What thickness of metal can be welded semi-automatically

Semi-automatic welding of stainless steel (MIG) | Tiberis

Semi-automatic welding of stainless steel is the most popular method of welding in a protective gas environment, which is used both in car repair shops and in large industrial production. From our article you will learn what the technology of the semi-automatic welding method of stainless steels is, what features it has, and what you should remember during the welding process in order to achieve ideal quality of the weld.

What is the semi-automatic welding method for stainless steel?

Semi-automatic welding of stainless steel (MIG) in a shielding gas environment is a high-tech process during which a wire is automatically fed into the welding zone, which simultaneously acts as an electrode and a filler metal, then it melts under the influence of the heat of the arc.

The quality of the arc is largely influenced by the correct choice of operating modes of the semiautomatic device: current, wire feed speed, choice of shielding gas and its consumption. The weld seam is formed quickly and is even. As a rule, during welding work this method uses a protective gas mixture of argon and carbon dioxide.

Oxygen is sometimes used instead of carbon dioxide, in which case the wettability at the edges of the weld increases (that is, the contact angle becomes sharper). Semi-automatic welding technology takes into account the structural features of the metal, its structure and chemical properties.

The question of how to cook stainless steel with a semi-automatic machine may have several answers. You can work with a semi-automatic machine in three different ways:

Short arc (for stainless steel with a thickness equal to or less than 0.8 mm);
Using jet transfer, the thickness of stainless steel ranges from 0.8 mm to 3 mm);
Pulse welding (stainless steel thickness more than 3 mm. But can also be used for thinner sheet steel).

Where is this method most often used?

Stainless steel is actively used in many areas of our lives, and, of course, in the process of working with this metal, as well as in the process of making certain parts from it, we have to resort to welding. The MIG method is rightfully considered universal.

The high efficiency of the method allows it to be used in garage conditions, and in the manufacture of household appliances and dishes, for example, in the case of installation and welding of various fences, metal tanks in the country, and in large production facilities in the automotive industry with serious requirements for the quality of the weld seam and efficiency welding process.

Is it necessary to use shielding gas?

It is possible to weld stainless steel semi-automatically without using gas. This welding method is characterized by the fact that a special flux-cored wire is involved in the process. The result is a high-quality seam. But the disadvantage of this method is that the suture material will become rusty over time. Therefore, when working with stainless steel, it is better to use stainless steel wire and supply of shielding gas to the weld pool.

What are the advantages and disadvantages of this method in contrast to MMA and TIG welding?

When compared with other welding methods, such as TIG welding, manual welding of stainless steel MMA, the semi-automatic method of welding stainless steel (MIG) (with gas) has the following advantages:

High performance;
A small amount of smoke.

The disadvantages of this method include:

The need to purchase a gas cylinder;
Limited outdoor use.

The gasless MIG method using cored wire has its pros and cons. So the advantages of this method include

Lack of gas cylinders;
Ideal for outdoor welding processes.

And among the shortcomings there are:

The need to remove waste;
Costs for cored wire.

Conclusion : High performance outweighs the inconvenience of having to use a gas cylinder, which is why the gas method is the most popular, especially indoors.

Welding materials and equipment for semi-automatic stainless steel welding

In order to weld stainless steel semi-automatically you will need:

Although it is possible, as mentioned above, to cook without gas, then it will be necessary to purchase self-protecting flux-cored wire.

Many people are interested in what kind of wire to weld stainless steel with. The electrode wire is selected depending on the thickness of the parts being welded (Table 1). Thin wire ensures stable arc burning to achieve greater penetration depth. Thick wire requires significant amounts of welding current, on average 100 A for each additional mm of diameter.

Sheet thickness, mm	Wire diameter, mm	Current strength, A
1	0,8	65
1,5	0,8	115
2	0,8	130
3	1	215
3	1	210
4	1	220
4	1,2	280
5	1,2	300
5	1,2	190
6	1,2	300
6	1	115
8	1,2	300
8	1	130
10	1,2	300

What types of metals (steel) can be welded with stainless steel

The MIG-MAG method is used when it is necessary to weld low- and high-alloy (stainless) steels, as well as aluminum and its alloys. A fairly new use of the method is semi-automatic soldering MIG-Brazing in a protective gas environment. Moreover, various combinations of welded materials are possible: copper-copper, steel-steel, copper-steel, etc.

Features of the welding process and recommendations

There are several features of the MIG welding process that must be taken into account in order to achieve the best result. Here are recommendations from experienced welders:

The gas mixture for welding should include: 30% argon and 70% special welding carbon dioxide (food grade can be used).
The protrusion of the electrode wire should be within 6-12 mm. When welding, the distance from the nozzle should be 5-15 mm. The working flow rate of the gas welding mixture will be 6-12 m³/min at a pressure of 0.05-0.2 atm. If the amount of gas is reduced, the weld will be of poor quality.
When operating, reverse polarity is used. Straight polarity is only possible with submerged arc welding.
The welding angle must be maintained in such a way that it looks backward, that is, the welder moves from left to right. The slope should be approximately 5-10 degrees. This gives a good penetration depth, the seam is smoother and of higher quality. When the angle is tilted forward, a wide seam is obtained, and the penetration depth decreases. This option is more suitable for thin sheets of metal.

Conclusion : Attention to the details of the welding process directly affects its result, in other words, the quality of the weld.

Semi-automatic processing of stainless steel after welding

In the process of welding stainless steel by any method, including the MIG/MAG method, a porous layer of oxide appears, and the chromium contained in the steel weakens the metal, increasing its ability to rust. Therefore, it is necessary to carefully process the product after welding.

What models of semi-automatic machines are best suited for welding stainless steel?

Today, the welding equipment market offers a wide range of semi-automatic units of Russian and foreign production,

Depending on the required voltage, you can choose:

Models of semi-automatic welding machines (MIG/MAG) for 220V mains voltage:

Inexpensive models - Svarog EASY MIG 160 (N219), FEB NORMA-205MP, These are fairly compact welders that, despite their affordable cost, can be used for MIG welding with or without gas.

Premium models - EWM Picomig 180 Puls, KEMPPI MinarcMIG EVO 170, KEMPPI MinarcMIG EVO 200, Lincoln Electric Speedtec 200C. These are devices of the latest generation of welding equipment, created for professional welding, providing solutions to a wide range of problems. Inverters remain functional even with falls and shocks.

Models of semi-automatic welding machines (MIG/MAG) for 380V mains voltage:

Among the budget options are BRIMA MIG 250, TRITON MIG 300, characterized by high performance characteristics despite their compact size.

And premium models for professional welding, characterized by versatility and high quality from reputable European manufacturers EWM Phoenix 351 Puls, KEMPPI FastMig Pulse 450.

Conclusion : The choice of a specific model of welder depends on the task being pursued, working conditions and the material capabilities of the welder. In Tiberis you can easily select the unit that suits you in all respects. Here you can get professional advice from experienced specialists on all issues related to the MIG welding method.

