Selecting electrodes for welding inverter

For a novice welder, choosing an electrode can be a challenge. There are more than two hundred brands with different properties, purpose and characteristics. And about 100 brands are suitable for manual electric arc welding with inverter machines. It is impossible to tell about all of them, and it is not necessary to begin with. Just briefly characterize the main types and what electrodes for inverter welding are more suitable for beginners.

What is an electrode and what is the cladding for

An electrode is a piece of metal wire with a special coating – cladding. During welding, the core melts from the arc temperature. At the same time, the cladding burns and melts, creating a protective gas cloud around the welding area – the weld pool. It cuts off the oxygen contained in the air. In the process of burning the cladding, part of it becomes liquid and covers the molten metal in a thin layer, also protecting it from interaction with oxygen. So the cladding ensures good weld quality.

Any electrode is inspected before welding: the coating should not have chips. Otherwise, you will not achieve homogeneous heating and a high-quality weld. Also pay attention to the tip of the electrode: the thickness of the coating should be the same on all sides. Then the arc will come out in the center. Otherwise, it will be displaced. For welders with experience this is not terrible, but for beginners it can create tangible problems.

It is necessary to monitor the moisture content of the cladding. Some of them at high humidity ignite very poorly (for example, UONI). Due to this “capriciousness” of the grease, they should be stored in a dry place, providing if possible hermetic packaging. You can put the box in a bag, and also put a few bags of salt, which are in shoe boxes.

It is not worth buying wet electrodes: they can, of course, be dried, but their characteristics will be reduced. If it still happens that the electrodes have become damp, they can be dried in an ordinary household oven at low temperatures (they are usually indicated on the package). The second method is to put them for a long period of time in a dry, well-ventilated room.

Types of coating and their characteristics

There are only four types of coatings:

• Basic.
• Rutile.
• Acidic.
• Cellulose.

Basic (UONI) and cellulose coatings are suitable only for direct current welding. They can be used on responsible seams: they create a strong, elastic weld, resistant to shock loads.

The other two (rutile and sour) – can work for both AC and DC welding. But the acid coating is very toxic: it can only work indoors if the workplace is equipped with forced exhaust.

Rutile cladding has a greenish or blue tint, electrodes are characterized by easy ignition. They are well ignited even if the inverter has a low idle voltage (a good volt-ampere characteristic is required for confident ignition of the main coating, how to choose an inverter welding machine, read here.). When welding with rutile electrodes (MP-3), the metal is almost no spatter, but there is a lot of slag and it is not easy to get away: you have to work with a hammer.

Perhaps you will be interested in how to weld a gazebo from a metal pipe or how to make a shed on a frame from a pipe.

How to choose electrodes for inverter welding

First of all, the composition of the core is selected: it should be similar to the type of metal being welded. In the household, structural steel is most often used. Here from the same wire and should be electrodes. Sometimes it is still necessary to weld stainless steel. Then the core should also be made of stainless steel, and for high-alloy and heat-resistant make of metal with the same characteristics.

Perform all work at home or on the construction site can be done with the use of only a few brands of electrodes:

• MR-3
• UONI 13/55
• ANO 21
• OK 63.34

They are recognized by many as the best electrodes for beginners who work with inverter welding machines: it is easier to work with them, at the same time, they allow you to cook high-quality welds even in the absence of significant experience. Below are the characteristics and general application of those consumables that many specialists consider good electrodes for inverter. In any case, they are often recommended to novice welders to gain experience.

Electrodes with rutile coating MP 3

Most often beginners are advised to start mastering welds with MR-3 electrodes. They are easily ignited, even with not very good volt-ampere characteristics of the welding machine, give good protection of the weld pool, allow you to control its position quite easily. If the electrode is not ignited, calcine it at a temperature of 150-180 ° for 40 minutes.

They are used in machines with alternating (welding transformers) and direct current (welding rectifiers and inverters). Inverters are usually connected in reverse polarity (+ on the electrode). They are suitable for any type of weld except vertical top-down.

Read about the types of welding machines here.

MR 3 electrodes are not capricious to the quality of welded surfaces. They can be used even on untreated, rust-covered and wet parts. Welding is carried out with medium (2-3 mm) or short arc.

The feature of MP 3 is very important for novice welders: they “hold” the arc well, it is easy to work with them. For this, not all professionals like this brand: they call them Bengal lights. They weld too softly: slow movements are necessary for good heating. Which is not to the taste of the pros, for beginners it’s just what they need. Try to start your welding training just with MP3. You should be fine.

UONI 13/55 with basic coating

These are probably the most widespread and popular electrodes with basic coating. They are recommended for welding carbon and low-alloy steels. They are suitable for joints of critical structures. Seams are obtained strong to shock loads and plastic, well tolerate the effects of low temperatures.

The disadvantage of these electrodes: they are well ignited only at a sufficiently large value of idle speed at the inverter (above 70 V). The second significant disadvantage: high requirements for cleaning and processing of welded metals. If rust, dust, oil or other contaminants remain on the edge, the seam will be porous.

Work with UONI 13/55 is possible only on DC welding machines, including inverters, with reverse polarity (+ is fed to the electrode), and a short arc (keep the tip of the electrode closer to the welded surface). The minimum idle voltage is 65 V.

