What is Tig Welding

How does a welding machine work?

A welding machine is a machine that allows you to fix the connection of two materials. The connection is achieved by melting both materials or a feed material can be added which, when melted, is placed between the parts to be welded and when cooled becomes a fixed connection.

The welding machine typically bonds metals or thermoplastic materials. The energy source for welding can be gas, electric arc, laser or ultrasound. - more details on the website

Why do you need a welding machine?

Welding machines are most often found in the industrial sector, in those industries where materials, parts, tools or metal machines are produced.

Likewise, it is very likely to find a welding machine in any home as we often have to do household tasks where we need to join two metals together.

Types of Welding Machines

There are different types of welding machines depending on what you want to use them for.

Arc welder

This is the most popular type of welder today. This machine uses electrical energy , which creates an electric arc between the metal being welded and the electrode being used. There are different types depending on the electrode used.

• Manual metal arc welding
• Metal arc gas welding
• Arc welding with molten core
• Tungsten Gas Arc Welding
• Submerged arc welding

Tin soldering iron

Delicate work and repairs to small appliances are highly recommended Very used in electronics. This machine consists of a copper tip which is heated by electrical energy and melts.

Gas soldering iron

Used when welding copper or aluminum materials. These machines use flammable gas which makes it friction to produce a flame which melts the metal input. The molten material is placed into a joint, which leaves a cord when cooled.

Laser welder

They heat the area to be welded and then apply pressure, ensuring high precision. They are very useful for joining small areas and very quickly, making them useful for mass production as well.

Soldadores Inverter

This is the latest in soldier technology. They can make different types of welds without changing the equipment. In addition, they have the advantage that they are easy to carry, have a long service life, and the visible welds are more aesthetically pleasing than other machines.

As we have seen in the previous paragraphs, there are many types of welding machines, each used to perform different tasks. But they all base their functioning on the same form of work.

Welding machines require a power source (electrical, combustion, mechanical) to convert it into energy that allows the creation of a fusion of material that is used to join two or more elements.

As we mentioned above, these machines process a lot of energy in the form of heat to melt the materials for feeding. That is why it is necessary to take into account all the safety measures necessary to use these machines without risk to humans.

Welding machine parts

For the welding machine to operate properly, it must consist of a number of parts , which we will consider in detail below.

• Welding machine: It is responsible for converting the energy source into the type of energy required to perform the welding process.
• Electrode Holder Cable: This cable extends from the welding machine winding onto the workpiece.
• Ground Wire: This wire is connected to the part where the electrode is located.
• Current selector knob - select the current strength with which the work was performed.
• On/Off button: Turns the welding machine on and off.

How to perform basic step-by-step welding

Source: https://topnewsrussia.ru/19/01/2020/26105/kak-rabotaet-svarochnyj-apparat.html

What do electric welders usually say before welding?

You cannot watch welding work without additional protection. The means of providing personal protection to a person are considered to be a welder's mask, safety glasses and shields.

Would you marry a welder?

I often receive letters from readers who are perplexed as to why they are unable to weld thin metal with a mm electrode. Well, let's remember physics. More precisely, we won’t even remember, we’ll just imagine the welding process. Gross mistakes of the welder The welder brings the electrode to the part, lights the arc, it heats the metal and immediately creates a hole.

I returned to my office in deep thought. along with Gio. I asked her why the quality of welding work had deteriorated so sharply. I'm afraid to even ask how things are going with the training of workers. “To what extent?

It is difficult to name any segment of production that does not require the work of a welder. As a profession, electric welding provides beginners with the opportunity to obtain promising work.

Welders work on construction sites, creating systems of various communications and structures, in industry, applying their skills and experience, in shipbuilding, mechanical engineering, energy, agriculture, and the oil refining industry.

First of all, the welder must be fluent in welding equipment.

At the same time, he, as a specialist, is required to have a thorough knowledge of the principles of its operation, preparing the equipment for operation and identifying possible malfunctions. The welder must master the technology of carrying out welding work from preparing the surfaces to be joined to cleaning the weld. A specialist performing welding work must know how to properly weld with electric welding, determine the optimal mode for welding various materials, and set the current value.

Fear is not as terrible as everyone thinks. A valid way to completely get rid of all your fears without exception is here. Click on the link and read how

The complexity of the work of a gas-electric welder also lies in the fact that during the welding process, changing the welding mode can negatively affect their quality, therefore it is extremely important to correctly determine the welding speed from the very beginning.

Wed 17 Jun, In your case the front shock absorbers need to be lengthened, but in mine they don’t. And in terms of geometry, my option is more correct.

When asking a question about a semi-automatic aluminum welding machine, I meant maybe. Why am I afraid to advise you on expensive devices?

