How to make cored wire

Features of flux-cored wire welding

Novice welders often ask the question: “Why do we need other components at all if there is a semi-automatic machine that performs fast and high-quality welding using ordinary wire and gas?” Yes, semi-automatic welding equipment is often used for amateur and professional welding.

In such devices, the wire is fed continuously, so the seams are strong and durable. There is no need to constantly change the electrode if you need to weld a long seam or deposit a lot of metal. At the same time, the quality of welding work is head and shoulders above that of work with electrodes. However, there is one “but”.

Welding using a semi-automatic machine requires a gas cylinder, the weight of which reaches 80 kilograms. If you work outdoors or are forced to constantly move from place to place while welding, then a semi-automatic + gas cylinder combination significantly complicates the task. This problem can be solved using a gas hose, but it is not cheap. An alternative is powder-cored arc welding (FCAW), which simulates gas-shielded welding without the need for a gas cylinder.

What is this? How does it work and what are the advantages and disadvantages of flux cored electrode welding? Let's figure it out.

articles

• basic information
• Application
• Advantages and disadvantages
• Welding Features
• Instead of a conclusion

basic information

Welding with flux-cored wire in a gas-free environment is a very interesting method. During operation, the electric arc forms a seam, and oxygen can enter the welding zone, which will negatively affect the quality of the welded joint.

To avoid problems, you need to protect the welding area from negative influences from the atmosphere. For these purposes, you can use a bulky gas cylinder, but this complicates and slows down the work process.

Therefore, semi-automatic welding with flux-cored wire without gases was invented.

What is the hallmark of flux-cored arc welding? First of all, the composition of this material. The wire is hollow, its walls are equipped with stiffening ribs, and a special powder is placed inside. Thanks to this unique design, the wire does not wrinkle and conducts current well. At the same time, the surface and powder melt, forming a gas cloud that protects the metal from the negative effects of oxygen.

The powder inside the wire is flux. Each manufacturer uses its own composition, so it may vary. The scope of application of flux-cored wire also depends on the composition. Usually the composition is written on the wire packaging; it is regulated by a special GOST. Carefully study this information on the packaging to avoid mistakes when welding with flux-cored wire.

Manufacturers produce wire in a large number of diameters, so you can weld almost any metal. You can choose from components with diameters from 0.8 to 3 millimeters. You can weld thin steel, carbon steel, stainless steel and even galvanized steel. Just choose the right type of flux in the wire and get to work, all you need is a semi-automatic machine.

Application

Welding with self-shielded flux-cored wire is useful for working in hard-to-reach places. For example, for welding at high altitudes or in deep tunnels. For such purposes, we recommend purchasing a compact welding machine that can be hung on your shoulder and that works with a standard 220V socket. Powder welding of metal structures using this method requires some skill in order to carry out the work quickly and efficiently.

Advantages and disadvantages


Any technological process has its advantages and disadvantages, welding with flux-cored wire without gases was no exception. Let's start with the positives:

• No need to use bulky gas cylinders.
• Unobstructed movement, you can work at any height and in hard-to-reach places.
• High labor productivity compared to welding with electrodes.
• The arc is practically insensitive to wind.

Welding with flux-cored wire in a gas-free environment also has its disadvantages. The main one is the high price of components. If you just want to save gas, then the option of cored wire will not work here. However, its use in ordinary work is not entirely justified. If you work in a comfortable workshop or garage, then it is better to carry a gas cylinder and do not overpay. Another disadvantage is the poorer quality of the weld compared to gas welding.

Welding Features

When welding with flux-cored wire, there are several key features to consider in order to get a quality result. It is sometimes difficult for beginners to conduct an arc and form an even seam, so it is recommended to set straight polarity on your semiautomatic machine when welding. To do this, you need to switch the contacts located inside the semi-automatic device. The wire connected to the burner must be disconnected and connected to ground, and the cable from ground is switched to the burner.

To work with wire, you also need to install special rollers that feed the material. The rollers are selected in accordance with the diameter of the wire itself. Typically, one set of rollers can be used with several diameters at once; they are indicated on the side.

Don't forget that the wire is hollow and you don't need to clamp the rollers too hard so as not to deform it. In order for the wire to be pulled through easily, you need to remove the tip. It is also not necessary to use a nozzle, because we do not use gas in our work.

To prevent metal splashes from sticking to the tip, you need to lubricate it with a special product that can be easily found in a welding store.

Powder core welding with wire should be performed at low voltage and with a minimum wire feed speed. Therefore, we do not recommend using overly powerful devices for these purposes. Their “power” may be too much for working with cored wire.

If you need to weld metal one and a half centimeters thick, then set the voltage to no more than 15V and the feed speed to no more than 2 meters per minute. At first it may seem to you that this speed is insufficient, but believe me, you will not waste much time. It is better to hold the burner at an angle and move it forward.

The arc should be intermittent.

Note! During welding, slag is formed, which then solidifies on the weld seam. After the metal has cooled, the slag must be removed mechanically. If multi-pass welds are planned, then removing slag is a must. To improve the characteristics of the seam after removing slag, you need to clean the surface with a wire brush.

An important fact is that the joints are rough and not entirely smooth (compared to gas welding); sagging and visible defects similar to scales can form. This is a consequence of working with an intermittent arc. Uncooked areas are also common. This should be taken as a given and powder welding should be used only in special cases.

Instead of a conclusion

Semi-automatic welding with flux-cored wire without gas is an excellent method if you need to carry out work in hard-to-reach places and there is no need to save on gas. It is enough to set the straight polarity when welding on your machine and get to work. Of course, you will need time to get used to this method of welding, but it is a very useful experience.

The advantages of this method greatly simplify welding in various situations: from working at height to quickly repairing metal structures with the need to constantly move. It may be more difficult for beginners at the first stage, but over time you will get used to it and will feel all the features of the “behavior” of the arc. Be sure to test powder electrodes and tell us about your experience in the comments. Also share this article on social networks. Good luck!

Source: http://home.nov.ru/osobennosti-svarki-poroshkovoj-provolokoj/

Flux-cored wire for semi-automatic machines: application features, properties, price:

Modern welding processes come in many variations. The most popular are electrode arc welding (MMA) and semi-automatic welding (MIG/MAG) in a protective environment created by inert gases.

Despite the convenience of semi-automatic operation, this method has insufficient mobility. A bulky gas cylinder ties you to your permanent place of work. The use of cored wire for semi-automatic machines will help solve this problem.

Working with a semi-automatic machine

Semi-automatic welding machines have long ceased to be a technical novelty. They migrated from the professional environment to the everyday environment. The popularity of MIG and MAG machines is due to the fact that to work with them, the requirements for welding skills are minimal. Knowing the correct current and wire feed speed settings makes it easy to get a quality connection.

Semi-professional devices are inexpensive compared to professional ones and are available to those who want to do the repairs themselves. But there is a drawback that minimizes the use of these devices - a heavy gas cylinder.

The welding process takes place in a protective environment. Inert gases are used as it: argon, helium, carbon dioxide. Their choice depends on the metals being connected. Structural steel grades are most often welded. They use carbon dioxide. It is pumped under a pressure of 55 atm. in a cylinder whose weight is more than 60 kg. Therefore, this type of welding has a number of disadvantages:

1. The need for periodic refilling of cylinders. Gas stations are not located in every locality.
2. Low mobility. To transport gas cylinders, a special device is required.
3. Once every few years, the cylinder needs to be re-examined, which incurs time and financial costs.

