Welding metal with an inverter: tips for beginners. How to cook with a welding inverter Is it difficult to learn how to cook with an inverter

17.06.2019

Carrying out manual welding using an inverter is gaining more and more popularity among home craftsmen, due to the wide offer various models with different price ranges. To connect iron products using inverter welding, a minimum of equipment is required, characterized by its versatility along with low energy consumption and compact dimensions, which even more attracts the attention of inexperienced craftsmen. Learning inverter welding technology for beginners will not be the slightest difficulty.

The principle of operation of the welding inverter

The welding inverter is the most powerful power supply, which is similar to the switching power supply in terms of energy conversion.

The main stages of energy conversion in the inverter:

Reception and rectification of mains current with a voltage of 220 V and a frequency of 50 Hz.
Converting the received rectified current into alternating current with a high frequency from 20 to 50 kHz.
High frequency reduction and rectification alternating current into a current, the strength of which is in the range of 100 ... 200 A, and a voltage of 70 to 90 V.

The conversion of high-frequency electric current to the current of the desired value allows you to get away from the inconvenient dimensions and heavy weight of the inverter, which have conventional transformer devices, in which the current value is achieved by converting the EMF in an induction coil. Also, when the welding inverter is connected to the network, there will be no sudden surges in electrical energy, and moreover, the device contains special storage capacitors in its circuit that protect the machine during welding during an unexpected power outage and allow the inverter arc to be ignited more gently.

Obtaining a high-quality weld during welding depends on many factors, therefore, before starting work, the master must be familiar with how to properly use the inverter according to the attached instructions, as well as the basic rules and nuances of welding, which will be described in detail below.

Particular attention should be paid to the diameter of the welding electrodes. It is important to know that the amount of energy consumed directly depends on the thickness of the welding rods, and, accordingly, the larger their diameter, the higher the energy consumption. This information will help to correctly calculate the maximum consumption of electrical energy by the inverter, which will prevent adverse effects from its operation in reflection on household appliances. There is also a dependence of the electrode diameter on the current strength chosen for operation, a decrease in which will lead to a deterioration in the quality of the weld, and an increase in it will lead to an excessive combustion rate of the welded rod.

The design of the inverter for welding

In order to understand how to properly use the welding machine, the novice master should familiarize himself with the design of the inverter.

Welding inverter is metal box with an internal component, with a total weight of about 7 kg, which is equipped with a handle and a shoulder strap for ease of carrying. The housing of the welding inverter may contain ventilation holes that contribute to a better outflow of air when the unit is cooled. The front panel has buttons for switching the working state, knobs for selecting the required voltage and current, outputs for connecting working cables, as well as indicators that signal the presence of power and overheating of the inverter during welding. The cable for connecting the device to the mains is usually connected to the connector located on the back of the inverter.

When the electrode contacts the metal plates being welded during welding, a high-temperature arc is formed, as a result of which both the elements of the welded rod and the metal of the welded joint are melted. The pool formed in the area of the arc by the molten metals of the plates and the electrode is protected from oxidation by a liquefied coating of the electrode. After complete cooling of the metal, the upper surface of the weld, protected by the electrode coating during welding, will turn into a hardened slag, which can be easily removed by light mechanical action (for example, by tapping). It is important to observe the same distance-gap between the metal of the welded joint and the electrode (arc length), which will prevent its extinction. To do this, the electrode should be fed into the fusion area with constant speed, and the leading of the welded rod along the joint of the weld should be even.

Safety

Before starting home welding, an electric welder needs to take care of safety precautions:

put on a protective suit made of durable high-density natural fabric, which is not subject to fire and melting when sparks hit it. The suit should cover the neck area, and have sleeves that fasten tightly at the wrist.
protect hands with mittens made of coarse linen;
put on comfortable leather shoes with thick soles;
protect your eyes with a welder's mask with a light filter, which depends on the strength of the welding current.

The place where welding will be carried out must also be carefully prepared:

a wooden flooring was laid, which performs a protective function against possible electric shock;
the place of welding is freed from everything superfluous (to prevent the ingress of welding spatter);
lighting must be of high quality;
the welder's movements should not be constrained.

The basics of inverter welding

Learn to cook welding inverter not difficult. The very first step in mastering the welding technique will be the preparation of the metal plates to be welded:

cleaning the edges of the plates from traces of corrosion with a metal brush;
degreasing the edge with a solvent.