What does direct and reverse polarity mean, where to connect the plus and where the minus? For example, reverse connection polarity is used when welding thin-sheet metals, alloy steels and stainless steel that are sensitive to overheating. In addition, polarity affects the transfer of metal from the electrode to the part. I'm going to learn how to cook, what's the easiest way to do it? It is easiest and most comfortable to cook with direct current; it is even simpler and easier to cook with a semi-automatic device, since the arc and metal are clearly visible in it.

If you take an inverter, then it is desirable that it has functions that make the work easier - quick ignition, anti-sticking of the electrode, arc force reset, etc. When welding on the inverter, the electrode sticks, it ignites very poorly after almost 10 times of poking into the metal, how can I stop this? There could be many reasons:

How to start working with electric welding for dummies

Quick response form In principle, there is nothing complicated. Even on the first ten electrodes, or even earlier, you will understand what and how, especially if you use modern inverter devices. Electronics largely help to ignite the spark, protection against short circuits and sticking of the electrode, so for a beginner it’s just the thing.

Unfortunately, I myself am not very good at keeping track of the birthdays of people leading Live. I myself don’t have argon welding at home, and in general, is it worth it? And I’m afraid to get involved with welding due to lack of financial resources.

What is the basis for the reliability of welding? Heating of metal alloys with an electric arc causes plastic deformation of the materials. As a result of the mutual penetration of the electrode particles and the elements being connected, ultra-strong intermolecular bonds are formed. Electric welding is the key to the strength of the connection of metal parts. The introduction of advanced technologies now makes it possible to weld using laser and electronic radiation; metals are welded with ultrasound and gas flame.

Most often, the energy source is an electric arc created by an inverter or welding machine. It’s worth starting your training with the simplest and most common welding methods. Therefore, it is necessary to know what a novice welder who has received theoretical information and wants to apply the knowledge needs to stock up on. Welding is associated with the risk of burns from splashes of molten metals, poisoning by toxic secretions, and the possibility of electric shock.

The radiation can cause burns to the cornea of ​​the eyes. Prepare thoroughly without skimping on gear and equipment. But if there is no practice in this matter, it is advisable to rent or buy welding equipment with a device for continuously adjusting the current indicators, the maximum values ​​of which are about A. The following will help you learn the skill of a welder:

Electrodes stick during welding

Administrators 25 Reasons to Wear a Welding Helmet A welding helmet is a piece of protective equipment that ensures the safety of the welder. Undoubtedly, the scope of application of a welding helmet is much wider. A welding helmet is such a practical item that it should be in every home.

Gas welding and metal cutting. Types of welds I Dimka am studying to be a welder, I learned how to weld in the lower in the vertical and now we are.

In the modern world, welding is of fundamental importance in construction and the creation of many structures, without which it is difficult to imagine everyday life: The welding process requires serious knowledge and skills; you cannot just take a welding machine and apply a seam.

First of all, you need to determine the personal qualities that a candidate for the position of welder must have in order to achieve serious results in this profession.

An important requirement for welders is good health, because their work is constantly accompanied by harmful factors.

Everything should be normal: However, harmful working conditions entail many benefits: accelerated retirement, short working hours, long vacations and free milk.

The welder will need patience and endurance, because he is often forced to work in an awkward position in a cramped and narrow space.

A welder must be hardworking, although this quality is characteristic of every profession, he is characterized by perseverance and flexibility of all parts of the body, because sometimes he has to climb into the most inaccessible places.

A professional welder will have to master electrical engineering, metal melting technologies, the properties of gases that are used for anti-oxidation, methods and principles of operation of the units and equipment used. He will have to understand the physical essence of all ongoing processes and know the features of welding different types of metals.

And taking into account the fact that technologies do not stand still and are constantly evolving, the welder is required to constantly improve his skills and study modern promising trends. Particular attention is paid to safety precautions. If an office worker can read the instructions and forget, then it is better for the welder not to play with fate; the safety of his life directly depends on these rules. A welder has to improve his skills through experience.

How to learn to work with electric welding

They are completely different on the inside. Inside they are similar to these. But anyone who closely follows this forum thread remembers what debates there were about the length of the cycle. And the only thing that helped us out was that we did not switch to the Soviet standard with all models, after we realized that a 10-minute cycle was needed in our country.

Page - Welding stainless steel of an unknown brand. The worst thing is that I don’t know what brand of stainless steel, I’m afraid it will happen later.

Thank you very much for your answers, it’s a shame to even show the photo - everything is in slag. Thank you, I’ll try! Thin metal does not need to be welded with a “crescent”, “eight”, etc. By making circular movements, you heat up the metal greatly, and in order to avoid burn-through, you reduce the current too much, resulting in non-fusion and slagging.

Weld such thicknesses with a thread seam without hesitation, or with small fluctuations from left to right depending on the situation, do not be afraid to increase the current, you can avoid burn-through without losing penetration, you can also use an intermittent welding mode to set a point, break the arc, light it again slightly moving the electrode, and so on the flake This is how small pipes are welded behind the scales in an overlap.

