Semi-automatic aluminum welding: features and technology for beginners

Aluminum is widely used by humans in many areas. However, according to professional welders, it belongs to the category of metals characterized by a rather complex welding process. This is justified by the presence of specific physical and chemical properties in aluminum alloys. Therefore, compared to the standard material - steel - the implementation of the welding process with aluminum is associated with a large number of nuances.

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Semi-automatic aluminum welding (MIG) can effectively solve most of these difficulties. This welding method will ensure that difficulties in overcoming the protective micron oxide film on aluminum parts are eliminated, ensuring welded joints with excellent characteristics and high quality.

In addition, both experienced and novice welders must understand that:

• It is required to carefully prepare the surfaces of the aluminum parts to be welded. You can remove the oxide film not only using a metal brush or sandpaper, but also solvents, for example, gasoline, white spirit, acetone. Well-performed cleaning will increase metal penetration, increase welding speed, improve the wettability of welded edges, and reduce the likelihood of warping.
• Due to the higher thermal conductivity of aluminum compared to conventional steel alloys, it is necessary to set the welding arc to higher power.
• It must be remembered that this material has a fairly low melting point, and this may cause the risk of burning through.

The welding process of aluminum and its alloys using semi-automatic machines is carried out using a special wire (welders in most cases call it a consumable electrode) using a protective gas environment. The most common shielding gas for semi-automatic welding of aluminum and its alloys is pure argon.

The use of inert gas makes it possible to eliminate:

• an increase in porosity in the weld, increasing its strength characteristics;
• strong splashing of molten metal drops;
• instability of the electric arc.

Welding work associated with the manufacture of products from any aluminum alloy using inverter power supplies is used both in industrial enterprises and in car repair shops. For the semi-automatic aluminum welding process you will need:

• high quality filler wire and inert gas;
• professional welders;
• technological welding equipment.

A well-organized combination of these three most important factors allows us to provide first-class results.

Features of semi-automatic aluminum welding

There are several reasons that forced engineers to develop welding equipment taking into account the peculiar properties of aluminum, among them:

• increased thermal conductivity, 5-6 times higher than that of steel;
• fast-forming, inconspicuous oxide film with high density and high melting point;
• low melting point;
• formation of a crater at the end of the seam.

A modern semi-automatic aluminum welding machine allows you to overcome the difficulties of work. This is achieved by special parameters of welding equipment.

• The high thermal conductivity of aluminum requires a maximum welding current of the machine of at least 200-500 A.
• High-quality welding is performed using pulsed current. The high-voltage pulse destroys the oxide film, and in the rated voltage mode a weld pool is formed. This mode also reduces splashing. Cheap welding machines operating on direct current produce low-quality seams.
• A wide range of welding current adjustments does not allow raising the welding temperature so much that metal burns will form.
• A special software function that correctly completes the weld without creating a crater.
• Increased wire feeding speed with four rollers with Teflon liner. This will prevent the wire from curling into rings.

Devices that support such functions and parameters provide professional quality welding.

Types of aluminum welding machines

To weld aluminum, you can use specialized TIG welders, as well as semi-automatic machines. Aluminum welding at the household level can be carried out using MMA machines. Each type of welding equipment differs in the result of its work and has many other features that determine the appropriateness of use. Let's look at each device in order.

TIG devices

The abbreviation TIG stands for Tungsten Inert Gas. With this method, non-consumable tungsten electrodes are mainly used in an inert gas environment. The connection of parts using a TIG welder is carried out using alternating current (AC). Therefore, within the framework of TIG welding technology, both universal electrodes for alternating and direct welding current (AC/DC) and those designed exclusively for AC are used.

TIG welding machines mainly use argon as protection for welding aluminum, which is why the process itself is known as “argon arc welding”. Inert gas is heavier than air and does not react chemically with the material being welded, so it contributes to excellent insulation of the weld pool. Also, in the process of such work, helium or a mixture of helium and argon is often used.

