The most common and reliable way of joining various metal parts is welding. But there are a number of metals that are very difficult to join in the usual way. Argon welding is used to create a solid permanent contact of metals such as titanium, aluminum, stainless steel and many others. For beginners, the technology causes some complexity.
Features of argon welding
The connection of metal surfaces occurs in the area of argon. The use of inert gas in metal welding is a kind of protective barrier against the oxidation process, which occurs as a result of interaction with oxygen in ambient air. It is simpler to say that an inert gas covers the welding site from the penetration of oxygen into the area of the parts to be joined.
All argon welding technology provides for manual, semi-automatic and automatic work. It is from the methods of welding and the type of electrode used that qualifies the modes of the welding process.
As a non-consumable electrode, a tungsten wire is used, which guarantees a reliable connection of metals.
Connection Technique
Knowing the basic rules of the work will make it much easier to argon welding, and lessons for beginners will help to achieve good weld quality.
Some practical tips from experienced welders:
- The quality of the connection parts significantly reduces the long arc. The longer it is, the wider the seam will be and the shallower the melting depth. Non-consumable electrode must be located in the immediate vicinity of the junction of products.
- To create a deep and narrow seam, it is necessary to achieve a longitudinal movement of the burner and electrode. Even small deviations significantly impair welding. When welding with argon, special care and accuracy must be observed.
- So that nitrogen with oxygen does not penetrate into the welding zone, the electrode and additive must be in this zone, but under a layer of argon.
- Wire feed is a difficult operation, as jerking leads to metal spraying. The input of this component is carried out evenly and smoothly.
- If the seam is convex and round, this indicates a low melting of the metal, which indicates a low quality of argon welding.
- To create a small seam and its flat surface, the filler wire must be led in front of the burner and at an angle to the metal plane. This condition will allow reliable control of the entire argon welding process.
- So that nitrogen and oxygen do not penetrate into the joining zone of parts, the welding process cannot be started and completed with sudden movements. Beginning of work must be carried out 15–20 seconds after the gas supply, and finish - until the burner is turned off.
- It is necessary to complete the work by reducing the current strength with a rheostat entering the apparatus for welding with argon. If you just take the torch to the side, then you can open the access of oxygen with nitrogen to the welding zone.
The main requirement before work is the quality cleaning and degreasing of the mating surfaces of the product.
Advantages of using this type of welding
Given that argon welding is an effective method of joining metals that are poorly suited to other types of joining, the advantages of its use are based on this property. These include:
- Low heating temperature of the joined surface, which allows you to maintain the shape and dimensions of the part.
- Inert gas is denser and heavier than air, therefore it is able to protect the weld place well.
- A rather high power of the thermal arc contributes to the short-term nature of argon welding.
- The ability to focus the weld allows you to work in hard to reach places.
- Welding of thin parts is easily feasible due to the not very high temperature in the melting zone of the metal.
Disadvantages of argon welding
Like any other compound, argon welding has some disadvantages that must be considered when performing work. The main disadvantages of this connection:
- The presence of a draft significantly reduces the protection of the soldering place, so work is recommended to be carried out indoors. Only in this case it is necessary to take care of good general ventilation of the object.
- If it is necessary to obtain a high-ampere arc, it is necessary to provide cooling of the connected products.
- The equipment belongs to the category of complex fixtures, so argon welding for beginners is a difficult process. Only an experienced welder can make the correct settings.
Argon Compound Modes
In order for the welding to take place qualitatively, it is necessary to choose the correct optimal mode of operation. Such an action, as a rule, is possible only for specialists with extensive practical experience.
Conditions for choosing the right welding mode:
- The direction and polarity of the current directly depend on the properties of the metals being joined.
- The current strength is determined based on three main characteristics, namely polarity, diameter of the electrode used, thickness and type of material. It is in choosing this parameter that you will need your own experience as a welder.
- The uniformity of the inert gas flow affects the flow of argon. The flow when welding aluminum with argon should be without ripple.
Part of the equipment
Before you understand the principle of operation of the device, you need to familiarize yourself with the main components of the equipment. For high-quality welding you will need:
- A welding machine of any type with an idle speed of 60–70 volts.
- Power contactor transmitting voltage to the head from the welding machine.
- Oscillator. This is a device that converts a standard voltage to a voltage of 2000-3000 V with a frequency of 150-500 kHz, which facilitates the ignition of the arc.
- Ceramic burner.
- A device designed for blowing argon.