I recently started cooking with electrodes myself. At work, everything is on the PDG. That week I was welding a frame from a professional pipe 20x20 wall either 1.5 or 2 mm. Electrodes Monolith 2mm, inverter Atom M. Fillet weld at 65A welded. On horizontal ones I reduced the current to 50A. If the current is not large, then with fillet welds, two edges of the pipe simply melted, but I probably didn’t have enough connection experience.

Try to weld with the shortest possible arc, as if pressing the electrode metal into the seam, leaning on the electrode in a reverse motion.

Is it worth taking Fast and Furious 161?

Previously, transformers were used for welding. Professional welders prefer direct current. The welding inverter allows you to select the polarity. Reverse polarity when welding:

Alexander Dolgushev: If I’m wearing glasses, it doesn’t mean that I was damaged by electric welding. . Petr Kuznetsov: With the development of robotics, you are not afraid.

The power plant generates a powerful welding current, which is supplied through cables to the work station. An electric welding arc is created between the electrode and the surface of the metal being welded - a stable discharge characterized by the highest temperature values. This leads to melting of the metal and filler material. A so-called weld pool is formed - an area of ​​fusion, which the welder controls and directs to form a seam.

After removing the arc, crystallization of the molten metal occurs and a strong monolithic connection of the parts is created. This very simplified scheme is implemented in several welding technologies: a special feature is the use of fusible electrodes with a special coating. Advantages - no particularly complex technical support or gas equipment is required. The disadvantage is that welding can only be done with ferrous metals or stainless steel.

Manual arc welding MMA In the vast majority of cases, if welding is considered at the household level, then this technology is meant. Welding using T technology allows you to work with alloy steels and some non-ferrous metals. In this case, an arc is created between the surface to be welded and an infusible tungsten electrode, and a filler rod of one type or another is introduced as a filler.

Welder's Handbook

Source: https://pkb-sistema.ru/chto-prinjato-govorit-u-jelektrosvarshhikov-pered-svarkoj/

Manual arc welding: RDS technology and pipe welding methods, equipment and advantages

The famous MAW is manual arc welding, a people's favorite and the most popular welding technology for a long time. Such an achievement is worth a lot. The method is based on the use of special electrodes.

All actions in the RDS are performed manually by the welder. Despite the popularity and seemingly well-studied nature of this method, it would not be harmful for you and me to repeat the basic facts and check how our dear RDS is doing today.

The main thing is the arc

The essence or technology of manual arc welding is the formation of a regular and stable arc between the end of the electrode and the weld pool. Lighting an arc with a quick touch so that it ignites immediately and burns steadily in the future is one thing.

Correctly hold and guide the electrode, observing the standards for the height of the consumable above the surface, the speed of moving the electrode along the seam, and much more - that’s another matter. You need to know a lot, and you need to be able to do it too. Well, modern welding is also not something to go out for a walk, it’s a field with professional players and high competition.

No one else will pass here at amateur performances. So let's repeat and understand the details and nuances of modern RDS.

Basic actions using electric holders:

• supplying the electrode to the working area;
• ignition of an electric arc;
• moving consumables along the edges of parts;
• support of stable arc burning.

Manual arc welding drawing.

So, we ignited the arc by touch and moved the electrode a short distance from the surface to be welded. The electrode rod begins to melt due to high temperature. It is from this melting rod that the very welding seam is formed, for the sake of which all the fuss around it was started.

Together with the metal rod of the electrode, its special coating melts, the clever composition of which forms the protection of the weld with slag and gas from oxidation. Immediately after the arc goes out, the slag is removed from the surface of the working area.

Any welding seam cannot be made due to the limited length of the electrode: as soon as the rod melts completely, the process must be stopped in order to change it. And these kinds of breaks have no significant effect on the quality of the seam: because of them, defects simply form in the seam.

All this is necessary to optimize the combustion of the arc and the length of the continuous seam - “no more and no less, but just right” - this is the main rule that arc welding technology, perhaps, requires.

What we cook with RDS

Yes, almost everything. If we talk about steels, then these are both alloyed and unalloyed grades. True, there are restrictions on thickness; it should be no more than 5 cm. Too thin sheets of metal will not work either: if the workpiece is thinner than 1.5 mm, the metal will instantly burn out during RDS.

The RDS is most suitable for working with workpieces with a thickness of 3.0 to 20.0 mm.

Of course, depending on the composition of the metal, the strength of the seam changes. For example, it decreases with increasing proportion of carbon in steel alloys. In other words, high-carbon steel can be welded using RDS methods, but the quality of the weld in terms of welding will be lower.

Where the manual arc is not used, here are just some of the examples:

• production of pipes of various types and purposes;
• mechanical engineering;
• shipbuilding;
• all repair work at numerous service stations;
• all types of public works where joining of metals is necessary.