Manual welding machines for welding aluminum with argon are distinguished by the fact that they provide the ability to connect a gas cylinder and are equipped with a torch for simultaneous supply of shielding gas. They also provide an additional MMA welding mode.

The working process using a TIG installation is as follows:
1)
the workpieces and filler rod are cleaned of the oxide film to a matte shine and degreased;

2)

the supply of protective gas is adjusted;

3)

settings are set on the control panel of the welder (the main parameters are adjusted using a parametric curve);

4)
the arc is ignited after approaching the torch and a seam is formed using a filler rod;
5)
the torch is held above the metalworking site for some more time (at the end of the seam).

As a result of using argon-arc technology, a durable and airtight seam is obtained that does not require mechanical processing. Thanks to the use of a non-consumable electrode, a minimum of slag and smoke is released during operation. It is possible to work with very thin parts and make seams 2-3 mm wide. The workpieces are practically not deformed, since only the processing zone is very hot.

The disadvantages of TIG devices include high price (including consumables), low process speed, and the ability to form only short-length seams. If sheet metal is welded, then a substrate is necessary, since the heated material can collapse under its own weight. In addition, the protective gas properly performs its function only in a calm environment, when there is no wind or draft.

MIG/MAG devices (semi-automatic)

The abbreviation stands for Metal Inert Gas / Metal Active Gas. These are welders that feed filler wire directly into the torch. They are used for welding aluminum in large quantities. Allows you to get moderate quality and work on stream. The working process is carried out with direct current in reverse polarity mode.

Another advantage of semi-automatic machines is the pulse operating principle (more often found in some expensive professional models). After applying energy, the tip of the wire melts, turning into a drop of molten metal. Under the influence of an impulse, the filler material is pressed into the surface of the workpiece. Thanks to pulse technology, a very high-quality result is obtained.

Other advantages of semi-automatic welding machines for aluminum welding include:

• high speed of the process;
• the ability to create continuous long seams;
• one-handed control;
• better visual control of the weld pool;
• enhanced strength characteristics of the connection due to additives and additives;
• less smoke during metalworking, no slag;
• support for working with extremely thin workpieces (from 0.5 mm).

As you can see, semi-automatic aluminum machines are even more efficient than argon arc machines in some use cases. But they also have significant disadvantages. Semi-automatic machines are not cheap. Additionally, you will have to spend money on shielding gas and wire. If you often need to alternate between welding steel and aluminum, it will be problematic to change the wire feed channel, contact tip, and feed rollers each time (you will need rollers for aluminum with a U-shaped groove). The consumable electrode itself, due to its small thickness and significant flexibility, is more difficult to control than its non-consumable counterparts.

Manual arc welding machines

Conventional MMA (Manual Metal Arc) devices can also be used for welding rolled aluminum. However, this method has the greatest number of disadvantages, and therefore is not used for connecting structures that must withstand heavy loads. It is widely used as an inexpensive alternative for home use.

The technological operation is carried out mainly with direct current in reverse polarity mode. Such welding inverters for aluminum are characterized by high efficiency, efficient energy consumption, protection against instability in the electrical network, precise adjustment of amperage, and rapid ignition of the arc. Special electrodes are selected for them - for working with alloys or pure metal.

Among the disadvantages:

• the need for more careful preparation of parts;
• high difficulty of forming an even seam;
• significant spattering when the electrode melts;
• low quality of connection due to porosity;
• very strong slag crust.

Advantages of the method: low cost of equipment compared to other possible options, quick switching to operations with other necessary materials.

Pros and cons of semi-automatic aluminum welding

Before choosing a welding machine for aluminum welding, you need to weigh the positive and negative aspects of the technology. After this, decisions can be made.

Advantages of mechanized gas-shielded gas welding

Properly organized semi-automatic aluminum welding provides a number of advantages:

• High performance. Compared to argon arc welding, the MIG process is 3 times faster.
• Easy to use. Unlike the argon arc welding method, even a novice welder can quickly master the semi-automatic welding method. In this regard, making welded joints of aluminum parts with your own hands is popular among amateurs.
• Equipping the semi-automatic machine with a pulse mode allows you to achieve high quality welds and accuracy of geometric dimensions. This minimizes wire losses due to spattering.

