WHAT IS ARGON WELDING
The expression “argon welding” adopted in everyday life is fundamentally incorrect. Argon itself is an inert gas and does not directly connect the two metal parts.
There is another concept – welding in an inert environment, where argon or other gas serves as a protection and prevents the initialization of negative processes. In this way, various metal alloys, including non-ferrous ones, are welded today.
- What is argon welding?
- Classification of argon welding by type
- What do you need for argon welding
- Welding with an inverter in argon
- Argon burners
- How to cook argon properly
- We do argon welding at home
- What metals are cooked with argon?
- Advantages and disadvantages
- What is argon welding?
The hybrid technology, which combines gas and electric welding methods, makes it possible to work with a wide variety of volumes and materials.
It has proven itself in the welding of cast iron, steel, copper, and other metals. With its help, large steel pipes and miniature bronze hooks from the hanger are well welded.
Working with stainless steel is another example of the versatility of equipment and technology.
Without studying the theory of welding skills, it is impossible to become a good specialist. This is especially true for complex technologies, which include the argon method.
In order to understand in detail the essence, advantages, and features of the argon welding method, it is necessary to master the physics of the processes that occur during operation.
In order to connect two metal blanks together, it is necessary to meet some of their parts. And this can only be done by heating.
The increase in temperature involves the use of fire, which in turn needs oxygen. The latter enters into chemical oxidation reactions. And the faster the metal is oxidized, the harder it is to weld. Oxidation is one of the undesirable phenomena in the welding of metals.
During the chemical reaction, many small bubbles are formed inside the metal, which greatly impairs the mechanical characteristics of the joint.
And it is almost impossible to work with aluminum: with a sufficient amount of oxygen, it simply burns.
Argon is designed to isolate the working area from the external environment. Its main function is to displace oxygen from this area.
It is heavier than atmospheric air and replaces the entire volume around the welding arc. Inert gases perfectly cope with the task. In addition to argon, helium is used in welding. But it is used much less often because of the higher cost and expense.
Another important caveat – when working with helium, it is necessary to protect all parts of the body with special clothing.
Nitrogen is used even less often: it is in demand when welding copper. Argon remains the main component for welding in a protected inert environment. Hence the colloquial name of the technology.
Basic properties of argon:
Gas is heavier than air. Due to this, it displaces atmospheric oxygen and other unnecessary volatile compounds from the welding bath.
Inert gases do not react chemically with other elements. They do not participate in metal welding and do not affect the process in any way.
It is important not to forget about one feature of argon: it becomes an electrically conductive medium in the case of applying a current with reverse polarity.
Classification of argon welding by type:
The division is based on the level of mechanization of the process. Argon welds are of three types:
Manual ones. Both the filler wire and the burner itself are moved by the welder. For such work, only non-melting tungsten electrodes are used.
Semi-automatic. In this case, the burner is controlled by the welder, and the wire feed is controlled by the mechanism.
Automatic: The burner and wire are moved mechanically, and the operator controls the operation of the machine.
Nowadays, it is not uncommon to find installations that work even without human intervention. Robotic systems are used, for example, when welding pipes.
What you need for argon welding
The method of metal welding using an inert gas implies great opportunities in terms of the choice of equipment and materials.
Sometimes novice welders are confused by this. But in fact, their fears of doing the wrong thing are completely unfounded.
Most of the equipment and accessories available on the consumer market are universal and suitable for a wide range of work.
Installations designed for argon-arc welding are divided into three groups:
Specialized: Designed specifically for performing the same type of work. It is most often in demand in the industry when you need to quickly and accurately process the same type of workpieces.
Special: Another type of equipment that is in demand in industrial enterprises, which is designed to work with blanks of the same size.
Universal: It has become the most widespread and in-demand among a wide variety of categories of users – from professionals to novice welders.
- In addition to the device, additional equipment is also needed:
- tungsten burner and consumables
- contractor-used to connect the power supply to the burner;
- cylinder with gearbox for inert gas
- relay-responsible for connecting an oscillator or contractor
- rectifier-converts the voltage to DC 24V.
Timer-used to control the period of time when the working area is blown with argon;
- ammeter-measures the current strength
- power supply valve
- battery for stabilizing the AC circuit
- filter-controls high-voltage pulses.
To work, you will need two transformers: the main and the auxiliary. The oscillator is connected to the circuit in parallel with the power supply.
It is required to supply a high-frequency pulse, which ignites the arc between the metal and the non-melting tungsten rod.
In the household network, the voltage is 220 V, and the frequency is 50 Hz. After the oscillator, these values are 6,000 volts and 500,000 Hz.
To work with workpieces of large thickness or to increase the productivity of welding equipment, additional equipment is required:
A special burner in which several electrodes are inserted at the same time. As a result, a good quality seam is obtained at a higher speed of movement of the burner;
device for preheating the filler wire.
