What does reverse polarity electrodes mean - Metals and their processing

Polarity of welding electrodes: how to determine direct and reverse polarity?

Electric arc welding can be carried out using equipment that produces direct or alternating current. If working on alternating current does not have any nuances regarding the correct connection of the ground and the electrode holder, then when welding on direct current, the polarity of the welding electrodes is of great importance.

General concepts

Depending on which pole of the welding machine is connected to the holder, the type and features of the welding mode are determined:

Welding with direct polarity involves connecting the positive pole to the workpieces being joined (ground), and the negative pole to the electrode holder.
To perform work with reverse polarity, the poles are swapped (plus to the holder, minus to ground).

Regardless of the polarity of the electrodes used, welding with direct current has common features compared to the use of alternating voltage:

Due to the fact that the direction of electron movement is constant, during welding there is no excessive splashing of the molten metal. That is why the seam itself turns out to be of higher quality and more accurate.
The polarity of connecting the electrodes plays a big role because the positive and negative elements heat up differently, and this affects not only the penetration depth, but also the amount of metal transferred from the melting electrode.
In any case, it is necessary to ensure high-quality contact of the wire with the workpiece; this is the only way to ensure the stability and reliability of the welding arc.

Straight polarity welding

With this method of connecting electrodes, the workpiece is exposed to more heat, not the electrode . This mode is characterized by the release of significantly more heat.

Therefore, straight polarity welding is recommended for the following operations:

Cutting metal with any type of electrodes.
Welding of workpieces of considerable thickness.
Working with metals that have a higher melting point.

It is in these cases that the workpieces need to be heated to higher temperatures; significant heat generation is required to perform these works.

Reverse polarity welding

In this case, the electrode is subjected to greater heating, so less thermal energy is transferred to the workpiece.

Thanks to this, reverse polarity electrodes allow you to perform work in a softer (delicate) mode.

This is true in many cases, for example, welding stainless or thin sheet steel, alloys that are sensitive to heat.

This connection is also used for work in shielding gases or submerged arcs.

Determining the required polarity

There are many disputes about how to determine the polarity of electrodes during welding, with each side giving seemingly correct arguments. Opponents of the above version refer to textbooks on welding technology published in the middle of the last century, believing that the information contained in them is the most correct.

But it is worth considering that since then there has been a significant improvement in welding equipment and consumables. Therefore, it is still not worth relying on recommendations regarding outdated technologies. The choice of polarity described above is considered the most correct.

There is another group of welders who believe that it is better (or rather more convenient) to perform any work exclusively with reverse polarity. This is primarily due to the fact that in this mode the electrodes stick less and there is no risk of burning through the metal. But the advent of inverter welding equipment solved this problem.

It is worth paying attention to the type of electrodes. There are brands that can only be used with direct or reverse polarity; violation of the manufacturer’s recommendations can not only complicate the welding process, but also make it impossible in principle.

Today, manufacturers already offer electrodes that can operate at any voltage and different polarities.

The correct choice of electrode connection polarity helps to simplify the welding process and improve the quality of the seam.

Source: https://steelguide.ru/svarka/svarochnye-materialy/polyarnost-svarochnyx-elektrodov.html

Direct and reverse polarity when welding with an inverter, welding modes and recommendations

The emergence of inverter welding machines has significantly expanded the scope of their application. This type of work has become available to every home craftsman. But model owners do not always know the features of use. In particular, why is direct polarity needed and in what cases is reverse polarity used when welding with an inverter.

Basics of using an inverter welding machine

This type of equipment is designed to perform electric arc welding, which can be used to join or cut steel workpieces. For application, you need to decide on the basic parameters - select the welding current and type of electrodes. Then you can get to work.

General procedure for using the inverter

Preparation of the surface of the material - cleaning from rust and degreasing. This is necessary to form a reliable seam.
Select the welding current mode and electrodes. They depend on the characteristics of the metal and the parameters of the future weld.
The ground terminal (plus) must be connected to the metal surface. It is important that it does not interfere with basic operations.
A “minus” is connected to the electrode holder.
Arc formation. This can be done by striking or tapping the electrode on the metal in the area of the seam.
After forming the joint, it is necessary to remove the scale with a hammer.

These types of welds are important for cylindrical vessels such as local VOC treatment plants, oil and gas separators, and construction tanks.

How to choose the right model

The use of forward and reverse polarity modes is available for all types of inverters. However, in addition to this function, the devices must have additional characteristics. The scope of their application, the speed and comfort of performing work depend on this. Therefore, the choice of model must be approached professionally.

Recommended functionality of inverters:

Hot start. There is a short-term increase in current to quickly form an arc.
Anti-stick. At high current values, there is a high probability of its welding to the metal. Reducing this value will allow you to create the most even seam.
Fast and Furious. Activates automatically when molten metal appears at the end of the electrode. A brief increase in operating current will prevent sticking.
Alternating current. It is necessary for welding work with aluminum workpieces.
Reduced idle speed. Refers to safety precautions when operating in places with high humidity or small rooms. Using a special block, the voltage is reduced to 15 V.
Indication type. The best option is a digital display of current parameters.

It is also important to choose the welding current, which directly depends on the diameter of the electrode used and the thickness of the metal.

When working with inverter welding machines, electrodes of the ANO and MR brands are most often used. They are suitable for forming seams on steel surfaces. Welding aluminum products or workpieces made of complex alloys requires the selection of special consumables; additives can be used.

