Most modern welding machines have a rectifier diode unit in their design, which, in turn, provides a constant welding current. For machines that use wire as a welding material (welding semiautomatic devices), this is a prerequisite. For devices that use electrodes for work, this is already an option that allows you to use almost any brand of electrodes for welding.

Classification of the welding arc by DC polarity:
a - direct polarity; b - reverse polarity

When working with a semiautomatic device, it is imperative to observe the polarity of the connection. So, welding with a conventional copper-plated wire in a shielding gas environment is performed with a current of direct polarity. That is, a plus is supplied to the product, and a minus to the holder (direct polarity during welding). With this connection, the current flows from the wire to the product, and therefore the heating of the product is higher than that of the welding wire. And this is natural. The parts to be welded have a much larger area, and therefore require more heat to form the weld pool. The wire, which has a smaller area, melts quite easily and enters the welding place already in the form of a molten drop. The flowing current, and it flows precisely from plus to minus, captures the melted material, again contributing to the formation of a high-quality weld pool.

Judging by the comments of our site visitors, there was a little confusion with the direction in which the current flows in the circuit. Let's try to clarify this issue!
It is necessary to understand that the "direction of current" in electrical engineering is more of a convention adopted for drawing circuits. Traditionally, on diagrams, it is customary to draw from plus to minus, as if the current moves from plus to minus, although the real movement of charge carriers in most cases occurs in the opposite direction! In the event that a metal (wire, electrode, etc.) acts as a conductor, the real charge carriers - electrons, fly from minus to plus (since electrons are negatively charged particles). If an ionized gas or liquid with ions acts as a conductor, then the ions fly in both directions.

When working with a semiautomatic device without a protective gas environment, a special flux-cored (flux) wire is used. In this case, the polarity of the holder and "mass" connection must be changed. That is, on the mass "minus", and on the holder plus (reverse polarity during welding). This is due to the fact that the melting temperature of the flux is approximately the same as the melting temperature of the metal, however, to obtain a high-quality weld, it is necessary that the flux burns out and forms a small gaseous cloud in the environment of which the welding process will take place. As noted above, the current flows from minus to plus, therefore, the drop of the molten metal drop will be somewhat lower, which will ensure less heating of the metal being welded, since the latter is not cooled by a shielding gas medium and the formation of the weld pool will be approximately the same as in welding in a gas environment.
Welding of non-ferrous metals, in particular aluminum, is performed, as a rule, with a special tungsten electrode. In this case, usually use direct polarity when welding - minus at the electrode. This type of connection allows you to obtain a higher temperature in the heating zone, which is especially critical for the same aluminum, since it is initially necessary to "break through" the oxide film, especially since the melting point of the latter is much higher than that of the metal itself.
Direct polarity, among other things, allows you to get a more concentrated and narrow electric arc, deeper penetration of the metal, and, accordingly, a better weld and, importantly, use a smaller diameter of an expensive tungsten electrode, as well as reduce the consumption of no less cheap gas.
When connecting a tungsten electrode in reverse polarity when welding - with a plus on the holder - the seam is shallower. This method is good when welding thin plates - in this case there is no danger of burning the material to be welded. However, another disadvantage is the "magnetic blast" effect. In this case, the resulting arc turns out to be wandering and the seam turns out to be less beautiful and tight.

Question: What kind of filter should be used when welding with this or that electrode, for example, 3 mm and 5 mm?

Answer: Here is a comparative table on the use of light filters for different types of welding and current strength - on which the brightness of the welding arc depends:

Compliance of Russian standards with European: C3 = 8 DIN, C4 = 9 DIN, C5 = 11 DIN, C6 = 12 DIN, C7 = 12 DIN, C8 = 13 DIN

Welding type	Welding current, A
	1	2,5	5	10	15	20	30	40	60	80	100	125	150	175	200	225	250	275	300	360	400	450	500	more
Manual arc	9							10		11				12					13					14
MIG, heavy alloy	10										11			12					13					14
MIG, light alloy	10										11			12			13			14				15
TIG	9					10		11			12			13			14
MAG	10									11		12		13					14			15
Plasma cutting	11												12				13
Microplasma. cutting	6	7	8	9	10		11		12			13				14						15

Question: What does forward and reverse polarity mean, where to connect plus and where to minus?