It is possible to weld with wire without carbon dioxide, but the quality of the connection will be very low. When working at low currents, the wire will stick to the surface because the welding arc will be unstable. At high current, the weld pool will spatter and the seam will become porous.

A solution has been found: enclose powdered flux inside the semi-automatic welding wire, which, when melted, will create a protective environment. In terms of its external parameters, such wire does not differ from ordinary wire and is suitable for working with the drawing mechanism of the device.

Advantages of cored wire

In what cases should you switch to semi-automatic flux-cored wire welding? For small amounts of work, as well as if the device is used occasionally, there is no need to purchase a gas cylinder. The protective composition of flux will successfully replace carbon dioxide. The absence of gas equipment will allow the use of the MIG and MAG apparatus in all jobs where previously, due to their mobility, MMA inverters were used.

Semi-automatic welding with flux-cored wire provides the following advantages:

1. Lack of additional equipment: hoses, reducers, cylinders. All this limits the freedom of action of the welder.
2. The use of special fluxes that allow you to create wire for welding structural, alloy steels, as well as cast iron.
3. Higher productivity compared to electrode arc welding.

Flaws

Initially, MIG and MAG devices were created to work in conjunction with gas equipment. Flux-cored wire for semi-automatic machines appeared later. There was less time to develop the technology, so it has a number of disadvantages:

1. Fragility of the material. The wire is a long, thin-walled tube filled with flux and rolled into a coil. Therefore, when working with it, you should avoid manipulating the bend of the welding sleeve.
2. Presence of slag on the surface of the weld.
3. The weld pool is not visible during operation due to the layer of molten flux. It is more difficult to control the quality of the connection.
4. It is difficult to weld parts less than 1.5 mm thick.
5. Higher cost. The price of flux-cored wire for a semi-automatic machine is more than 3 times higher than the cost of regular wire and starts from 700 rubles. If we take into account that the consumption of flux-cored wire is higher, then the economic benefit is on the side of traditional materials.
6. Welding modes (current strength, feed speed, polarity) depend on the type of flux in the wire.

Wire shape and composition

In order for the flux-cored wire for a semi-automatic machine to withstand the loads of the feeding mechanism, its cross-section has several types:

• simple round;
• with bends inside;
• multilayer.

The internal cavity is filled with flux consisting of several substances:

1. Slag-forming components. When melted, they form a liquid protective medium, protecting the weld pool from oxygen entering it. They are made from crushed chalk, manganese ore, and quartz sand.
2. Alloying additives. Depending on what material the wire is intended for welding, cobalt, chromium, manganese, and molybdenum are added to it.
3. Rutile. Mineral containing titanium. Not used everywhere. Only in wire intended for welding silicon-manganese, low-alloy and high-strength steels.
4. Components for arc stabilization.

How to check wire quality

For a semi-automatic machine without gas, cored wire must meet the following requirements:

1. Possibility of welding in any spatial position without slag flowing down.
2. High-quality seam with minimal porosity. No cracks or lack of penetration.
3. Stable burning of an electric arc without spattering of molten metal.
4. Easy slag separation after weld cooling.

Compliance with these requirements is established during the work process. There are additional ways to check quality that can be checked in the laboratory: x-raying the weld, as well as testing it for tensile strength.

Working with a semi-automatic machine

Cooking with a semi-automatic device in a carbon dioxide environment is easier than with flux-cored wire. The second option resembles coated electrode welding. Here you also need to visually monitor the molten slag and metal and be able to distinguish them from each other. In addition, care must be taken to ensure that the slag does not extend beyond the arc. Otherwise, it will spread in front of the device’s nozzle and interfere with boiling the base.

Although cored wire has a profile that strengthens it, it is still less strong than copper-clad steel wire. Therefore, it must be used in welding machines with the ability to adjust the pressing force of the feed roller. In addition, the semi-automatic machine comes with special rollers with a groove for this consumable.

How to get a quality seam

The diameter of the standard flux-cored wire for a semi-automatic machine is 0.8 mm. Its use in vertical and overhead positions requires higher qualifications than when welding with carbon dioxide.

This is explained by the fact that a higher temperature is required to melt the flux; accordingly, the metal in the weld becomes more fluid and tends to flow out of the weld pool. In addition, molten flux flows down.

Therefore, ceiling and vertical seams may have pores and lack of penetration.

When working with flux-cored wire, strong splashing occurs. To prevent the tip of the welding gun from constantly becoming clogged with slag and molten metal, it must be periodically treated with silicone spray.

It is difficult for beginners to make a beautiful, even seam. To make work easier, you need to change the reverse polarity to direct. That is, apply minus to the welding holder, and plus to ground. Modern semi-automatic machines have a terminal with a wire that allows you to manually change the polarity.

conclusions

In conclusion, we can say that the main disadvantage of this consumable is the price. Semi-automatic flux-cored wire without gas is good where mobility or imparting special properties to the welding seam is required. But if the volume of work is large, then the use of copper-plated wire in a carbon dioxide environment is beyond competition.

Source: https://www.syl.ru/article/437502/poroshkovaya-provoloka-dlya-poluavtomata-osobennosti-primeneniya-svoystva-tsena

Flux-cored wire and welding using it

Each welding technology has its own specifics, advantages and disadvantages. Often, only a certain welding method may be suitable for a particular type of welding. Flux-cored arc welding is considered to be a fairly popular welding method at the moment.

Wire requirements

Flux-cored wire is made in the form of a tube. Welding flux with the addition of metal powder is placed inside it. It is classified depending on its purpose, the type of protection used, mechanical characteristics and position during welding.

The vast majority of flux cored wires are suitable for use on low alloy or less durable mild steel.

Among the main requirements for it are:

• stability in heating by an electric arc and the ease with which the arc occurs;
• uniform melting of the wire, absence of large splashes;
• the slag that appears during the powder welding process at the weld site must be easily cleaned off after cooling and ensure uniform coverage of the entire surface of the seam;
• the seam should not have any flaws.

The use of various fillers, as well as changes in the shell design, can improve the characteristics of flux-cored wire and use it for specific purposes.

Welding wire, which has a flux core, is used to ensure welding of low-carbon steels with a high degree of deposition.

It is used when installing low-alloy steels, as well as when welding in various, sometimes uncomfortable, positions. Flux-cored wire is used to weld cast iron and galvanized steel.

Main types of wire

Depending on the method of use and the method of protection from external influences, wire for flux-cored welding can be gas-protected or self-protective.

Gas-protected type

Gas shielding wire is used when welding is carried out using semi-automatic and automatic machines for low-alloy and carbon steels.

The process involves carbon dioxide or its mixture with argon. Gas comes from outside. The powder filler can be selected to improve welding parameters. For example, you can increase the speed of vertical welding or firmly join difficult-to-weld steel.

This technology is used when it is necessary to create overlaps, when working at joints and at the corners of structures, both for automatic and semi-automatic machines . The use of such technology ensures a constant jet, a reduced level of spatter, as well as resistance to the formation of pores and slag.

The material, which is used in the welding process, has an increased deposition rate, has a low smoke level and allows for high-quality welds.