When to apply forward and reverse polarity

The change in polarity during operation is due to ongoing processes. In addition to selecting the basic welding parameters, you can swap the connected terminals. Current flows from the negative element to the positive element. As a result, the first one heats up.

Such operations are recommended in the following cases:

Straight polarity – “minus” is connected to the electrode, “plus” is connected to the metal. The surface of the latter is heated. This mode is necessary for processing deep seams with large workpiece thicknesses.
Reverse polarity - the electrode is connected to the “plus”, the metal to the “minus”. The reverse process occurs - heating of the electrode when the metal is cold. This is necessary for processing thin-walled workpieces, but leads to rapid burnout of the electrode.

The use of one mode or another depends on the tasks assigned. The ease of changing terminals allows these operations to be performed while processing one workpiece.

Source: https://ismith.ru/welding/pryamaya-i-obratnaya-polyarnost-pri-svarke/

What is direct and reverse polarity when welding with direct current

A high-quality welded connection when working with DC devices largely depends on their settings. Even the simplest inverter has not only current settings, but also polarity.

Most often, the default is straight polarity when welding and you can work with your inverter for years without knowing all its capabilities.

If you have a need to weld high-alloy steel or cannot achieve a high-quality seam, then knowledge of all the subtleties of the settings is simply necessary for you. We will talk about what polarity is and how it affects welding work.

What is forward and reverse polarity

DC welding implies the presence of a socket for connecting to the “+” and “–” of the welding machine. Depending on where the ground is connected and where the electrode is connected, the polarity is distinguished.

Direct polarity is a connection diagram in which ground is connected to the positive socket, and an electrode is connected to the negative socket. In this case, the type and polarity of the current determines the existence of anode and cathode spots. With this connection, the anodic (hotter) is formed on the workpiece side.
Reverse polarity - the mass is connected to the minus, and the electrode to the plus. In reverse polarity when welding with direct current, an anode spot with a higher temperature is formed on the opposite side, that is, the electrode.

Note! Welding with alternating current involves independently changing the polarity up to hundreds of times per second, so in such cases it makes no sense to follow the connection diagram.

What determines the choice of polarity

By changing the type of connection, you can concentrate the heat either on the part being welded or on the electrode (by moving the anode spot). The positive socket is responsible for heating, therefore, with a direct connection, when the plus is connected to the metal, the welded joint heats up more, and with reverse polarity, the electrode heats up more. We recommend! How to cook semi-automatically with carbon dioxide

Thanks to this feature, we can choose a connection diagram based on:

Metal thickness. If we are welding thick or medium-thick parts, then a direct connection is suitable, in which the heat concentrated on the product will help to obtain a deeper seam and high-quality penetration. This type of connection is also suitable for cutting metals of various thicknesses. Thin metals are best welded in reverse polarity, concentrating most of the heat on the electrode. This way the part will not succumb to overheating, and the electrode itself will melt faster.
Kind of metal. The ability to change the localization of the heat spot helps to select the most effective operating schemes for various metals. For example, if we are welding stainless steel or cast iron, then a reverse connection is necessary to help avoid overheating of the alloy and the formation of refractory compounds. For aluminum, a direct connection is necessary, otherwise it will be very difficult to break through the oxides. Before starting work, carefully study the recommendations for setting up the device for a specific alloy.
Type of electrode or wire. Like metals, electrodes have their own temperature regimes, which are largely related to the type of flux. For example, when working with carbon electrodes, you cannot use reverse polarity, otherwise the flux will overheat and the electrode will become unusable. To select the setting that suits your electrode, look at the type of wire and flux, or use the manufacturer's recommendations. Speaking about wires for semi-automatic machines, they also have recommendations regarding connecting the minus and plus of the device.

Now you know what can affect your connection settings. There are cases when the metal requires one setting, and the electrode requires completely different settings. In such cases, compromises must be made by adjusting the amperage and duty cycles.

Remember! The type of connection does not depend on the spatial position.

Features of welding with straight polarity current

Straight polarity when working with direct current has a number of features. We have already listed some of them, the rest are worth paying special attention to:

the weld seam is deep, but quite narrow.
Suitable for most steels with a thickness of 3 mm or more.
Non-ferrous metals using a tungsten rod are welded only with straight polarity.
characterized by a stable arc and, as a result, a better quality seam.
It is prohibited to use electrodes for AC welding machines.
better suited for cutting metal.

We recommend! How to weld aluminum with an inverter using an electrode

Features of welding with reverse polarity current

Like direct polarity, reverse polarity when welding with an inverter has a number of features, knowing which you can avoid a number of mistakes common to beginners. It is worth highlighting the following features:

when welding with direct current with reverse polarity, the seam is less deep, but wider
Excellent for welding thin and medium thickness metals. When working with thick workpieces, the quality of the seam decreases sharply.
It is prohibited to work with reverse polarity with electrodes sensitive to overheating.
at low currents there is a significant decrease in the quality of the weld due to the jumping arc.
In addition to the reverse connection, when working with high-alloy steels, the recommendations regarding the work cycle and cooling of the workpiece must be strictly adhered to.

Conclusion

DC welding machines, such as inverters or semi-automatic machines, are simple enough to use at home. That is why the demand and supply of these devices on the market is constantly growing. This is facilitated by their availability, low cost, and it is easier to cook with direct current than with alternating current.