Let's talk about electrodes

You can write “War and Peace” about modern electrodes, no less. They don’t make any kind of alloys and coating compositions now - for every taste.

But seriously, the classification of today's electrodes is extensive; new technologies require that the chemical composition of all consumable parts without exception match the metals of the parts being welded. These materials contain substances to stabilize the arc, form a protective slag, etc.

Scheme of manual arc welding with covered electrodes.

The functions of modern electrode coatings are quite specific and clear:

• Formation of slags to protect the metal from oxygen oxidation in the air and moisture.
• Gas formation for the same protection. It is formed as a result of combustion of organic substances that make up the electrode coating.
• The so-called deoxidation of the seam is the removal of oxygen oxides from it.
• Alloying of the base metal due to additives in the coating.

Special electrodes are produced for RDS. All of them correspond to the properties of the deposited metal and are provided with the letter “E” in the name.

The number after the letter indicates the level of tensile strength in kilograms per square millimeter. If the letter “A” is next to it, the electrode composition is very plastic and has high impact strength.

Snow, rain and wind

You can cook even on the ceiling, that is, in any position. But if you have the opportunity to choose, it is still more convenient to work in the lower position. Here you can take a larger electrode and run a stronger current so that it cooks powerfully and quickly.

If you have to weld on the ceiling or positioned vertically, you will not be able to weld vigorously and quickly: the weld pool will be small, the diameter of the electrode will be very modest, and the speed of work will decrease by an order of magnitude.

Source: https://tutsvarka.ru/vidy/ruchnaya-dugovaya

What is a welding arc

The welding arc has been used by mankind for the permanent, hermetically sealed connection of metals for more than a century. The physicist Volt studied it. Then welding devices appeared. An electrical discharge occurs when there is a short circuit between the electrode and the part being welded. Electrical energy is converted into thermal energy and a melt pool is formed. A diffuse homogeneous layer of metal is created at the site of the welded joint.

Having studied the current-voltage characteristics of the process, scientists improved the welding process and created welding machines that support stable arc burning.

What is a welding arc, definition

What can be called a welding arc is, in fact, a long-lasting conductor consisting of ionized particles, existing in time thanks to a supporting electric field. An arc discharge is characterized by a continuous form, high temperature, and occurs in a gas environment capable of ionization.

In welder's textbooks, the definition of a welding electric arc is as follows: this is a long-term electrical discharge in a plasma consisting of a mixture of ionized air or shielding gases, as well as evaporated components of the filler and base metal.

Nature and structure

In a short time, the metal can be heated to its melting temperature using a powerful welding arc. Its properties are characterized by current density and current-voltage indicators.

From the point of view of electrical engineering, an arc column is an ionized gas conductor between the cathode and anode with high resistance and the ability to glow.

A detailed examination of the structure of the welding arc will help to understand the essence of temperature effects. The average length of the electric arc is 5 mm, it is divided into main zones:

• anodic, it is no more than 10 microns;
• cathode, it is 10 times smaller than the anode;
• pillar - a visible luminous strip.

The temperature of the welding arc is determined by the flow of free electrons. They are formed at the cathode spot. It heats up to 38% of the plasma temperature. In an arc column, electrons move towards the anode and positive particles move towards the cathode. The column has no charge of its own; it remains neutral. Inside, the particles are heated to 10,000°C, while the metal is heated on average to 2350°C, the standard temperature of the melt bath is 1700°C.

The place where electrons enter and are neutralized is called the anode spot. Its temperature is 4–6% higher than that of the cathode.

The voltage in the anode and cathode zones is significantly reduced, and no glow occurs. Only plasma that emits ultraviolet, infrared and light waves is visible. They are harmful to the organs of vision and skin. Therefore, welders use personal protective equipment.

Types of welding arc

There are several criteria for classifying a welding arc. Based on the type of welding current and the position of the electrode relative to the elements being welded, the following varieties are distinguished:

• direct action, the discharge is perpendicular to the workpiece, parallel to the electrode;
• indirect action, the discharge occurs between two electrodes inclined to each other at an angle of 40 to 60°, and the metal.

Column plasma composition classification:

• open type occurs in the air atmosphere due to components evaporating from the coating and metal;
• closed, arising under the layer of flux due to the gaseous phase formed from particles of the electrode, metal, and flux components during the passage of the discharge;
• with the supply of a gas mixture or one-component protective gas.

Source: https://svarkaprosto.ru/tehnologii/svarochnaya-duga

Manual arc welding for beginner welders

MMA welding, or manual electric arc welding, is widely used in many industries. But today the trends are such that in the modern world preference is given to higher-speed welding methods, such as automatic and MIG/MAG. Their share has only grown over the years.

However, in spite of everything, MMA welding remains indispensable in conditions of limited access zones, when working outdoors and at home, since the cost of welding machines and consumables is more or less affordable.