Source: https://www.tiberis.ru/stati/svarka-nerzhavejki-poluavtomatom-mig-mag

Welding thin sheet metal semi-automatically

Standard devices for working with thin sheet metals cannot always be used. They can burn through workpieces and not provide the required quality of welds. In this case, another technology is required that allows similar work to be performed with minimal heat input.

Why is the use of classical welding with a short arc of low power limited?

Standard semiautomatic machines for welding thin sheet metal use low voltage and welding current values. In this case, the process of transition of the electrode material into the seam occurs with a certain cyclicity, as shown in the figure below.

Changing welding arc parameters

There is an alternation of phases of arc burning and short circuits. The process looks like this:

1. After the arc is ignited, a drop of molten metal forms at the end of the electrode.
2. With a short arc, after a short period of time it comes into contact with the metal in the weld pool.
3. The electric arc goes out.
4. Under the action of surface tension, the drop detaches from the electrode and is drawn into the weld pool.
5. The electric arc is re-ignited.

The welding current and voltage also change:

1. The moment a droplet at the end of the electrode comes into contact with the metal in the weld pool, a short circuit occurs. The resistance in the resulting circuit drops sharply, and with it the voltage decreases abruptly and the current begins to increase.
2. Before a drop of metal separates from the electrode, the resistance, and with it the voltage, begins to increase rapidly. The welding current drops relatively slowly due to the inductance of the power source circuit.
3. The arc is ignited after a drop is torn off from the end of the electrode at high voltage. Because of this, part of the liquid metal of the ruptured jumper evaporates explosively, without having time to get into the weld pool. This is the reason for the formation of splashes. This process can only be prevented by counteracting the increase in current.

Short arc welding is an excellent tool for working with thin sheet metals, but it does not produce quality welds when joining parts made of heat-sensitive materials (galvanized or high-strength steel). In the first case, due to temperature effects, the protective zinc coating may evaporate; in the second, the steel may lose its strength properties.

Options for improving short arc welding

The main problem with short-arc welding is its high heat input when re-igniting after a short circuit. Attempts have been made to change this situation.

In the 80s, it was proposed to reduce the current before the rupture of the molten metal bridge, which occurs when a drop passes from the electrode to the weld pool, and then apply a high voltage pulse to facilitate arc ignition.

As a result, splashing was indeed reduced, but it was not possible to significantly influence the heat input.

Another attempt was the use of a modified short arc with an adaptive control system. In this case, intermittent wire feed technology was implemented. At the moment of a short circuit, it was pulled back and the bridge of molten metal was torn. This approach made it possible to reduce the duration of a short circuit and metal spattering.

The disadvantage is the complexity of the process itself. To put it into practice, a two-stroke drive with two wire feed motors was needed. As a result, such technology has become possible only for robotic or automatic welding.

EWM coldArc technology – the optimal solution for welding thin sheet metals

In coldArc technology, the determining factor is the cyclic change in voltage during short arc welding. Depending on its value, the current strength is adjusted.

Scheme of the modified short arc welding process

Timely response to voltage changes is achieved using highly dynamic instantaneous value adjustment. Smooth, spatter-free ignition is possible thanks to the digital signal processing used in EWM technology. It allows you to reduce the current and energy of the arc just one microsecond before it ignites.

The changes in welding current shown in the figure above clearly demonstrate the effectiveness of coldArc technology. Obviously, after re-ignition of the arc, this parameter increases briefly. The schematic image shows a characteristic step in the third phase zone, which is called the melting pulse.

A molten dome is formed at the end of the electrode after each short circuit, and the process of transition of the electrode metal into the weld pool occurs evenly. As a result, it becomes possible to use low current in the phases between short circuits.

coldArc technology involves regulating a modified short arc only in the energy source without interfering with the mechanical part of the wire feeder. Accordingly, you can use conventional welding torches and do all the work manually.

When using coldArc technology, the power peak when re-igniting the arc is significantly reduced and the heat input at the stage of melting the electrode metal is reduced. Thanks to these features, it can be used where conventional short arc welding is not possible.

Thus, metals up to 0.2 mm thick are already in demand in the automotive industry. When using standard MIG/MAG welding, in this case it is no longer possible to obtain high-quality seams. For such conditions, EWM semi-automatic machines with coldArc technology are indispensable.

Conclusion

When welding thin-sheet metal workpieces, much depends on the equipment used. coldArc technology allows us to perform this type of work efficiently.

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Source: https://vistek-weld.ru/reviews-articles/svarka-tonkolistovogo-metalla-poluavtomatom/

Thickness of welded metal semi-automatically

The demand for semi-automatic welding machines in the welding equipment market continues to grow every year. This is due to their obvious advantages: affordable cost, wide range of operating modes, ease of setup and operation. However, it is not always possible for a novice master to figure out how to use a semi-automatic machine correctly. The first thing you need to know is the structure and operating principle of the unit, as well as basic recommendations for choosing wire for welding.

Design and principle of operation of a semi-automatic device

The main purpose of a semi-automatic welding machine is arc welding using a consumable electrode, which is blown with shielding gas . The device is used for joining low-alloy and low-carbon steels, both with extended and intermittent seams.

This equipment is intended for operation in closed, well-ventilated rooms at air temperatures from -10°C to +40°C.

The semi-automatic device consists of the following elements:

the main unit that generates the welding current of the required value;
wire feed unit;
welding torch with a connected cable, through which passes the power wire, gas hose, control wire and guide for the wire electrode.

The operating principle of the unit is as follows. When you press the start button located on the torch handle, the flow of electrode wire (4), current and shielding gas through the nozzle (2) begins. Current flows to the wire through the conductive tip (4).

When it comes into contact with the base metal, an electric arc occurs, which begins to melt the electrode. Drops of electrode metal, falling on the base metal (8), form a seam (6). In this case, the weld pool (7) is blown with shielding gas (10), which prevents oxygen and nitrogen from entering it from the atmospheric air.

Thanks to gas protection, the weld is strong and of high quality.

The operation of the semi-automatic device is possible without protective gas. In this case, electrode wire with a special powder coating is used. At high temperatures, this coating evaporates, and the resulting gases perform a protective function for the weld pool.

Electrode wire selection

Electrode wire is an accessory without which the welding machine cannot operate. It is supplied using a special mechanism and performs the function of an electrode.

For semi-automatic machines there are two groups of materials for welding:

solid wire;
flux cored electrode wire.

There are more than 76 varieties of the first option. But most often, only a small part of them is used. The remaining types of equipment are highly specialized and are used in production. The main thing to consider when choosing wire is the type of metal from which the structure will be welded. Most often, you have to automatically weld low-carbon and low-alloy steels using non-copper-plated and copper-plated wire.

Copper-clad wire is the most popular among welders due to its anti-corrosion coating. But not everyone knows that when copper is smelted, harmful fumes are released into the air. Non-copper-plated wire is more harmless and has a corrosion-protective coating.