However, in order to obtain a high-quality, beautiful and durable welded joint, you need to know a number of technological features, including the purpose and types of polarity. With the knowledge from this article and a DC source, you can do any welding work with your own hands.

The main thing is a careful approach to work and compliance with all protective measures.

Source: https://svarkagid.ru/tehnologii/pryamaya-i-obratnaya-polyarnost-pri-svarke-invertorom.html

DC electrodes for welding: brands, which ones are better, markings, features of constant current

Welding with direct current has a wider range of applications than welding using alternating voltage. This is due to several undeniable advantages of this type of welding. Therefore, electrodes for DC welding are more in demand. It is the permanent materials that we will consider in the article.

THIS IS INTERESTING: How to convert a welding machine from alternating to permanent

It should be noted that not all equipment has the ability to provide constant voltage. If the welder has a transformer without a rectifier or an alternating current generator, then it is necessary to use consumables for alternating current.

Features of DC welding

The welding process using constant voltage has a number of distinctive properties. Some characteristics can be considered as advantages, others as disadvantages.

Pros:

the almost complete absence spattering ensures a reduction in electrode costs;
the constant makes the welder’s work easier ;
high productivity and labor efficiency;
stability and stability of the arc even when exposed to negative influences: gusts of wind, voltage fluctuations and others;
high-quality and neat seam;
thin products ;
absence of uncooked areas.

Minuses:

welding using direct current is carried out using inverter machines. This equipment is highly expensive ;
“magnetic blast” creates problems with an unstable arc in difficult places (eg corners).

Forward or reverse polarity

A welder needs to know! Connecting metals with direct current can be carried out in two modes: with direct and reverse polarity. First mode: a minus is connected to the electrode, and a plus to the metal product. When welding, reverse polarity is the opposite: positive to the electrode , negative to the workpiece.

Welding with direct polarity forms a cathode spot at the tip of the electrode, and reverse polarity creates an anodic spot. In the area of the anode spot the temperature reaches 3900°C, in the area of the cathode spot – up to 3200°C.

During reverse polarity welding, heat is concentrated on the workpiece , causing the root of the weld to deepen .

Therefore, it is better to use reverse polarity voltage when welding thick-walled products and in cases where high temperatures are required .

Direct polarity current is used to work with the following materials:

structures made of thin sheet steel;
fusible metals;
overheat-sensitive steels : stainless, alloyed and high-carbon.

Features of welding with reverse polarity:

large spattering and high penetration are due to the fact that the metal from the materials is transferred into the weld pool in large drops;
the electric arc is unstable ;
correct heating of the product;
some welding consumables show an increase in deposition rate ;
the weld seam has a non-standard material composition : no carbon, a large amount of silicon and manganese.
less heating of the rod allows the specialist to use currents with a higher value .

Features of connection with reverse polarity:

the need to reduce the current potential to reduce the temperature of the product;
It is recommended to weld with intermittent seam;
very thin parts are welded with periodic interruption of the arc; flanging (see features of welding thin metal)
When joining with an overlap, the workpieces must be pressed tightly against each other. Failure to comply with this condition may result in burning of the upper part.
the butt connection should be made with a minimum gap or, best of all, no gap at all;
When welding thin products with uneven edges, a copper or steel plate should be placed under the joint . Such an auxiliary layer will take away some of the heat from the welding process;
it is possible to flange the edges to be joined, the angle is 90°.

Source: https://WeldElec.com/info/elektrody-postoyannogo-toka/

Reverse polarity when welding

Unlike traditional gas welding, the electric arc method has a number of features. One of the most significant of them is considered to be the arc temperature, which can reach 5000 ºС, which is much higher than the melting point of any existing metal. This partly explains the wide variety of methods and technologies of this welding method, which make it possible to solve a wide variety of problems and applications with its help.

In electric arc welding, it is possible to use several types of arc, electrodes with different properties and different degrees of mechanization.

In this case, the process can be carried out by an electric arc fed by currents of various types (direct or alternating), with direct and reverse polarity in welding seams of different spatial positions.

In addition to these factors, the speed of welding, diameter, type and brand of electrode and arc voltage with the strength of the welding electric current are of great importance for the welding mode. Each of these parameters can significantly influence the progress of the process and requires careful consideration in the welding mode.

In selecting the diameter of the electrode, in addition to the thickness of the metals being processed, the location of the seam in space, as well as the number of welding layers, is important. Of the various options for spatial positions, the lower one is preferable as the most convenient. Based on the selected diameter of the electrode, taking into account the location of the seam, the strength of the welding electric current is determined. In determining its type with polarity, in addition to the thickness of the metal being processed, its type and physicochemical properties influence.

When welding with direct current of reverse polarity, a large amount of heat is generated at the electrode. Therefore, it is used for thin metals, helping to avoid burn-through. Reverse polarity is also necessary when welding with an inverter when processing high-alloy steels, so as not to overheat them. In all other cases, alternating current is usually used as it is cheaper than direct current.

Welding with direct and reverse polarity current

Welding with straight polarity means that in its process, current is supplied from the welding rectifier to the workpiece with a positive charge. In this case, the “plus” terminal of the device is connected to the product using a cable. Accordingly, a negative charge is supplied to the electrode connected to the minus terminal through the electrode holder.

The anode, which is the positive pole, has a higher temperature than the cathode, which serves as the negative pole. Therefore, the use of electric currents of direct polarity is advisable in welding workpieces with thick walls.