Most companies that produce expensive welding equipment also do not ignore MMA welding; year after year they improve the devices, adding modes to them that simplify the work of the welder.

Closer to specifics

When talking about welds, beginners need to decide what the criteria are for a good and a bad weld. Therefore, first master a little theory.

When welding household greenhouses from small cross-section corners, installing fence sections, staircase handrails, cornices, awnings and other similar things, the quality of welding does not play any leading role, since the loads on such products are insignificant.

And completely different requirements for weld strength are imposed when welding highly loaded structures: supports, floors, load-bearing units of cars, trailers, main liquid, gas and oil pipelines under pressure, bridges.

The seams of such structures are already checked using non-destructive testing methods (NDM).

However, the very first method by which the quality of a weld is assessed is visual inspection. If the welder himself can evaluate his seams, then his skill will begin to grow quickly, he will see his mistakes and will not allow them to be repeated in the future.

How to learn welding? It would be a good idea to start by studying the paper part

Go to menu

Normative documents. How to use

According to GOST 5264-80 for manual arc welding, the entire variety of welded joints can be classified into four main types (the abbreviated designation in Russian capital letters is given in parentheses):

• Butt (C);
• Angular (U);
• T-bar (T);
• Lap seams (H)

An example of an abbreviated entry for the type of connection and its number in order: T1, C17, etc.

Also, GOST 5264-80 (pdf) indicates the main dimensions of the weld. For example, on a butt weld, the parameter “e” is the width; “g” - convexity, or reinforcement of the seam.

For fillet (or T) welds, the letter “k” denotes the leg.

According to the European standard EN ISO 2553-2013 “Joints by welding and soldering,” the letter “a” indicates the thickness of the seam; “z” – seam leg; “S” – penetration depth. When designated according to the European standard, the letters z, a, S are present in the drawings, so it is important to know this.

GOST 5264-80 (pdf) also gives us an idea of ​​what the gap between parts should be, how to properly prepare edges, what possible edge geometry is possible when welding on one or both sides, with a backing under the root of the seam, etc.

According to the European standard, the requirements for the preparation of parts for welding are determined according to EN ISO 9692-1:2003 “Welding and similar processes - recommendations for the preparation of joints”

If a novice welder is faced with the task of welding two plates, then the most asked questions are as follows:

• what diameter or type of electrode should I take?
• what current to cook with?
• how to set the gap between the parts?

What do the standards recommend for us regarding clearances? According to GOST 5264-80, for example, for a three-millimeter plate, the edges will be straight with a gap between the parts of 0-2 mm. Seam reinforcement is offered in the range from 0.5 to 2.5 mm, and the seam width is no more than 7 mm.

According to EN ISO 9692, for one-sided welding of a 3 mm thick plate, it is recommended to prepare edges with a straight bevel and a gap between the parts of approximately 3 mm. Weld convexity parameters are determined according to ISO 5817:2009.

When welding an 8 mm plate on one side, GOST 5264-80 recommends making a V-shaped bevel of the edges at an angle of 22 -27 degrees with a blunting of the edges of 0-2 mm and a gap of 0-3 mm.

According to EN ISO 9692, for the same plate 8 mm thick and one-sided welding, the opening angle of the edges is selected ? = 40-60 degrees, the gap between the parts is 0-4 mm, the bluntness is 0-2 mm.

As you can see, both in GOST and in European standards there are no hard numbers, there are size ranges. The welder decides which gap or blunting of edges to choose, based on the brand and diameter of the electrode, the spatial orientation of the seam, the welding current and his skill.

Go to menu

Briefly about the designation of seams in the drawings

Source: http://svarka-master.ru/ruchnaya-dugovaya-svarka-dlya-nachinayushhih/

Electric welding of metals: types, technologies, features

Electric welding is the most popular metal welding method today. This method is based on the use of an electric arc to melt the edges. The article describes the physical processes occurring during electric welding work. A classification of types of electric welding and their differences from each other is given. The causes of defects in welds and methods for quality control of welded joints are described.  

What is electric welding

To be precise, electric welding is a process of rigid permanent connection of metal workpieces by melting the base and filler metals with their subsequent crystallization. Welding work is carried out using electric current in a shielding gas environment.

 The electric welding process uses a welding transformer, a welding head with filler material (electrode) and parts to be welded together.

A positive charge of electric current is supplied from the transformer to the welding head, and a negative charge (grounding) is supplied to the parts being welded.

When an electrode is brought to a grounded metal under the influence of an electric current, a welding arc is ignited. The electrode is heated to the melting temperature, melting the edges of the base metal of both parts being connected.

Positively charged particles of the molten electrode are attracted to the grounded base metal and move into the weld pool, mixing with the base metal.

When the weld pool cools, the mixed particles of the base and filler metals crystallize and form a weld - it is a monolithic permanent connection of two metal parts.