Self-defensive appearance

Self-shielding flux-cored wire is made in the form of a special “inverted” electrode (as if it is turned inside out). The use of this type of welding allows work to be carried out under different temperature conditions (even extreme ones), with strong gusts of wind, and the like.

The main components of the core are various additives (dioxidizing, slag-forming and protective), which allows welding to be carried out without the use of gas.

Self-shielding welding wire has a number of positive features, among which are:

• the ability to carry out welding work in various positions;
• due to the openness of the arc, it is possible to carefully move the deposited metal;
• a special type of wire coating ensures its resistance to pressure exerted by the rollers;
• By controlling the chemical composition, it becomes possible to obtain a very specific composition of the slag.

In installation environments, mechanized powder welding is becoming increasingly common. Although many people complain about the high cost of consumables, the efficiency of powder welding is significantly higher, you just need to choose the right brand of wire.

Advantages of the powder method

A large number of advantages have determined the popularity of powder arc welding technology. When working with flux, it becomes more difficult to accurately hit the electrode at the desired point, and difficulties arise in controlling the seam.

In semi-automatic welding, problems arise with the flow of shielding gas. Air currents can blow it away, and the nozzles can splash.

The use of flux-cored wire for semi-automatic machines solves such problems. No flux, gas cylinder or all related tools are required. Powder welding combines the advantages of open electrodes and an automatic welding method.

It will only be enough to clearly determine the direction of the electrode to the desired point and control the process of formation of the weld. This makes it possible to achieve deposition exactly as intended during the manufacturing process of the consumable material. The welder only needs to select the right brand of wire by studying its characteristics and the manufacturer’s recommendations.

Filling and outer shell

The outer part of the cored wire itself is made of cold-rolled strip, which has a special level of softness. The purpose of the wire is determined by the chemical properties of its core.

It is based on dielectric components, including iron powder of rutile and fluorite concentrate, additives to increase the quality of the weld, organic and carbonate additives for the release of protective gases.

Powder welding by this method has similar specifics to work performed using electrodes. The protective layer melts under the influence of the welding current, and the core itself melts due to the presence of an electric arc and under the influence of the temperature of the hot metal.

If there is a need to apply several layers of welding, then the working surface is cleaned of slag formed on the previous layer.

Where is the method without protective gases used?

Often, it is inconvenient to carry out welding work using ordinary electrodes, since the location of the surfaces to be welded makes it difficult to connect them. To provide comfortable conditions, special consumables were developed.

It makes it possible to carry out welding work in any position and in the absence of a gaseous environment. Special-purpose wire ensures forced formation of seams, allows welding under water, as well as automatic welding.

You can weld both in a lower position and vertically (in some cases) due to the fact that the welding baths have a corresponding connector. The type of material used is selected based on its characteristics and the specifics of the work to be done.

Flux-cored wire is considered the most optimal option when work is carried out in open areas.

Wind and drafts have virtually no effect on the quality of welds, but their parameters are somewhat inferior to those provided by gas or electrode welding.

Flux-cored wire is selected not only on the basis of its technical features, but also guided by the need for a specific diameter for a given welding.

The diameter should not be less than 2.3 mm. Wire of a smaller cross-section is used only when welding on metal structures with the smallest thickness.

When carrying out welding work, they use a special automatic or semi-automatic hose welding machine, which has a section for placing a coil of wire.

It is secured by a latch in the handle, and is fed through a special hose, which ensures the stability of the arc and allows the core to completely melt. Semi-automatic machines for using flux-cored wire usually have a “No Gas” mode, which makes it possible to change the polarity.

Welding work using shielding gases

Gas shielded welding involves supplying a gas jet to the melting area using a torch. Or powder welding is performed in special chambers containing gas inside.

The most common is jet protection. Its quality is determined by the dimensions and design of the nozzle, as well as the distance between the nozzle cut and the surface of the material being welded. The most effective protection is achieved by using stationary chambers containing gas. The product is placed there during work.

Semi-automatic welding in carbon dioxide is carried out using special equipment, which ensures excellent quality of the weld, a narrow heat-affected zone, and a high wire melting rate. All this increases the productivity of the process and increases the reliability of the finished structure.

Source: https://svaring.com/welding/vidy/poroshkovaja-svarka

Cored wire for semi-automatic machines - a solution to the problem of a large gas cylinder

Welding work in which semi-automatic machines are used has a number of undeniable advantages - the possibility of long-term continuous operation, large volumes of metal applied to the surfaces being processed, and high quality of the seam.

But the semi-automatic device has one very significant drawback. Unlike the widely used coated electrodes, which are very convenient and easy to use, it requires a large cylinder with working gas and a multi-meter gas hose.

This circumstance makes it impossible to work with a semi-automatic welding machine in places with difficult access - at high altitudes, underground or under water. This difficulty is solved by using flux-cored wire for a semi-automatic machine.

Features of the use of cored wire

Welding with it is often used when installing large metal structures in unusual conditions (for example, at a height or, on the contrary, underground). Despite the fairly high quality of the seam, it is not suitable for welding highly loaded joints and pipes designed for significant operating pressure.

Flux-cored wire for semi-automatic machines has a wide range of grades - they differ in sheath material and powder composition. This must be taken into account when welding different metals or their alloys. Each of them requires its own variety.

Another feature of working with it is to set straight polarity on the semi-automatic welding machine before starting work. Since this is usually done by switching the terminals inside the device body, it is also worth calibrating the pressure rollers that ensure the supply of consumables from the reel.

The rollers should press on it with just enough force to ensure its movement and fixation. Any deformation by pressure rollers is unacceptable - this will lead to damage and jamming of the wire in the cable channel of the semi-automatic welding machine.

And finally, you should take care of the burner tip. Before the flux-cored wire for a semi-automatic machine appears when fed from the torch, the tip must be unscrewed. And only after it comes out, screw it back on, but without the nozzle. Since gas is not supplied, there is no need for a nozzle.

The main thing is to choose the optimal ratio of the diameter in the tip and the thickness of the supplied electrode - they should be as close as possible, but not coincide. It is recommended to coat the tip itself ahead of time with a special substance that protects against the adhesion of drops of melt and slag.

Primary requirements

All its varieties must meet four groups of requirements:

1. When melting there should be no significant spattering, and the melting process itself should be uniform;
2. The electric arc between the workpiece and the electrode (which is the tip of the wire protruding from the torch) should occur without difficulty and be stable. A draft and even wind should not be a hindrance for her.
3. The slag formed during work should be distributed evenly and not penetrate deep into the seam. It should come off easily from the metal.
4. The seam itself, with the usual qualifications of the welder, should be smooth, without pores or cracks.

Operational Features

As already mentioned, it is used to weld metals with direct polarity.

• Straight polarity means that the positive contact of the welding machine is connected to the workpiece itself with a ground cable, and the negative contact is connected to the electrode via a welding cable

In the settings of the welding machine, the minimum feed speed and operating voltage are set. For example, when using a 1.2 mm diameter, the optimal feed speed would be 2 meters per minute and the voltage would be 14 V.

It is common for her to form a thick slag layer on the seam made. If the seam is planned to be multi-pass, then this slag must be carefully removed with a metal brush and hammer.

In general, according to reviews, the seam is almost always quite rough, has large scales and sagging. If the welder acts carelessly and hastily, lack of penetration may occur. This is virtually inevitable when working with an intermittent electric arc.

