Semiautomatic welding machine is a very convenient device for working at home and in small workshops. You can work with it in any conditions, special preparation of the workplace is not required, it is compact almost like a regular inverter.
Unlike manual arc welding, it does not require a highly qualified welder to work with it. Correct setting of the welding semiautomatic device allows to perform high-quality work for a welder of low qualification.
Depending on the type of material being welded, its thickness, it is required to correctly set the feed rate of the wire, shielding gas. Further, the welder needs to evenly run the burner along the seam, and a high-quality weld will be obtained. The whole difficulty lies in the correct selection of welding parameters for a particular material.
For high-quality tuning of the welding semiautomatic device, an understanding of the characteristics of welding is required, it is also necessary to understand the features of the semiautomatic device.
Semiautomatic welding machines allow you to work with almost any metal and their alloys. They can weld non-ferrous and ferrous metals, low-carbon and alloy steel, aluminum and coated materials, can weld thin metals up to 0.5 mm thick, and can even weld galvanized steel without damaging the coating.
This is achieved due to the fact that a flux, cored wire or shielding gas, as well as a welding wire can be supplied to the welding area, moreover, the feed takes place automatically, everything else is done as in manual arc welding.
Semiautomatic welding machines are available in different classes, but they all consist of:
- control unit;
- power source;
- wire feed mechanism with a coil;
- welding torch;
- power cables.
The wire feed mechanism consists of an electric motor, gearbox and feed or pulling rollers.
Recommendations in the instructions
Before performing work, it is necessary to reliably ground the apparatus for welding and only then start setting up. The semiautomatic welding machine must be connected to a gas cylinder system with protective gas.
It is necessary to check the presence of welding wire in the coil, if you need to recharge it and stretch it to the torch handle. The gas flow rate is of great importance during the welding process.
Therefore, it also needs to be installed. Gas equipment has gearboxes with gas flow in liters. It is very convenient, you just need to set the required flow rate within 6-16 liters.
In the instruction manual for the device, recommendations are given on how to properly configure the welding semiautomatic device, what current to cook a particular metal, with what speed to feed the wire.
The instructions should have special tables in which everything is written. If you set all the parameters in accordance with them, then everything should work out.
In practice, there may be difficulties. A lot of parameters influence the quality of welding a semiautomatic device. If the power supply network does not comply with the standards, then the power source will produce voltage and the current is not what you need, the parameters will be unstable.
The temperature of the medium, the thickness of the metal, its type, the condition of the surfaces to be welded, the type of the weld, the diameter of the wire, the gas supply volume and many other factors affect the quality of the semi-automatic welding.
Tables of recommended welding conditions are given for specific conditions that are not always possible to provide. Therefore, when welding semi-automatic, many adjustments are carried out empirically.
Of course, the recommended values are initially set, then there is an exact adjustment of the welding parameters.
Setting current and wire feed speed
First of all, the welding current strength is set, which depends on the type of material being welded and the thickness of the workpieces. This can be found according to the instructions for the semiautomatic device or found in the relevant literature.
Then the wire feed speed is set. It can be adjusted in steps or continuously. With stepwise adjustment, it is not always possible to choose the optimal mode of operation. If you can choose a device, buy a welding semiautomatic device with smooth adjustment of the wire feed speed.
The control unit must have a forward / reverse wire feed mode switch. When all the settings in accordance with the operating instructions for the semiautomatic device are made, you need to try working on a draft sample with the same parameters. This must be done because the recommendations are averaged, and in each case the conditions are unique.
At a high wire feed speed, the electrode simply will not have time to melt, there will be large depositions or shifts on top, and at low it will burn without melting the metal being welded, the weld bead will sag, and recesses or gaps will appear.
The adjustment of the current or voltage depends on the thickness of the workpieces. The thicker the item being welded, the greater the welding current. In simple semi-automatic welding devices, the adjustment of the current strength is combined with the wire feed speed.
In professional semiautomatic devices, the adjustments are separate. The correctness of the setting can only be determined empirically by making an experimental seam on the test piece. The roller should be of normal shape, arc stable, without splashes.