! For proper crystallization of the molten metal in the weld pool, it must be completely isolated from oxygen. This is achieved by supplying shielding gas to the welding area, which displaces oxygen molecules from the crystallization zone and ensures a high-quality welded joint.

Classification

Depending on the method of supplying filler material to the weld pool, the following types of electric welding are distinguished.

Manual arc welding with consumable electrode

In this case, the filler material is an electrode (a metal rod made of calibrated wire 400 - 450 mm long and with a diameter of 2, 3, 4, 5 mm and above). Shielding gas is formed as a result of combustion of the electrode coating (rutile, cellulose, etc.). The electrode is fed into the weld pool by a forward movement of the welder’s hand.

Semi-automatic gas welding

The welding material used is welding wire wound on a spool. Wire diameter – 1.2 or 1.6 mm. The spool is inserted into a semi-automatic welding machine with a pulling mechanism, which allows you to feed the wire into the welding zone by pressing a button installed on the welding head. Carbon dioxide or argon supplied under pressure acts as a protective gas.

Automatic submerged arc welding

Large diameter welding wire (3, 4, 5 mm) wound on spools is continuously fed into the welding zone through an automatic feeder. To protect against oxygen, flux is automatically added to the weld pool, under which the process of melting and crystallization occurs.

Types of weld defects and causes of their occurrence 

As required by regulatory documents, the mechanical properties of the welded joint should not differ from the properties of the base metal. The reasons for the appearance of defects arise from violations of the welding process, which stipulates all the requirements for welding materials, the qualifications of the welder, the sequence of welding seams, and the temperature conditions for cooling the welded joint.

Weld defects include:

• deformation of the base metal,
• cracks,
• pores,
• fistulas,
• lack of penetration,
• undercuts,
• lack of fusion,
• violations of the geometry of the weld, etc.

The reasons may be as follows

• Inconsistency of welding materials with the requirements of the technological process. Such inconsistencies include: Increased humidity of the electrode coating; Before use, the electrodes must be dried in thermal ovens according to the regime provided for by the technology. Rust or dirt on the welding wire for automatic or semi-automatic welding; welding wire with deviations from the specifications must undergo mechanical cleaning in special installations. Inconsistency of the chemical composition of the protective gas with technological requirements.
• Low level of qualification of the welder. To confirm their skill level, welders weld samples that undergo ultrasonic testing and MPD testing, as well as mechanical tests for tension, fracture, etc. Based on the results of testing the samples, the welder is assigned the appropriate qualification category. The category of performer required for welding work is indicated on the title page of the technological process for each welded unit. Welding performed by a less qualified welder with a 100% guarantee will lead to defects.
• Violation of welding conditions. The technical process specifies the optimal settings for the welding transformer, the feed speed of the welding wire, the thickness and order of application of the welding beads. The desire of the performer to increase the productivity of his work by increasing the operating modes inevitably leads to defective welded joints.
• Violation of the cooling conditions of the welded joint after welding. To form a weld with a uniform structure without internal and external cracks, cooling must occur evenly at a rate specified in the technology. The result of violating this section of the technical process is obvious.

Methods for quality control of welded joints

The requirements for the quality of welds in mechanical engineering are quite high. If external defects can be detected by a simple visual inspection of the weld, then identification of internal defects is possible only with the help of tests and special equipment. The main task of any control method is to determine the degree of homogeneity of the weld structure and identify areas with detected foreign inclusions or voids.

Quality control of the welded joint can be as follows:

• Kerosene control. This type of control is used for welds in open metal containers that require hermetically sealed connections between parts. In this case, on one side the seam is covered with an aqueous solution of chalk powder. After the chalk has dried, kerosene is applied to the other side of the seam. After some time, if there are defects in the welded joint, kerosene leaks through them and forms dark spots on the chalk coating. Defective areas of the seam are selected mechanically and welded. After that, repeated control is carried out with kerosene.
• Pressure control. Used to control welded joints of closed containers. The inlet openings of the closed container are hermetically sealed and compressed air with excess pressure is supplied inside. If over a certain period of time the pressure gauge needle does not show a decrease in pressure inside the container, then all seams are considered suitable. If the pressure drops, then defective areas are identified by washing with a soap solution and corrected.
• Magnetic particle flaw detection (MPD) is used to detect external defects in a weld. The welded joint, cleaned to a metallic shine, is coated with a special solution - an indicator and illuminated with a lamp with ultraviolet radiation. If an increased concentration of the indicator solution is detected, the defective area is rejected and subject to correction.
• Ultrasonic testing (UT) is used to detect internal defects and is based on the principle of changing the length of the sound wave when passing through materials of different densities. The change in wavelength when passing through the defective area is recorded by the device and the depth of the low-quality deposited metal is determined.
• X-ray. The control method is used for hard-to-reach welds for which other control methods are impossible. When X-rays pass through a weld, defective areas with a density different from the main composition appear on the X-ray image. Based on the shape and size of the defective area, the nature of the defect is determined and a decision is made to reject or discard the welded joint.