Types of cored wire

Flux-cored wire for semi-automatic machines is divided into four types according to the nature of its design:

1. simple tubular shape;
2. with one bend of the shell;
3. with two shell bends;
4. two-layer.

Its overall dimensions vary in a wide range of diameters - from 0.8 mm to 2.5 mm.

A simple tubular one can have slight nuances in its design - it can either be seamlessly drawn from one piece of metal, or bent from a sheet of metal into a cylinder with a butt joint. There may also be an overlap connection between the workpiece and the shell.

A special powder is evenly placed inside the wire. Its composition may vary depending on the purpose of the parts being welded and the characteristics of their further operation.

In general, the powder consists of ferroalloys, minerals and other chemicals of complex composition. In any proportion, they create a protective layer of neutral gas that separates the melt from atmospheric oxygen. In addition, the gas released by the powder:

• alloys;
• deoxidizes;
• stabilizes the electric arc;
• simplifies the formation of a uniform seam.

Depending on the composition of the powder, self-shielding wire for semi-automatic machines is divided into types:

• Fluorite;
• Fluorite-carbonate;
• Rutile;
• Rutile-fluorite;
• Rutile-organic.

All of the above types have self-protective properties. To weld with them, there is no need for an additional carbon dioxide cylinder.

Features of welding technique

Fundamentally, welding using it does not differ from welding using widely used consumable electrodes. The formed weld seam is clearly visible throughout the work, which facilitates application in several stages.

• A feature of flux-cored wire is the intensive formation of slag covering the seam. It is recommended to clean it immediately after formation with a suitable tool (for example, a wire brush). Otherwise, there is a risk of slag getting into the working area and, as a result, the appearance of defects and a decrease in mechanical strength

Due to the peculiarities of the technology, the seam formed is inferior in strength to that created using consumable electrodes. Therefore, to prevent an even greater decline in quality indicators, you need to carefully adjust the feed rollers before starting work. This will stabilize the feed and eliminate accidental deformations, jams and breaks.

Source: https://prosto-instrumenty.ru/poroshkovaya-provoloka-dlya-poluavtomata/

The essence of powder welding

When a metal is heated, a process of diffusion occurs between the materials. The ingress of foreign substances from the environment into the welding area has an extremely negative effect on the quality of the seam.

It oxidizes and rusts over time, products become fragile, and this situation can lead to serious consequences, especially if these are critical structures. To protect metal from corrosion, protective mixtures are used that create a special shell into which oxygen does not penetrate.

Cooking using a gas cylinder is not always appropriate, so the idea arose to modernize the technology and use wire filled with protective powder.

The uniqueness of the flux-cored wire welding method lies in the content of the protective composition. The wire is made hollow, built-in stiffening ribs prevent the wire from breaking, and a powder called flux is placed inside. The components are good conductors of electric current. When heated, the tube melts and the contents flow directly into the weld pool, providing the necessary protection for the seam.

Manufacturers make different flux compositions depending on the application. Its components are written on the wire packaging container and designated by the corresponding guest. This information is extremely important to avoid errors during operation.

The diameter of the cored wire varies in gears from 0.8 mm to 3 mm. You will be able to weld thin metals, stainless steel, carbon surfaces and galvanized steel. All you have to do is choose the appropriate flux composition and purchase a semi-automatic machine.

Application area

The use of welding with self-shielding wire is in demand in hard-to-reach places. To make it easier to move the welding machine for work at heights or in narrow tunnels, purchase compact models that can be hung over your shoulder and do not require a power source more powerful than a standard 220V network. Such welding requires practical experience; beginners will not always be able to cope with such tasks.

Advantages and disadvantages of powder welding

Mechanized cored wire welding has not become an exclusively universal method, but there are certain advantages:

• there is no need to move large gas cylinders;
• no obstacles in movement;
• Efficiency is higher than when welding with electrodes;
• The electric arc is not knocked down by the wind.

The disadvantages of such welding include:

• high cost of components;
• the connection is of poorer quality than when using shielding gas.

It is not profitable to use the powder method in everyday welding work. Although it has a number of positive aspects, more classical methods of joining metal will be more effective.

Features of the welding process

To ensure that the welding seam is as strong as possible when using flux-cored wire, certain features should be observed during the work process. Beginning craftsmen have difficulty drawing an arc and forming an even joint. In this regard, we recommend setting the welding current to straight polarity. The polarity adjustment is located inside the semi-automatic body. Accordingly, you need to swap the ground and burner cables.

To work with wire, it is necessary to attach rollers that will rotate the filler material. The rollers are sold separately and are designed for several wire diameters. Their markings are indicated on the side of the box. Do not press the rollers too hard as the wire may break. You can also remove the nozzle, which is designed to concentrate the gas flow. To prevent sticking, purchase a special coating at any welding shop and apply it to the tip.

For welding in a powder environment, it is not necessary to use powerful welding machines. The low arc voltage and slow feed speed of the self-shielding wire will provide a better quality weld.

If you are welding a thickness of 1.5 cm, then set the arc voltage to no more than 15 V, it should be intermittent, and fix the feed speed at two meters.

At first it may seem to you that the work is moving too slowly, but for the formation of a seam it is just right. Tilt the torch and move the seam forward.

Slag formation is inevitable. It must be removed after each cooling. If you are making multi-layer seams, then this procedure is mandatory. After the slag has been removed, brush the seam with a wire brush.

No matter how hard you try to follow all the recommendations, the seams when welding with flux-cored wire have some irregularities. The imperfection of the seam is caused by an intermittent arc. Sometimes there are unwelded areas, so use this welding method only in extreme cases when another method is impossible.

conclusions

Semi-automatic welding with flux-cored wire is a very convenient way of welding in hard-to-reach places where it is not possible to work in other modes. Although such welding is rarely used, we still recommend mastering it. Experience will never be superfluous. If you have your own opinion on this matter, please share it in the comments.

Source: https://svarka-weld.ru/o-svarke-poroshkovoj-provolokoj

Self shielding cored wire

Welding, as a process of joining two metal workpieces, is being improved all the time. The need to create a unique technology leads engineers and scientists to various discoveries that improve the quality of the welding process. For example, gas shielded welding using filler wire.

And this is sometimes the only optimal solution for many welding operations, which is associated precisely with the quality of the wire used. So, in the middle of the last century, experts invented a new product, which was a tubular structure with a special powder inside.

In 1957, a gas-protective model appeared on the market, and in 1961, a self-protecting flux-cored wire.

How does the powder model differ from the solid model in terms of improving the quality of the process of welding two metal workpieces?

• Firstly, it increases the speed of the welding operation itself.
• Secondly, it reduces metal spattering.
• Thirdly, welding can be carried out in any position.
• Fourthly, increasing the quality of the metal that fills the gap between two parts. In addition, its chemical composition is observed.

The last position is determined by the ability to put various additives into the tube, which will allow you to move away from some of the difficulties in carrying out the welding itself. For example, you can add deoxidizers to the powder, which combine well with oxygen, thereby removing it from the welding zone, forming their own oxides. They are slag deposits that are easily removed from the surface of the weld.

Or stabilizers are added to the powder to ensure ionization of the process, which leads to stabilization of the electric arc. There are alloying additives (nickel, chromium, etc.) that improve the metal filled with wire. Slag-forming additives are components that form slag on the surface of the weld. In essence, this is a kind of protective layer.