THIS IS INTERESTING: What you need to be a welder

Semi-automatic machines also use flux-cored wire, which does not require protective gas during cooking. The electrode wire has a special marking, for example, this: SV-08G2S . It is deciphered as follows:

SV – welded wire;
08 – means that the mass fraction of carbon in the composition of the equipment is 0.08%;
G – this letter denotes manganese, which is contained in the wire;
2 – the number indicates that the manganese content is 2%;
C – this letter indicates the presence of silicon in the equipment; if there is no number after the letter, then it contains no more than 1%.

The following is a table in which the letter designations of all additives included in the composition of the welding wire are deciphered.

For example, using the table, you can decipher the marking SV-06Х21Н7БТ, which means: welding wire has 0.06% carbon, 21% chromium, and nickel - 7%; the wire is alloyed with two metals, niobium and titanium.

For welding low-alloy steels (this is 90% of all rolled metal), 08G2S wire with a diameter of 0.6 mm is used. It can be used both at home and for body repairs. In addition, it can be used on units with current up to 500A.

For welding stainless steels, wire of the S01X19N9 grade is used. Aluminum and copper are boiled in an argon atmosphere corresponding to the composition of the wire. Aluminum is welded by grades SV-97, SV-A85 and SV-AMts.

For copper welding, equipment of the SV-97, SV-A85 and SV-AMts brands is used.

The diameter of the electrode wire is selected in accordance with the thickness of the metal being welded.

Semi-automatic welding rules

First of all, when starting to work with a semi-automatic machine, the parts intended for connection must be well cleaned of paint and rust. You should also clean the area where the mass clamp will be attached.

How to hold the burner

You can hold the torch with one hand, but the quality of the seam will be better if you use both. One hand serves as a support, and the other holds the burner.

With this method, it is easier to control the angle and distance of the torch from the workpiece, as well as carry out the necessary movements to form a high-quality seam. To keep your hands free, you need to use a welding mask that is attached to your head.

There is no ideal angle when working with a semi-automatic machine. Typically, to connect workpieces lying in the same plane, a torch tilt (from the vertical position) of 15-20 degrees is used. When connecting parts that are at an angle to each other, a burner tilt of 45° is used. Each welder, with experience, selects the most convenient angle of inclination of the tool, taking into account various situations.

Torch movements

To form a high-quality seam, there are many ways to move the torch.

For metals with a thickness of 1-2 mm, a wavy-zigzag movement is used. Thus, the arc captures both sheets of metal and does not have time to burn through it. As a result, the seam is tight and durable.
For welding metals of any thickness, a straight seam is used, eliminating any sideways movements.
But in this case, the operator is required to have some experience so that when moving the torch, the arc evenly affects both mating parts.
If you are going to work on metal with a thickness of less than 1 mm, then you should reduce the current strength and wire feed speed, and also use wire of a smaller diameter.

Welding should occur in short pulses, with a pause between them of about 1 second. A pause is needed to cool the metal and merge the next segments into a monolithic seam.
If long, thin parts are mated, then welding is carried out in short segments or points located at a certain distance.

Also, to avoid deformation of parts, you can cook alternately, in short segments, from different ends of the mating segment.

Welding speed

This is the speed of movement of the electric arc along the joint of the parts, and it is controlled by the operator of the semi-automatic machine. The speed of the tool must correspond to the arc voltage, wire feed speed, metal thickness and the required weld shape.

At a high speed of movement of the torch, a lot of splashes are generated, the protective gas remains in the quickly solidifying seam and causes the formation of pores in it. When the torch moves at a slow speed, excessive exposure of the electric arc to the material is formed, which can burn through it. In addition, when connecting massive parts, a thick seam is formed.

The following figure shows what the seams look like at different torch speeds.

Gas flow rate

The gas supply must be sufficient to provide airflow to the fed wire. If the gas flow is weak, the seam will not be protected from oxidation. But even at high flow speeds, protection will be insufficient due to the occurrence of turbulence. All these deviations from the norm make the seam porous and fragile. Therefore, it is very important to achieve an even supply of gas so that the flow does not cause turbulence and fully protects the welding site.

Wire output length

The wire should extend 6-13 mm from the tip before it touches the metal. The resistance and temperature of a given section of the electrode depend on this value. The more the wire extends from the tip, the smaller the arc size will be. As a result, the seam will be thick and narrow, with low penetration into the metal. If the length of the tool exit is reduced, the penetration of the arc into the metal will increase, and the seam will become thinner and wider.

Polarity

Polarity in welding equipment refers to the direction of current in its circuit. With direct polarity, a negative charge is applied to the wire, and a positive charge is applied to the part being welded. With reverse polarity, the opposite is true: the wire is positive, and the workpiece is negative.

Source: https://vi-pole.ru/tolshhina-svarivaemogo-metalla-poluavtomatom.html

What thickness of metal can be welded with a semi-automatic machine?

Which semi-automatic welding machine is better to buy for a garage, they are all so different?! You've been asking yourself this question very often lately.

Let's talk about a semi-automatic welder; it welds with wire with or without protective gases.

Trans or inverter

Let's consider the pros and cons of transformer and inverter welding equipment. The advantages and disadvantages of each of them will help you make your choice.

The transformer semiautomatic device has simple adjustments on the front panel:

wire feed speed;
power - 1, 2, 3, etc. These are the stages of switching according to which the welder is guided by the thickness of the metal. For example, for welding 3 mm metal, set the machine to 4 or 5 (each has its own settings);
Many transformers have a starting-charger (a convenient feature for cars).

The trans consists of a transformer, diodes for voltage rectification, resistors and thyristors, and a wire feed mechanism.

Disadvantages of transformer semi-automatic machines:

large dimensions and weight;
sensitive to voltage sags in the network. For example, when the voltage drops, the welder adds power to the machine and continues working. When the voltage increases, we get a burn through the metal;
they eat up the tension by draining the network, everyone's lights flicker along the street (neighbors express dissatisfaction).

For areas where low voltage is a common occurrence, it is better to buy an inverter. But in case you don't cook in winter.

Pros:

It’s hard to burn a transformer, you need to try really hard.
not afraid of dust, moisture, temperature. Can be cooked all year round.

Inverter semi-automatic welding machine for body work

Minuses:

no starting charger;
electrical boards collect dust, which reduces the durability of the device;
there are many parts, any of them can fail;
the inverter refuses to work at sub-zero temperatures.

Pros:

smooth power adjustment with digital display;
high-quality seam, the device smoothes out voltage surges;
light weight;
cooks at reduced voltage and a long extension cord;
uses energy economically;
higher efficiency compared to a transformer.

Conclusion: it is afraid of dampness, dust and cold, but with careful care the inverter will last a long time.

Useful tips

So, you have made your choice. What else to pay attention to when buying a semi-automatic machine for the garage:

The burner is the most wearable part; it must be removable and have a Euro connector. The built-in burner is designed for a maximum current of 130 A.
Possibility of polarity replacement. On ground plus, on the torch minus for welding using flux-cored wire, without a carbon dioxide cylinder. Cored wire with filler inside, requires reverse polarity.

The negative clamp terminal comes with a spring from the factory, it is better to replace it. Buy a terminal where the two parts are connected by a special bus. This will reduce the current drop and the loss of spring elasticity.

