Electric welding machines: types, characteristics, purpose

Electric welding is one of the ways to create permanent joints, where the heating and melting of the metal of the parts to be connected is made by means of an electric arc. For the implementation of the technological process and the creation of an inseparable connection between metal elements, electric welding machines are used. In this case, it is also possible to cut metal structures or separate parts from them.

Classification

The field of application of 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 the home master, an electric welding machine is extremely necessary, since there is a constant need to create permanent joints, when it is necessary to install a fence, repair a defrosted water pipe, weld the hinges to the gate or the gate, make a brazier and do many other things. The services of professional welders and finished products purchased in the store are expensive. It is advisable to purchase an electric welding machine and blanks from metal, the costs for which are sometimes comparable with the purchase of finished products. Even if they are more, especially the savings will be felt in the future, when all the necessary equipment will already be available.

The simplest welding device is a powerful transformer, connected directly to the network. He has many shortcomings: heavy weight and dimensions, significant energy consumption, the complexity of mastering the welding process. But there are also advantages: unpretentiousness, exceptional reliability, simplicity and cheapness.

An inexperienced welder finds it difficult to obtain a quality weld from metal using a transformer. For proper work it is necessary to develop special skills. Working on alternating current makes it difficult to keep a stable welding arc. It is difficult for an amateur to choose the appropriate mode of operation.

Characteristics of welding transformers

The transformer contains primary and secondary reduction windings. The first is connected to the network, and the second one is used for welding. The voltage on it is 30-60 V. Welding 220 volts is suitable for domestic use, and for industrial often use models with three-phase power supply for 380 V. The connection is made through the machine on a separate line.

The choice of the unit is based on the following characteristics.

1. Limits of welding current regulation. The possibility of changing the power means that you can select convenient operating modes and change the diameter of the electrodes. The higher the maximum current, the larger the size of the electrode can be used.
2. Diameter of the electrode. For household use, 3 mm is sufficient, and to increase the productivity of the welding process in the workshop or workshop it must be 4-8 mm (current from 120 to 400 A). If the current is lower than required, the quality of the seam will be low.
3. Voltage of the network. For household use, transformers of 220 V are chosen. Industrial models can operate from a three-phase network. There are devices that can be connected for both types of power.
4. 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 marking. For household use, models of transformers with a rated current of 160-200 A are selected.
5. Rated operating voltage. The value of the voltage on the output winding determines how much metal can be welded.
6. The operating mode or the on-time duration indicates how much of the time the transformer is in the welding mode. Powerful units can be switched on during the entire shift (100%), and for domestic use 40% is enough. If you go beyond the specified limits, the device overheats and may be damaged.
7. The efficiency of the transformer means the ratio between the output power during welding and the consumed power. The maximum efficiency is about 80%. If it is lower, you should look for another model.
8. The idling voltage facilitates the appearance of an electric arc as it increases. The safety threshold for the operator is 80 V with alternating current and 100 V at constant.

Welding rectifiers

Devices can create a stable electric arc during operation. In addition to the transformer, the welding rectifier contains silicon or selenium blocks at the output, which provide direct current to the welding rods.

It is much easier for a beginner to learn welding with a direct current. In addition, it is possible to weld cast iron, heat-resistant alloys and non-ferrous metals.

Electric welding machines have disadvantages: high cost, sensitivity to short circuits and jumps in mains voltage, and loss of power during operation. Despite this, devices are used by both amateurs and professionals.

Welding rectifier is unpretentious in maintenance, but requires the following measures:

• Checking the integrity and reliability of the connection of contacts;
• Avoidance of moisture from outside and inside;
• Blowing with compressed air to remove dust.

Which rectifier should I choose?

How much does an electric welding machine cost, depends on power, maximum current and dimensions. For fans of the device is suitable Telwin Quality 220 AC / DC. 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 usually do not apply due to the high price (100 thousand rubles and above), heavy weight, dimensions and power.

Welding inverters

The device is a current source that provides easy arc formation and automatic support of its combustion. The electric welding inverter works according to the following scheme:

• The 220 V voltage is applied to the rectifier, where the signal is filtered and converted to DC;
• High frequency current is generated (inverter);
• The voltage drops to the level of the welding (transformer);
• The alternating current is rectified.

The complication of the circuit is associated with the need to reduce the dimensions and weight of the transformer due to a significant increase in frequency. 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 novice welder mode. If the welding transformer creates significant jolts of voltage in the network, the inverter does not overload it, and the ignition of the arc is softer.

The reliability of the apparatus is lower than that of the transformer, because of the electronic circuit. It is sensitive to low air temperature and high humidity. The device generates electromagnetic interference, which is reduced in more expensive models.

Features of welding with an inverter

Devices have three functions.

1. Hot start. In the initial period, the current increases and does not require the heating of the electrode, as in the case of a transformer. When starting, the arc is made more powerful, and welding is successful.
2. Anisalipanie - increase in operating current when the electrode is caught. As a result, a rapid separation occurs, and the welding parameters are immediately restored.
3. Forcing the arc. The parameters of the welding current in the anti-slip mode are adjusted so that the metal is not too spattered.

Electric welder for home and cottages

For everyday life, an inexpensive inverter with an optimum duty cycle of 60% is selected. They are often used by professionals, because with a slow work and with a small working current, the device can be switched on continuously. It is important that the voltage of the network is normal. In this case, a device with a capacity of up to 160 A is selected. Welding 220 volts, with a current of up to 200 A, is suitable when frequent power surges occur. From 180 A and higher, it is possible to weld an electrode with a diameter of 4 mm in sheets up to 5 mm thick.

Types of electric welding machines and manufacturers

Everyone is trying to buy a device that is cheaper, but with good characteristics. From imported models it is good to weld "Resanto" and "Interskolom", for which the price category is from 6 to 11 thousand rubles. Of the domestic well-proven "Torus" and "Cedar" (price - 8-16 thousand rubles.). Apparatus cheaper than 6 thousand rubles. Have a lower quality.

Prices for electric welding machines do not always reflect the quality of the model. Worthy devices are also selected by indirect indicators: the availability of service, quality instruction, positive feedback, etc.

Welding "Resident AIS 220" allows creating reliable connections of products from tin and thick metal, thanks to a wide range of current control. For the apparatus, there is no problem reducing the mains voltage by 30% of the nominal value.

Electrowelding inverter "Caliber SVI-205AP" - a cheap model of Chinese production is well suited for periodic applications in everyday life. Judging by the reviews, the device does not always turn out reliable, although often there are models that work for a long time without breakdowns.

Conclusion

Electric welding machines are chosen according to the needs. For the domestic 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 procedure and maintenance according to the instructions.