But the most important thing is the gas-forming elements. Their purpose is to create a gas protective layer that would protect the weld pool from the negative effects of nitrogen, hydrogen and oxygen. By the way, the last two additives make the cored wire self-protective.

These include cellulose, wood flour, marble, soda ash, alkali metals and carbonates.

It should be noted that the self-protective modification of flux-cored wire allows welding to be carried out even in the open air in windy weather. And you don’t need to use any additional equipment.

Classification of flux-cored wire for welding

There are many divisions of wire according to welding criteria. But most often the classification is carried out according to the type of components added to the powder. Hence the wire grades.

For example, flux-cored wire for semi-automatic machines of the E71T-1 brand is used to connect critical structures. The thing is that this brand ensures rapid solidification of the slag that covers the bath.

With the help of this wire, the productivity of the process is increased, especially when welding is performed uphill. The productivity indicator in this case is 3 kg/h. None of the other wires and electrodes have this indicator (this refers specifically to uphill welding).

Therefore, E71T-1 is the most popular filler wire in the world.

If it is necessary to weld two metal plates with a thick wall in the lower position, then it is recommended to use E70T-4 wire in semi-automatic welding.

In this position, this type of electrode conductor has the highest productivity - 18 kg/h. The only condition for it is the welding of thick-walled steel products, which have minimum requirements for impact loads.

By the way, all the filler materials described above belong to the category of self-protective ones.

But the E70T-1 brand is a gas-protective wire with the highest productivity in its group - 14 kg/h. But welding with it means a stable arc and excellent impact strength of the metal melted into the gap between the workpieces being welded. Another advantage may be the ability to cook parts that do not require cleaning. For example, rusty or contaminated workpieces can be easily welded with such wire. This brand is most often used for the construction of various types of metal structures.

Galvanized or chrome-plated steel workpieces are best welded with self-shielding wire grade E71T-14. It contains special substances that simply explode in the arc flame, thereby knocking off the protective coating layer from the workpiece. This minimizes cracking of the weld seam. Most often this brand is used in mechanical engineering.

For difficult-to-weld steel, grade E70T-5 is often used. Its powder contains slag-forming elements that remove sulfur and phosphorus from the welding zone. Namely, these chemical elements lead the molten metal to cracking and porosity, and, accordingly, to a decrease in strength characteristics. In addition, such a connection provides high impact strength of the joint.

It is better to weld vertical seams with PP-AN7 or PP-AN11 wire. The powder contains additives that quickly crystallize the slag. This means that the molten metal will not move downward under the influence of its own mass. Experts recommend welding with this type of welding at a speed of 120 m/min, while maintaining a current of 130-170 amperes.

PPT-7 is mainly used for connecting pipelines. Wire of this brand is made from steel strip 0.3 mm thick. The powder contains zirconium dioxide. This substance is a barrier to the penetration of nitrogen into the welding zone. The seam made with this material is highly smooth, completely free of flakes and has a characteristic metallic luster. True, experts recommend welding with this wire only in the lower position.

PP-2DSK flux-cored wire is a material that contains slag-forming components. Namely aluminum powder and fluorspar. By the way, the latter is almost 50% in powder. This makes it possible to easily separate the slag from the material melted into the gap. The speed of welding operations with this wire is 337 m/h, while the current is set at 200-450 amperes.

For automatic welding, the additive PP-2VDSK is usually used. It has a very complex powder composition that is designed to neutralize oxide and nitride compounds within the molten metal. It is in these compounds that nitrogen and oxygen are located. The main ingredient of welding powder is nickel.

Production technology

Flux-cored welding wire is produced using the following technology.

• To make the tube, a steel strip 10-15 cm wide is used.
• It is cut into pieces from which tubular products will be twisted.
• The blanks are wound onto special cassettes, and the product is immediately cleaned and dried.
• The powder itself is prepared according to the required recipe. It must be sifted and dried. It is important that the granules of the ingredients are not very large, because this is what determines the filling density of the tubular structure.
• The finished mixture is sent to a drawing machine, where the tube is formed. The mixture enters the filling device of the mill.
• Next, the prepared powder is supplied to the tape, from which the wire itself will be formed.
• A tube is formed, inside which the powder mixture is immediately formed.
• The wire is then pulled through six drawing drums. On each one it decreases in diameter and increases in length. By the way, the wire drawing speed is quite high - 300 m/min.

After this, the finished product undergoes several types of control. There are two main ones. First of all, the cored filler wire is checked for fill factor. It is calculated as the ratio of the weight of one meter of wire to the weight of the entire coil.

Optimal range: 25-40% (it all depends on the brand). The second type of control is the determination of mechanical and welding-technological characteristics. To do this, simply weld with a small piece of wire, after which the seam is checked and tested.

Source: https://svarkalegko.com/materials/poroshkovaya-provoloka.html

Semi-automatic welding with self-shielding flux-cored wire

Welding on semi-automatic machines is characterized by relatively high productivity and the ability to work on equipment without skills or extensive experience. Flux cored wire makes the process of joining parts even easier. The composition filling the tube improves arc burning, activates the melting of metals and protects the bath. When welding with wire and powder, there is practically no spatter, the seam is smooth, finely flaked, and light.

Main characteristics and advantages

A wire with powder is an endless electrode, in which the role of a coating is performed by a composition inside a metal tube . Powder welding is performed under submerged arc without the use of additional installations for its supply. Inside the metal tube there is a mixture of crushed iron, its oxide, phosphates, chromium and other components, which:

• stabilize the temperature in the bath and around the arc to the optimal temperature for a particular material;
• promote mixing of molten metal parts and electrode;
• uniformly cover the entire width of the seam from contact with oxygen and nitrogen;
• make the bath boil evenly, without splashing;
• allow you to increase the speed of welding parts.

Flux-cored wires can be used to surfacing parts on the surface and welding in any spatial position in a specially equipped place and in the field.

Composition details

The outer body - the cylinder - is made of ductile low-carbon steel. Inside it is a special mixture, which includes:

• gas-forming and slag-forming charge;
• deoxidizers;
• stabilizing elements;
• alloying components.

Manganese, nickel, rutile concentrate, and marble powder are used as the charge . Chromium, aluminum, copper and other substances used for alloying steels are added to the material for welding alloy and stainless steels. Iron powder is used to stabilize the bath.

In addition, depending on the purpose of the wire, magnesite and fluorspar are added to the powder composition.

When working with refractory materials, wire containing graphite and aluminum powder is used, which increases the temperature in the bath and around the arc.

Principles of classification

According to the shape of the shell, tubes made of metal sheets are distinguished:

• round, with edges joined end-to-end;
• with lock-type bends;
• multilayer.

According to the use of a protective environment, a distinction is made between PP - gas-protective, flux-cored wires for welding in a gas environment and PS - self-protective, which does not require additional consumables.

In addition to indicating the type of wire, the marking uses a letter designation of the spatial position of the seam, which is performed with this electrode.

Steel grades are not reflected in the markings ; they must be looked at in the technical specifications for each type of cored wire.

Gas-protective

The gas shield wire requires covering the top of the weld pool. For this, argon or other inert gas is used. Used for welding carbon and low-alloy steels . It has positive technical characteristics and advantages over other electrodes:

• stable arc;
• slag easily comes to the surface;
• no porosity;
• low spatter;
• the slag is easily separated.