It is also justified for cutting metal products and in other situations that require the release of a significant amount of heat, which is what characterizes this type of connection.

When welding with reverse polarity current, the opposite connection order is required. The negative charge from the negative terminal is applied to the structure being welded, and the positive charge from the positive terminal is directed to the electrode. With a given polarity of the welding electric current, in comparison with a direct connection, a larger volume of heat is generated at the electrode end with relatively less heating of the workpiece, which facilitates “delicate” welding.

It is used when there is a possibility of burning through the workpieces. Therefore, welding with reverse polarity electrodes is suitable for working with stainless and alloy steels, other alloys that react to overheating, as well as for joining thin-sheet metal structures. No less effective is connecting reverse polarity in the welding process using an electric arc, gas protection and flux-cored welding.

Regardless of the power supply polarity used, there are a number of general factors that should be taken into account. If direct current is used, the resulting seam will be neater, without a lot of metal spatter. This is explained by the absence of frequent changes in polarity when working with direct electric current, which distinguishes it favorably from alternating current.

If consumable electrodes are used for welding, then due to the different heating of the anode and cathode, the method of connecting the electric current can affect the volume of molten electrode metal transferred to the product. To prevent possible burns of the workpieces being welded in the area where the power cable is connected, no matter what charge (positive or negative), it is necessary to use a clamping clamp.

What determines the choice of polarity?

The choice of electric current polarity is limited by the electrode coating material used for welding. An example of this is the welding process using carbon electrodes, which heat up more strongly when welding with reverse polarity and are destroyed more quickly. And uncoated wire, for example, burns better with direct polarity than with reverse polarity, and does not burn at all when powered by alternating current.

The depth of penetration and the width of the resulting seam largely depend on the parameters of the welding mode. Thus, with an increase in the strength of the welding electric current, even at a constant welding speed, the penetration increases, that is, the depth of metal penetration increases.

This is explained by an increase in the heat input of the arc, which depends on the amount of heat passing through a unit length of the welded seam. As welding currents increase, the pressure exerted by the arc on the surface of the molten pool also increases.

Under its influence, molten metal can be forced out from under the arc, this is fraught with through penetration of the part.

The shape and size of the seam formed can also be influenced by the type of electric current and its polarity. Thus, a direct current of reverse polarity can provide a much greater depth of penetration than a direct current with direct polarity, this is due to the unequal volumes of heat generated at the anode and cathode. As the speed of the welding process increases, the width of the seam and the depth of penetration decrease.

Source: https://promplace.ru/svarka-metallov-staty/obratnaya-polyarnost-pri-svarke-1580.htm

What does reverse polarity mean when welding?

Direct and reverse polarity when welding with an inverter (or any other welding machine) sets the tone for the entire work process and the correct choice of this parameter directly affects the quality of the welded joint. With reverse polarity, “minus” is applied to the metal parts, and “plus” is applied to the electrode. In the case of direct polarity, the opposite is true. And this is just one of several features that need to be taken into account when welding. But today we will focus on reverse polarity.

In this article we will talk in more detail about reverse polarity when welding. You will learn what reverse polarity is, under what conditions this type of current direction is selected, what equipment is used when working with reverse polarity, and how to set up the device to get the job done efficiently and quickly.

general information

What is reverse polarity in welding? Reversing current polarity is the process of applying a positive electrical charge to the electrode and a negative electrical charge to the metal part being welded.

In this case, the heat is distributed in the reverse order: the electrode significantly overheats, but the part, on the contrary, does not warm up at all.

For this reason, reverse polarity in arc welding is used in special cases when there is a high chance of deforming the metal at high temperatures or a very neat seam is required. Due to exposure to high temperatures, the metal easily warms up, the seam is formed quickly and evenly.

Reverse polarity is simply necessary when welding stainless steel, thin metal, alloy and high-carbon steel, aluminum and other alloys that are easily subject to overheating. For example, a current of reverse polarity is a mandatory satellite of electric arc welding using flux or welding in an inert gas environment. You simply won’t be able to deposit metal well if you use, say, argon arc welding and set straight polarity.

Many beginners still wonder why some jobs use reverse or direct polarity when welding with an inverter? We will try to explain in more detail. Reverse polarity is used in work, since when the arc burns, areas with a high concentration of anodes and cathodes are formed at the end of the welding rod. In this case, the temperatures differ significantly; the anode region can be hotter than the cathode region by 700 degrees Celsius!

Based on this, it is not difficult to guess that with reverse polarity, a huge amount of heat is released, which contributes to high-quality welding of the metal. If this indicator is important for welding a particular metal, then reverse polarity is used. Direct current direction is used in all other cases.

By the way, when working with direct current of reverse polarity, the electrode burns out much faster than when working with direct polarity. This is again due to excessive heating of the rod. So be prepared to overuse components. If you are using alternating current, then the choice of polarity is not relevant at all, since the direction of the current will constantly change during operation.

So, let us repeat: polarity is set only when working with direct current. Reverse polarity is used when welding special, easily deformable metals, when the seam needs to be formed quickly and efficiently.

Welding with reverse polarity current cannot affect the properties of the electrode used in the work. A large amount of heat passes through the rod, which means that the part itself heats up very quickly, the metal is easily and deeply boiled, and there is practically no spattering (especially when welding with flux).

Is it possible to change the polarity directly during operation if the welding inverter (or any other type of equipment) has such an option? You can, of course, try this method as an experiment, but we will not recommend it to you. This is simply not necessary.