If you are interested in welding stainless steel, ferrous and non-ferrous metals in compliance with quality standards, then the company JSC Pilyako Plant is ready to offer its services. Our professional welders will carry out welding work in accordance with the most stringent technological requirements. We carry out manual arc welding, semi-automatic gas welding, as well as argon TIG welding. We will be glad to cooperate!

Source: https://piliako.com/stati/item/39-elektrosvarka-metallov-vidy-tehnologii-osobennosti

Manual arc welding: what it is, how it is performed and where it is used, features of the technology

Manual arched metalworking is also known by the abbreviations MMA, RDS and RD. It was invented by Nikolai Bernardos at the end of the 19th century.

Manual arc welding technology was patented in almost all European countries, which made it possible to carry out work at a new level. A few years later, resistance machining and gas-shielded arc welding were invented.

Almost 150 years have passed since the discoveries, and this has allowed welding to change significantly. Beginners in 8 cases out of 10 began to use processing of rods that melt.

Arched manual arc welding with a carbon mechanism has faded into the background. Welding units have been equipped with new capabilities. Designs that have unusual properties were put into production.

Working with arc arc welding today is considered a complex process. In our article we will tell you what this type of manual arc welding is.

You will learn what are the pros and cons of working using this technology and how to carry out metal processing using this method.

Total information

Manual arch (arc) processing of MMA is the process of creating a weld using an electric arch. The latter is ignited between the electrode and the upper part of the metal. Its combustion is stable, while creating an even seam.

When welding, it is necessary to work with electrodes equipped with a special coating. It can protect the welding zone from the negative effects of oxygen. When working, electrodes are used, the length of which is up to half a meter.

During manual processing, the arch lights up either by tapping (when the master knocks the end of the mechanism on the surface of the structure) or by scratching. The last method is similar to lighting a match from a box.

The arch melts the metal, and at the same time the electrode is ignited. In this case, the metal is directed and a direct connection is obtained. The structure may splash, but this indicator is not critical.

Metalworking using coated electrodes is considered a simple processing method. This creates nuances that appear during the work. Labor time is misused because a lot of effort goes into making the connection.

This technology is popular for home work, but not in a factory.

Using manual arc welding, you can melt shafts and carry out quick home repairs. If you are a master with 10 years of experience, then you will be able to carry out labor-intensive processes.

Advantages and disadvantages

Manual arc welding is not just used by craftsmen of our time. Using this method, it is possible to create strong connections and quickly repair the mechanism. The benefits don't end there.

If we compare this type of welding with other technologies, the equipment for it costs several times less. In addition, small machines are easy to move from place to place.

It is not necessary to use gas or other materials to protect the work area. Only one electrode solves this problem. Another advantage is that it can work in all weather conditions.

You can work even in high temperatures, indoors or in a factory. The quality of work will not be affected.

Manual arc welding is suitable for processing both carbon metals and alloy steel. You can work with copper, aluminum or cast iron. Despite the fact that the part reaches a couple of centimeters in thickness, the welding unit will be able to process it.

If we highlight the disadvantages of this method, then during work you need to take frequent breaks. This time is necessary in order to replace the melted structures with unprocessed ones.

If you don’t have enough experience, then the metal consumption can be high. Please note that in the case of an electrode with a length of 5 cm or less, you need to think about replacing it with a new one.

When you do metalworking using this method, then there is a lot of slag in the metalworking and joining area. The residue can additionally protect the manual arc welding zone from the influence of air.

But after finishing the work, you need to remove all excess from the surface. This may take several hours, which is inconvenient from a time-saving point of view.

For this reason, metal processing is a slow process that may not suit everyone. Even MIG welding is many times faster. If speed of work is important to you, then you need to choose a different working method.

The cost of work increases when you need to constantly replace old electrodes with new ones. More than half of the components will be considered waste because they cannot be fully used.

Although this processing method is quite universal, it cannot be used to work with metals that have a low combustion temperature. This is due to the high levels of heat input that are observed during the operation of the electric arch.

This method is not suitable if you need to work with metals that have active chemical characteristics. This is due to the fact that it is not able to protect them from future oxidation.

Another disadvantage that cannot be ignored is that during operation, current flows throughout the entire electrode. If the indicators are high, then the protective properties may disappear. This may result in poor quality welding work.

Types of welding

It is impossible to settle on one method of working with manual arch welding. There is more than one reason for this. There is no further division by method because the technology is not considered complex.

Some distinguish welding by the type of electrode, connection technology or type of arch. This makes the job more difficult and does not make it easier. It is worth focusing on the basics of manual arch processing and not getting hung up on its types.

Connection principles

You can start the welding process only when you understand all the principles of operation of the mechanism. The first step is to understand when arc welding can be used.