PP is characterized by deep penetration. It is used to create butt, corner and overlap joints when creating metal structures and pipelines .

Self-protective

Self-shielding wire for a semi-automatic machine is suitable for working in any spatial position of a seam in field conditions. It does not require any additional consumables. During operation, a cloud of molten gas-forming charge forms above the bath. An even layer of flux is applied to the seam, completely covering the hot joint in a wide strip.

PS is used for welding outside equipped places , outdoors for welding alloy steels, stainless steel, non-ferrous alloys and cast iron. And also for soldering various parts made of aluminum and its alloys. Stainless steel is welded with electrodes containing a high content of chromium, nickel and ferromanganese in the core.

Production Features

To produce cored wire, a sheet with a thickness of 1.18 - 0.25 mm is cut lengthwise into strips. The filler is prepared separately, mixing all the components of the core in certain proportions.

Wire production occurs in several stages in one installation.

1. Cleaning the strip from dirt, oil, scale and moisture at the beginning of the machine.
2. Slight longitudinal deformation of the pipe with the formation of a semicircle.
3. Filling the strip with powder.
4. Connecting the ends, forming a tube with flux.
5. Calibration of the connection and the profile itself. Creating a regular circular section.

In modern welding production, welding strips made of low-carbon steels are most often used.

To remove moisture and oil from the surface of PP and PS, the coil should be placed in an oven before installation on the device. Maintain for 2 hours at a temperature of 230 - 250⁰.

Description of popular brands

When welding metal structures and pipelines on a construction site, the most commonly used grade is PP-AN11 or PP-AN7, which has similar characteristics. In production, a tape with a thickness of 0.18 mm is used. The charge contains slag-forming elements.

The welding mode is semi-automatic, current with reverse polarity. Shielding gas argon and helium or a mixture thereof .

When a conditional ceiling passes through a vertical into the floor, for example when welding pipes with a continuous seam and critical structures, experts recommend the PP-AN19 grade for low-carbon steels. When welding, the amount of slag is much greater. It holds well on verticals and ceilings.

The stainless metal is joined using PP-2VDSK, the core of which contains large amounts of nickel. Protective medium – inert gases.

The essence of arc powder welding

When welding with flux-cored and self-shielding wire, the body and the metal powder included in the filler melt. They fill the seam, connecting with the molten metal of the edges of the parts.

The flux contained inside melts and closes the bath from oxidation and combination with nitrogen . In self-shielding wire, it completely closes the seam, slowing down the cooling rate of the metal and allowing slag, gases, and moisture to come to the surface. A strong crust is formed on top along the entire width of the seam, which is easily removed when cold.

Technology and some of its disadvantages

Flux-cored welding wire is welded on semi-automatic machines and used on automatic lines . The consumable material is fed into the welding zone at a constant speed. The arc heats the bath and distributes the melt evenly in a non-contact manner - without touching the edges of the parts being joined.

The welding process is carried out using alternating current, the polarity is reversed. The quality of the seam complies with GOST 26271-84. Uniform wire feed and a stable arc allows you to make any seams of complexity, position and length without joints. Productivity is 2–4 times higher than when working with solid wire.

PPs are excellent at welding parts, but they also have the following disadvantages :

• relatively high cost;
• narrow specialization of each brand of consumables;
• it is difficult to weld sheets up to 1.5 mm thick;
• low viscosity and ductility; when bent, the wire breaks;
• feeding is carried out by special rollers with reduced compression only;
• Only the pulling mechanism on the handle is used.

When welding with self-shielding wire, the weld pool is difficult to see under the submerged arc. The cost of powder welding is justified when applying long seams . When welding short sections, a lot of waste is left.

The use of flux-cored wire on semi-automatic machines significantly increases the productivity and quality of the seam. For home use with a small amount of work, it is expensive. In workshops and production, where you need to weld well and quickly, you can get by with the efforts of welders with low grades, without inviting expensive specialists.

Source: https://svarka.guru/oborudovanie/rashodniki-i-kompletuyushie/poroshkovaya-provoloka.html

Flux-cored welding wire: application, characteristics, features, pros and cons

Welding wire is an important part of any metalworking work. If we are talking about semi-automatic welding, then welding is impossible without this accessory.

To improve the quality of work, there are several types of wire. It is needed for many types of metal. The wire is made of copper, aluminum or steel.

Powder stands out significantly from the rest. It is possible to work without using gas. At the same time, metal processing is possible in different locations.

In our article we will talk about what powder-based wires can be. We will talk about the advantages of working with such material in metalworking.

Total information

The core cable is considered an empty tunnel that is produced from metal. There may be flux inside it, which is combined with metal powder. You can work with this type of wire if we are talking about semi-automatic equipment without using gas.

If the wire is made in the CIS countries, it is needed for a certain steel. We are talking about durable black metal and low carbon options. There are fewer other types.

The cable may have a specific function, or be ordinary. Wire is an impurity matter. You can work with them when there is metalworking in any workshop type of welding. Common wires are used in factories and for everyday purposes.

The cored wire works so that the arch ignites easily and burns stably. In this case, the cables melt slowly and there is no spattering.

Slag separation occurs in the inner part of the wire. It comes off easily when you need to clean the surface. To do this, it is important to reduce the temperature of the part. The connection will be smooth if you already have experience working with a welding inverter.

Pros of work

The first thing you need to know is that you can operate a semi-automatic without using gas. A cylinder operating on a gas installation is not needed. The wire is intended for metalworking without gas.

It contains fluxes in its interior. When the wire burns, it comes out into the outer part of the apparatus. In this case, a cloud appears that has the characteristics of gas compounds.

With this technology, metal processing is possible in any location, even in hard-to-reach ones. Do not transport heavy cylinders. The only thing you need to do is thread the wire into the machine and feed it into the weld pool yourself.

You need your other hand to guide the torch. The connection will be visible. You will be able to watch how it is formed.

Self-shielding wires intended for metalworking are used in industry for surfacing purposes. The use of cored wires helps in obtaining metal with a similar composition of parts.

You need to buy wire, which consists of flux and metal powder. The wire is selected based on what metal is used in the work.

Disadvantages of work

Flux cored wire has disadvantages. They can be both important and secondary in metalworking. But you still need to pay attention to them.

Craftsmen note the fragility of the wire, which is intended for arched metalworking. We are talking specifically about powder types. If it is tucked into the mechanism and a lot of force is applied, it may break.

Another disadvantage when working is the limited placement. You can do metalworking vertically or from below.

This state of affairs is explained by the relative size of the bath during metalworking. Slag will appear at the top of the metal, which plays a negative role in this matter.

Vertical metalworking can be difficult. The issue will not be resolved even if you reduce the current strength.

This is due to the diameter of the cored wires and their output from 2.5 mm. In order for such a wire to function correctly, high current levels must be used. The cable will melt without interruption.

Craftsmen also say that the connections are of poor quality. Powder core cables have a void inside. It is impossible to place the flux inside so that it fits tightly to the structure.

There are large pores. Beginners who do not have much experience in welding face significant difficulties.

How to use cored wire

If you have once worked with natural welding using electrodes, then the new method will not bring difficulties for you. Powder additive is similar to conventional metalworking using electrodes. In this case, flux is used.

You can work in several ways. It is possible to feed wires independently, as well as to hold them in your hands. Another option is that you place the wires in the device and make the process simple.