Functionality of welding machines

Manufacturers are constantly improving semi-automatic welding machines for welding aluminum alloys. The result is a variety of modes and additional features that enhance the quality. Of course, the price also increases.

In order not to overpay for unnecessary functions, you need to understand why they are needed. Perhaps this is just a marketing ploy by the manufacturer.

MIGPulse is one of the most common and universal welding methods with non-contact transfer of a drop from the electrode to the weld pool. In this mode, the electrode never touches the bath. One drop is formed in one pulse and is transferred by the arc to the welding zone. The process of metal fusion occurs during its cooling in the background phase of applying voltage between pulses. This mode allows you to reduce the wire feed speed. Welding speed and arc power are controlled by the height and width of the peaks and the distance between them. The mode does not create splashes and reduces the risk of cold rubbing.

DoublePulse MIG - in this mode, the pulse current has two levels. The high phase drives the drop into the melt zone. In the low phase of the pulse, the metal is welded and cooled. The operator can adjust the level of the pulse pads and adjust the length of each pulse. It fully controls the shape and amplitude of the voltage and can perfectly select the welding mode.

The S4T mode allows you to control the burner. If the machine has a “Quick Start” function, which is activated by pressing the torch trigger, the operator can start welding aluminum without preheating - cold. After releasing the trigger, the welding current is reduced to operating current.

DownSlope - ensures crater welding at the end of the seam, smoothly reducing the welding current.

Adjusting the arc inductance reduces spatter and improves connection quality. Varies depending on the thickness of the wire.

Digital control significantly reduces the time for setting welding parameters. Thanks to synergic control, almost all welding parameters are set automatically. The operator is only required to indicate the thickness of the wire and the type of metal. The computer has several welding programs in memory, which allows you to instantly set the ideal operating mode.

The 4-roller mechanism ensures smooth wire drawing. Unlike welding machines for ferrous metals, where it is enough to have a 2-roller filler material supply system, in a semi-automatic machine for welding aluminum alloys it is necessary to use only a 4-roller mechanism. This is due to the fact that the wire for welding aluminum is not hard and soft and can get tangled, forming rings. Therefore, it requires a more complex feed system with tension adjustments and Teflon channels.

Differences between semi-automatic welding and argon arc welding

Semi-automatic aluminum welding has several differences compared to argon arc welding. The main difference between these two technologies is the type of electrodes used:

• In the semi-automatic welding method, aluminum wire is used, and in the argon arc welding method, the base of the electrode is refractory tungsten, and the filler metal is fed into the welding zone in the form of a rod.
• The argon arc method is most often used for manual welding.
• The TIG welding process is used to obtain permanent connections in more critical areas, as it ensures higher accuracy of the weld geometry.
• Carrying out welding work using the TIG method is associated with large monetary costs for components and consumables, and also requires significantly more time to complete the welded joint.

Semi-automatic welding machines for welding parts made of aluminum alloy are traditionally equipped not only with standard functions, but also with the ability to operate in pulse mode. The use of the latter makes it possible to achieve a more aesthetic appearance of the seam, as well as improve the quality of the connection. Exposure to a powerful pulse of electric current makes it possible to instantly break through the oxide film of the parts being connected.

Each current pulse, as it were, presses into the surface of the weld pool every drop of molten metal formed when the aluminum wire melts at the base (lower) current. When using a pulsed welding mode, the transfer of electrode metal becomes controlled. This technology allows you to significantly improve the quality parameters of the weld, eliminating as much as possible the spattering of aluminum.

Review of popular models

The industry offers a lot of semi-automatic welding machines. The review describes three popular models, sorted from simple and cheap to complex and expensive.