So, which semi-automatic welding machine should you choose for car repair? Owners of transformers claim that there is nothing better than their equipment, but owners of inverters say the opposite. The choice is yours!

The best option is to purchase a trans and inverter. Use the inverter in the warm season, and the transformer in the winter.

How to weld body metal

Each car mechanic selects the equipment settings for himself. For example, for 1 mm of Soviet metal and 0.7 mm of foreign-made metal, the power on the transformer apparatus is set to 1 or 2. Wire feed to the average value. The pressure from the cylinder to the semiautomatic device is 0.1 MPa.

Before work, the metal of the car is cleaned of paint, primer and rust. Normal wire feed is set:

With low feed, the seam turns out bad.
At maximum feed, the seam looks like a bump, and there is an overuse of wire.
The optimal value of wire exit from the torch to the welding surface is 1 cm.

Consumer Reviews

“I bought a semi-automatic welding machine for body work Ergus i-Mig 195 8 months ago. The price was 15,000 rubles.

I use it in the auto repair shop to the fullest, I’m very happy with the purchase. The inverter is equipped with a EURO connector for connecting a 3-meter BINZEL gun. For ease of work, the device has a wire pulling button. Also, there are voltage and welding current adjustments.

The bobbin holder with brake adjustment allows you to install a coil weighing 5 kg. The wire feed mechanism is assembled from iron products. The housing has contacts that change polarity for welding with flux-cored wire.

The device is equipped with a quick-release ground clamp contact with a cross-section of 25 sq. mm. Let me note that when you cook for a long time at maximum values, the quick release overheats and slow burnout occurs. This is such a small flaw, otherwise everything is in order.”

Nikolay Rytov, 33 years old, Chita.

“I purchased an inverter semi-automatic Eland MIG 200 2 years ago for 12,000 rubles.

Cons: built-in 1.5 meter burner, weak for large jobs. The burner gets very hot. A short sleeve causes a lot of inconvenience when welding. I wanted to re-equip the device, install a Euro connector and buy a pistol from another manufacturer. But it turned out that the mechanical gas supply valve is located in the burner, and not on the equipment.

The quick-release contact of the mass has a cross-section of 25 sq. mm, which negatively affects the service life. The semi-automatic machine is not equipped with polarity reversal; you can’t cook it with cored wire. Changing the wire is inconvenient, the internal space is small. The feeding device was already breaking (plastic), so I had to buy another one.”

Nikita, 29 years old, Saratov.

“I purchased a cheap semi-automatic welding machine for body work, Cyclone PDG 200, 9 years ago.

Plus of the device: it cooks with wire and an electrode. True, during electric welding, the unit heats up (there is no cooler). There are no overheating problems when working with wire.

On the front panel of the device there is a table with voltage switch settings depending on the wire diameter. During the period of operation there were breakdowns:

Repaired the wire feed regulator and feed roller. I changed the burner, I don’t have a Euro connector, I had to get creative. Modern Cyclones are equipped with a Euro connector and an additional function: +12V start and warm-up mode.

A semi-automatic transformer is a necessary thing in the garage. I’m thinking of buying a modern inverter device for car repairs.”

Sergey, 40 years old, Vladivostok.

When searching for welding inverters, incidents happen. You can purchase a transformer unit instead of an inverter unit. Check the model information on the manufacturer's website.

Source: https://stroyka.ahuman.ru/kakuju-tolshhinu-metalla-mozhno-varit-poluavtomatom/

What thickness of metal can be welded with a semi-automatic machine? — Metals, equipment, instructions

Modern manufacturers of welding machines produce dozens of different models of devices for semi-automatic welding. Semi-automatic metal welding technology allows metal parts to be firmly connected to each other, ensuring reliable fastening of structures.

The concept of semi-automatic metal welding refers to the process of attaching several metal parts to each other, in which the electrode wire enters the welding zone at a certain speed in automatic mode.

At the same time, an inert or active gas is supplied to the welding area. Its task is to protect the electrode wire and welded parts from environmental influences.

All other actions for working with the welding machine when welding in semi-automatic mode must be performed manually.

The advantage of semi-automatic welding processing is that this technology allows you to work with materials of any thickness. Semi-automatic metal welding is suitable for working with parts made from thin metal (metal is considered thin if its thickness does not exceed 5 millimeters). To carry out welding work on such structures, it is enough to use devices with low or medium productivity.

Semi-automatic welding machines are also suitable for processing parts made of thick metals. Semi-automatic welding effectively connects structures whose thickness does not exceed 250 millimeters. The specifics of working with thick metal products depend on the material from which they were made. To process such structures you will need equipment with a high level of performance.

TIP: when welding thick metal structures made from low-alloy steel, it is recommended to pre-heat treat the parts. The high temperature will help soften the metal and prepare it for further welding work. Preheating will help you weld faster and with a higher chance of a successful result. If the structure is not heated, then there will be a risk of deformation in the material.

The semi-automatic device for welding thick metals successfully copes with welding sealed parts using the high current density it creates. It ensures deep melting of the processed material, which allows for stronger fastening of mounted structures. This type of welding work is most suitable for processing rigid metal structures, as well as products made from steel grades with high heat resistance and special strength.

When welding products made from metals that are resistant to temperature changes, the strength properties of the material may deteriorate. The reason for this is that in the zone of temperature influence exerted by the welding machine, microscopic cracks appear, which soften the steel. Therefore, during semi-automatic welding work on thick metals, additional protective measures are taken to protect the structures being processed from softening of the material.

TIP: remember that semi-automatic welding of thick metal can lead to cracks in structures. Also, welding work can damage the anti-corrosion layer of parts, making them susceptible to the harmful effects of rust. For this reason, it is recommended to take protective measures after welding. The metal must be treated with a special coating that can restore the product’s protection against corrosion.

When processing metal structures of small thickness, there is no need to strive to obtain a surface seam. The structures must be welded as tightly as possible - this is the only way to achieve their full connection. That is why a semi-automatic machine is used for welding thin metals - it works extremely effectively when welding such structures.

Read also: Techniques to relieve metal stress after welding

Before semi-automatic welding, the structures being processed must first be prepared. The metal must be cleaned of dirt, pieces of paint or enamel, dust or lubricant coatings. If this is not done, the melting metal will splash too much and the seam will come out bent. In addition, foreign elements can be toxic.

To weld thin metal semi-automatically, you will need the following equipment:

welding machine;
welding electrodes;
source of electricity;
protective equipment for a welder (reinforced helmet, heat-resistant gloves, tinted glasses).

TIP: in order for the seam to be neat and even, the welder must independently regulate the speed of the welding machine. He also needs to select the correct type of electrodes and monitor a stable current supply with a constant strength indicator.

Technology of semi-automatic welding of galvanized metals

A feature of galvanized metals is their high resistance to corrosion. It's all about the properties of zinc - this element successfully protects various products from rust, which increases the stability of the structure and extends its service life. When welding galvanized metal with a semi-automatic machine, the anti-corrosion stability of the entire structure may be compromised.