Answer: Direct polarity is connected to the part +, and to the electrode -, with reverse polarity, vice versa, to the part -, and to the electrode +. The difference is that the + generates more heat than the -, therefore, depending on the specific welding task, you can switch the polarity. For example, the reverse polarity of the connection is used when welding thin sheet metals, sensitive to overheating of alloy steels, stainless steel. In addition, polarity affects the transfer of metal from the electrode to the workpiece.

Question: I'm going to learn how to cook, what's the easiest way to do it?

Answer: The easiest and most comfortable way to cook with direct current, it is even easier and easier to cook with a semiautomatic device, since the arc and metal are clearly visible in it. If you take an inverter, it is desirable that it has functions that facilitate the work - fast ignition, anti-sticking of the electrode, reset of the arc afterburner, etc., the more adjustable functions, the more comfortable it will be to perform a number of operations, but the higher the cost of the device.

Question: When welding on the inverter, the electrode sticks, it ignites very badly almost after 10 poking into the metal, how to stop it?

Answer: There can be many reasons: a) wet electrodes, then they must be ignited and kept in a sealed container; b) some electrodes, for example UONII, are very sensitive to the selected current, while welders try to increase the current, which aggravates the problem (since the rod burns faster than the coating), i.e. you need to adjust the current strength - most likely to reduce it or change the polarity.

Question: Which is better to buy - a welding transformer or an inverter?

Answer: This is a large and complex topic, the choice depends on the specific operating conditions, manufacturer, model, upcoming work, etc. Here are the main pros and cons of transformers and inverters.

Transformer:

Reliable, durable, permits continuous operation, can be easily combined with an oscillator (for example from TIG welding), is insensitive to voltage surges, etc.

Heavy and inconvenient to carry, inconveniently adjustable voltage and current

Inverter:

Small, compact, lightweight, easily adjustable voltage, current and other parameters (when the arc is off)

Overheating is unacceptable (therefore, for each model, the work / rest time is written depending on the mode), it is difficult to connect an oscillator (on most models), it is afraid of dampness, iron dust and sawdust (and attracts them), undervoltage, many models are afraid of cold, on In most models, it is unacceptable to rotate the setting while the arc is operating - and the lower the quality of the apparatus, the higher the probability that the apparatus will fail as a result of violation of one or several rules.

Question: How to properly weld a galvanized part to ferrous metal, what kind of flakes arise during such welding?

Answer: Galvanized parts must be thoroughly and qualitatively cleaned from the galvanized layer, both at the welding site and nearby, since zinc during combustion forms compounds that are very toxic to health, and zinc residues falling into the seam greatly reduce its quality.

Question: The crocodile with which I attach the mass to the corners sparkles, warms up, turns black - is it possible to attach the mass better?

Answer: It is best to use a clamping clamp to connect the mass, it will provide reliable contact.

Question: Can aluminum parts be welded with manual arc welding?

Answer: Yes, for this there are special electrodes for aluminum, but such welding requires a high qualification of the welder, the electrodes should not be stale, mandatory preliminary heating of parts is required. Those. however, it is better to weld aluminum with TIG welding to obtain a quality weld.

Question: Is it possible to weld titanium parts with manual arc welding and are there special electrodes for this?

Answer: No, it is impossible and there are no titanium electrodes for RDS. Titanium can only be welded in an argon atmosphere of very high purity, otherwise titanium actively absorbs oxygen and hydrogen in large quantities, as a result of which the seam inevitably bursts.

Question: How to weld holes in a thin sheet of metal?

Answer: It is better to weld thin metal by semi-automatic welding with wire, but if there is no such welding, then you can weld a bead around the hole and, continuing to weld it and narrowing it inside the hole, gradually weld it all over. Also to avoid perforation thin metal you can put a copper plate under the metal and cook on reverse polarity.

Administration Overall assessment of the article: Posted by: 2012.05.16

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

About the physical meaning, as well as the terms "forward" and "reverse", I wrote a separate article earlier. And now I will tell you the basic principles of using the forward and reverse polarities of the welding current. And the main thing that you need to know: where the "+" 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 straight. And the part, on the contrary, heats up more when welding with a current of straight polarity.

Subtleties and features

With a detail, the situation is a little more tricky. When "+" is on the part, the penetration spot is wider, but the depth is not greater, or even less than when the part is "-". With a "minus" on the part, the spot of the weld pool is smaller, but its depth can be no less, or even more, than when welding with straight polarity current. Due to this, when there is a "minus" on the part, it is better to control the movement of the weld pool.