- Inert gas tank.
- Additive wire and non-consumable electrode.
The principle of operation of the device
After preliminary cleaning of the connected surfaces and setting the desired welding mode, we take the wire in the left hand and in the right torch. Using the gas supply button, which is located on the handle of the burner, we supply gas to the welding zone.
The electrode must be inserted into the burner so that it protrudes about 5 mm. We bring the torch to a distance of 2 mm from the welding surface. Then we turn on the unit and apply voltage to the electrode until an arc occurs. Argon at this time enters the welding zone.
With the other hand, the welder directs the filler wire into the gap, which melts, forming a connection of metals. Moving gradually along the seam, we completely weld two parts.
The difficulty of welding aluminum
Aluminum is considered the most common material in industry. Its welding is of great complexity due to the oxide film, in which the melting is higher than that of the metal. Before you start welding aluminum with argon, you must carefully study all the nuances of the connecting process:
- The main mistake of novice welders is poor-quality preliminary cleaning of metal. There can be no question of a good metal compound if dirt, dust or grease film is present on the surface.
- The low melting point of aluminum and its high thermal conductivity require inert gas welding to consume large amounts of energy.
- Aluminum melts at low temperature, in order to avoid damage to the material, you need to set the correct mode on the inverter.
- The welding machine for aluminum must have a special function, which before the start of welding supplies an amplified current to melt the film, and in the end - completely brew the crater.
Metal surface cleaning
The main condition for high-quality argon welding is a good preliminary cleaning of the metal surface.
Cleansing is carried out in two ways:
- The chemical treatment method contributes to the destruction of the oxide layer on the metal due to the action of a special solution. You can prepare such a composition yourself, for which you need to dissolve technical sodium 50 grams and 45 grams sodium fluoride in one liter of water. Next, you need to stir this mass until a solution is obtained. With this composition, the surface is treated, and then washed off with running water.
- A mechanical cleaning method involves treating the part with an iron brush or sandpaper. In this case, it is necessary to ensure that there are no inclusions of another metal on the surface of the cleaning tool, particles of which can significantly worsen the final result of the work.
Features of stainless steel welding
Stainless steel is a metal that has high corrosion resistance and high strength, and is widely used in all weather conditions. The special properties of this metal require special product processing technologies. It is stainless steel welding with argon that allows to achieve a good quality connection of such products.
The main problem when working with stainless steel is its cracking. In addition, there are other features:
- Due to the low thermal conductivity of the stainless steel during the welding process, the temperature in the melting zone must be high, which creates a high risk of burning metal. To avoid such a nuisance, it is required to choose a lower current strength than that of ordinary steel.
- Stainless steel has an increased linear expansion, so when welding there is a large casting shrinkage, which can lead to metal cracking. To avoid this, you need to create a larger gap between the parts of the product.
- Since the stainless steel has a high electrical resistance, the electrode heats up very much during the welding process, which also negatively affects the quality of the connection.
When welding disks with argon, it must be borne in mind that an improperly selected temperature of the welding mode can lead to a loss of the corrosion-resistant properties of a stainless steel.
Semiautomatic connection
The process of welding with argon semi-automatic significantly increases work productivity. The technology of using welding in a semi-automatic mode allows to obtain reliable and externally attractive welding seams.
The main nuance of semi-automatic welding is the need to use nickel in the composition of the welding wire. If there is a need for welding the pipe with argon, then with a large thickness of the part, carbon dioxide is also added to the protective composition, which improves the miscibility of the welding edges.
Semiautomatic welding process can be carried out according to several technologies:
- pulse mode;
- jet transfer;
- short arc.
Safety precautions
When welding in argon, the rules for safe operation must be observed. Basically, they are not much different from the rules that must be observed during conventional welding, but there are some nuances:
- It is important to control gas cylinders for tightness, since the gas in them is under pressure.
- Avoid leakage of argon, because this gas is heavier than air and has no smell. Therefore, its gradual accumulation can lead to suffocation.
- Work in a protective mask, special shoes and clothing.
- Strictly observe electrical safety rules. Unit equipment must be properly grounded.
- Particular attention should be paid to combating the likelihood of a fire. All flammable objects must be removed from the welding zone.
- It is necessary to prohibit the presence of strangers in the area of welding.
Remember that argon welding allows you to get a high-quality metal compound, which cannot be done in other ways. A novice welder will have to make a lot of effort and patience to master all methods of argon welding.