Comparison MegaTec StarMIG 175 vs Kentavr SPAV-200N

Among the main types of welding can be called manual arc (MMA), semi-automatic (MIG / MAG), argon-arc (TIG), spot (SPOT), spot (STUD) and plasma cutting (PLASMA) welding.

— MMA. Welding using an electric arc and a consumable electrode with a special coating. The electrode is fed and moved manually by the welder. Shielding gas supply is not provided; protection of the weld pool from air can be carried out due to the combustion of the coating deposited on the electrode. This welding technology allows the use of the simplest equipment, it is undemanding to the quality of the current and the design of the welding machine. On the other hand, the quality of the resulting weld is highly dependent on the skills of the welder, the productivity of the process is relatively low, and this technology is poorly suited for non-ferrous metals — its main purpose is the welding of steel and cast iron.

— MIG/MAG. Partially automated welding in an inert (MIG) or active (MAG) gas environment. The gas enters directly to the place of welding through the burner and, when the arc burns, forms a protective sheath that covers the weld pool from exposure to air. And the term "semi-automatic" means that filler material in the form of a thin wire is also automatically supplied to t...he place of work (but you need to move the burner manually). The choice between inert and active gas is made depending on the materials being welded — for example, the first option is usually used with non-ferrous metals, the second with steel. Such welding provides a much better quality of the seam than manual welding, and also increases the convenience and speed of work — in particular.

— TIG. Manual welding with a non-consumable electrode in an inert gas environment. With such welding, the electric arc melts only the edges of the parts to be joined, and the final seam is formed from them, without using the electrode material (in some cases, additives in the form of pieces of metal of the appropriate shape can be used). To protect the seam from exposure to air, a protective gas, usually argon, is supplied to the heating point. TIG welding is well suited for stainless steel as well as copper and aluminium alloys. It allows you to create a more accurate seam than the same MMA, and more precisely control the process. On the other hand, this technology is quite demanding on the skills of the welder, and the speed of work is relatively low.

— SPOT. Electric welding, carried out due to the point impact of high currents. It is used for connecting thin sheets of metal (mainly up to 3 mm), as well as for attaching pins and studs to a flat base. When connecting sheets of metal, two electrodes with a relatively small diameter tightly press the workpieces against one another, after which a current is passed through them with a force of the order of several kiloamperes; the metal at the point of contact is heated to the melting point, which ensures the connection. When attaching pins and studs, the role of one of the electrodes is played by the pin itself, the role of the second is played by a flat base. SPOT type welding is very popular in car manufacturing and car service: it is in this way that some elements of car bodies are connected, and it can also be useful for straightening. There are unilateral and bilateral. The first uses a single electrode, which is pressed against the workpiece with force. The main advantage of this option is the ability to work with surfaces that are accessible only from one side — for example, car doors. Actually, one of the main areas of application for one-sided SPOT welding is a car service, in particular, straightening car bodies and other car surfaces. The second welding (two-sided) involves the use of a pair of electrodes that compress the junction from both sides, like a vice. This variant is better suited for work with thick parts or where a high reliability of the connection is required — due to the compression described, it is easier to achieve the desired depth of the weld pool. On the other hand, its use requires access to both sides of the workpiece. Note that some models of welding machines are able to work according to one and the other scheme; this makes the device very versatile, but may come at a cost.

— STUD. Spot welding technology using a lifting (pulling) arc. Mainly used for flat base plus stud connections. The welding process itself takes place in the following way: the stud is pressed against the base; the current is switched on; the pin rises; an arc ignites between it and the base, which melts the surface of the base; the hairpin is lowered into the melt; the current is turned off, the metal freezes. STUD welding involves the use of mechanized welding torches with a spring or hydraulic system that raises and lowers the stud, and an inert gas or flux is used to protect the joint from atmospheric air.

– PLASMA. Cutting metal using a stream of heated plasma — a highly ionized gas. To do this, gas (inert or active) is supplied to the place of work, which, due to the influence of an electric arc, is ionized, heated and accelerated. The plasma temperature can exceed 10,000 °C, and the speed is 1,000 m/s, which makes it possible to work with almost any metals and alloys, including refractory ones. At the same time, cutting is carried out quickly, the cut is clean and neat, and the cutting depth can reach 200 mm. The main disadvantage of plasma cutting is the high cost of equipment.

The maximum power consumed by the welding machine during operation, expressed in kilowatts (kW), that is, thousands of watts. In addition, the designation in kilovolt-amperes (kVA) can be used, see below for it.

The higher the power consumption, the more powerful the current the device is capable of delivering and the better it is suitable for working with thick parts. For different materials of different thicknesses, there are recommendations for current strength, they can be clarified in specialized sources. Knowing these recommendations and the open circuit voltage (see below) for the selected type of welding, it is possible to calculate the minimum required power of the welding machine using special formulas. It is also worth considering that high power creates corresponding loads on the wiring and may require connection directly to the shield.

As for the difference between watts and volt-amperes, the physical meaning of both units is the same — current times voltage. However, they represent different parameters. In volt-amperes, the total power consumption is indicated — both active (going to do work and heat individual parts) and reactive (going to losses in coils and capacitors). This value is more convenient to use to calculate the load on the power grid. In watts, only active power is recorded; according to these numbers, it is convenient to calculate the practical capabilities of the welding machine.