Relying on the diameter of the electrodes, the choice of which is based on the grade of the metal being welded, it is necessary to choose the amount of current for welding. The value of the welding current will also be determined by the cross section of the elements to be welded. So that the quality of the seam does not suffer when welding with an inverter, the pre-welded rods should be dried in an oven with a heating temperature of 200 º for 2-3 hours.

In order to weld metal, the ground terminal must be connected to the plane of the element to be welded. Next, you need to ignite the arc. You can do this in two ways:

striking on the metal surface of the plate, by analogy with the ignition of a match head;
by tapping the electrode on the surface to be welded.

Working with a welding inverter will be more convenient if, when welding, the holder cable is pressed against the body, after wrapping it around the forearm working hand. In this position, the cable will not pull to the side of the holder and adjustment of its position will be more convenient. Therefore, when choosing an inverter, special attention must be paid to the length and flexibility of the cables, because the convenience of the welder will depend on these indicators.

After ignition of the arc, the electrode must be removed from the plane of the metal plate to a distance equal to the length of the arc (approximately 2-3 mm) and you can start welding. To make high-quality welding, you must constantly monitor the length of the arc. A short arc (about 1 mm) can cause a welding defect called undercut. This welding defect is characterized by the appearance of a shallow groove parallel to the weld, and leading to a decrease in the strength of the weld. A long arc is unstable, provides a lower temperature in the welding zone, and, as a result, such a seam has too little depth and “smearing”. A welder who knows how to correctly adjust the length of the arc will get a high quality seam.

After welding is completed, the scale that has solidified over the seam should be carefully beaten off with a hammer.

Polarity when welding with an inverter

The melting of the metal is caused by exposure to the high temperature of the welding arc, which occurs as a result of connecting the opposite terminals of the inverter to the metal plate and to the welded rod. Depending on the connection order of the terminals of the welding inverter, there are direct and reverse polarity.

Polarity is the direction in which electrons move. Both direct and reverse polarity are used when welding with an inverter, so it is important for a novice welder to know the differences between these types of connections.

Direct polarity is the polarity that occurs after connecting the electrode to the minus terminal, and the metal plates to the plus terminal. With this connection, the current flows from the electrode to the metal, as a result of which the metal heats up more intensively, and the melting zone becomes sharply limited and deep. The direct polarity of the connection of the welding inverter is selected when welding thick-walled elements and during inverter cutting.

Reverse polarity is characterized by connecting the “minus” to the metal plate, and the “plus” to the electrode. The fusion zone with this connection is wider and has a shallow depth. The direction of the current is directed from the metal workpiece to the electrode, resulting in a stronger heating of the electrode. This order reduces the risk of burn-through and is used when welding thin-walled metal products.

Working with thin metal

Welding of thin-walled metal products with an inverter is carried out by connecting the terminals according to the scheme corresponding to the reverse polarity, and placing the electrode at an angle forward. This welding technique provides a smaller hot zone with a sufficient weld width.

Ignition of the electrode should be done very carefully, because the beginning of the bath during welding thin metal often accompanied by burning. Welding of thin metal with an inverter must be carried out gradually, welding small areas with a short-term removal of the electrode from the pool. At this point, you need to make sure that the yellow glow of the electrode tip does not go out.

The quality of the weld directly depends on the quality of the electrodes, which will help to avoid excessive slag formation in a small cross-section weld. Also, the use of small diameter electrodes avoids burning through the metal.

At the end of the seam, you should not abruptly tear off the electrode to extinguish the arc, because in this case a noticeable crater will form at the end of the seam, which will worsen the strength of the metal of the welded joint and the result of the operation of the welding machine equipment will be unsatisfactory.

Another defect that often occurs when welding thin metal is the deformation of the product. To prevent its occurrence, it is necessary to carefully fix the parts to be welded before welding.

A welder with little experience often wonders how to properly weld metal with electric welding. General Tips for working with an inverter and the rules for welding metal with an electrode will be given in the section below.

When welding metal with an inverter, it is necessary to carefully control that the weld is flush with the metal. An electric arc penetrating the metal at an intense speed and sufficient depth causes the puddle to move backwards and creates a weld that can become defective if the speed of the electrode movement is too high. An ideal seam will be obtained if the electrode makes zigzag and circular vibrations.

When changing the direction of the electrode movement, remember that the bath follows the heat. The formation of the undercut occurs against the background of insufficient metal of the electrode, so it is worthwhile to strictly monitor the boundaries of the bath and control them.