9 times out of 10, when working with cored wires, you need to use static current and the opposite polarity. Certain cable models require the use of active current.

This happens in rare cases. This happens because direct current creates strong welds. In this case, the metal does not splash.

You need to watch how the cable flies out. The indicator should be from one and a half to two centimeters. You will find the exact figure in the instructions for the device.

It must be remembered that the burner must comply with the parameters. The hole at the outlet should be larger in diameter than the wire. The end of the light should be copper or one that consists of a copper alloy.

When making a connection, do not make any sudden movements with the torch. Everything should happen smoothly and using small fluctuations. Remember how the wire should be lit.

Before metalworking is carried out, it is heated in a furnace or using a torch. The outlet temperature should be 250 degrees.

The impurity material is heated for 120 minutes or more. The wire should not be heated if it consists of organic elements.

Let's sum it up

The wires used for semi-automatic welding are made of metal if we are talking about shielding gas. They can be made of flux, which will work in a similar way to gas.

The use of such wires will result in poor-quality seams. But sometimes powder additives are indispensable in work.

In many cases, the technician is unable to move the large device. If metalworking is carried out in a difficult location, then cored cables will be indispensable.

Even though there are pros and cons to this wire, sometimes they are not comparable to other materials. If you have had experience working with such wire, then write about it in the comments. We wish you success in your work!

Source: https://prosvarku.info/prisposobleniya-i-detali/poroshkovaya-svarochnaya-provoloka

The first production of flux-cored wire for welding was opened in Russia

The first Russian production of flux-cored wire for welding was launched by the Mezhgosmetiz-Mtsensk plant in the Oryol region. This was announced by the head of the company’s marketing department, Elena Bubnova. Flux-cored wire is in demand in the oil and gas industry. The project was implemented with the support of Gazprom and Transneft. About $1.5 million was invested in the construction of the new line.

 “We are working on an import substitution program. And there are no analogues of our products in Russia. Flux-cored wire is used for welding main gas and oil pipes. A seam made using such wire has virtually no defects,” Bubnova noted. JSC "Mezhgosmetiz-Mtsensk" (Mtsensk) is one of the leading manufacturers of welding electrodes and welding wire in Russia.

Take advantage of our services

Its products comply with Russian and European quality standards and have all the necessary certificates for sale on the Russian and CIS markets.

The distributor network covers all regions of the Russian Federation, Belarus, Kazakhstan, and other CIS countries. For 7 months of 2018, the volume of shipped products and services of own production of Mezhgosmetiz-Mtsensk JSC exceeded 680 million rubles (110% compared to the same period in 2017).

), the amount of tax payments amounted to 103 million rubles. Today 214 people work here.

Such powder products began to be used in welding technology relatively recently. At the same time, they immediately gained a good reputation among specialists, since with their help it was possible to solve many difficulties associated with the mechanization of surfacing and welding activities in the field and in open production areas. In addition, the use of flux-cored wire allowed:

• increase surfacing and welding productivity by 2–5 times;
• “forget” about very difficult and labor-intensive procedures for removing metal splashes from welded structures;
• guarantee excellent metal quality of welded joints and seams.

PPs are used for automatic and semi-automatic welding of low-alloy and carbon steels in a carbon dioxide atmosphere and in argon mixtures. Due to good metal penetration, such electrodes are optimal for making lap, butt and corner joints in several or one pass.

Flux-cored wires for welding are characterized by high resistance to the appearance of slag inclusions and the formation of porosity on the metal, provide stable jet transfer, and make it possible to perform welding work in any position. And the welding seam obtained using PP has a truly precise chemical composition both when used for welding argon mixtures and when welding in a carbon dioxide atmosphere.

Details of the composition of cored wires

The software described in the article consists of:

• special filler (called core);
• shells.

The sheath refers to a strip (cold rolled) made of soft, unpolished steel with a low carbon content. In terms of width and thickness, such a tape can have different sizes, which are determined by what diameter the finished shell should have.

As a rule, the thickness of the tape is in the range of 0.2–0.8 millimeters.

The tape we are interested in is supplied in circles or rolls, and a preservative lubricant is applied on top of the material, which is then removed (removing all contaminants along the way) using ultrasonic or mechanical methods.

The wire core is a combination of various ferroalloys, ores, minerals, metals and other elements that ensure the production of welds with specified operational parameters, as well as a stable and stable implementation of the welding (surfacing) procedure. All elements included in the core are divided into the following types of additives:

• Deoxidizing. By such components we mean metals with increased affinity for oxygen (that is, active), which are introduced into the core as powders and ferroalloys.
• Stabilizing. Elements with a low ionizing potential, due to which a stable electric arc is ensured under different welding modes.
• Gas-forming agents: wood flour, cellulose (organic), soda ash, marble (alkaline earth metals and alkali carbonates). They are needed to ensure that a gas phase is formed in the welding area, which protects the liquid metal from hydrogen and nitrogen, and also to displace air from the surface of the bath.
• Alloying agents: nickel powder, chromium, ferrovanadium, ferrochrome and others. Alloying components impart the desired characteristics to the weld metal.
• Slag-forming materials: alkali metal oxides, magnesite, aluminosilicates, silica, fluorides, other ores and minerals or combinations thereof.
• Special. Most often, iron is introduced in the form of powder, which performs the task of additionally influencing the surfacing or welding process.

It is worth saying that, based on the type of filler, the PPs in question are classified as one of five types. They are: rutile-fluorite, fluorite, rutile-organic, rutile and carbonate-fluorite. Most often, products with cores of the last listed type are used.

Principles of classification of flux-cored wires for welding

Such products are classified according to:

• core type;
• the ability to perform work in different positions of the welding electrode;
• main purpose;
• mechanical characteristics;
• the type of protection used.

The most significant is the classification based on the mechanical characteristics of the joint and the weld metal, since it allows one to clearly establish the feasibility of using a specific brand of wire for welding a given product or structure. The principle of this classification is based on the calculation of two required indicators for the weld metal - impact strength and tensile strength, which are determined during studies of standard samples.

According to the spatial position of the welding process, wires are divided into those that are used:

• in any position (marking – “T”);
• for welding vertical (“Vu”) and horizontal (“Bx”) seams;
• in the lower, vertical and horizontal position (“B”);
• in a horizontal and lower position on a vertical plane (“H”).

The classification of PP according to its type is also widespread:

• self-protective (PS);
• requiring additional protection of the weld pool (PG).

When using PG wire, the bath is additionally protected with flux or a mixture of gases. But PS products can be used without all these tricks that complicate the welding process. When a self-shielding wire is used, the bath is protected by melting and dissociating the slag and gas-forming materials present in the wire electrode.

The main advantages of self-protective software include the following facts:

• the product effectively resists increased load from feed rollers;
• welding is allowed in any position;
• the composition (chemical) of the seam has predetermined indicators;
• visual control of the welder over the open welding arc;
• compactness of equipment for welding (no need for devices for supplying gas and flux).

Wire with its own protection has been manufactured for more than half a century, and it was first produced at a plant owned by Lincoln Electric.

Let's note separately. Powder electrodes differ from each other in purpose. Some wires can be used for welding metal and steel pipes, others - for metal structures, while others are used exclusively at increased speeds for welding activities. But we will talk about this in more detail later when we consider different brands of PP.