Some semi-automatic models have an inductance adjustment (arc settings). With a small inductance, the temperature of the arc decreases, the penetration depth of the metal decreases, the seam becomes convex.
This is used when welding thin metals and alloys that are sensitive to overheating. With a large inductance, the melting temperature increases, the weld pool becomes more liquid and deeper. The seam roller becomes flat. Welding in this mode is used for thick workpieces.
The wire feed speed switch in models capable of working with different diameters requires additional adjustment based on the specific wire thickness.
Even having fully studied the manufacturer’s recommendations, it is not always possible to get the desired mode of operation of a semiautomatic device.
Having set the optimal settings for welding the workpiece today, it may turn out that the next day they will become non-optimal because the network quality has changed or the position of the product on the desktop has changed.
Video: How to Replace Cord In Trimmer Semi-Automatic
That is, the setting of the modes is a constant and individual process, because it also depends on the manner of work of the welder himself.
An error in the settings of the welding semiautomatic device is indicated by a distinct crack. Loud clicks indicate that the solder feed rate is low. It is necessary to increase the feed rate until the cod disappears.
Often there is a strong spray of metal. This is due to insufficient insulating gas in the area of the weld pool. It is necessary to increase the gas supply, adjust the semi-automatic gearbox.
There are lack of fusion or burn seam. This is due to too low or too high voltage of the arc, it is regulated by adjusting the voltage or inductance.
The uneven width of the weld bead is related to the speed of the torch and its position relative to the weld, that is, it is associated with the welder’s working technique.
Subject to the recommendations of the manufacturer and understanding of the processes occurring in the weld pool, methods for their adjustment, you can perform quite complex types of welding work at home.
A semiautomatic welding machine is a functional device that can be purchased ready-made or made from an inverter with your own hands. It should be noted that the manufacture of a semi-automatic apparatus from an inverter device is not an easy task, but it can be solved if desired. Those who set such a goal should well study the principle of the semiautomatic device, see thematic photos and videos, prepare all the necessary equipment and components.
Scheme of semi-automatic welding in shielding gas
What is required to convert the inverter into a semiautomatic device
To remake the inverter by making a functional semiautomatic welding machine from it, you must find the following equipment and additional components:
- an inverter apparatus capable of generating a welding current of 150 A;
- a mechanism that will be responsible for the supply of welding wire;
- the main working element is a burner;
- hose through which the welding wire will be fed;
- a hose for supplying shielding gas to the welding execution zone;
- a coil with a welding wire (such a coil will need to be subjected to some alterations);
- An electronic unit that controls the operation of your homemade semiautomatic device.
The electrical circuit of a homemade semiautomatic device
Special attention should be devoted to alteration of the feeding device, due to which a welding wire that moves along a flexible hose is fed into the welding zone. In order for the weld to turn out to be of high quality, reliable and accurate, the wire feed speed through the flexible hose must correspond to its melting speed.
Since when welding using a semiautomatic device, wire of different materials and different diameters can be used, its feed rate should be regulated. It is such a function — regulating the feed speed of the welding wire — that the feeding mechanism of the semiautomatic device should fulfill.
Appearance of a homemade semi-automatic welder
The most common diameters of the wire used in semi-automatic welding are 0.8; 1; 1.2 and 1.6 mm. Before welding, the wire is wound on special coils, which are prefixes of semi-automatic devices, fixed on them with the help of simple structural elements. In the process of welding, the wire is fed automatically, which significantly reduces the time spent on such a technological operation, simplifies it and makes it more efficient.
The main element of the electronic circuit of the semiautomatic control unit is a microcontroller, which is responsible for regulating and stabilizing the welding current. The parameters of the operating current and the possibility of their regulation depend on this element of the electronic circuit of the welding semiautomatic device.
How to remake an inverter transformer
In order for the inverter to be used for a home-made semiautomatic device, its transformer must be subjected to some alterations. Doing such an alteration with your own hands is not difficult, you just have to adhere to certain rules.