But sometimes there are situations when you started working with the wrong polarity and suddenly discovered this, so you want to set other settings. Try to finish what you started without changing the polarity (unless the requirements for the weld are very high). Yes, the electrode will stick, but you have to live with it.

If the seam should turn out to be of high quality and beautiful, then it is better to start the work again, setting a different polarity.

Polarity selection

Let's spend a little more time choosing the correct polarity. In addition to the metal itself, it is important to consider the electrodes or wire that you use in your work. The choice of direct or reverse polarity when welding depends on the type of coating.

If you work with a carbon electrode, then connecting in the opposite way is undesirable, since such rods quickly collapse when overheated.

If you use a wire that does not have any coating at all, then it will melt without problems even with straight polarity, but when used with alternating current it will not even heat up.

The choice of polarity is also influenced by what kind of seam you want to make, what size and shape it should have. When working with constant and reverse direction, the seams are well fused, the welded joint is narrow and shallow, since the welding process does not last long due to high temperatures.

Source: https://crast.ru/instrumenty/chto-znachit-obratnaja-poljarnost-pri-svarke

Reverse and direct polarity when welding with an inverter - Ice advice

Business October 10, 2017

THIS IS INTERESTING: What is welding flux used for?

When welding a structure using direct current, it is important to know that the quality of the seam will depend largely on the settings of the machine. An important nuance is that in addition to the current regulator, it is necessary to select the correct polarity. There can be only two types - direct and reverse polarity when welding with an inverter.

What does straight polarity mean?

In order to achieve a high-quality seam when welding various steels, it is important to know which polarity is suitable for the material that needs to be processed. The general essence of welding with an inverter is that the machine must have “+” and “-“ sockets. Depending on which socket the ground will be connected to and which the electrode will be connected to, the polarity will depend.

Direct polarity is connected in this way: a ground is added to the positive socket, and an electrode is added to the negative socket. It is important to know here that the type and polarity of the current will be determined by the existence of the anode and cathode spots. During straight polarity welding, an anodic spot, which is hotter, will form on the workpiece side.

What does reverse polarity mean?

With reverse polarity, it is logical that the connections of the ground and the electrode are swapped. That is, an electrode is connected to the positive socket, and ground is connected to the negative socket. Here you need to understand that when connecting the sockets in this way, an anode spot will also form, but it will appear not on the side of the workpiece, but on the opposite side from it, that is, on the electrode.

Important note! Connecting the polarity manually is carried out only when welding with an inverter, that is, in the presence of direct current. When carrying out the same process, but on alternating current, the polarity is changed up to hundreds of times per second independently. Therefore, the connection method does not matter.

As you can see, the difference between direct and reverse polarity when welding with an inverter is that the anode spot will form in different places.

Source: https://LEDsovet.ru/obratnaia-i-priamaia-poliarnost-pri-svarke-invertorom/

Features of reverse polarity welding

Equipment

Welding with reverse direct current is carried out only on welding machines designed for such work. Choosing a welding machine is a very important topic, so in this article we will tell you only the most important things.

First of all, your welding machine must be able to work with different modes and feed wire at different speeds.

So you can weld with argon or carbon dioxide (this is very important when welding stainless steel), but you cannot weld with flux-cored wire, since this requires straight polarity.

With the help of reverse polarity, it becomes possible to use semi-automatic welding equipment in your work. Here the holder and ground are connected to “plus” and “minus”, respectively. Due to this, the flux burns out gradually and completely, and the welding itself occurs in the resulting gas cloud.

Instead of a conclusion

Choosing polarity when welding with DC is not an easy task if you are a beginner welder.

You need to take into account all possible nuances related to the type and thickness of the metal, the electrode or filler wire used in the work, and also successfully select a welding machine with the set of functions you need.

All this seems like something very complicated, but believe me, with experience you will set up the device and select components without even thinking. Study a lot of theory and don't forget to put it into practice.

Tell us in the comments about your personal experience with reverse polarity welding if you are an experienced craftsman. This will be very useful for beginners. Also share this article on social networks. We wish you good luck in your work!

Source: https://svarkaed.ru/svarka/obuchenie-svarke/osobennosti-svarki-s-obratnoj-polyarnostyu.html

How to determine the polarity of the electrodes?

Welding is a manual labor, but welders must have a sufficient amount of technical knowledge, even if physics was something supernatural for them at school.

One of the mandatory concepts that you need to know is “welding current” . The welder must have a good understanding of polarity and the impact it has on the welding process.

On welding machines and electrodes you can see the designations AC or DC, which describe the polarity of the current. Why do electric currents and polarities occur during welding? Let's look at these concepts carefully.

What is alternating (AC) and direct (DC) current?

AC from English “alternating current” means alternating current , and DC “direct current” means direct current .

AC alternates the direction of current, but DC flows in only one direction.

Welding machines and electrodes marked DC have a constant polarity, while those marked AC change polarity 120 times per second with a current frequency of 60 hertz.

How do alternating and direct current differ in welding?

Direct current (DC) welding creates smoother, more stable arcs and produces less spatter. It is easier to weld in the vertical and upper positions.

However, alternating current (AC) may be the preferred choice of new welders as it is often used in low-cost, entry-level welders. AC is also common in shipbuilding welding or any environment where the arc may float from side to side.

What is polarity?