By positioning the electrode at a certain angle, it is possible to control the direction of movement of the pool, while the vertical position of the electrode will contribute to sufficient penetration. The tub in this position will be pressed down and have good borders, and the seam will have less bulge. Too much tilt of the electrode will not allow you to control the bath.

Inverter welding is also applicable when performing pipe welding work. Welding takes place in rather difficult conditions, so it is necessary to pay great attention to the quality of penetration at the rotary joints. An angle equal to 30º is the standard angle of inclination of the electrode to the pipe surface. On pipes made of low-alloy steels with a wall section of up to 12 mm, the seam will be single-layer. For pipes with thicker walls, a second seam should be applied, thereby increasing the overall strength of the weld. After each new suture, it is imperative to clean the hardened slag. Pipes with a diameter of up to 0.5 m must be welded continuously.

The inverter is a simple welding machine that is ideal for a novice welder to carry out welding work at home. When choosing an inverter, you must rely on your own needs, and the suitability of the selected device, thus meeting your needs.

Welding sheets of thin metal with an inverter allows you to quickly and efficiently produce a metal product.

Thin-sheet material is called a material with a thickness of up to 5 mm, it is often used in the production of blanks for cars, motor boats, as well as for the manufacture of pipes, various hull structures, etc.

The main problem when welding thin sheets of metal is the high probability of their damage.

The reason for this may be the careless movement of the welder, as a result of which a burn may form on the workpiece.

In addition, welding of thin metal, carried out by a person without experience, may turn out to be of poor quality due to non-compliance with the technology.

Since the welding process is carried out exclusively by the inverter using low current, even a slight gap in the working distance between the workpiece and the electrode must not be allowed.

Otherwise, an arc break cannot be avoided. Therefore, it is not recommended to start welding thin sheets with an inverter without knowledge of the process features.

Welding thin metal requires, like any other welding process, to have protective clothing on hand: a special welding helmet, gloves and outer clothing made of coarse fabric, but in no case should rubber gloves be worn.

Step one

We carry out the setting of the welding current and select an electrical conductor that will allow you to work with an inverter.

We take the welding current indicator based on the characteristics of the metal sheets being joined.

Usually, the manufacturer indicates the current strength for specific cases on the inverter case.

Electrodes for inverter arc welding we use with a diameter of 2-5 mm. Next, we insert an electrical conductor into the holder, connect the ground terminal to the workpiece.

To avoid sticking, do not bring it to the part too sharply.

step two

Welding of thin metal using an inverter apparatus begins with the ignition of the arc.

We touch the line to be welded at a small angle with the electrode a couple of times, which will activate it.

We hold the electrical conductor at a distance from the workpiece to be welded, which will correspond to its diameter.

Step Three

If all of the above is done correctly, a high-quality seam connection should be obtained.

At the moment, there is scale or scale on the surface of the weld, they must be removed with the help of some object, for example, a hammer.

The following video for beginner welders will demonstrate how to properly connect thin sheets of metal with an inverter.

How to control the arc gap?

The arc gap is the distance formed during welding between the elements to be joined and the electrode.

Be sure to maintain a stable size of the specified distance during the operation of the inverter.

If you cook thin metal with an inverter and at the same time keep a small arc gap, then the welded seam joint will be convex for the reason that the main part of the metal does not warm up well.

If you cook thin metal with an inverter semiautomatic device and at the same time keep too much distance between the electrical conductor and the workpiece, then such a large gap can interfere with penetration.

The electric arc will bounce, the weld metal will lie crooked.

The correct and stable distance will make it possible to obtain a high-quality seam connection, while it is necessary to weld thin metal with an inverter, as mentioned above, with a gap corresponding to the diameter of the electrode.

Having gained experience and the ability to control the inverter arc length, it will be possible to achieve optimal results.

Due to the electric arc, which is fed through the gap and melts the base metal, a weld pool is formed. It also moves the molten metal into the weld pool.

Features of the formation of the weld

If during the welding process the movement of the electrode is too intense, then all that can be achieved is a deformed joint.

This fact is explained by the fact that the line of the weld pool is below the level of the base metal, and if the penetration of the arc into the base metal is strong and fast, it pushes the pool back, as a result, a seam appears.

That is why it is necessary to control that the welding seam line is located on the surface of the metal sheets.

A high-quality seam can be achieved by circular and zigzag movements of the electrode along the surface to be joined.

With zigzag actions, it is necessary to monitor the formation of the seam line alternately in three positions: from one edge, from above the weld pool, from the second edge.

