Welding of metal products and structures is a complex technological process that can be organized in different ways. The traditional method involves manual operations. This is a labor-intensive method that justifies itself with a low cost. A more modern approach is represented by semi-automatic welding, which facilitates the tasks of the master and improves the quality of the seam.
Technology description
The principle of semi-automatic welding is quite simple. In the course of work, the welding gun is directed to the target zone, after which the workpiece melts from the heat of the formed arc. Unlike other welding methods, in this case, the wire can perform both the function of a conductive electrode and filler tasks.
As a means of protecting the work area, semi-automatic welding technology provides for the formation of gaseous media - in particular, those that do not allow penetrationoxygen to the treatment area. But later, the regime in which the process occurs without gas will also be considered. Conversely, other protective media and materials may be added. So, to minimize the splashing of metal droplets due to the absorption of moisture in the working area, silica gel or copper sulphate is used, placed in the dehumidifier.
Ultimately, the operator can expect the following benefits from the technology:
- High workpiece protection.
- Convenience in working with equipment - the master can perform operations from almost any position, since there are no restrictions on the direction of welding.
- The seam is smooth and with a minimum slag content.
MIG and MAG welding methods
In the specifications and regulatory documents, this is how semi-automatic welding using wire and gaseous media is indicated. Target blanks can be steel and aluminum alloys, although in practice the technology has a wider range of applications. How is semi-automatic MIG welding different from the MAG method? In fact, the difference is in the type of gas used to protect the work area. For example, MIG welding uses inert gases like argon and helium, while MAG works with active nitrogen and carbon dioxide environments.
As practice shows, MAG provides a better and more reliable seam compared to the MIG effect, although much depends on the skill of the performer. If we compare both methods with MMA formats andTIG, then we can talk about the balance of semi-automatic. It gives optimal performance with proper seam quality, but specifically for delicate high-precision operations or providing ultra-strong joint structure, it is still worth turning to alternative methods.
Welding modes
Different conditions and technical purposes will require the use of certain processing parameters. Depending on operational tasks and equipment settings, the following modes of semi-automatic welding are distinguished:
- Short Arc. With low current and series fault support in low current conditions up to 200 A, melt droplets are transferred. In the course of work, a wire with a thickness of 0.8 - 1.2 mm is used.
- Spray Arc. The operation is performed at a current strength of 200 A, which ensures a higher penetration of drops into the melt. Wire diameter - more than 1 mm. This mode is suitable for thick-walled workpieces.
- Pulse Arc. At low current, this welding format provides a high melting speed with a low volume of melt spatter. Ideal for stainless steel and aluminum, but only if they are thin.
- Pulse on Pulse Arc. The mode allows, due to the regulation of temperature and the level of currents, to obtain a strong seam with a smooth surface.
Specially for work at low temperatures, a special mode of semi-automatic MIG welding with soldering elements is also used. The connection of the parts in this case occurs against the background of the addition of a melt from the solder material. This method is used inworkshops when performing body repairs.
Welding without shielding gas
Managing the working environment provides the operator with many benefits - both in terms of safety and as a means of improving the quality of the seam. But there are conditions under which the use of gaseous media can be ruled out in principle. For example, semi-automatic welding in a carbon dioxide environment allows you to effectively solve the problems of processing steel billets, but due to the need to connect a cylinder with a gearbox, safety requirements are significantly increased, which may impose restrictions. In this regard, it is appropriate to highlight two main ways to use MIG-MAG technology without gas:
- Welding with flux-cored wire. The consumable material is brought by a caliper to an electric arc and, as it burns, covers the melt bath. The method is environmentally friendly and safe, but can only be applied to soft non-ferrous metals.
- Welding with flux-cored wire. A consumable is used based on a mixture of siliceous and silicate, which is rejected by the melt and forms a protective film on its surface. The coating performs the task of a barrier in front of oxygen, replacing the same carbon dioxide. This method also has a number of limitations due to the low power of the thermal arc.