The electrical circuit that occurs when the welding machine is turned on has a negative and a positive pole - this property is called polarity . Polarity is important in welding because choosing the correct polarity affects the strength and quality of the weld. Using the wrong polarity can result in a lot of spatter, poor fusion and loss of control of the welding arc.

When welding with alternating current, polarity is not required!

In turn, welding using direct current is of two types:

— welding with direct polarity

— welding with reverse polarity

Polarity

straight reverse

negative positive

(–) (+)

The welding process will vary depending on the direction, polarity of the current: positive (+) or negative (–) .

Positive DC polarity (DC+) will provide high penetration rates, while negative DC polarity (DC–) will give less penetration but higher deposition rates (eg on thin sheet metal). Various shielding gases can further influence the welding process.

Welding with straight polarity current

Direct polarity welding is usually understood as welding, during which a positive charge the part (product) being from the welding machine, i.e. The welding cable connects the workpiece being welded to the (+) terminal of the welding machine. A negative charge is supplied to the electrode through an electrode holder connected by a cable to the (–) terminal.

When welding with direct polarity current, the main temperature load falls on the metal part being welded . That is, it heats up more, which allows the root of the weld to be deepened.

Direct polarity current is recommended to be used when it is necessary to cut metal structures and weld thick-walled parts, as well as in other cases when it is necessary to achieve a large heat release, which is precisely a characteristic feature of this type of connection.

Reverse polarity current welding

Reverse polarity welding is usually understood as welding, during which a negative charge is the part (product) being welded from the welding machine, i.e. The welding cable connects the workpiece being welded to the (–) terminal of the welding machine. A positive charge is supplied to the electrode through an electrode holder connected by a cable to the (+) terminal.

When welding with reverse polarity current, more heat is released at the electrode , and heating of the part comparatively reduced . This allows for more “delicate” welding and reduces the likelihood of burning through the part.

Welding with reverse polarity current is recommended for use when it is necessary to weld thin sheets of metal, stainless steel, alloy steel, and other steels and alloys that are sensitive to overheating.

Since alternating current (AC) is half positive and half negative, its welding properties are right in the middle of the positive and negative polarity of direct current (DC). Some welders choose alternating current (AC) if they want to avoid deep penetration. For example, during repair work on rusty metals.

Although alternating current itself has no polarity, if alternating current welding electrodes are used with direct current, they will show poorer results. Therefore, electrode manufacturers usually indicate the most appropriate polarity on the electrode coating and packaging.

Understanding the direction and polarity of welding current is important for proper welding. Knowing how these factors affect your weld will make your job easier.

Source: https://rem-serv.com/kak-opredelit-polyarnost-elektrodov/

Direct and reverse polarity when welding with an inverter - Metalworker's Handbook

The advent of inverter welding machines has helped to open up new areas of application. Thanks to this, every home master can use it for their own purposes. But not all owners know the features of such tools. Particularly relevant is the question of what reverse and direct polarity are when welding with an inverter. It is this topic that will be discussed in the article.

Why do you need this type of welding machine? Most often, a welding inverter is used for electric arc welding. It is this that allows you to connect or separate workpieces made of steel of various types. Before using such a device, it is necessary to select two main parameters - welding current and type of electrodes. After this, you can safely begin working with this unit.

How to use the inverter

Having learned about the basics of using this device, you need to consider how to operate it. This includes the following stages:

The surface of the material is separated from dirt and rust. This will be needed in order to form a reliable seam;
Select the welding current mode and electrode type. Here it is important to consider both the material and the parameters of the weld;
Connect the positive terminal to a metal surface to carry out the necessary operations;
We connect the minus to the electrode holder;
We form an arc, then use a hammer to remove scale from the resulting seam.

This is the standard sequence of actions. However, it does not take into account the shape of the connection and the orientation of the electrode. Such subtleties are necessary to form special types of seams for welding. The latter are used for cylindrical containers (separators in the oil and gas industry, construction tanks).

Choosing the right model

For all units, both direct and reverse polarity are available when welding with an inverter. But such inverters must have additional characteristics, which determine the scope of application, speed and comfort of the work performed. And therefore it is necessary to take a professional approach to choosing a welding inverter. The recommended functionality of such a unit is as follows:

Hot start for rapid arc formation;
Anti-stick allows you to form a seam of the correct shape (as smooth as possible);
Automatically activated when there is molten metal at the end of the electrode. A short increase in current will avoid sticking;
Alternating current for working with aluminum workpieces;
To work in rooms with high humidity or a small area, a reduced idle value is required;
The type of indication is also important, ideally digital symbols of the parameter.

In addition, you need to clearly select the welding current, since it directly depends on the diameter of the electrode used and the thickness of the material. The most commonly used electrodes are the ANO and MR brands, which are suitable for creating a seam on metal surfaces. If you need to weld aluminum structures or several alloys, you will need special materials, including additives.

Application of direct and reverse polarity

The change in polarity occurs due to ongoing processes. In addition to selecting the basic parameters, you can swap the connected terminals. As a result, current will flow from the negative element to the positive one and the first one will heat up to the required values.

Direct polarity is needed in cases where deep seams are processed on thick workpieces. Here the minus is connected to the electrode, the metal has a plus. It is also good to use this polarity when welding cast iron and deep penetration of the main metal (aluminum, iron, and so on).

Reverse polarity (plus to the electrode, minus to the metal) . The metal is cold, the electrode heats up. It is used only for thin-walled workpieces, since the electrode fails very quickly. Depending on the goals of the process, the wizard applies one of the operating modes.