The highest current that the welding machine is capable of delivering through the electrodes during operation. In general, the higher this indicator, the thicker the electrodes the device can use and the greater the thickness of the parts with which it can work. Of course, it does not always make sense to chase high currents — they are more likely to damage thin parts. However, if you have to deal with large-scale work and a large thickness of the materials to be welded, you simply cannot do without a device with the appropriate characteristics. Optimum welding currents depending on materials, type of work (see "Type of welding"), type of electrodes, etc. can be specified in special tables. As for specific values, in the most “weak” models, the maximum current does not even reach 100 A, in the most powerful ones it can exceed 225 A and even 250 A.

The largest diameter of the electrode that can be installed in the welding machine. Depending on the thickness of the parts, the material from which they are made, the type of welding (see above), etc. the optimal electrode diameter will be different; there are special tables that allow you to determine this value. Large diameter may be required for thick materials. Accordingly, before purchasing, you should make sure that the selected model will be able to work with all the necessary electrode diameters.

In modern welding machines, an electrode diameter of 1 mm or less is considered very small, 2 mm — small, 3 mm and 4 mm — medium, and powerful performant models use electrodes of 5 mm or more.

— Hot start. A function that facilitates arc ignition: when the electrode touches the welding spot, the welding current increases for a short time, and when the machine enters the mode, it returns to standard parameters.

— Forcing the arc (Arc Force). Devices with this function are able to increase the welding current with a critical reduction in the distance between the electrode and the parts to be welded. This increases the rate of melting of the electrode and the depth of the weld pool, which helps to avoid sticking.

— Protection against sticking (Anti-Stick). In this case, a protective measure is implied in case sticking of the electrode still could not be avoided: the automation of the welding machine significantly reduces the welding current (or even turns it off), which makes it easy to disconnect the electrode, and in addition — to avoid unnecessary energy consumption and overheating devices.

— Decreased voltage x. X. (VRD). This function is used to significantly reduce the open circuit voltage of the machine. When the VRD is turned on, the open electrodes receive not a standard voltage of several tens or even hundreds of volts, but only 9-12 V. At the same time, the operating parameters are restored automatically — when the electrode touches the workpiece and a high current occurs; and when the arc is e...xtinguished, the voltage again drops to the minimum values. This format of work provides two main advantages. Firstly, it provides additional safety: in particular, closing contacts with a hand or other part of the body does not lead to a serious electric shock, and the risk of such an injury in high humidity is also reduced. Secondly, lower voltage helps to save energy.

— Pulse welding. Usually, this refers to gas-shielded arc welding (MIG / MAG or TIG), carried out in the so-called pulsed mode. With this format of operation, the main welding current, which is relatively low, is supplemented by high-power pulses (7-10 times higher than the background current), which follow at a frequency of several tens per second. There are also various modifications of the pulse mode, with more complex current control; however, the basic principle remains the same. Anyway, the advantages of pulsed welding are the uniformity of both the arc itself and the resulting seam, as well as an improvement in the overall quality of the joint: pulses help to mix the metal in the weld pool and eliminate pores, oxides and other defects. The disadvantage of this function is traditional — an increase in the cost of welding machines.

— 2/4-stroke mode. Possibility to choose the control mode of the device — two-stroke or four-stroke. This allows you to further adjust the control to the specifics of the situation. Recall that in push-pull mode, the device works while the button is pressed, and turns off when it is released; this is especially useful for short seams and other similar tasks when welding does not need to be switched on for a long time. In turn, with a four-stroke control format, the first press-release turns on welding, the second turns it off. This method is indispensable for long-term work, when it would be tiring to keep the button pressed all the time.

— Synergetic management. A function mainly used when operating in the pulse mode described above. Synergic control can also be called "intelligent": it is carried out using built-in electronic microcontrollers that control most of the settings and automatically change them if necessary. In fact, it looks like this: it is enough for the welder to set a number of inputs (type and thickness of the material, composition of the shielding gas, wire thickness, etc.), and based on this, the machine will automatically select the optimal operating parameters (output voltage, pulse configuration, feed rate wire, etc.). Moreover, if one of the inputs changes in the course of work, the other parameters of the work change accordingly.
Synergic control greatly simplifies the operation of the device and at the same time improves its quality, reducing the likelihood of burns and other serious errors. This is especially convenient for inexperienced welders who are not accustomed to dealing with fully manual parameter settings; however, even professionals appreciate the ease and speed of adjustment that is characteristic of synergic models. The main disadvantage of this feature is that it has a significant impact on the cost.

— Digital display. The presence of its own display in the design of the welding machine. This is, usually, the simplest segment screen, designed to display 2 – 3 digits and some special characters. However, even such screens are more informative than light and other similar signals: they can display a wide variety of data (input and operating voltage, time until shutdown "to rest", error codes, etc.). And the advantages over dial indicators are in small size and versatility — the display can display different types of information. As a result, this function can greatly simplify the work with the welding machine.