The reason for this is the different melting temperatures. If welding of most metals requires a temperature in the range of 1700-2200 degrees Celsius, then the melting of zinc begins at 420°C. At 907°C, this element boils and turns into oxide, which forms microscopic pores and cracks on the surface of the metal structure. This leads to the fact that the metal becomes susceptible to corrosion.

Modern technology for semi-automatic welding of galvanized metals consists of one innovation - MIG soldering. It allows welding work to be carried out using high-frequency electrical vibrations at low temperatures.

In this case, the zinc does not melt, so it does not turn into an oxide compound and does not damage the base material of the structure being processed.

This technology allows us to solve the problem of destruction of the anti-corrosion layer during semi-automatic welding of galvanized metals.

The process of semi-automatic welding of non-ferrous metals begins with checking the condition of the equipment. During its inspection, it is necessary to adjust the operating mode of the welding device, select the current strength, voltage level and wire speed. If the thickness of the metal being processed is less than three millimeters, then the suitable current strength is in the range of 120-145 amperes. In this case, the speed of movement of the wire should be 900 meters per hour.

When semi-automatic welding of non-ferrous metals, the torch must be moved in only one direction. It is best to weld parts at high speed and through one seam. If the non-ferrous metal is very thick, then it must be heated to 150-300°C.

Semi-automatic argon welding of ferrous metals

Semi-automatic welding of ferrous metals with argon differs in some features. It should be noted that moisture poses a great danger to ferrous metals during welding. It may remain inside the weld, after which condensation will begin.

When evaporating, moisture particles will form small pores and microscopic cracks in the seam, which will negatively affect its strength in the future. Therefore, before starting welding, it is recommended to warm up the structures being processed to 100-150 degrees Celsius.

Read also: Features and example of calculating a fillet weld in metal

For semi-automatic welding of ferrous metals, it is necessary to use special electrodes. Without them, the weld will be sloppy and too fragile.

For welding ferrous metals, it is best to use non-ferrous metal electrodes with a high graphite content.

The best choice is copper-nickel components, which help to reliably weld the metal and do not leave a large amount of graphite impurities in the resulting weld.

Semi-automatic welding of cast iron and steel products

Inert gas is used not only for processing non-ferrous metals. Argon is also used to work with cast iron and steel structures. Iron and carbon are used to produce cast iron. The process of welding it is very labor-intensive due to the fact that the resulting seams often crack.

Another feature of cast iron is its predisposition to accelerated oxidation. Therefore, argon is needed for its welding - it helps to form connecting seams without the formation of slag deposits. Cast iron's rapid oxidation has made it a popular material for repairing older cars. This material is connected to thin metal structures that require repair.

Semi-automatic welding of cast iron and brittle metals is often carried out using tungsten wire. The processed products also require preheating. Both direct and alternating current are used for welding cast iron structures. Its strength depends on the thickness of the metal and the diameter of the wire (for every millimeter of wire there is from 50 to 90 amperes of electrical current). Instead of tungsten, graphite, copper or nickel can be used as wire material.

Semi-automatic welding of stainless metal parts

Semi-automatic welding of stainless metals is characterized by high productivity. In addition, it can be carried out in almost any conditions. To weld stainless steel structures, you need a welding machine that operates in an argon environment.

Electric engraver, what can it do?

The shielding gas helps prevent nitriding and oxidation of the created joint, which without the argon protection of the weld would begin to come into contact with the outside atmosphere and become weak.

Argon is also suitable because even at particularly high temperatures it does not enter into any chemical reactions - it is much heavier than air, which helps to easily displace it in the welding area.

Welding of stainless metal with argon is carried out using electrodes made of non-consumable materials. During operation, they must be positioned strictly perpendicular to the surface being welded. If this condition is met, the weld will be of high quality.

Finally, it should be noted that at the moment semi-automatic metal welding has become particularly widespread in several areas of production closely related to metal processing. Semi-automatic welding is most in demand in the automotive industry.

It is there that there is always a need for processing thin metals, for which semi-automatic welding is suitable. Often in the automotive industry, semi-automatic welding of metals with a thickness of 10 mm or less is used.

Also, semi-automatic welding is often used in construction work, which often requires welding rigid metal structures of large thickness.

Source: https://spb-metalloobrabotka.com/kakuyu-tolschinu-metalla-mozhno-varit-poluavtomatom/

What thickness of metal can be welded semi-automatically

Used cars become corroded if not properly cared for. Sometimes, if this problem is not corrected in time, a complete replacement of individual body parts is required. At the same time, welding work cannot be done without. And welding a car body with your own hands requires skills and at least a little experience.

For welding work on a car body, the most acceptable option is to use a semi-automatic welding machine. This allows you to work with any material thickness: from 0.7 to 4 mm. Both, for example, thinner wings and powerful spars fit into this interval.

Methods for connecting elements during automotive welding

Different components and options for car repair using welding require a different approach to pairing new inserts with the old body. Let's look at three main ways to install metal patches.

Butt mate

Welding a car body with a semi-automatic machine is most often carried out using a butt joint. In this way, additional unnecessary thickenings on the body are not created. This method is used when welding patches or small inserts that are not subject to high tensile strength.

Connection types

Before working with the patch, you can chamfer the sides that you plan to weld.

If the sheet thickness is up to 2 mm, then you can do without chamfers. This method of mating requires more painstaking adjustment of the welded part and the prepared area of the car body. Gaps should be kept to a minimum, and ideally, they should be avoided. The method is usually used for external external elements.

When performing this operation, the welder must have sufficiently high qualifications.

Butt welding

The work is carried out using a continuous spot weld. A high-quality result does not require labor-intensive straightening and lengthy cleaning. Sometimes putty and grout are enough. Thicker sheets of iron are easier to weld, and they can also be welded with a continuous spot weld. Thin sheets are more difficult to cook.

Lap joint

This connection is the simplest and therefore has become widespread among automotive welders. So, one of the pieces of metal is superimposed on the other, and the hole that needs to be patched is completely blocked.

Welding overlap

The method is suitable for welding load-bearing structures: thresholds, spars, etc.

Welded electric rivets

This method is rather a type of overlap connection. However, it is similar to spot welding. It is actively used in automotive welding. For example, it is used to install new fenders and reinforcing linings on the body frame.

Types of Welds

Regardless of the joining methods, in each case, semi-automatic welding technology involves the use of different types of seams. There are three popular seam options:

solid;
point;
continuous intermittent.

Types of seams

Each of them can be applied in any of the mating methods, both with overlaps and butt joints.

Source: https://steelfactoryrus.com/kakoy-tolschiny-metall-mozhno-varit-poluavtomatom/

What metals can be welded semi-automatically

A semi-automatic welding machine can quickly and efficiently connect two parts. Due to the fact that this type of device can work with any metals of various thicknesses, automatic and semi-automatic welding is used in all industrial sectors.

Compared to manual arc welding, it has a much higher efficiency, with low material costs. Semi-automatic welding for beginners includes several aspects - theoretical and practical.