It should also be taken into account that with alternating current low-carbon steels are welded with rutile-coated electrodes, in the presence of magnetic blast of thick-sheet structures made of low-carbon steels.

There is no dependence on the type of polarity; you can use any one that is convenient for a novice specialist.

Summarize. We looked at what a welding inverter is and why you need to know about direct and reverse polarity.

Often, novice craftsmen do not know the specifics of the work, which is why difficulties arise when melting metal or welding structures made of various alloys. However, changing polarities is quite simple.

By changing the terminals with each other, you can achieve the necessary parameters for working with different products. Study welding inverters carefully, and your work will become noticeably more comfortable!

Source: https://ssk2121.com/pryamaya-i-obratnaya-polyarnost-pri-svarke-invertorom/

Reverse polarity when welding and direct polarity: differences and how to choose for an inverter

All articles and reviews related to welding have an electrical theme. Be it devices, be it electrodes, be it types of seams – in any welding question the type of current is mentioned and specified. In some places it is constant, in others it is variable, and it also has two options - direct and reverse polarity when welding.

THIS IS INTERESTING: How to choose a welding machine

It's time to figure out what's what in order to choose the right materials, devices, electrodes and welding methods. Knowledge of the nuances of electricity in welding will help you quickly and correctly configure the inverter, on which the quality of welding seams depends to a large extent.

Anodic spots, cathodic spots

Of course, you can work all your life on your inverter machine, in which by default the direct current is set to straight polarity: you do not have any hassle or problems with adjustments to the welding electricity.

This wonderful idyll is possible only on the condition that the type of work you do is the same, you don’t change, you still don’t know all the capabilities of your device, and in general why talk about electricity, everything is fine as it is, there’s no need to complicate it

It’s not necessary, it’s not necessary, but if you need to weld, for example, high-quality high-alloy steel, then your idyll will immediately be disrupted: you won’t be able to produce a high-quality weld with the old electrical settings. You will have to understand the concept of reverse or forward polarity when welding, which we will help you with right now.

Firstly, working on an inverter device involves direct current. And it, in turn, implies two sockets for connecting the positive and negative terminals. Let's remember the polarity when welding with an inverter by connecting the electrode, it’s easier. If the electrode is connected to the negative socket, then this is straight polarity when welding. If it’s positive, it’s the opposite.

Direct and reverse polarity.

In principle, with the direct version, the electrode that is connected to the negative terminal itself becomes the cathode. And our metal blank becomes the anode. In the opposite case, the electrode begins to work as an anode, because it is connected to the positive pole. Well, the workpiece, accordingly, turns into a cathode.

In both cases, anodic and cathodic spots are formed. The anode cloud is hotter, and significantly: the difference in the temperatures of the anode and cathode regions reaches 800°C.

Let us not lose sight of an important detail: if we are talking about two options - forward and reverse, this always relates only to direct current. The fact is that with alternating current the polarity itself changes from direct to reverse with a high frequency.

Once again: switching direct and reverse polarities makes sense and is only possible with direct current, this is direct current welding. With alternating current, such switching makes no sense or is possible. Friends, this is physics.

Straight polarity

So, the electrode is connected to the minus, the metal workpiece is connected to the plus. This is the classic polarity when welding with an inverter. On the plus side, a wonderful anode cloud spreads its heat.

Direct DC connection has some features that must be taken into account:

with direct connection, a stable and even arc is obtained with all the ensuing consequences in the form of high-quality seams;
the welding seam is narrow and deep;
shall not be used in any case if the electrodes indicate that they are intended for alternating current technology;
with some metals, when working in inert gases, the deposition rate increases;
the composition of the metal in the weld with direct polarity has its own characteristics: there is practically no carbon in it, but silicon and manganese are present;
quite high degree of metal spattering;
quick melting of the consumable with its frequent replacement.

Reverse polarity

Reverse polarity when welding.

We remember that with reverse polarity when welding with direct current, the positive anode warm spot is on the electrode. Thus, we eliminate additional heating of the metal to which the negative terminal is connected. The main type of welding for reverse connection is electric arc with flux and the method in a shielding gas environment, in particular in argon.

The main metal “consumers” of reverse connection are high-alloy steels and thin workpieces made of any metal: what matters here is the thinness of the edge, which is easy to burn through at the slightest overheating. So the work on the reverse connection can be called quite delicate. And where there is delicacy, there are performance features and professional advice.

Here are the technological features of using reverse polarity that need to be taken into account:

the seam with reverse connection is wider and shallower than with direct connection;
copes excellently with joining thin and medium-thick edges of metal workpieces;
the welding arc is not as stable as with direct polarity; if the voltage is low, the arc begins to jump and be interrupted;
if you are welding high-alloy steel, then in addition to the reverse connection, you must comply with additional requirements for the operating cycle and cooling temperature of steel workpieces;
Never cook with electrodes that are sensitive to overheating;
an additional reduction in temperature on the workpiece can be achieved by reducing the voltage potential;
the fact that the arc is not very stable can be used for good: it is better to weld very thin edges with intermittent seams - interrupting the arc;
if in reverse polarity direct current welding you make a butt seam, the gap between the surfaces should be minimal, but if the seam is overlapping, the surfaces should fit together hermetically. Otherwise you will get a burn;
flanging the edges of the surfaces to be welded will help greatly to reduce the risk of burn-through.