Manual arc metalworking is used when the part has a thickness from 2 to 50 mm. Most often, stainless steel, alloyed mechanisms or carbon steel are welded.

Manual arc welding works well if you need to weld small parts and structures in small quantities. In all other cases, you should choose MAG processing.

Thin structures will melt too quickly, and this is not always good. Some defects may occur and the connection will not be smooth. This can happen even when the current is minimal.

In this case, other technologies that are safer for such work will be suitable.

Despite the fact that the process involves working with parts 50 mm or more, it is worth working only with structures 20 mm thick. Hand arch metalworking is not suitable if you are going to weld thick parts.

This does not apply to cases where it becomes necessary to weld short joints. You won't be able to work with expensive equipment if the welding area is small.

When should you use MMA welding technology? You can work with it even if the part is up to 20 cm in diameter.

The manual arc processing method involves working with parts in any position. But it is not so. Not every electrode is capable of working with a ceiling joint or a seam located vertically.

Such compounds melt in minutes, and the seam may turn out uneven. The metal will flow due to the force of gravity. Please study this point carefully before you begin.

Due to the occurrence of such situations, craftsmen recommend working in a horizontal position of the structure or in a lower position. Even a beginner who has no experience can do such work.

In this case, it is possible to work with electrodes of large diameter. It is possible to set a high current value on the device. This will speed up welding work. Choose bottom seams if possible.

Selection and configuration of equipment

When manual arc welding with a coated substrate, if you need to work on a ceiling joint, there are some rules to follow. Take electrodes whose diameter will be no more than 5 millimeters.

The operating voltage should be minimal. Don't rush to work and lead the arch quickly. This will allow you to control it and not deviate in different directions.

When choosing the type and polarity of the current, you can work with both direct and alternating voltage. This depends on the characteristics of the electrodes. To determine your work, it is worth studying the information on the packaging of the components.

There are electrodes that only work with one type of current. Consider these points.

What remains unchanged is that with static current the arch will operate uninterruptedly. Active voltage does not have this characteristic. Beginners should not be afraid to experiment.

In this case, you need to purchase universal components that are suitable for all types of work. Change the settings and select those that are ideal for your type of work.

The choice of polarity directly depends on how quickly the electrodes should melt. To ensure that the mechanism melts slowly, it is worth choosing the opposite polarity and static voltage

You need to choose those electrodes that work equally well with any type of voltage.

When working with iron or nickel alloys, magnetic blowing may occur. This process involves deflecting the arc of the weld pool. The magnetic characteristics of the structure are to blame for this.

Working with an active current, which must first be installed on the device, will help to avoid the situation.

Choosing electrodes

Mesh is as important as welding technology. If you choose them correctly, then the seam will be smooth and will last 20 years. Choose rods based on the characteristics of the metal that will be processed.

The marking of the electrode indicates its characteristics. It is placed on the packaging. To read the information, it is worth remembering the basic meanings of the design.

The properties of the electrodes depend on what kind of coating is applied to them. Manual arc welding in 9 cases out of 10 uses rutile or base spraying.

There is no exact information about which one is better for the job. It's worth talking about their pros and cons.

Mineral-coated electrodes are suitable for beginners who have not yet understood manual arc welding. This material makes it easy to light the arch and carry out further manipulations with it.

You can choose both expensive and cheap components. Stamps with a brand name should not be purchased for work at home. You may not be able to fully appreciate their benefits.

Among the disadvantages of this spraying is the high hydrogen content in the seams. This degrades the reliability of connections. At the same time, the metal will not splash, which a beginner will like.

They can choose MP3 type electrode. It is used in 8 cases out of 10 for such work.

The choice of electrodes with a base coating is made by those who are already experienced in welding matters. Such materials are difficult to process. This is due to the fact that the arch that is set on fire during operation must be short.

In order to ensure this, you need to practice for more than one year. By experimenting with electrodes, a beginner can quickly learn how to cook.

Each time the seam will come out smoother. A basic coating is also needed when you need to work with thin walls of a metal structure.

The choice of electrodes must be justified by economic considerations. Conventional manual welding is slow. It is worth determining the melting rate of the base. This way you will understand how many electrodes and time are needed to work.

Use electrodes at 70%, but not less. Many beginners leave the base with a reserve, for fear of not guessing the length of the electrode. This will lead to waste of material.

If you act this way, then you will have to pause twice as often and stock up on a large number of electrodes.

Let's sum it up

MMA welding is a method of metalworking structures. To master this method of work you do not need to have ten years of experience. Even those who hold the device in their hands for the second time can do this.

But in any business, experience is important. Welding work will improve every time if you go deeper into the technology.

Do you have experience with manual arc welding? Share your opinion in the comments. We wish you success!

Source: https://prosvarku.info/tehnika-svarki/ruchnaya-dugovaya-svarka