They are closely interrelated, and before starting welding work, a beginner must master the basic basics.

What is a semi-automatic machine and its types

To weld with an automatic welding machine, you need to understand what it is and how it works. A semi-automatic welding machine is a mechanical device in which a coil of wire is installed, acting as a consumable electrode, and a mechanism for automatically feeding it. The current strength and electrode feed speed are set by the welder on the machine himself, depending on the type of metal that is being fused and the speed of movement of the torch.

There are many different units for welding work. To organize them a little, there are several classifications. Let's consider the most basic one - the method of protecting the material during the process:

semi-automatic welding under a layer of flux (flux is a powdery composition that is located in the middle of the working wire. In its chemical properties, it resembles electrode coating);
welding in inert and active gases;

In addition, there are single-phase and three-phase units for semi-automatic welding. Single-phase models operate from a regular 220V outlet. In this case, if the network does not match the power of the unit, the arc will not be stable, which will lead to defects when creating a seam. A three-phase device cannot be connected everywhere, but at the same time it is distinguished by high quality of work under different loads.

Although the listed semi-automatic welding machines differ from each other, they all have the following equipment:

current source;
gearbox for moving the electrode;
burner;
welding cable with clamp;
control system;
gas cylinder;
gas supply hose.

Semi-automatic welding technique

Let's look at how to weld semi-automatically, since this type of work has several options - welding with shielding gases and welding without gas, using flux-cored wire.

Gas shielded welding technology

For semi-automatic welding, you can use several types of gases. The most commonly used gases are carbon dioxide or helium. This is due to their availability and low cost of use.

Gases are used to reduce oxidation of the metal from which the part being welded is made, in order to increase the strength of the weld. The main condition for operating a semi-automatic machine with carbon dioxide is preliminary preparation of the part.

This means thoroughly cleaning it to remove all dust, dirt, paint residue or rust. To do this, use sandpaper or an iron brush.

There are three types of welding technology:

continuous welding, when the torch or electrode is carried out from the beginning to the end of the seam;
spot welding, in which parts are connected not by a continuous path, but by welded spots;
Short circuit welding is carried out mainly for thin sheet metal and involves melting the metal by applying pulses from a short circuit that forms in the welding machine. Once closed, the molten material is pulled together into a droplet, which is used to join the two parts.

Most often, semi-automatic welding with carbon dioxide is performed in alternating current mode. Before starting work, you need to prepare everything for welding. The device is adjusted depending on the type of metal and its thickness. The gas consumption from the cylinders will depend on the welding mode. The wire diverges almost equally - on average 4 centimeters per second.

More precise settings can be found in the GOST tables, which indicate the modes and standards for each type of metal. When both the equipment and parts are ready, you can begin connecting the products using a semi-automatic machine. First of all, you need to turn on the gas supply and then excite the arc. To do this, you need to touch the part with the wire.

When you press “start/start” on the body of the device, the mechanical feeding of the electrode wire begins.

The quality of the seam depends on many nuances. For example, it is important to hold the wire and guide it straight, but not too close to the workpiece. So as not to block your view of the weld pool. During work, it is important that the required interval is maintained between the edges of the parts being welded.

The operating technology is such that when the product is up to a centimeter thick, the gap should be no more than 1 mm; when the product is more than a centimeter thick, the gap is 10% of this value.

Very often, parts in a lying state are welded on a special iron substrate, placing it from below very tightly to the base metal.

Aluminum welding technology

A semi-automatic machine can be used to weld various metals, and aluminum is no exception. But there are special rules, since this metal has some special features.

On its surface there is a thin layer of amalgam, whose melting point is much higher than that of aluminum (more than 2000 degrees, while the base metal melts at 650 degrees). In this case, argon is used as an inert gas.

Since aluminum quickly melts and begins to flow, a substrate is used to work on a semi-automatic welding machine.

The welding process itself occurs with consumable electrodes under the influence of direct current of reverse polarity - this is when a negative charge is attached to the part, and a positive charge to the torch. Such welding techniques contribute to high-quality melting of the workpiece and rapid destruction of the top layer. Although for such a connection you can use another trick - pre-clean the product to remove the oxide film. You can read more about the features of working with aluminum here.

Source: https://crast.ru/instrumenty/kakie-metally-mozhno-varit-poluavtomatom

What wire should I use to weld stainless steel semi-automatically?

This article will provide all the basic information about stainless steel welding wire. You will learn the features of its marking, the requirements that a quality product must meet, and what you need to pay attention to when choosing.

The features of semi-automatic welding technology with wire will also be analyzed, and the current state of the market for these materials will be analyzed for the main manufacturers and their pricing policy.

Wire welding

The wire is an element that, when welding semi-automatically, takes on the functions of an electrode and transmits current to the surfaces being welded. In addition to this, the knitting wire acts as a filler material, when melted, a welding seam is formed.

Marking of stainless wire for welding

Below is a standard type of wire marking and an explanation of its meaning.

Explanation of standard welding wire markings

Diameter of metal thread. Stainless steel threads with a diameter of 1.6 mm, 1.2 mm, 1 mm, 0.8 mm and 0.6 mm for semi-automatic welding
Product brand.

Cell No. 2 – purpose: SV – welding, or NP – surfacing; cell No. 3 – carbon concentration in the raw material, which is indicated in hundredths of a percent. For example: CB09 is a product for welding with a carbon content of 0.09%. Cells No. 4, No. 5, No. 6 and No. 7 indicate the concentration of additional alloying impurities.

The marking features are as follows: Y - aluminum, D - Copper, T - titanium, G - manganese, C - zirconium, M - molybdenum, X - chromium, N - Nickel, S - silicon. In the cell next after the indicated letter there is a number , which indicates the concentration of a given element, but if the content of the element is within one percent, then, as a rule, the number is not given.

For example: stainless steel knitting wire for semi-automatic welding SV09N5X21T contains 0.9% carbon, 5% nickel, 21% chromium, and 1 percent titanium.

Cell No. 8 - marking in this cell is placed if the welding thread meets the increased requirements for harmful sulfur and phosphorus impurities.

Depending on the standard of the wire, two indicators can be placed in this cell: A - indicating that the product is manufactured according to high cleaning standards, AA - the principle of maximum cleaning was used in the production process, this is how the highest quality stainless steel welding wire is usually marked;

Production technology (smelting method): Ш – electroslag smelting, VI – smelting in vacuum-induction furnaces (the most preferable option in terms of the final quality of the product), VD – smelting in vacuum-arc furnaces;
In the case where electrodes can be made from this thread, the marking contains the indicator E;
O – marking element highlighting copper-coated wire;
Product compliance with the State Quality Standard.

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About making wire

The current standard, according to the requirements of which stainless steel welding wire is produced, is GOST of the Russian Federation 2246-70 “Welding wire made of high-alloy, heat-resistant and corrosion-resistant steel.”

Coils of stainless wire for semi-automatic machines

Since the efficiency of semi-automatic welding directly depends on the quality of the welding wire used, this GOST puts forward strict requirements for the raw materials used to create it.