Here, one should not forget that the weld pool moves with heat, which is very important when changing the working direction.

With a lack of electrode metal, an undercut is formed - a narrow groove in the base metal along or along the edges of the weld, appears as a result of a lack of metal to fill the bath during transverse movement.

In order to avoid the formation of such a lateral recess or undercut, it is recommended to monitor the outer boundaries and the weld pool, if necessary, adjust the groove width.

Operate the weld pool allows the force of the electric arc located on the tip of the conductor.

Do not forget that when working with a welding product at an angle, the bath will not stretch, but will push.

Therefore, a vertically located electrical conductor allows you to get less convex welding joints.

The process is explained by the fact that at this time, all thermal energy, the weld pool is pushed to the bottom, melted and distributed around.

With a slightly inclined position of the product, all the force is repelled back, as a result, the weld pops up.

If the electrode product is tilted too much, the force is transferred in the direction of the seam line, which does not allow effective control of the bath.

To achieve a flat seam connection, apply the slopes of the electrical conductor at various angles.

In this case, welding should begin at an angle of 450, which will make it possible to control the bath and correctly connect the metal with a semi-automatic device.

Welding of thin sheet metal with a consumable electrode

In order for the process of welding thin metal with a semiautomatic device to be successful, it is necessary to use an electrical conductor with a suitable diameter.

For example, for sheets of thin metal with a thickness of up to 1.5 mm, products with a diameter of 1.6 mm should be used.

Correctly welding thin metal with a consumable electrode means preventing overheating during the welding process, which can lead to burning in the product.

The electrical conductor is moved along the line to be welded at an average speed, as soon as there is a risk of combustion, the speed is increased.

The current strength during inverter welding of metal sheets should not exceed 40 amperes.

When choosing the current strength for working with a consumable electrode, it is better to make a test weld, which will simplify the solution of the task.

At the same time, on a test product, it is possible to cook semi-automatically in different modes, taking into account the speed of movement of the electrode.

It is necessary to cook in such a way that it is possible to fully ensure the penetration of the steel edges and at the same time not burn through the material.

A feature of welding thin metal with a consumable electrode inverter is the instantaneous melting of the edges, which does not allow you to fully monitor the weld pool.

That is why it is better to start semi-automatically cooking thin sheets of material after gaining experience.

In the process of welding thin sheet metal products, spot or intermittent welding technology can be used.

Due to the short functioning of the arc, tacks are formed, subsequently the electric arc is extinguished, then the process is repeated at a distance equal to the size of 2 or 3 electrode diameters.

The period between the creation of points is best minimized so that the molten metal does not have time to cool.

This method is ideal if you need to weld leaky structures made of thin sheets with an inverter. Spot tacks will eliminate the possible risk of warping of the metal.

How to choose the polarity when working with an inverter?

Polarity is the basis of a good welded joint. Direct polarity provides for reduced heat input to the base metal with a narrow but deep melting area.

With reverse polarity, there is a reduced flow of thermal energy into the material with a wide and shallow melting area of the base metal.

It is the polarity of the electrons that must be paid attention to before starting work with the inverter.

If you cook metal at direct current, then you can use the positive and negative charge of the source.

But at the same time, you need to know where to connect which charge.

Here it is necessary to take into account that if a material being welded is provided with a positive charge, it will become very hot.

If this charge is connected to an electrical conductor, then the electrode will get very hot and burn, which can lead to burning of the metal.

The way out is the reverse polarity of the inverter and the optimal current strength.

In the process of working with an inverter, the electrode is connected "+" to the inverter arc, and "-" to the sheet of metal.

Several following tips and thematic video material will also be useful for novice welders:

The ability to observe the weld and control it from all sides in the process of arc welding with an inverter will allow you to get a high-quality result and eliminate the formation of burnt holes;
During welding, the electrical conductor must be kept as close as possible to the product until a red spot begins to appear. This will mean that there is already a metal drop under it, due to which the metal sheets are connected;
When the electrodes move slowly over the metal surface, hot metal drops that appear connect the segments of the sheets and thereby form a welding seam.

After studying the above information and watching the videos, it will be much easier to weld thin sheets of metal with an inverter.

If you do not know how to learn how to cook with a welding inverter, video and prepared step-by-step instruction will help you understand all the nuances of this process. It is not uncommon for novice welders to pick up a machine to weld a car body, patch holes in metal structures, etc.

