Electric welding is one of the ways to create permanent joints, where the heating and melting of the metal of the parts to be joined is carried out using an electric arc. Electric welding machines are used to carry out the technological process and create an inseparable connection between metal elements. You can also cut metal structures or separate parts from them.
Classification
The scope of the devices is determined by the value of the welding current:
- Up to 150 A - household electric welding machines.
- Up to 250 A - semi-professional.
- More than 250 A - professional.
For a home craftsman, an electric welding machine is essential, because there is a constant need to create permanent connections when you need to install a fence, repair a defrosted water pipe, weld hinges to a gate or gate, make a barbecue and do much more. Services of professional welders and store-bought finished productsare costly. It is advisable to purchase an electric welding machine and metal blanks, the costs of which are sometimes comparable to the purchase of finished products. Even if they are larger, especially the savings will be felt in the future, when all the necessary equipment is already available.
The simplest welding device is a powerful transformer connected directly to the network. It has many disadvantages: large weight and dimensions, significant energy consumption, the complexity of mastering the welding process. But there are also advantages: unpretentiousness, exceptional reliability, simplicity and cheapness.
It is difficult for an inexperienced welder to get a quality weld from metal using a transformer. For proper work, you need to develop special skills. Working on alternating current makes it difficult to maintain a stable welding arc. It is difficult for an amateur to choose the appropriate mode of operation.
Characteristics of welding transformers
The transformer contains a primary and a secondary step-down winding. The first is connected to the network, and the second is used for welding. The voltage on it is 30-60 V. Welding 220 volts is suitable for domestic use, and for industrial use models with a three-phase power supply of 380 V are often used. The connection is made through an automatic machine on a separate line.
The choice of the unit is made according to the following characteristics.
- Limits of welding current regulation. The ability to change the power means that you can select convenient operating modes and change the diameter of the electrodes. The highermaximum current, the larger electrode size can be applied.
- Electrode diameter. For domestic use, 3 mm is enough, and to increase the productivity of the welding process in a workshop or workshop, it should be 4-8 mm (current from 120 to 400 A). If the current is lower than required, the quality of the weld will be poor.
- Network voltage. For domestic use, 220 V transformers are selected. Industrial models can operate from a three-phase network. Devices are available that can be connected to both types of power.
- Welding current. Its maximum value determines which electrodes can be used, as well as the possibility of cutting metal. The parameter is always indicated on the label. For domestic use, models of transformers with a rated current of 160-200 A are selected.
- Rated operating voltage. The amount of voltage on the output winding determines how thick the metal can be welded.
- The mode of operation or the duration of the inclusion indicates what part of the time the transformer is in the welding mode. Powerful units can be turned on for a whole shift (100%), and 40% is enough for domestic use. If you go outside the limits, the device will overheat and may be damaged.
- Transformer efficiency refers to the ratio between welding output power and power consumption. The maximum efficiency is about 80%. If it is lower, you should look for another model.
- The open-circuit voltage makes it easier to start an electric arc as it increases. The safety threshold for the operator is 80 V atAC and 100 V DC.
Welding rectifiers
The devices allow you to create a stable electric arc during operation. In addition to the transformer, the welding rectifier contains silicon or selenium blocks at the output, providing a direct current supply to the welding rods.
It is much easier for a beginner to master DC welding. In addition, cast iron, heat-resistant alloys and non-ferrous metals can be welded.
Electric welding machines have disadvantages: high cost, sensitivity to short circuits and power surges, as well as power loss during operation. Despite this, both amateurs and professionals use the devices.
The welding rectifier is unpretentious in maintenance, but requires the following measures:
- Checking the serviceability and reliability of the connection of contacts;
- prevention of moisture from outside and inside;
- blowing with compressed air to remove dust.
Which rectifier should I choose?
How much an electric welding machine costs depends on power, maximum current and dimensions. For amateurs, the Telwin Quality 220 AC/DC device is suitable. The power is 6 kW, the maximum current is 160 A, the weight is 30 kg, the price is up to 13 thousand rubles. Professional units for domestic use are usually not used due to the high price (100 thousand rubles and more), large weight, dimensions and power.
Welding inverters
The device is aa current source that provides easy arc formation and automatic maintenance of its burning. The inverter electric welding machine works as follows:
- 220V is applied to a rectifier where the signal is filtered and converted to DC;
- high frequency current is generated (inverter);
- voltage drops to welding level (transformer);
- AC is being rectified.
The complexity of the circuit is due to the need to reduce the size and weight of the transformer due to a significant increase in frequency. The output characteristics of the device are supported by an electronic regulator. This is the main advantage of the device, which can be used by a beginner in the mode of a novice welder. If the welding transformer creates significant voltage surges in the network, the inverter does not overload it, and the arc ignition is softer.
The reliability of the device is lower than that of a transformer due to the presence of an electronic circuit. It is sensitive to low air temperature and high humidity. The device generates electromagnetic interference, which is reduced with more expensive models.
Features of welding with an inverter
The devices have three functions.
- Hot start. In the initial period, the current increases and heating of the electrode is not required, as in a transformer. When starting, the arc becomes more powerful, and welding is successful.
- Anti-sticking - an increase in the operating current when the electrode is stuck. As a resulta quick pull-off occurs and the welding parameters are instantly restored.
- Arc forcing. The welding current parameters in the anti-stick mode are adjusted so that the metal does not spatter too much.
Electric welding machine for home and garden
For everyday life, an inexpensive inverter with an optimal duty cycle of 60% is selected. It is often used by professionals, because with slow work and with a small operating current, the device can be turned on continuously. Here it is important that the mains voltage is normal. In this case, a device with a power of up to 160 A is selected. Welding of 220 volts, with a current of up to 200 A, is advisable when frequent power surges occur. From 180 A and above, it is possible to weld sheets up to 5 mm thick with an electrode with a diameter of 4 mm.
Types of electric welding machines and manufacturers
Everyone is trying to get a device cheaper, but with good performance. Of the imported models, it is good to weld with Resanta and Interskol, whose price category ranges from 6 to 11 thousand rubles. Of the domestic ones, "Torus" and "Kedr" have proven themselves well (price - 8-16 thousand rubles). Devices are cheaper than 6 thousand rubles. are of lower quality.
Prices for electric welding machines do not always reflect the quality of the model. Worthy devices are also selected according to indirect indicators: the availability of service, quality instructions, positive reviews, etc.
Welding with "Resanta SAI 220" allowscreate reliable connections of products from tin and thick metal, thanks to a wide range of current regulation. It does not create problems for the device to reduce the mains voltage by 30% of the nominal value.
The Caliber SVI-205AP inverter electric welding machine is a cheap Chinese-made model well suited for occasional use in everyday life. Judging by the reviews, the device does not always come across as reliable, although there are often models that have been working without breakdowns for a long time.
Conclusion
Electric welding machines are selected based on needs. For a home master, a household model is suitable, and for a professional, you should choose a device that is more expensive, with the possibility of constant work during the shift. For any device, it is necessary to follow the correct welding technology and maintain it according to the instructions.