VEGAMIG 180/2 TURBO

A household welding machine operating from a single-phase network in MIG/MAG mode, designed for welding aluminum, ferrous metals and stainless steel in an argon environment. The unit creates a welding current in the range from 30A to 170A with a power consumption of 5.2 kW.

Although the device is considered a household device, not every apartment has wiring that can withstand a load with a current of 23A. Therefore, before turning on the device, pay attention to what current strength the network in your home, garage or workshop is designed for.

The semi-automatic welding machine VEGAMIG 180/2 TURBO for aluminum supports the use of wire with a diameter of 0.8-1 mm and can weld sheets up to 2 mm thick. The arc is formed by direct current.

Equipped with two step regulators:

• current strength;
• wire feed speed.

There are no automatic adjustments, therefore, when working with the device, the welder should rely only on his knowledge and experience.

When choosing a welder, pay attention to the protection class. VEGAMIG 180/2 TURBO is classified as IP21, which means that it cannot be used outdoors.

PICOMIG 180 PULS

Mobile inverter semi-automatic MIG/MAG welding machine, supporting pulse welding mode. In total, the device supports four types of welding at a professional level:

• MiG/MAG;
• MiG/MAG PULS;
• MMA;
• TiG DC.

The device is powered by a single-phase network, consumes 6.4 kVA and supports a maximum welding current of 170A.

The unit is equipped with an automatic adjustment system, an electronic control unit and a digital display.

The device comes with a minimum set of “readytoweld” accessories.

SPEAKER ALUMIG 300 P DpulseSynegric

The universal welding machine operates in semi-automatic MIG/MAG and manual MMA arc welding modes. Thanks to a wide range of workflow settings, the unit welds not only aluminum, but also non-ferrous and ferrous metals, stainless and galvanized steel.

The device is powered by a three-phase network and can create a maximum welding current in the following modes: MIG - 300A and MMA - 250A. This is enough to ensure high-quality work in industrial environments. The device can be used wherever the electrical network can provide a power of 10.60 kVa.

The device has a number of useful functions, including:

• MIGPulse;
• DoublePulse MIG
• S4T mode;
• fast start;
• DownSlope
• and etc.

The welding machine is equipped with a computer with digital display for synergic control. The memory stores 10 programs of the most frequently used processes. The transition from one type of welding to another takes a few seconds. Synergic control automatically sets the current strength, frequency and pulse shape depending on the thickness of the wire and the type of metal.

Conclusion

When choosing a semi-automatic welding machine for aluminum, you should understand exactly what you need it for. It’s one thing when you need to weld something at the dacha and another thing when you provide welding services or start production. Welding machines are not cheap, so choose the best option, taking into account:

• welding current strength;
• presence of synergetic management;
• versatility and the possibility of manual welding;
• protection class;
• completeness;
• presence of software functions and settings memory for different processes;
• price.

You should also make sure that your electrical network supports the power consumption of the device you are purchasing.

If you are interested in the topic of semi-automatic aluminum welding, express your opinion, offer ideas or argue with the author in the comments block. This is interesting.

What are the features and difficulties of welding aluminum parts?

The main difficulty in joining aluminum parts by welding is that on the surface of this metal there is always a refractory oxide film that must be removed. If you neglect this requirement, it will be very difficult to weld aluminum, and the resulting compound will be of very low quality.

Welding aluminum semi-automatically or using any other equipment is also complicated by the fact that this metal has very high thermal conductivity and a low melting point. It is because of this that aluminum workpieces are often burned and deformed during welding.

Cleaning an aluminum workpiece with an angle grinder

Preparing parts made of aluminum and alloys based on this metal for welding must solve two problems at once: removing the refractory oxide film from the metal surface and eliminating the possibility of deformation of the workpieces being joined during the welding process.

The film is removed by mechanically cleaning the joint area with metal brushes, files and grinders or special fluxes. To avoid deformation of the parts being joined during the welding process, they are preheated in ovens or using a gas burner.

High-quality welded connection of aluminum parts