You can learn how to cook a car body or other parts for beginner welders using an inverter. Correctly using a welding inverter is not as difficult as many people think. Even if you have never picked up this tool, and are poorly versed in the types of electrodes, this will not become an obstacle on the way to self-repair car or the manufacture of some kind of metal structure.

There are a lot of reasons to learn how to cook with an inverter. Having at your disposal Svaris 160, Svaris 200 or any other good device, it will be even easier to master the welding business. Not the last role is played by the apparatus used in the welding process.

The whole process is divided into three main stages:

Training;
Inverter arc ignition;
Making a weld.

Training

The inverter is a welding device. This device provides the connection of metal elements by welding them together. So you can properly weld the body of your own car, repair holes in a metal fence, fix window bars and perform a number of other household tasks.

Preparation consists of several steps.

Place of welding by the inverter. Determine in advance the space where your Svaris 160 or 200 will be located for welding activities. To do this, you need to clear the area of debris, wooden, paper objects that can catch fire due to a flying spark. It is best to cook by placing the inverter on a concrete floor.
Inverter connection. Usually, a single-phase circuit is used to connect a household inverter. This allows you to work with an inverter from a 220V outlet. The whiskers of the inverter have plus and minus terminals. The electrode goes to the minus, and the plus is connected to one of the treated surfaces.
Worker protection. An important point that directly affects your safety. Is it possible to work without gloves? In no case. You can only cook if you have complete set protective equipment- gloves, mask, tight suit, rubber boots. The body must be completely closed.
Turn on the inverter. Take in your hand the terminal on which the electrode is installed. A special toggle switch turns on the device and you can start the ignition process. Pre-set the desired value of the welding current. If the electrode for the inverter has a diameter of 3 mm, the current will be 100 A. It would be correct to first study the technical documentation that your Svaris 160, 200 or other inverter model was equipped with. It is extremely important for beginners to understand how to cook the same car body. But it is better to get the first experience on simpler surfaces. Try just welding a couple of metal blanks together.

arc inverter

The next stage is the ignition of the inverter arc. Here, follow a few recommendations so that the device does what you expect from it.

Learning how to ignite an inverter is not difficult, but it will take time. At first, you may encounter certain difficulties, but soon it will take a minimum of effort;
For all novice welders, the main difficulty begins precisely with the ignition of the arc. Therefore, it is not right to think that only you are doing so badly;
To ignite the arc of the inverter during the first welding on cold metal, a strike is used. This method is similar to lighting a match on a box;
Pass the electrode over the workpiece, slightly touch the surface of the part you are going to weld;
The first time you may encounter sticking, that is, the electrode will simply stick to the metal. To correct the situation, simply tilt the terminal to the other side. So you break the rod. If it does not work, just disconnect the inverter from the power supply;
You need to strike until the arc appears. In no case do not start striking without lowering the mask over your face. Looking at the arc without filters is detrimental to vision;
To maintain the arc, you need to fix the electrode tip at a distance of 3-5 millimeters from the surface to be welded;
Here, for beginner welders, another difficulty arises - holding the desired distance. If you get too close, the electrode will stick. When removed, the arc is lost, so you will have to re-ignite;
During welding, the electrode will gradually be consumed, and the coating will burn out. The metal will begin to fill the space in which the welding process is performed. Therefore, do not forget to gradually move the electrode along the seam with your hand.

Weld

In addition to the weld, you need to understand the essence of the weld pool. This is the only way to achieve the desired result.

When the arc is ignited, a puddle of molten metal forms. It is called a welded bath.
To connect the parts, weld the car body, the electrode should be gradually moved along the boundaries of the two elements to be welded.
A pool will move behind the electrode, which is called the liquid metal zone.
To achieve the desired quality of the connection of parts, the welder must oscillate the electrode relative to the seam being created.
If you lose the arc when you start welding, you don't have to worry about having to re-ignite. Now it is easier to do. To do this, bring the end of the electrode a few millimeters closer to the surface.
Special masks are good because you can see a bright arc and a weld pool through them. The direct contact of the electrode with the surface is less visible, but you cannot remove the mask with light filters for this.
When the length of the rod remains literally 5-6 cm, welding should be stopped. Turn off the inverter with the toggle switch, change the electrode, after which you can turn on Svaris 160 or 200 again.
After completing the welding operation, restoring the car body, be sure to tap the seam with a hammer. So you remove the formed slag from the surface. You can determine the cleaned surface by its appearance. The seam devoid of slag shines.