According to the requirements of GOST 2246, the presence of the following materials in the product is strictly standardized:

The amount of carbon contained in raw materials directly affects the quality of the final product. If the carbon concentration is sufficient, which is extremely important for a welding thread, then the stainless threads will have good ductility, which has a positive effect on the ease of use in the welding process, and, at the same time, high strength and wear resistance, as a result of which wire consumption will be reduced.

Manganese and silicon impurities.

These elements are used to deoxidize raw materials during the smelting process. The optimal concentration of manganese and silicon gives the stainless thread high resistance to abrasion, resulting in increased wear resistance and elasticity.

However, it is extremely important that phosphorus and silicon impurities are evenly dissolved in stainless steel, since accumulations of oxides in which silicon molecules can accumulate negatively affect the elasticity of the welded wire.

These elements belong to the category of harmful impurities, therefore their quantity in the raw materials for the manufacture of stainless steel products for semi-automatic welding is strictly standardized.

Stainless Welding Wire Production Process

According to the current GOST 2246, the total concentration of sulfur and phosphorus in stainless steel should not exceed 0.05%; when this norm is increased, stainless steel acquires the property of “red brittleness” - increased brittleness under the influence of high temperature, which makes it difficult to use during welding.

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Chromium is a foreign element that enters stainless steel blanks during their smelting in blast furnaces. The presence of chromium negatively affects the strength characteristics of the final product, so manufacturers are taking various measures to reduce its concentration, which, according to GOST, should not exceed 0.1%.

The presence of nitrogen impurities in stainless steel has virtually no effect on the strength and elasticity of fresh thread. However, over time, nitrogen provokes an increase in the properties of strain aging - loss of performance characteristics of the product, such as elasticity, strength and fragility.

The rest (non-metallic impurities).

Any non-metallic impurities in the composition of stainless thread for semi-automatic welding are defects and indicate low quality of the product.
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Features of use

There are two main technologies for semi-automatic welding using stainless wire: welding using a short arc, and the pulse method. There is also jet transfer welding; this method does not necessarily require the use of gas, but flux-cored binding wire is better suited for its implementation.

Welding using a short arc (jet transfer) - used in most semi-automatic welding machines. This technology requires the device to maintain a constant output voltage with a high current density.

Source: https://varimtutru.com/kakoy-provolokoy-varit-nerzhaveyku-poluavtomatom/

Features of semi-automatic welding of ferrous metals, stainless steel and aluminum. Wire selection

Semi-automatic welding is gaining more and more popularity among welders every year. And this is not surprising, semi-automatic provides advantages over traditional welding methods (MMA and TIG):

High speed, convenience and ease of operation;
The electrode wire acts as both an electrode and a filler material;
Semi-automatic welding is quickly mastered by beginners, showing good results even after several beads;
Welding thin metal less than 1 mm thick (megapopular when welding automotive body iron). Read the article “Do-it-yourself car body repair.”
High quality seams;
Possibility of welding in various modes;
When using self-flux-cored wire, no forced gas supply is required and there is no need to transport large and heavy cylinders. You take with you only a welding machine and wire wound on a euro spool, which is especially convenient when the welding team is working on the road.

However, despite all the listed advantages, you will never get seams with high mechanical and physical properties if you make a mistake when choosing an electrode wire. What are the criteria for choosing wire for a semi-automatic machine?

Let's list them in order:

The wire must match the chemical composition of the base metal or part as closely as possible.
The wire must be produced taking into account the requirements of domestic GOSTs and foreign standards.
Wire storage conditions must be observed.

Ferrous metal welding

It must be said that ferrous metal accounts for 90% of all rolled products produced in Russia. Therefore, wire for welding ferrous metals (excluding cast iron) is one of the most popular among welders. It is used both in everyday life and in almost all spheres of the country’s national economy: it is indispensable in mechanical engineering, aircraft manufacturing, automotive industry and service maintenance, etc.

Welding low-medium carbon steels with a carbon content of up to 0.45% (st. 3, st. 5, st. 10 st. 45) and low-alloy steels with a total content of alloying elements up to 2.5% (06G2SYu, 20KhGS, 12GN2MFAYu, etc. .

) is carried out using Sv-08GS or Sv-08G2S wire, the quality control of which in our country is regulated by GOST 2246-70. It should be noted that among the carbon steels there are also grades that are difficult to weld, for example, Art. 6; MSt.6; KSt.6; Bst.6, as well as art. 45, because they contain from 0.38 to 0.49% carbon, which is certainly a lot.

When welding, they must not be overheated; preheating and immediate heat treatment after welding must be applied to them.

Gas protection principle

Protective environment – 100% CO2.

The carbon dioxide welding process was invented by Soviet engineers Lyubavsky and Novozhilov. The method became instantly popular all over the world due to the low cost of carbon dioxide, in contrast to the expensive argon, which was most often used before the innovation, since welding in helium was even more expensive.

If in argon arc welding the task is to protect the weld pool as much as possible from the harmful effects of oxygen, because it is a very harmful element, then with semi-automatic welding in CO2 the task changes to the diametrically opposite one: to oxidize the pool as much as possible, and then remove the oxygen using the wire contained Sv-08G2S silicon and manganese deoxidizers. It is they, due to their activity, that form compounds with oxygen and bring it to the surface of the liquid metal in the form of slag. As people say, “they knock out a wedge with a wedge.” Sometimes, to stabilize the welding process, not pure CO2 is used, but an argon-based mixture of 85% Ar + 15% CO2 .

Copper plated surface

Most ferrous welding wires are coated with a thin micron layer of electroplated copper.

There is an opinion that copper is intended for good electrical contact in the tip-wire pair and protection against petting corrosion, which very quickly affects unprotected wire when stored in warehouse conditions, where the temperature is low and the humidity is high.

Dampness is a good environment that promotes intensive electrochemical processes of metal destruction. But welding with wire, which is corroded by rust here and there, is still a “pleasure”; the seam will turn out unsatisfactory with inclusions and the like.

However, despite the opinion that copper protects, and many online stores write about this, in fact, the coating even accelerates the destruction mechanism, since EMF induction occurs at the steel-copper interface and oxygen enters through numerous pores in the copper-plated layer. Therefore, if you do not want your wire to deteriorate, follow the manufacturer’s recommendations and store the euro spool in a hermetically sealed plastic bag with silica gel added.

The quality of copper determines the safety of the semi-automatic feed mechanism, the uniformity of wire feeding into the welding zone and, ultimately, the quality of the seams. Cheap wire from low-quality Chinese manufacturers, as a rule, has thick copper plating due to the reduction in the cost of the production process; because of this, the coating becomes very dusty and forms flakes or scales. To avoid the problem, ESAB has developed a wire that is produced without any coating .

Who should you buy from?

High-quality wire is produced by the American company Lincoln Electric and European companies ESAB, Cloos, ISAF, etc.; large Chinese industrial giants Jasic, FARINA WELDTEC, Riland, etc.

What to choose? Foreign analogues of sv-08G2S

Copper-bonded wire OK Autrod 12.51 from the Swedish company ESAB. High quality - high price.

