Aluminum is a very popular material. It is widely used in the manufacture of various building structures, household appliances and much more. Aluminum has a high performance, but is very capricious. Often, users have questions about whether it is possible to cook it with a semiautomatic device. Sure you may. But for cooking you need to use strictly defined equipment and consumables. In addition, you need to know about the features of such cooking and strictly follow the instructions.
The scheme of aluminum welding semiautomatic.
The main features of working with aluminum
You can boil aluminum with a semiautomatic device using melting electrodes. Constructions are cooked on linings with a forming groove. This process has several advantages. The main one is the high performance of this method, which significantly increases with increasing thickness of the material being processed.
Table of characteristics of aluminum alloys.
The process of aluminum welding with a semiautomatic device using consumable electrodes is performed under conditions of a constant current of reverse polarity. The arc burns in fumes of metal. The cathode spot on the surface of the weld pool during operation is subjected to constant exposure to a stream of aluminum ions. Upon reaching the surface, ions emit heat in large quantities. Due to this, the refractory oxide film is destroyed. But it is important to take into account the fact that only a thin oxide film is destroyed by this scheme. In order to destroy more coarse formations, before starting a semi-automatic machine, the film will need to be removed by etching or mechanically.
When the electrode is melted by an arc between the electrode wire and the tires being welded, the resulting liquid metal droplets will fill the space between the edges and create a seam. Cook semiautomatic can be in different spatial positions. For work it is better to use semiautomatic devices with pulling supply mechanisms.
Aluminum is often boiled using pulsed arc welding. A pulse is superimposed on the welding current, which makes it possible to reduce the residence time of the weld pool metal in the liquid phase. This method helps to increase the mechanical characteristics of the welded joint and makes cooking in different spatial positions easier.Back to table of contents
How the seam shape depends on the welding mode
Welding classification scheme.
When working with aluminum using a semi-automatic machine, it is important to know how the welding mode affects the shape of the seam. It is necessary to take into account that such parameters as penetration depth and geometrical characteristics of the seam are directly related to almost all factors of the welding mode. The smaller the diameter of the electrode, the deeper the penetration. This dependence becomes especially pronounced when working with small currents. With an increase in the welding current, the dependence of the penetration depth on the electrode diameter becomes less pronounced.
The width of the seam also depends on the diameter of the electrode. So, the bigger it is, the wider you can get a welding seam.
To understand all the intricacies of aluminum boiling by a semiautomatic device, you also need to know about the dependence of the penetration depth on the welding speed. Low speed will ensure minimal penetration. With an increase in speed, the penetration will increase until a certain critical value is reached, after which an increase in speed will decrease the penetration depth. However, in those modes that are most often used when working with semiautomatic devices, speed, as a rule, does not have a significant effect on penetration depth.
The welding speed and the width of the weld are inversely related. The slower the transverse movements of the end of the electrode, the wider the seam will be. This relationship is very important, it must be taken into account when processing aluminum products with a semi-automatic.Back to table of contents
Difficulties you need to know about
Scheme of the device welding semiautomatic.
Cooking aluminum semiautomatic has a number of difficulties. The main one is the oxide film already mentioned above. It is formed on the surface of the product and has a melting point that significantly exceeds this indicator for aluminum itself. The technology of welding with aluminum is such that a good seam can be achieved only if it is possible to break through the film and melt the aluminum itself. Therefore, pulse welding is ideal.
During operation, you must be very careful not to burn the aluminum part itself, since The metal has a relatively low melting point and high thermal conductivity. Therefore, before proceeding to the cooking work, it is necessary to heat the workpiece itself. This will increase the penetration depth.
In addition, before starting to cook aluminum with a semi-automatic machine, the part must be cleaned with a metal brush. Due to this, the layer of oxide film will be destroyed, and the speed of cooking and penetration of the parts will be increased. Aluminum should be started to weld no later than a day after grouting.
In the process, it is necessary to maintain a constant arc length. As a rule, it is 1.2-1.5 cm. In case the length of the arc exceeds the required length, there will be non-fusion, but if it is less, the burn through. This characteristic depends on the chemical composition of the processed alloy and the thickness of the workpiece. Different grades of alloy should boil under the appropriate modes, because their thermal conductivity varies.
Aluminum quickly gains hardness and cools down. Because of this, in the process of welding crater at the end of the seam, there may be some difficulties. To successfully complete this step, you will need either the appropriate skill or a special semi-automatic machine that will give a stronger current at the start of work, piercing the oxide film and heating the aluminum, and a weaker current at the end of the work for welding the crater.Back to table of contents
Requirements for equipment and consumables
Types of welded joints and seams.
Aluminum is a capricious metal. You can cook it only if you have the appropriate skills and high-quality welding machine. Almost any semi-automatic can be adapted for this. However, if you want to get a weld of excellent quality and the presentable appearance of the part is important for you, it is better to use a semiautomatic device with a pulsed mode and aluminum welding function or an inverter unit of argon-arc welding for such work.
Semiautomatic devices are more popular due to the fact that they allow you to perform work at a higher speed. Working with argon-arc welding on alternating current will take about 3 times longer.
To work with thick metal, you need to take a higher power device. If regular aluminum cooking is planned, then purchase a unit with a capacity of over 200 A. Ideally, the model should have a pulse welding mode. This mode will allow to destroy the oxide film and eliminate the possibility of overheating and burn-through of the workpiece. Pulse mode allows to obtain higher quality welds.
When welding aluminum, pure argon is used. If thick sheets are boiled, you need to use a mixture of argon and helium. Welding is performed using aluminum welding wire. The burner of the semiautomatic device deserves special attention. Due to the fact that the aluminum wire is very soft, the torch hose must be straight, without twisting and not more than 3 m. In order to reduce the friction of the wire, the usual channel in the torch should be replaced with a special Teflon-like aluminum. If the three-meter torch hose is not enough, you will need to buy a unit with a separate feeder. They are equipped with a five-meter cable and the possibility of its additional lengthening up to 20 m. This will allow to move away from the source as much as required, and to work with a three-meter torch without the risk of breaking aluminum wire in its channel.
For welding of aluminum it is necessary to use special contact tips. Their difference from the usual is the larger hole. This need is justified by the fact that when heated, aluminum expands more than steel.
For work with aluminum, semi-automatic machines with a four-roller clamping mechanism are best suited.
Rollers should be with a U-shaped groove. The pressure of the clamping mechanism should be as low as possible.
Aluminum boiling has another important difference from steel boiling. When working with aluminum, the wire feed will be more than in the case of steel. This and all the other features listed above are very important. Such strict requirements are assigned primarily to ensure that the semiautomatic device does not squeeze the soft aluminum wire during its supply during welding.
Thus, if you want to purchase an ordinary semi-automatic welding machine for work using classic steel wire, but occasionally you will need to cook aluminum as well, then you can safely buy a vending model. However, immediately take into account the fact that the use of a semi-automatic aluminum welding requires a certain amount of experience, skills and ingenuity. If, more often than not, you will be cooking aluminum, then pick up a semi-automatic of the appropriate profile with the necessary options and functions. Good choice and excellent work!