Electrode movement

Many beginners who start brewing for the first time mistakenly think that Swaris 160 or 200 will do all the work for them. We do not argue, Svaris 160 and Svaris 200 are really good inverters. But having a quality device is not enough to do the job right.

The main mistake is straight-line movements when creating a seam. Professionals don't cook like that. In order to repair the car body or perform a number of other operations, you need to learn how to use the device correctly and observe the seam.

Having prepared the car body for welding, and turning on your Svaris 160 or Svaris 200, you need to gradually move along the intended seam line.
At the same time, the movements are zigzag, spiral, Christmas tree - that is, a return trajectory is used. In this way, the desired quality of melting is achieved, and the risk of gap formation is minimized.
The formed welded surface depends on the speed of movement - the thickness of the weld, width, depth, etc.
When completing the line, linger on the last point for a few seconds. This will make the seam complete, will not allow the formation of craters - recesses. Only after that change the electrode.

A welding inverter is a device that allows metal to be joined by welding. Compared to a rectifier or transformer, welding with an inverter is easier, simpler and more affordable. How to learn how to weld metal with an inverter?

Inverter welding: sequence of operations

Welding technology consists of a series of sequential steps. Their correct execution delivers quality results strong connection two metal surfaces. How to cook metal with an inverter, what to look for when learning to weld?

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Preparing for welding

Preparation of a place for welding. The space within a radius of a meter is freed from wooden, paper, plastic items. They can be ignited by a hot electrode or spark. The inverter is installed on the ground (concrete floor) and connected to the electrical network. Two mustaches (wires with terminals "+" and "-") are strengthened as follows: the plus terminal is attached to one of the metal surfaces to be welded, an electrode is inserted into the minus terminal (this connection is called direct polarity, it is the most common). The body of the welder is covered with protective clothing (trousers, jacket, gloves), a shield with dark glass (light filter) is put on the face.
We take in hand the terminal with the electrode. We turn on the inverter (toggle switch) - a small hum appears. We set the value of the welding current (with the regulator on the front panel). For a traditional electrode with a diameter of 3 mm, a welding current of 100 A is required. We lower the mask on the face (Fig. 1).

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Ignition of the arc at the beginning of welding

Figure 1. Dependence of the diameter on the thickness of the parts.

Let's start welding. In the beginning, you need to kindle an arc. With experience this will be easy. For a novice welder, ignition of the arc is the first difficulty. Before starting the ignition, the electrode is tapped on the metal surface to remove the coating from its end. To ignite the arc on cold metal (at the beginning of welding), the strike method is used. It is like lighting a match. The electrode is carried over the metal, slightly touching the surface of the part to be welded. For an inexperienced novice welder, the rod often sticks (sticks to the metal). To unstick it, it is necessary to sharply tilt the terminal with the electrode to the other side (break off the rod from the part). If it fails, turn off the inverter power. When the current is turned off, the sticking will disappear.
We strike until an electric arc is formed. It is very bright, you can only look at it through a light filter.
To maintain the arc, we fix the end of the electrode 3-5 mm from the metal. At the beginning of training, it will be difficult to maintain the required distance. If the electrode is too close, a short circuit will occur and it will stick to the part. If removed, the arc will be lost and will need to be re-ignited. During the welding process, the electrode is consumed, its coating burns out, and the base metal fills the seam between the surfaces to be welded. Therefore, the hand with the terminal gradually lowers down.

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Weld pool and weld

Figure 2. Dependence of the diameter on the thickness of the parts.

When the arc is ignited, a liquid puddle of molten metal is formed. This is a welded tub. For connection metal parts over the entire contact surface, the electrode slowly moves along the interface. Behind him moves the weld pool (liquid metal zone). The end of the rod oscillates (back and forth, left and right) relative to the seam between the two parts. This ensures the quality of the connection.
If the arc has been lost (the electrode is too far away from the weld), re-ignition is easier. To ignite the arc, it is enough to bring the end of the rod closer to a distance of several millimeters.
A bright electric arc and a less bright weld pool are clearly visible in the welded shield. The contact surfaces to be welded in the welding zone are less distinguishable. However, it is impossible to remove the shield and peep at welding without a protective light filter. At best, the eyelids will itch unpleasantly (feeling of sand in the eyes). At worst, you can lose your sight without the possibility of restoring it.
When the rod is shortened to 5-6 cm, welding is stopped, the inverter is turned off and the electrode in the terminal is changed.
At the end of welding, the frozen seam of metal is tapped with a hammer to remove the slag layer. The seam cleared of slag has a brilliant surface.