The production of PP is carried out in four stages. First, the charge and steel strip are prepared, then the profile is formed and the charge is subsequently poured onto it. These operations are followed by a drawing operation. At the final stage, quality control of the resulting product is performed.

The tape is prepared as follows:

• take a roll of steel material (its width usually varies between 10–15 centimeters);
• cut the workpiece on a special machine into the required strip width;
• wind the resulting strips onto cassettes (at the same time, moisture and lubricant residues are immediately removed from the strips);
• The charge is prepared according to a certain recipe, and then it is sent in the form of a homogeneous composition to the drawing mill (to its charging mechanism).

At the next stage of flux-cored wire production, the charge is poured onto a belt (the process is carried out in special forming containers), a profile (round) is formed from the resulting mixture, which begins to be drawn on drawing drum units. Moreover, there are six such units.

At each subsequent section, the cross-section of the original workpiece is reduced by a specified amount. As a result, on the final drum the wire receives the diameter required by technical conditions.

Note that in order to reduce the cost of finished products and increase the level of their productivity, the drawing process is carried out at fairly high speeds (at least 300 PP meters per minute).

Control of wire after drawing equipment means, first of all, the calculation of a special coefficient, which is the ratio of the weight of the charge per unit length of the PP to the total weight of the product. This value is called the fill factor. It is different for different brands of PP (varies from 25 to 40 percent). In addition, the wire is examined for the mechanical properties of the deposited metal and for its welding and technological characteristics.

Many welding jobs on construction sites are performed with vertical seams. The PP-AN11 and PP-AN7 products are intended for such events. The production of flux-cored wire of these grades is carried out from steel strip 0.18 millimeters (workpiece thickness).

Elements are added to the charge for AN7 and AN11, which make it possible to obtain quickly crystallizing slag. It helps the weld pool stay in a vertical plane for quite a long time, until the seam completely hardens. When using the described brands of PP, it is recommended to feed it at a speed of about 120 meters per hour, using a welding current ranging from 130 to 170 amperes.

Wires PP-AN19 and PP-AN24 are identical in many technological features to the products discussed above. But AN19 and AN24 produce more slag, which improves the protection of the welding zone (however, the welding itself becomes more difficult for the performer).

Due to the “excess” of the slag mass, such wires guarantee stable mechanical properties of the connection. They are usually used for welding structures in which the seam changes its location from the ceiling to the bottom (for example, in pipelines).

Joints of various pipelines are also often welded with PPT-7 wire. It is made from 0.3 millimeter tape. The slag of such an electrode contains zirconium dioxide, which perfectly protects the welding zone from nitrogen.

When using PPT-7, welded joints are characterized by the absence of scales on the seam, characteristic shine and unique smoothness.

According to the recommended welding modes, this wire is similar to PP-2DSK, which is designed to work in the lower position.

PP-2DSK is used at currents from 200 to 450 amperes, it is supplied at a speed of up to 337 meters per hour (minimum 100 meters), and the electric arc has a voltage from 23 to 31 volts. The peculiarity of the charge for this product is the presence in it of a large amount (over 50 percent) of fluorspar, as well as aluminum powder. Due to this composition, slag after welding can be removed from the seam without the slightest difficulty.

For welding in automatic mode, in most cases, PP-2VDSK is used, which has a complex charge composition aimed at ensuring that the slag formed during the melting of the wire helps to remove nitride and oxide compounds from the liquid metal as completely as possible. This is very important, since it is in them that the oxygen and nitrogen of the air are found in a bound state. The main component of the charge for PP-2VDSK is nickel.

Source: http://integral-russia.ru/2018/09/10/v-rossii-otkryto-pervoe-proizvodstvo-poroshkovoj-provoloki-dlya-svarki/

Flux cored wire welding | Welding and Control

The design of the flux-cored wire determines some features of its melting by an arc. The core of the wire consists of 50-70% non-metallic materials and therefore its electrical resistance is high - hundreds of times greater than that of the metal sheath.

Flux cored wire welding

 Therefore, almost all of the welding current passes through the metal shell, melting it. The melting of the core located inside the metal shell occurs mainly due to the heat radiation of the arc and heat transfer from the expanding metal of the shell. In view of this, the core can protrude from the shell, touch the liquid metal bath, or pass into it partially in an unmolten state. This increases clogging of the weld metal with non-metallic inclusions.

Flux cored wire sections

Flux cored wire welding technique 

 Typically, flux-cored wires are used for semi-automatic hose welding.

Due to the possibility of observing the formation of a seam, the technique for welding butt and fillet welds in various joints is practically no different from the technique for welding them in shielding gases with a consumable electrode.

However, the formation of slag on the surface of the weld pool, which under some conditions flows into the gap between the edges in the front part of the weld pool, makes penetration of the weld root difficult. When multilayer welding, the surface of the previous layers should be thoroughly cleaned of slag.

Advantages of the flux-cored wire welding method

Submerged arc welding, especially semi-automatic welding, is difficult due to the inability to accurately guide the electrode into the groove and observe the formation of a seam. When welding in shielding gases, the reliability of protection may be impaired due to drafts, splashing of gas nozzles, etc.

In these conditions, the use of flux-cored wires, which combine the positive properties of open steel electrodes (protection, alloying and deoxidation of molten metal), and mechanized welding with solid wires (high productivity) represents great production advantages, especially in installation conditions.

This is also facilitated by the absence of gas equipment (cylinders, hoses, gas reducers), flux and flux-based equipment, which complicate the welding process or increase its labor intensity (filling and cleaning up flux, etc.).

During semi-automatic welding, the ability to monitor the direction of the electrode into the groove, especially when welding with its transverse vibrations, as well as the formation of a seam, are the main advantages of flux-cored wire welding. Changing the composition of the flux-cored wire core filler makes it possible to influence the chemical composition of the weld and the technological characteristics of the arc.

Disadvantages of the flux-cored wire welding method

The low rigidity of the tubular structure of flux-cored wire requires the use of feed mechanisms with limited wire compression force in the feed rollers.

The production of wire mainly with a diameter of 2.6 mm or more, requiring the use of increased welding currents for stable arc burning, allows them to be used for welding only in the lower and rarely in the vertical position.

This is explained by the fact that the resulting weld pool of increased volume, covered with liquid-flowing slag, is not held in the vertical and overhead positions by the force of surface tension and arc pressure.

The presence of slag on the surface of the weld pool, slowing down the crystallization of the molten metal, also worsens the conditions for the formation of a weld in spatial positions other than the bottom. A significant drawback of flux-cored wires, which hinders their widespread industrial use, is the increased likelihood of pores forming in welds, caused by the presence of voids in the wire.

In addition, unmelted components of the core, passing into the weld pool, contribute to the appearance of gaseous products. Dissociation of marble, oxidation and reduction of carbon during heating and melting of ferromanganese in combination with marble and other processes can also lead to the formation of a gas phase weld pool in the metal.

As a result, internal and surface pores appear in the seams.

Under these conditions, the welding mode (current strength, voltage, electrode stickout) has a great influence on the possibility of pores appearing in the seams. The likelihood of pore formation is also increased by moisture that gets into the filler during storage of the wire, and in addition, grease and rust, traces of which are present on metal tape.

Flux-cored wire can also be used for welding in carbon dioxide. The likelihood of porosity forming in the seams in this case is reduced. Depending on the composition of the filler, a post is used for welding

Source: https://svarkka.ru/__trashed/