ANO 21

This type of electrodes with rutile coating is designed for working with carbon steels of small thickness. (Read about welding thin metals here.) When using them, the arc is easily ignited (including reignition), the weld is finely flaked (from small-sized waves), slag is easily separated. ANO 21 electrodes can be used for welding water or gas pipes.

They work both with alternating and direct current of any polarity. Before welding, they require heat treatment: they are calcined at 120°C for 40 minutes.

Stainless steel electrodes OK 63.34

If you need to weld stainless steel, try OK 63.34. They can also be used to weld structural steel. This produces a seam with a fine wave with a smooth transition to the main surface of the metal. The amount of slag is small, it is easily beaten off.

This electrode is good to weld vertical welds and metal 6-8 mm, passing from top to bottom. Suitable for multi-pass welding of butt and overlapping joints. Works with direct and alternating current of any polarity, minimum no-load voltage – 60 V.

For welding, you will still need a mask. To make it easier to work, take a welding mask-chameleon.

How to choose the diameter of the electrode, how to connect it and how to set the current strength

Choosing the brand of electrodes for the inverter is not everything. Even if you have decided, at least three questions remain:

• What diameter of the electrode to use when welding;
• what current to set;
• to which output “+” or “-” to connect the electrode.

Let’s talk about all of them in order. Let’s start with what diameter of the electrode is necessary for welding. In general, it is recommended to proceed from the thickness of the welded metals: for small thicknesses, the electrode is taken with a diameter of the same size as the metal. If you weld metal 3 mm thick, then the electrodes take a similar size. If you weld something thicker, respectively take 4 mm. But it will be difficult for beginners to work with large electrodes. Begin to master welding with a metal thickness of 3-4 mm. To do this, use electrodes 3 mm, or as they say “triple”.

Regarding how to what output to connect the electrodes. In the technical specifications on the pack, most likely, it is indicated for which polarity the electrode is intended. In reverse polarity, the electrode is connected to the positive output, the negative output is connected to the clamp, which is clamped to the part. With forward polarity, the plus is connected to the workpiece and the minus to the electrode. How it looks on the welding inverter is shown in the photo.

How do these two types of connection differ? The electron flow has a different direction. As you know, electrons move from “minus” to “plus”. Therefore, when welding, it turns out that the element that is connected to the “+” heats up more. By changing the modes of connection you can control the intensity of heating of the metal.

Let’s consider several situations. For example, you have an electrode 3 mm, metal 2 mm. If you apply “+” to the part can be burned through. Therefore, in this case it is better to use reverse polarity, which will be more heated electrode. If you want to weld 6 mm metal with the same three, it is better to do it on the direct polarity: so the heating of the metal will be deeper and the seam will be more durable.

How to choose an inverter welding machine read here. You may be interested in building a fence from corrugated steel.

Current strength when welding

In general, when installing the electrode, the strength of the welding current for the inverter is set depending on the diameter of the electrode used. In general, each pack has recommendations, but you can do without them: for each millimeter of diameter take 20-30 amperes of current. It turns out quite a wide range, but then you still need to take into account how you will put the weld: with or without a breakaway. For welding without tear-off put lower currents, with tear-off – higher.

For example, for an electrode with a diameter of 3 mm, the calculated current is from 60 A to 90 A. Really work in the range from 30 Ampere to 140 Ampere. When welding without breakaway, the current is set about 70-90 A, with breakaway – 90-120 A. These parameters can “walk” in both directions: it depends on the speed of movement of the electrode tip, on the brand and “fluidity” of the welded steel, on the position of the weld (for vertical and horizontal weld put a little less, for the ceiling – even less).

In general, even the currents recommended by the manufacturer are far from being a requirement. Start with them, and then select so that you were comfortable working and the seam turned out good. You should get a high-quality connection, and the ratio of current and speed you will select experimentally. At the same time, focus on the condition of the weld pool. She is your main indicator of quality.

On how to properly weld with inverter welding, read here.

Now you know not only how to choose electrodes for inverter welding, but also how to connect them, what diameter you need them for this work, and how to pick up the current for each type of electrode and weld. Now let’s talk a little about electrode holders.

Electrode holders

On one of the welding cables, there is a holder (holder) in which the welding electrode is inserted. There are two types of holders:

• with a trigger key, in them the electrode is clamped automatically when the spring-loaded key is released by pressing it;
• threaded – the handle is screwed and unscrewed, releasing or clamping the inserted electrode core.

Which one is better? It’s up to you, but by accidentally pressing the key, you can drop the electrode during welding. Nothing terrible happens in this case, but it is unpleasant …

When choosing an electrode holder, the main thing to pay attention to the strength of the current for which it is designed. You choose the maximum parameter, which is available for your welding machine.

How to connect the cable to the welding electrode holder with a threaded clamp is shown in the video.

The disadvantage of the clothespin holder is that over time, the spring that clamps the electrode core weakens and the contact deteriorates. It is necessary to put a new one. How to do it on a clothespin holder, see in the video.

Connect the electrode holder for welding is not difficult. Only there is one nuance: with frequent work, the welding cable is rubbed by its edge. You can, of course, shorten the cable and redo it, but you do not always want to cut off even 10-20 cm. To prevent this from happening, find a hose whose inner diameter is the same or slightly smaller than the outer diameter of the welding cable. Cut a small piece of it – about 15 centimeters – and cut it lengthwise. This can now be slipped over the cable, pulled upwards and secured there.