This is the technology of welding with an inverter as a whole. And now let's dwell in more detail on how to choose the right electrode and welding current.

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What electrodes to weld metal?

The electrode is a metal rod coated on the outside with a coating. The coating substance is a slag mixture, which also melts during welding, rises to the surface of the weld pool (it is lighter than metal) and protects the liquid metal from oxidation and saturation with nitrogen (Fig. 2). In some cases, gas-forming additives are introduced into the composition of the coating, which ensure the release of gas during the melting of the electrode.

The composition of the inner rod is determined by the type of metals being welded (low-carbon and low-alloy steels, brass and bronze, magnesium alloys, titanium alloys). To weld ordinary metal carbon steel, UONII brand electrodes are used. They are also used for corrosion resistant steels. UONII welding is performed only by direct current.

ANO marking rods are considered more universal. They are suitable for both forward and reverse current of any polarity.

The electrodes differ not only in the composition of the coating and the rod, but also in diameter. The dimensions of the rod in the coating vary from 1.6 mm to 5 mm in diameter. The thicker the parts to be welded, the larger the diameter of the electrode required for their fusion. There are mathematical formulas for calculating the diameter for a given thickness of metal parts. It is easier for a novice welder to use tables.

Secondary factors affecting are the type of connection of parts (horizontal, vertical or overhanging welding, butt or fillet weld). From the data in the table it can be seen that the diameter of the electrode for corner connection slightly different from the diameter for butt welding parts.

At the same time, welding rods are not used for welding overhanging surfaces. large diameter. For the ceiling, their dimensions are limited to a diameter of 4 mm.

Varying the diameter of the rod while maintaining all other parameters can increase or decrease the specific welding current (current per unit section of the electrode). This will affect the depth of penetration and the thickness of the weld. If the electrode is thinner, the current strength is concentrated and melts deeper, the weld is narrow. If the electrode is thicker, the specific current strength decreases, and the penetration depth becomes smaller, and the weld width becomes larger.

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How to choose the value of the welding current and its polarity?

The strength of the current determines the depth of penetration of the metal. The stronger the current, the more powerful the arc, the deeper the metal melts. The current strength is directly proportional to the diameter of the electrode and the thickness of the weld. It can be determined by calculations using formulas or use ready-made tables.

The current strength is affected by the location of the weld. The maximum current value is used to penetrate horizontal surfaces. In order to weld vertical seams, the current strength is 15% less, for overhanging (ceiling) joints - 20% less.

The household inverter has a current scale up to 200 A. In semi-professional models, the scale value is graduated higher, up to 250 A.

Figure 3. Movement of the electrode during welding.

Polarity is the direction of current flow. The inverter makes it possible to change the direction of the current. How is this done and why is the polarity reversal necessary?

The flow of electrons (the current moves from minus to plus) in welding with an inverter moves from the “-” terminal to the “+” terminal. The terminal to which the electrons ("+") come, warms up more. This fact is used to ensure high-quality welding on various metals, with various thicknesses of elements. If the parts are massive, then the “+” terminal is attached to their metal surface (to one of the parts). This connection is called direct polarity, it is more often used in welding work.

If a thin sheet of steel or a high-alloy alloy that is prone to burnout of alloying elements is alloyed, then the “-” terminal is connected to them. The resulting polarity is called reversed. With such a current flow, the maximum heating occurs in the electrode, and the base metal heats up less.

Reverse polarity is characterized by greater arc stability, it is easier to ignite and maintain its combustion.

Comments:

inverters are the best devices for welding. You should be aware that old transformers have big weight and it's hard to use them. Anyone can work with the inverter. To do this, you just need to know the basic principles of metal welding with this device.

The inverter welding machine has light weight and greater power, which allows the production of complex welding works even for a novice welder.

First of all, the advantages of the inverter welding machine are its light weight and great capabilities. Thanks to this, with the help of this device, it is possible to perform work that was previously carried out only by complex devices. Electrical energy consumed by this machine small sizes, will be directed only to the work of the arc, with the help of which the welding process itself is carried out.

How to learn to weld metal, what you need to know before performing the welding process?

Correspondence table for electrode diameter and welding current.