The pulsating current supply makes it possible to make micro-pauses in the work, which contribute to the crystallization of the melt and improve the quality of the seam.
Welding with an inverter in argon
Inverters are used both in industrial enterprises and in-home workshops. There is a whole class of argon arc welding equipment on the market that converts the incoming AC voltage to DC.
Inverters are perfectly adapted to voltage surges, which are everywhere sinned by domestic power supply networks.
The argon arc welding inverter is light in weight, compact in size, and reliable. It is suitable for working in different conditions and is easy to maintain. It is on such equipment that it is easiest to train novice welders.
The burner supplies a voltage to the tungsten rod and serves to form an inert gas shield around the working area.
It is important to pay maximum attention when choosing it, however, as well as the selection of consumables.
As mentioned above, argon arc technology is based on the use of tungsten electrodes, which do not melt, and inert gases.
From this follows the main criteria by which you need to select the burner:
- maximum permissible power and current
- is there a tungsten rod holder included?
- it is desirable that the nozzle is made of ceramic
- option for cooling the burner when working with thick and thin workpieces
- universal use of the burner. It means the possibility of its communication with welding machines of different types
- the length of the power supply cable.
The burner operation can be described in stages as follows:
Everything starts working at once: the cooling system circulates, an inert gas is fed to the burner, and the welding machine itself starts.
Immediately after the formation of the protective layer, the gas arc is initialized. The workpieces are heated to the melting point. At this point, you need to feed the filler wire into the working bath.
Next, the filler wire together with the tungsten rod moves in the direction of the joint of the workpieces.
Manual argon arc welding is usually completed with non-consumable tungsten electrodes. They are best suited for welding stainless steel and non-ferrous metals with high chemical activity-aluminum, titanium, magnesium.
The electrode is mounted in the current-carrying collet of the burner with a ceramic nozzle that directs the inert gas flows to the working area.
The system is equipped with water cooling. The diameter of the electrode directly depends on the current strength, which is selected depending on the thickness of the workpiece.
Due to the fact that during the welding of metals in this way there are no splashes, the burners are equipped with a mesh filter, which serves to evenly distribute the flow of inert gas.
The mechanized burner has a slightly different design. In addition to the elements already listed, it is additionally equipped with a flywheel for lifting and lowering the tungsten electrode.
The current-carrying collet is attached by means of a threaded connection for changing rods of different diameters.
Semi-automatic and automatic argon arc welding is most often completed with a burner with a melting electrode.
During the operation of the device, the arc is maintained between the surface to be welded and the filler wire.
Depending on the performance of the installation, the cooling system can be air or liquid. The design of the nozzle and the principle of operation are completely identical with analogs equipped with non-melting rods.
How to cook argon properly
Novice welders will not be superfluous to learn the basic rules and procedures for performing operations when working with argon welding:
The working surface is cleaned from third-party inclusions: dirt, oil, grease, paint, etc. It is important to perform high-quality cleaning since the metal compound does not tolerate any dirt. Any cleaning methods are allowed, including mechanical and chemical ones.
Apply the inert gas to the working area 20 seconds before starting welding operations. Pick up the wire and the burner, which is located closer to the surface to be welded. The arc is formed immediately after the power supply is applied.
Guide the gorilka along the joint line, avoiding transverse movements. Do not feed the filler wire into the welding area too quickly, because it will cause metal splashing. It is best to keep it slightly ahead of the burner and add or remove it with quick forward movements.
It is important to achieve the shortest possible arc. In this case, the seam will be narrow, deep, and aesthetic in appearance.
Especially pay attention to this nuance should be in cases of working with a non-consumable electrode. The burner and the filler wire must be inside the inert gas containment.
Brew the crater by lowering the voltage supplied to the burner, but not by interrupting the arc. The inert gas supply is shut off 15 seconds after the welding is completed.
The operating mode of the welding machine must be selected carefully, taking into account all the initial data. The result largely depends on this. So:
Direction and polarity of the current. The determining criterion is the metal with which you have to work. Most steel workpieces, including stainless steel, require a direct current. As for non-ferrous metals, magnesium, and aluminum, everything is exactly the opposite. It is best to choose an alternating current with reverse polarity.
The inert gas flow rate is determined by two factors – the operating conditions and the argon feed rate.
Welding metal in an open area in a strong wind entails an increased consumption of inert gas. Therefore, it is always necessary to have at least two wind-protected sides.
At first glance, it may seem irrational, but there is oxygen in the argon mixture. Its share is small and does not exceed 5% of the total volume. It would seem that this will negatively affect the quality of the seam. But no. In small doses, oxygen performs a positive function: it burns small harmful impurities. They react with the gas and burn up.
We do argon welding at home
Although the technology of argon arc welding is one of the most complexes and is characterized by many technical nuances, many home craftsmen manage to perform work using improvised tools.