How to choose the correct polarity

But if you work with different metals and metal workpieces of different thicknesses, you will have to independently adjust the parameters of the welding current and, in particular, the polarity. It's not difficult, let's go.

https://www.youtube.com/watch?v=edwILvaxWls

It's all about moving the warm anode spot, that is, the concentration of heating. With direct polarity, the plus goes to the metal workpiece, which is what heats up. The choice of connection option when working with different workpieces made of different metals depends on this factor. Everything is logical and simple, here are the criteria for decisions regarding connecting direct welding current:

Edge thickness of metal workpiece

Direct and alternating current welding.

Thick surface edges? Of course, welding with direct polarity current! Additional concentration of heat at the melting points in thick parts will contribute to deep testing and, therefore, obtaining a high-quality, durable seam. If the edges of the surfaces being welded are thin, then you need to reason and then act quite the opposite.

It is important not to overheat the thin edges to prevent burn-through. So we send the warm anode spot out of harm’s way to the other side – to the electrode. So we cook the thin parts when connecting them back.

Type of metal

Here, moving the thermal anode spot will help us: what metals will it not harm, but, on the contrary, will help? The correct thing to do would be to carefully read the instructions for electrical settings of the welding machine, which accompany any modern alloy.

But now you can remember the fact that aluminum, along with alloys, welcomes heat; it helps reduce the amount of oxides formed during the process. So welding of aluminum with direct current is carried out only with a direct connection. Officially, this will be called DC welding of aluminum in an argon environment.

Non-ferrous metals, like aluminum, are welded with non-consumable tungsten electrodes only when directly connected, without any exceptions.

Type of electrode

You know that modern electrodes are divided according to a huge number of criteria; they are produced in an incredible variety. Electrical parameters are also included in the description of each type of electrode. It never hurt anyone to read the instructions most carefully.

But here we can very well reason logically to choose the correct polarity for each type of electrode. The choice depends on the same thing - the warm anode spot, that is, the temperature regime. And such modes of electrodes depend on the type of flux and many other factors.

It is impossible to give short recommendations on current polarity for different welding consumables - there are too many of them. The only practical advice in this case is to read the instructions and not neglect them.

But what should you do if the instructions for the metal or alloy require the same electrical parameters, but the selected electrode requires completely different welding current settings? This happens, in this case there is only one answer: try and look for the best option experimentally.

Current strength, duty cycles, connection to poles - everything will have to be adjusted manually. But we are given a head to think, right?

Source: https://tutsvarka.ru/vidy/obratnaya-polyarnost

Welding current polarity - forward and reverse

The polarity of the welding current is one of the important parameters affecting the quality of the weld. After all, the direction of movement of the current, that is, electrons in the metal, depends on it, which affects the process of making the seam, the burning of the arc, the formation of the weld pool and, as a result, the quality of the welded joint.

I wrote a separate article earlier regarding the physical meaning, as well as the terms “direct” and “reverse”. And now I will tell you the basic principles of using direct and reverse polarities of welding current. And the main thing you need to know: where there is “+”, it heats up more. Accordingly, when welding on current with reverse polarity, when “+” is on the electrode, it heats up more than in the case of direct polarity. And the part, on the contrary, heats up more when welding with a current of direct polarity.

Subtleties and features

With detail, the situation is somewhat more tricky. When there is a “+” on the part, the penetration spot is wider, but the depth is no greater, or even less, than when the part is “-“. With a “minus”, the weld pool spot on the part is smaller, but its depth can be no less, or even greater, than when welding with direct polarity current. Thanks to this, when there is a “minus” on the part, it is possible to better control the movement of the weld pool.

How to use this in practice? There are many options. Usually, the default polarity of the welding current is used - especially when you need to strongly heat and weld parts. Reverse polarity is used in cases where it is necessary to more accurately control the movement of the weld pool.

For example, these are some types of vertical seams, especially from top to bottom.

Also, welding with reverse polarity current can help when making ceiling seams and welding thin metal - because in this case, the part heats up less, and this will minimize the flow of metal when making vertical and ceiling seams and through penetration of metal when welding thin sheets.

The polarity of the welding current also depends on the electrodes

Another important point is welding electrodes. Not all electrodes allow the use of welding current of any polarity. For example, with electrodes with the main type of coating, welding should be carried out only with a “minus” on the metal being welded. Such electrodes include, for example, UONI-13/55 electrodes. In any case, always check that the actual polarity of the welding current is correct for the specific electrodes being used.

Summary

So, it is important to understand that the choice of the direction of the welding current depends on the spatial position of the weld, the selected electrodes, the thickness of the metal and the personal skills of the welder. If all these conditions are met, then the seams will be of high quality, reliable and aesthetic.

And most importantly - experiment! I say this very often because in fact, only an experiment will give you the most accurate and correct answers to your questions!

Perhaps I covered this topic a little chaotically, so if you still have any questions, write them in the comments. And also be sure to tell us about your experience of using direct and reverse polarities!

More on the topic:

Which electrodes are best for an inverter?

Features of welding thin metal

Thin metal, vertical seam

courses:

How to cook with electric welding

How to set the welding current correctly

How to choose a chameleon mask

How to set up a chameleon mask correctly

How to choose a welding inverter

Source: http://www.elektrosvarka-blog.ru/polyarnost-svarochnogo-toka/

ACϟDC. Understanding Welding Current and Polarity