bath technology. In these cases, the wire should have either a special coating or a special chemical composition.
According to the structure of the wire, it is customary to distinguish solid, powder and activated varieties. The solid wire looks like a calibrated core fixed on coils or cassettes. Laying in rows in coils is also possible. Sometimes bars and ribbons become an alternative to such a wire. This variety is used for automatic and semi-automatic welding.
Powder welding wire looks like a hollow tube filled with flux. It, on the contrary, should not be used on semiautomatic devices, since the broaching of the thread is difficult. Moreover, the impact of the rollers should not transform the round tube into an oval one. The activated film is also a calibrated core, but with the addition of components used for cored wires. For example, it may be a thin layer.
By surface type
The welding film may be copper-plated and non-copper plated. Copper-coated filaments improve the stability of the welding arc. This happens because the properties of copper contribute to a better supply of current to the welding zone. In addition, feed resistance is reduced. Non-copper wire costs less, which is its main advantage.
However, an uncovered thread may have a polished surface, which makes it a kind of intermediate link between the two main varieties.
It is important that the chemical composition of the wire matches the composition of the materials being processed. Therefore, in this classification there are a large number of types of filament: steel, bronze, titanium or even alloy, consisting of several elements.
By the number of alloying elements
Again, depending on the number of alloying elements, the welding wire can be:
- low alloyed - less than 2.5%;
- medium alloyed - from 2.5% to 10%;
- highly alloyed - more than 10%.
The more alloyed elements are in the composition, the better are the characteristics of the wire. Heat resistance, corrosion resistance and other indicators are improved.
The diameter of the wire is selected depending on the thickness of the elements to be welded. The smaller the thickness, the less, accordingly, should be the diameter. Depending on the diameter, the welding current parameter is also determined. Thus, with this indicator less than 200 amperes, it is necessary to prepare a welding wire with a diameter of 0.6, 0.8 or 1 millimeter. For a current that does not go beyond 200-350 amperes, a wire with a diameter of 1 or 1.2 millimeters is suitable. For a current of 400 to 500 amperes, diameters of 1.2 and 1.6 millimeters are required.
There is also a rule that a diameter of 0.3 to 1.6 millimeters is suitable for a partially automatic process carried out in a protective environment. The diameter, starting from 1.6 to 12 millimeters, is suitable for creating a welding electrode. If the diameter of the wire is 2, 3, 4, 5, or 6 mm, the filler material can be used to work with flux.
The marking of the welding wire is determined depending on the grade of material that requires welding, as well as on the working conditions. It is designated in accordance with GOST and TU. In order to understand how the decryption is carried out, we can consider an example of the brand of wire Sv-06X19H9T , which is often used in electric welding, and therefore is very popular. The literal combination “Sv” indicates that the metal thread is intended only for welding.
The letters are followed by a number indicating the carbon content. The numbers "06" mean that the carbon content is 0.06% of the total mass of the filler material. Next, you can see what materials are part of the wire and in what quantity. In this case, it is “X19” - 19% chromium, “H9” - 9% nickel and “T” - titanium. Since there is no figure next to the designation of titanium, this means that its amount is less than 1%.
More than 70 brands of filler wire are produced in Russia. Products of the Bars brand are manufactured by Barsweld, which has been operating since 2008. The assortment includes stainless, copper, powder, copper-plated and aluminum wires. The manufacturing of filler material is carried out using innovative technologies. Another Russian manufacturer of metal filaments is InterPro LLC. Production is carried out on Italian equipment using special imported lubricants.
Welding wire can also be manufactured at Russian enterprises:
- LLC "SvarStroyMontazh";
- Sudislavsky welding consumables plant.
Chinese enterprises are widely represented in the market of filler material. Their main advantage is a combination of average prices and good quality. For example, we are talking about the Chinese company Farina, which produces wire for working with carbon and low alloy steel. Other Chinese manufacturers include:
How to choose?
When choosing filler material, two basic rules must be considered. As already mentioned, it is important that the composition of the wire is as similar as possible to the composition of the parts to be welded. For example, for ferrous metals and copper alloys different variations will be used. It is recommended to ensure that the composition is free from sulfur and phosphorus, as well as rust, paint and any contaminants.
The second rule is related to the melting temperature: for the filler material, it should be slightly lower than for the processed products. If the melting point of the wire is higher, burnout of parts will occur. In addition, you should make sure that the wire straightens evenly and will be able to completely fill the seam. The diameter of the filler should correspond to the thickness of the metal being welded.
By the way, the material of the wire must match the material of the guide channel.
Storage of the welding wire cannot occur under conditions of high humidity. The filler material in the original packaging can be stored at a temperature of 17 to 27 degrees with a humidity level of 60%. If the temperature interval rises to 27-37 degrees, then the maximum relative humidity, on the contrary, drops to 50%. The threads removed from the packaging can be operated in the workshop for 14 days. However, the wire will need to be protected from dirt, dust and oil products. If welding is interrupted for more than 8 hours, the cassettes and bobbins will need to be protected with a plastic bag.
In addition, the use of filler material requires a preliminary calculation of the consumption rate. It is most convenient to plan the consumption of wire per meter of filled connection. This is done according to the formula N = G * K, where:
- N is the norm;
- G is the mass of surfacing on the finished seam, a meter long;
- K - correction factor, which is determined depending on the mass of the deposited material to the flow rate of the metal required for welding.
To calculate G, you need to multiply F, y and L:
- F - means the cross-sectional area of the compound per square meter;
- y - is responsible for the density of the material used to make the wire;
- instead of L, the number 1 is used, since the consumption rate is calculated per 1 meter.
After calculating N, the indicator must be multiplied by K:
- when lower welding K is equal to 1;
- vertical - 1.1;
- with partially vertical - 1.05;
- with a ceiling - 1.2.
It is worth mentioning, not wanting to carry out calculations according to the formula, on the Internet you can find a special calculator of the consumption of welding materials. The welding wire feed mechanism, as a rule, consists of an electric motor, a gearbox and a system of rollers: feed and clamping. You can do it yourself or purchase a finished device. This mechanism is responsible for the transportation of filler material to the welding zone.
It should also be noted that the wire for gas welding with acetylene must be cleaned of rust or oils. The melting temperature must be either equal to or lower than the melting temperature of the processed material.
If it is impossible to find a welding wire of suitable composition, in some cases it can be replaced with strips of material of the same brand as the material being processed. The requirements for carbon fiber welding are similar.
In the next video, a comparative test of 0.8mm welding wire awaits you.