The welding inverter is an economical machine that is convenient to use. With it, even beginners can learn how to weld metal. Before welding, it is important to learn about the principle of operation of this device. The inverter is an electronic welding machine, so the main load will fall on the mains. When old welding machines are connected to the mains, there is a strong and maximum possible push of electrical energy. As a result, the power grid of the entire region is being cut off. The inverter has storage capacitors that are capable of storing electrical energy, as a result of which uninterrupted operation of the electrical network can be ensured. The electric arc of the device in this case will be kindled gently.

You should know that the larger the diameter of the electrodes, the more electrical energy it uses. Therefore, if you want to check the welding machine in operation, you will need to calculate how much electrical energy the device will approximately consume. This is necessary in order not to burn household appliances their neighbors.

For each of the electrode diameters, the minimum current is shown. Therefore, if you want to reduce the current, then the seam will not work. If you want to experiment and increase the current strength, then the seam can be made, but the electrode will burn out quickly enough, as a result of which the work will not be comfortable.

In order to be able to correctly install the metal blanks to be welded, clamps or a vice should be used.

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How to weld metal with an inverter?

First of all, you need to know what elements will be needed for protection when working with a welding inverter. You need to buy the following:

Leather gloves.
Helmet for protection.
Thick fabric jacket.
Metal brush.

You will need to adjust the welding current and select the electrode. In order to cook with a welding inverter, you will need to use electrodes from 2 to 6 mm. The welding current is set depending on the thickness of the elements of the apparatus and the material being welded. In most cases, there is information on the body of the device about how much current should be. No need to bring the electrode to the base for welding quickly. If this is done, sticking may occur.

The welding process must begin with the ignition of the arc. It is necessary to bring the electrode at a slight angle to the part that is being welded, and then touch the welding base several times so that it is possible to use the electrode for welding. The electrode is held by several elements from the workpiece that is being welded. In most cases, this distance is equal to the diameter of the existing electrode.

The result is a weld seam. Scale (metal scale in the upper part of the seam) is removed with a small hammer. You can use any other durable item that has a lot of weight.

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How to control the arc gap?

Figure 1. Arc gap suitable sizes will help form a good seam.

The arc gap is the gap that appears during welding between the metal workpiece and the electrode. It is important to continuously monitor and maintain the same value of this gap.

If there is a gap of small dimensions, then this can lead to the fact that the seam will be convex and not fused on the sides due to the fact that the main metal cannot warm up quickly.
If there is a large gap, then it will not be possible to weld the part, and the arc will jump. As a result, the metal that melts will fit crookedly.
It is important to provide a gap of the required size. This is necessary in order to be able to form a normal seam with good penetration. Visually, a gap of suitable dimensions can be seen in Fig. one.

If you learn to control the length of the arc, you will be able to get the best result. The arc will pass through the gap and melt the parent metal. The result is a weld pool. The arc will also be able to transfer the metal that is being melted into the bath.

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How to make a welding seam with an inverter correctly?

If the electrode moves quickly during welding, a defective weld will result. The bath line is located lower than the base of the main metal. If the arc penetrates quickly and deeply into the main metal, then it can push the bath back, resulting in a seam. During welding, it is necessary to ensure that the seam is located at the level of the metal. You can make a perfect seam if you use arc and zigzag movements. During the execution of circular movements, you will need to control the level of the seam, placing the bath evenly in a circle. In the process of movements in different directions, the same seam will be formed, therefore, it is necessary to control the appearance of the seam during welding, first of all from one edge, then in the upper part of the bath, and at the end on the other side, and so on.

The bath will follow the heat - this is important to remember when changing direction during the welding work. The formation of an undercut will occur when there is not enough metal of the electrode to completely fill the bath during transverse movements. In order to prevent the appearance of such a lateral groove, you will need to control the outer boundaries, regularly monitor the bathroom. If necessary, you can make it thinner. To manipulate the bath, you need to apply the force of the arc, which is located at the end of the electrode. In the process of tilting the electrode, the tub will push but not pull. Therefore, the more vertical the electrode takes during welding, the less convex the seam will be. When the electrode is placed in a vertical position, all the heat will be concentrated under it and the bath will be pressed down, melt well and spread around.

When the electrode tilts slightly, all the force will be directed back, causing the seam to rise (float).

When the electrode tilts too much during welding, the force will be applied in the direction of the seam, and this will not allow full control of the bath.

If you need to make a flat seam or move the bath back, you should use the electrode tilts at different angles.

Work should be started from 45° to 90°, because such angles make it possible to observe the bath and weld easily.