To characterize this product, it is enough to note that ESAB was at the origins of electrode production. Oscar Kjellberg, the founder of the company, was actually the first to present to the general public a finished version of a coated electrode for manual welding. Since then and to this day, the company has remained an innovator, a locomotive of progress, and the ESAB brand has become synonymous with quality.

Documents confirming the quality of OK Autrod 12.51:

GOST 2246-70;
EN ISO 14341-A: G 38 2 C1 3Si1
AWS A5.18: ER70S-6
Certificates VNIIZhT and NAKS.

Chemical composition of OK Autrod 12.51:

C - 0.06-0.14Si - 0.8-1.0Mn - 1.4-1.6

The amount of sulfur and phosphorus is reduced by no more than 0.25% for each element, respectively.

Mechanical properties: Yield strength: 470 MPa Strength: 560 MPa Elongation: 26% Impact strength: +20°C 130 J/cm2-20°C 90 J/cm2

-30°C 70 J/cm2

, Farina ER70S-6 and Deka ER70S-6 wires have an acceptable price-quality ratio .

Recommendations for preparing and welding ferrous metal parts:

Preparation of the edges of the welded joint is carried out in accordance with GOST 5264-80 (pdf). There you will also find recommendations on the angle and depth of chamfering, gaps and the advisability of using a particular connection. The metal must be cleaned at a distance of up to 30 mm from the cutting boundaries. Cleaning is done with a grinding wheel on an angle grinder, or with a brush with metal bristles until clean, shiny metal is achieved.

Dirt, oil, corrosion, paint coatings and other contaminants are not allowed and must be removed. If welding is particularly important, the surfaces can be degreased in any available solvent: white spirit, gasoline, nephras, acetone, etc. Welding is carried out with a short arc, i.e. the distance from the torch nozzle to the surface of the joint being welded should be minimal.

To reduce the unnecessary consumption of filler material for spattering the metal of the weld pool, it is necessary to ensure continuous jet transfer and keep the shielding gas flow rate in the range of 10-15 l/min for electrode wire with a diameter of 0.8-1.2 mm.

A further increase in gas pressure and, accordingly, its flow rate provokes a turbulent flow, which negatively affects the stability of the welding process and the quality of the seam (due to oxidation of the metal, numerous pores and cavities appear). Increasing the pressure is justified only in cases where you have to work in a draft.

If you work outdoors in windy conditions, use protective screens.

A decrease in pressure also provokes the occurrence of defects due to insufficient protection. Install a gas lens on the torch for more effective gas protection.

Welding thin-sheet steel is complicated by its tendency to distort heavily. Deformations occur due to strong local heating by an arc discharge, while the rest of the sheet remains relatively cold.

Using a pulse mode, as well as adjusting the inductance value on some devices, allows you to reduce heat input into the metal and ensure a high-quality welded joint of thin metal from 0.5 mm without defects, through burns, and with minimal thermal shocks to the sheet.

Preliminary and concomitant heating with a gas burner also reduces metal warping, and post-welding heating or forging prevents the development of hot cracks.

Welding ferrous metal with flux-cored wire

As already mentioned, welding with flux-cored wire does not require additional gas supply to the welding zone; therefore, there is no need to fool around with large and heavy gas cylinders, or use vehicles and special containers to transport them. Obviously, many problems are eliminated when a team of welders works on site.

However, the use of flux-cored wire is always a necessary measure. Every specialist will tell you that the quality of seams with such wire will never be the same as when welding with carbon dioxide protection or argon arc welding.

Therefore, there are often cases when they are additionally protected by the supply of CO2
. What is a self-fluxing wire is a tube made of low-carbon metal, the core of which is filled with powder. First, the metal melts due to its high electrical conductivity, then the powder, releasing the gas necessary for protection for the correct formation of the metal bath.

It turns out almost the same as with RDS (MMA) with a coated electrode, only there the fluxing substance is located outside the metal rod, and here it is inside and the current-voltage characteristics of the power sources are different. Powder composition: rutile, metal dust or other composition.

I want to buy this kind of wire, what should I ask in the store?

Ask for E71T-GS. This marking is used in accordance with the American standard AWS A5.20.

Which polarity should I use for cored wire welding?

For E71T-GS, DC current and reverse polarity are used, however, the polarity depends on the composition of the flux core.

Specifications E71T-GS

Source: http://svarka-master.ru/osobennosti-poluavtomaticheskoj-svarki-vy-bor-provoloki/

How to cook with semi-automatic and wire without gas

Semi-automatic welding has a number of significant advantages. Firstly, it makes it possible to weld long seams, and secondly, it has a better welding seam than electrode welding. Also, using a semi-automatic machine is most convenient for welding thin metal, the thickness of which is less than two 1.5 mm.

With all this, semi-automatic welding has only one significant drawback, which is the need to use shielding gas. To do this, with a small welding machine you need to carry a large gas cylinder, which in turn is very, very inconvenient.

You can eliminate shielding gas from use and use only wire welding. However, it is not ordinary wire that is suitable for this as a filler material, but flux-cored wire. You can learn about how to cook with wire without gas and what is required for this below, from this publication from the website mmasvarka.ru.

Semi-automatic welding: what happens and how

If with welding with electrodes everything is more or less clear: you inserted the electrode into the holder, threw the mass onto the workpiece and began to cook, but with semi-automatic welding, things are different. When semi-automatic welding, a wire is used as a filler material, which is enveloped in shielding gas during welding.

In turn, gas is needed to protect the weld pool from its interaction with the environment. This is the main disadvantage of semi-automatic welding, since you need shielding gas, which is not always at hand.

What to do in this case? Is it possible to cook with wire and semi-automatically without gas?

How to cook semi-automatically without gas

For semi-automatic welding without gas, you can use a special flux-cored wire. The structure of the flux-cored wire is designed in such a way that there is powder inside it, which, when the wire burns, enters the weld pool, thereby protecting it from harmful influences from the outside.

At its core, this powder is the same protective gas, or, if you like, an electrode coating, which also plays a protective role for the weld pool. This coating consists of rutile and fluorite, and its more precise composition can always be found on the packaging with the electrodes.

Thus, using a semi-automatic machine, you can weld with cored wire without gas. This provides an excellent opportunity to use semi-automatic welding in the most inaccessible places, for example, at heights, where it is not possible to deliver a gas cylinder.

Features of cored wire

Cored wire has different diameters, the smallest diameter starts from 0.8 mm. The thickest wire for semi-automatic welding without gas has a diameter of 2.4 mm. In turn, such a large selection of diameters provides the widest possibilities for semi-automatic welding: starting from welding thin metals only 1.2 mm thick, and ending with metals one centimeter thick.

Using flux-cored wire and a semi-automatic machine without gas, you can weld both carbon steel and galvanized iron with stainless steel. In this case, the filler inside the wire may differ in its composition, and this is very important to take into account when choosing flux-cored wire for welding.

Source: https://mmasvarka.ru/kak-varit-poluavtomatom-bez-gaza.html