How to use it in practice? There are many options. Usually, the default is the straight polarity of the welding current - especially when you need to strongly heat up and weld parts. Reverse polarity is used when it is necessary to more accurately control the movement of the weld pool. For example, these are some views, especially from top to bottom. Also, welding with reverse polarity current can help when performing ceiling joints and - after all, in this case, the part heats up less, and this will minimize the flow of metal when performing vertical and ceiling seams and through penetration of the metal when welding a thin sheet.

The polarity of the welding current also depends on the electrodes

Another important point is this. 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 welded metal. Such electrodes include, for example, UONI-13/55 electrodes. In any case, always check that the actually set welding current polarity is correct for the specific electrodes 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. Also, be sure to share your experience with forward and reverse polarities!

Depending on a number of factors, welding arc supplied in DC welding can be forward or reverse polarity. In the first case, a "plus" charge is supplied to the processed elements, and a "minus" charge is applied to the electrode. Reverse polarity during welding is distinguished by the supply of "plus" and "minus" to the part to the electrode. More on the specifics of the methods - below.

Process features

The dimensions and shape of the resulting seam also depend on the location of the poles. For example, deeper penetration is possible with a direct reverse current, which is due to increased heat generation at the anode and cathode.

It is important to remember that the faster the welding process is carried out, the narrower the seam width and penetration depth.

What equipment to use

The opposite direction is in demand in the work of special installations. The specificity is that the machine feeds the wire at a certain speed to the workpiece, therefore, several types of welding are possible.

For example, in a shielding gas environment (when using argon or carbon dioxide), or using powder-treated wire. The reverse direction of the current is applicable when working with gases, the forward direction - when the process is performed with flux-cored wire (also known as flux cored wire).

Semi-automatic welding involves a number of process changes. First, the connection of the "holder" and "mass" changes - on the first "plus", on the second "minus" (reverse). This is done so that the flux burns out completely, and the welding process takes place inside the formed gaseous cloud. The metal will heat up less and the splashing of drops will be minimized.

The straight line is used for welding non-ferrous metals when a tungsten electrode acts as a working consumable element. Thus, an increase in temperature in the heating zone is achieved, which can be critical for, for example, aluminum.

In working with alternating current, the user's task is to change consumables in a timely manner. Professionals or advanced amateurs prefer direct current as a reliable guarantee of high-quality welding. Working with an inverter allows you to choose one of two known options. Forward and reverse polarity in welding are methods, each of which has its own advantages and disadvantages. The choice of direction is dictated by a number of factors, the main of which are the material of consumables and the equipment used.

If you know other specific features of the choice of welding parameters, share the information in the comments to the article.

Electric arc welding, in comparison with gas welding, has some peculiarities. This is a higher, up to 5000 ° C, temperature of the arc itself, which exceeds the melting temperature of all existing metals, and a wide variety of types and types of welding, and, accordingly, methods and purposes of its application. Electric arc welding differs in the degree of mechanization, in the type of current, in the type of arc and properties of the welding electrode, as well as in other parameters. In this article I would like to consider some of the nuances of electric arc welding, depending on the polarity of the welding electrodes.

Types of welding.

By the nature of the current used, two types of arc welding are distinguished:

• welding with an electric arc supplied with alternating current;

• welding with an electric arc supplied with direct current.

In turn, DC welding is of two types:

• direct current welding;

• welding with current of reverse polarity.

Let's consider the features of each type of DC welding in more detail.

Welding with current of direct polarity.

Welding with straight polarity is usually understood as welding, during which a positive charge is applied to the workpiece (product) from the welding rectifier, that is, the welding cable connects the structure to be welded to the "plus" terminal of the welding machine. A negative charge is supplied to the electrode through the electrode holder, connected by a cable with a negative terminal.

Since the temperature at the positive pole (anode) is always much higher than at the negative (cathode), it is recommended to use a straight polarity current when it is necessary to cut metal structures and weld thick-walled parts, as well as in other cases when it is required to achieve a large heat release, which is exactly and is characteristic feature this type of connection.

Reverse polarity welding.

For welding with reverse polarity current, the connection should be made in the opposite way: apply a negative charge from the "minus" terminal to the workpiece to be welded, and a positive charge from the "plus" terminal to the electrode.

This polarity of the welding electrodes provides a situation opposite to the direct connection - more heat is generated on the electrode, and the heating of the part is comparatively reduced. This allows for a more "delicate" weld and reduces the likelihood of burn-through on the part. Accordingly, welding with reverse polarity current is recommended for welding thin sheets of metal, stainless steel, alloy steel, other steels and alloys that are sensitive to overheating.