— Connector for the remote control. Connector for connecting a remote control to the device. Depending on the model, we can talk about both traditional hand controls and foot pedals. Anyway, such an accessory provides additional convenience in some situations — in particular, it allows you to turn the power on and off, and even change individual operation parameters, without approaching the device every time. However most often welding machines are supplied without a remote control — however, this gives certain advantages: you can choose such an accessory at your discretion (the main thing is to make sure it is compatible).

— Liquid cooling. Presence of a liquid cooling system in the configuration of the welding machine. Such cooling is more efficient than air cooling, it intensively removes heat from the hardware of the apparatus, the burner and allows you to achieve a very high duty cycle (see above) — up to 100%, and at currents of 200 A or more. Its disadvantages are complexity, high cost, bulkiness and significant weight. In light of the latter, liquid cooling units are often made separately from the welding machines themselves and can be connected / disconnected depending on what is more important at the moment — efficient cooling or portability. Also note that for many models, the manufacturer recommends using specialized coolants, and they are most often not included in the delivery set.

— Built-in compressor. Compressor for air supply built directly into the machine. This feature is found only in models operating in PLASMA mode. Recall that this mode involves cutting metal using a powerful jet of highly heated and ionized air; To create the desired pressure, a compressor is needed. It can also be external; however, the built-in compressor allows you not only to always have all the necessary equipment with you, but also to reduce the overall dimensions of this equipment. In addition, with such equipment, you do not need to worry about the compatibility of the device and the air supply system. The disadvantages of models with built-in compressors include the increased cost, as well as the dimensions and weight of the entire body.

— Starting the car engine. The ability to use the device to start the car engine, namely to power the starter. In other words, models with this function are also able to work in the launcher mode. Such an opportunity will be useful if the regular car battery is dead, out of order or missing, but there is a power source (mains or generator) nearby from which you can power the welding machine. Note that most often in this case it means the launch of cars with 12-volt on-board networks — cars, light trucks and buses; however, technically, nothing prevents to provide compatibility with heavy equipment (trucks, buses) operating on 24 volts. These details should be specified separately.

— Transport wheels. The presence in the design of the welding machine of special wheels that facilitate transportation. The weight of some modern models can reach several tens of kilograms, and it is difficult even for several people to carry such a device manually. The presence of wheels makes it possible to manage by the forces of one person, even with a significant weight of the unit.

The type of MIG/MAG welding hose provided in the design of the welding machine.

Recall that MIG / MAG is welding in a special gas environment (inert or active); see "Welding type" for more details. And the welding sleeve can be described as a special hose connecting the torch to the machine (more precisely, the torch is usually part of the sleeve). Through such a hose, both the wire and the shielding gas are supplied to the welding site.

The sleeve for welding in modern MIG / MAG devices is most often made removable and fastened to a standard socket, known as a europlug. The advantages of this design are obvious: for storage, transportation or just long breaks in work, the hose can be removed and compactly rolled up so that it does not take up extra space or get in the way. In addition, if necessary — for example, in case of damage or in case of unsuitable length — the standard sleeve can be freely replaced with another one.

The non-removable design is much less common, as it is less convenient. Nevertheless, this option also has its advantages: fastening the sleeve to the device is as reliable as possible and at the same time inexpensive.

The insulation class determines the degree of resistance of the insulating materials used in a particular device to heat. To date, welding machines use materials mainly of the following classes:

B — have a resistance limit of 130 °C;
F — 155 °C;
H — 180 °C.

Note that the vast majority of modern welding machines have electronic overheating protection, which turns off the device long before reaching the insulation resistance limit. Therefore, this parameter will be relevant only in an emergency, when the built-in protection fails. Nevertheless, it fully allows you to assess the safety of using the device — the higher the insulation class, the more likely it is to notice dangerous overheating in time (for example, by a characteristic smell) and turn off the device before damage occurs.

The length of the electrode holder cable supplied with the device.

As the name implies, this cable is used to connect the clamp for the welding electrode to the machine. The longer such a wire is, the more freedom the welder has in moving, the farther he can go without moving the machine itself. On the other hand, excessively long cables create problems in storage and transportation, and often during operation (you need to look for a place where to place the excess wire). Therefore, when choosing, you should proceed from what is more important for you: the ability to move away from the device or the overall compactness. As for specific numbers, most often the length of this wire varies from 2 to 3 m, but in some models it can reach 5 m.

The length of the ground cable supplied with the machine.

The mass cable is a wire that is connected to the workpiece with a clamp. In other words, this is the second contact required to close the circuit during electric welding; connecting such a wire actually turns the workpiece into one solid fixed electrode (paired with a movable welding electrode). As for the length of such a wire, the longer it is, the farther from the connection point you can place the machine and the more freedom of movement the welder gets. On the other hand, excessively long wires create problems in storage and transportation, and often during work (you need to look for a place where to place the excess cable). In addition, freedom of movement can be ensured by increasing the length of the second wire — for the electrode holder or burner. Thus, the mass cable in modern welding machines usually has a length of 1.2 to 3 m (with some exceptions — both smaller and larger). This length allows you to comfortably place the device and at the same time does not create problems.