Applied Equipment
The main and most responsible tool in the workflow is a semiautomatic device - it isrectifier or inverter that provides power to the burner. These are electromechanical devices, due to which the process of melting the electrode is carried out with its supply to the weld pool. In particular, the parameters of the machine for semi-automatic welding will determine the range of wire feed speed and the stability of its movement in principle. There are models of inverters for domestic and professional use (for 220 V and 380 V, respectively) with monoblock and modular designs. You should also pay attention to the configuration of the connectors for connecting the same burner, but the most important thing in choosing is the direct operating parameters of the equipment.
Characteristics of the devices
For simple household tasks in a garage or a home welding workshop, you can use low-power devices of 4-5 kW with a maximum current of 90-120 A. Such models are quite capable of adequately working with workpieces with a thickness of 1.5-2 mm, saving while electricity. The professional segment represents models with a power of up to 14 kW and above. The supported current strength of such equipment can reach 350 A. For what tasks is this type of equipment used? Productive semi-automatic welding is good for versatility, which translates into the possibility of servicing metals such as titanium and nickel. The thickness of the workpiece in this case can be 10 mm.
What is important from the point of view of the organization of the workflow is the duration of the inclusion. It determines the relationship between the welding period and the rest time. So,in the case of powerful professional inverters, you can count on 6-7 minutes of welding, after which a break of 4-5 minutes is required. For household devices, working time will be 1-2 minutes, and rest - up to 10 minutes.
Feed mechanics
Special units are used to automatically guide the wire to the working area. They are a complex of electrical and mechanical components that support an uninterrupted welding process. The basis of the standard design is directly formed by the feed mechanism, welding sleeve, control unit and devices for initial loading of cassettes with new wire. At the same time, it is a mistake to think that the equipment works only with consumables. Thanks to the built-in sleeve-hose, semi-automatic welding with a feeder creates a protective environment. That is, a special organization of gas supply channels from the cylinder to the welding zone with the help of adapters, reducers and regulators is not required.
Welding torch
Tool for direct supply of a high-temperature torch to the workpiece. The device of such devices is quite simple. The main control element is a button or a mechanical flame regulator. It turns out manual semi-automatic welding, the control of which at the final stage of the formation of the seam is taken over by the master, and the auxiliary processes are supported by the same electrode supply mechanism. When choosing a gun torch, it is important to consider the diameter of the wire to be gripped, the current (up to 650 A) and the type of cooling - built-in orthird-party from semi-automatic.
Welding wire
The main consumable in such work is a wire or an electrode. The thickness of this element determines which workpieces the semi-automatic machine can work with. In addition, the diameter ultimately imposes restrictions on the use in the feeder. Ordinary machines are guided by 0.6-2 mm, but there are also non-standard models, which is important to consider when choosing. The material of the wire is also important. If semi-automatic welding of low-alloy and non-alloy steels is planned, then preference is given to copper elements, and aluminum equipment interacts well with magnesium and silicon blanks.
A special group is represented by activated wire models. Their difference lies in the content of special additives in the rod (5-7%) based on oxides and s alts from alkali metals. This modification allows you to get a neat seam and reduce melt spatter.
Accessories and equipment
When all the main components of the semi-automatic welding infrastructure are ready, you can proceed to the selection of additional accessories. In general, personal protective equipment will be required. Gloves, thermal boots, apron and mask are required for semi-automatic carbon dioxide welding. To protect against infrared and ultraviolet radiation, it is recommended to use filters for the viewing part. For example, "Chameleon" type masks are provided with self-adjusting tintedglasses, which provides not only protection for the eyes, but also comfortable to wear.
Conclusion
One of the main advantages of MIG-MAG welding technology is versatility. It is used both in the domestic sphere and in industries, in construction, etc. The technical organization of the process requires considerable resources, but for large volumes of work, these investments justify themselves. Why is semi-automatic welding in shielding gas attractive to ordinary home craftsmen who only occasionally turn to such operations? First of all, the quality of the seam. As already noted, there are more accurate and accurate technologies, but in this case, you can achieve the optimal result with a high level of safety and convenience. For example, many motorists purchase semi-automatic devices with consumables only for full-fledged maintenance of the car body. The ability to direct welding from different positions, in particular, allows you to perform the most complex operations during repair activities.