To do this, you must have an inverter welding, although in some cases it is allowed to replace it with a retrospective transformer installation. Naturally, it is necessary to have a cylinder with an inert gas, a mask, and a gearbox.
In addition, to implement the idea of a homemade argon device, you will need tools:
- electric drill, angle grinder, and a conventional welding machine
- wrenches, screwdriver, metal hacksaw, pliers
- tester, ammeter, micrometer, voltmeter.
The current source can be made from a welding transformer, and a rectifier, which in this case will need to be combined with an oscillator.
The primary winding must be made of copper wire up to 0.8 mm thick. For the secondary winding, you will need copper of a much larger diameter – no thinner than 3.5 mm.
The gas burner will be next in importance. For the body, it is desirable to use brass, and the nozzle itself can be turned out of copper. Heat-resistant rubber is suitable for sealing the joint between these two components. Moreover, it is not difficult to make a gasket from a flexible material.
Argon will be supplied to the burner via a copper tube, which is wound into a hole in the housing, and the connecting seam is sealed.
This same line will be an excellent conductor of current, which is necessary for ignition and maintenance of the arc. The tungsten electrode should have a sharp end that is ground at an angle of approximately 45 degrees. The approximate length of the rod will be 25-30 cm.
It is important to understand that making argon arc welding equipment at home is quite a difficult task. And not always “the sheepskin will be worth the dressing”.
If the equipment is rarely used, the cost of manufacturing it may never be recouped. Very often, it is much more practical to use the services of a specialist with your own equipment or to purchase a ready-made device of a budget price segment.
What metals are boiled with argon?
The principle of operation of argon arc welding determines a wide range of its applications. This means not only the scope of use but also the processed materials.
It can be used to connect cast iron, steel (including stainless steel), titanium, aluminum, as well as other ferrous and non-ferrous metals.
We work with aluminum
Without argon, connecting two aluminum billets is not that problematic, but almost impossible. Common in everyday life and in the industrial sphere, metal is one of the most difficult in this regard. The difficulties are caused by the properties of aluminum. At the slightest contact with oxygen on its surface, a protective film is instantly formed, which is aluminum oxide.
In itself, it is not a problem. The point is different: the melting point of the oxide is much higher compared to aluminum.
The inert gas is heavier than air, and when it moves into the working area, it displaces oxygen from there, preventing the metal from oxidizing and forming a protective film.
Under such conditions, the aluminum itself and the filler wire melt at a suitable temperature, and the welding seam turns out to be quite strong and outwardly pleasant.
The use of alternating current is implied. The reverse polarity significantly increases the melting point due to the cathodic purification of the metal oxide.
And vice versa. Direct polarity makes it possible to form a short and stable arc. However, the power is not enough to destroy the oxide film. Conclusion: reverse polarity is necessary because in this case the quality of the weld increases.
The use of direct current when welding aluminum workpieces is not excluded. But in this case, another inert gas is needed – helium.
It is much more expensive than helium and is spent much more actively. In addition, working with direct current is very difficult from the point of view of the execution technique.
In any welding technology for aluminum parts, pre-treatment of the surface is very important. It should not be neglected, regardless of the skill level of the welder. Cleaning is carried out in the following order:
- the parts of the workpieces intended for welding are decreased with a solvent
- the oxide film is removed mechanically or chemically
- the cleaned surface is allowed to dry.
We cook copper
High resistance to aggressive environments and corrosion distinguishes copper from other non-ferrous metals in terms of chemical activity.
When working with it, experienced welders do not use pure argon, but its mixture with helium (added in smaller fractions). Tungsten electrodes are used for both melting and non-melting applications. The current is selected constant.
When it is necessary to cook blanks with a thickness of 4 mm or more, they need to be preheated to a temperature of 800 degrees Celsius.
The filler wire can be made of pure copper or copper-nickel alloy. Often it is replaced by a similar composition of the bars. The arc is formed stable and stable during operation.
Due to the high thermal conductivity, the edges to be welded must necessarily be cut. If the thickness of the workpieces does not exceed 12 mm, then it is enough to cut one of the two edges. With a larger thickness, it is desirable to process both sides.
Advantages and disadvantages
Argon welding has a few disadvantages and it will not be difficult to list them:
- the equipment is technically complex, and its configuration requires certain knowledge and skills;
- the method can not be used by beginners due to technical complexity.
The advantages against this background look much more impressive:
- high-quality seams
- due to the moderate heating of the metal, there is no deformation of the weld joint
- unique ability to work with a wide range of metals
- welding of non-uniform workpieces is allowed
- the use of high-temperature mode allows you to significantly speed up the work.
The list shows that the shortcomings are among the minor and solvable problems. While the advantages are due to the features of the equipment and technology. Exclusive features that cannot be obtained using any other technology.