To bring the characteristics of the inverter transformer in line with those that are necessary for the semiautomatic device, you should wrap it with a copper strip, on which a winding of thermal paper is applied. It must be borne in mind that for these purposes it is impossible to use an ordinary thick wire, which will be very hot.
Converted Inverter Transformer
The secondary winding of the inverter transformer also needs to be redone. To do this, do the following: winding a winding consisting of three layers of tin, each of which must be insulated with a fluoroplastic tape; the ends of the existing winding and made by yourself to solder together, which will increase the conductivity of the currents.
The design of the inverter used to include it in the welding semiautomatic device must necessarily include a fan, which is necessary for efficient cooling of the device.
Setting up the inverter used for semi-automatic welding
If you decide to make a semi-automatic welding machine yourself, using an inverter for this, you must first disconnect this equipment. To prevent such a device from overheating, place its rectifiers (input and output) and power switches on the radiators.
Power diodes on additional radiators
After all of the above procedures are completed, you can connect the power part of the device with its control unit and connect it to the electrical network. When the network connection indicator lights up, an oscilloscope should be connected to the inverter outputs. Using this device, it is necessary to find electrical pulses with a frequency of 40-50 kHz. The time between the formation of such pulses should be 1.5 μs, which is regulated by a change in the magnitude of the voltage supplied to the input of the device.
Waveform of welding voltage and current: on the left on the reverse polarity, on the right. on the straight
It is also necessary to check that the pulses reflected on the oscilloscope screen have a rectangular shape and their front is no more than 500 ns. If all the parameters checked correspond to the required values, then you can connect the inverter to the mains. The current coming from the output of the semiautomatic device must have a force of at least 120 A. If the current strength is less, this can mean that a voltage is supplied to the equipment wires, the value of which does not exceed 100 V. In the event of such a situation, the following must be done: test the equipment by changing the current strength (in this case, the voltage across the capacitor must be constantly monitored). In addition, you should constantly monitor the temperature inside the device.
After the semiautomatic device is tested, it is necessary to check it under load. To make such a test, a rheostat is connected to the welding wires, the resistance of which is not less than 0.5 Ohms. Such a rheostat must withstand a current of 60 A. The current strength, which in this situation is supplied to the welding torch, is controlled by an ammeter. If the current when using a load rheostat does not meet the required parameters, then the resistance value of this device is selected empirically.
How to use a welding inverter
After starting the semiautomatic device, which you assembled yourself, the current value equal to 120 A should be displayed on the inverter indicator. If everything is done correctly, then it will happen. However, eights may appear on the inverter indicator. The reason for this is most often insufficient voltage in the welding wires. It is better to immediately find the cause of such a malfunction and quickly fix it.
If everything is done correctly, then the indicator will correctly show the strength of the welding current, regulated by means of special buttons. The interval for adjusting the operating current provided by the welding inverters is in the range of 20–160 A.
Approximate modes of semi-automatic butt welding
How to control the correct operation of equipment
In order for the welding semiautomatic device that you assembled with your own hands to serve you for a long time, it is better to constantly monitor the temperature mode of the inverter. To carry out such control, two buttons must be pressed simultaneously, after which the temperature of the hottest inverter radiator will be displayed on the indicator. A normal operating temperature is considered to be one whose value does not exceed 75 degrees Celsius.
If this value is exceeded, then, in addition to the information displayed on the indicator, the inverter will start to produce an intermittent sound signal, which should be immediately noted. In this case (as well as in the event of a breakdown or short circuit of the temperature sensor), the electronic circuit of the device will automatically reduce the operating current to 20A, and an audio signal will be emitted until the equipment returns to normal. In addition, an error code (Err) displayed on the inverter indicator may indicate a malfunction of DIY equipment.
Setting the welding mode on the Resanta inverter
In what cases is a semiautomatic welding machine used
Practice shows that a semiautomatic device is better to use in those cases when it is required to obtain accurate and accurate connections of parts made of steel. With the help of such equipment, which, if desired, can be made with your own hands, welded joints of thin metal are performed, which is very important when repairing a car body.