Each zealous owner considers it necessary to have welding semiautomatic equipment in his workshop, garage or on a suburban area, with which you can repair the fence, make various metal structures for household needs, and also repair the car. Moreover, all these operations can be done independently, without the help of assistants and without spending additional funds.
The purchase of a factory model costs a lot of money. Therefore, the dilemma between buying equipment or a do-it-yourself welding semiautomatic device with your own hands is most often solved in favor of the latter option. The benefit is the manufacture of the device, the principle of operation, its types and forms are easy to master for a person who knows at least a little basic electrical engineering and has experience in carpentry.
Technology and features of welding
The do-it-yourself welding process with a do-it-yourself semi-automatic welding machine was developed in the mid-twentieth century. The main technological features of such a compound of various metals are used at present.
The full and correct name for such welding is GMAW (Gas metal arc welding, or metal arc welding in a shielding gas environment). True, the abbreviation MIG / MAG (Metal Inert Gas / Metal Active Gas) is most often used both in literature and in practical work.
Homemade semiautomatic device operates on direct current. The electrode for welding is a special wire that is fed to the junction at a certain speed. The process of creating a weld occurs under the protection of gas. MIG technology involves the use of inert gas (helium, argon). But the do-it-yourself self-made welding semiautomatic device, operating according to the MAG system, uses active carbon dioxide and its mixtures to protect the welding site.
By semi-automatic welding, it is possible to make a high-quality connection not only of steel parts, but also products of non-ferrous metals (copper, aluminum, magnesium, nickel), which are easily oxidized without protective operations.
Operating principle
The welding process with a home-made semiautomatic device takes place using an electric arc in a shielding gas medium, which is formed between the surface of the metal being welded and the wire used as an electrode.
The quality of the weld completely depends on the voltage, wire feed speed and the amount of gas supplied to the joint. All these parameters are set in advance, based on the thickness and type of material being welded. In order for the protective gas to exert an appropriate effect, the end of the wire must protrude to a strictly defined length.
Since the welding wire arrives at the junction automatically, and the welder is only required to manipulate the torch, this method of welding metals is called semi-automatic.
Positive aspects of using a semiautomatic device
The main advantage of using a home-made semiautomatic device for welding is getting a high-quality connecting seam, with a high speed of work. These parameters allow you to use the equipment not only for small jobs, but also for professional purposes.
Since the inverter operates by the method of converting high-frequency currents, rather than voltage, there is the possibility of making a home-made semiautomatic device with your own hands to significantly reduce its weight and dimensions, which ensures its mobility when working in difficult conditions.
Also, the advantage of using a home-made semiautomatic device is the possibility of using electrodes, both alternating current and constant. And the ability to regulate the welding current in a wide range allows the use of non-consumable electrodes in argon-arc welding.
Disadvantages of semiautomatic devices
Do-it-yourself home-made semiautomatic welding, just like an inverter, has a higher price than similar transformer-type units.
Semiautomatic machines are very afraid of the harmful effects of dust, therefore, in order to extend their trouble-free service life, it is necessary to clean the unit at least once every six months.
Semi-automatic equipment does not work well at low temperatures. And at air temperatures below -15 ℃ it cannot be operated at all.
Another significant drawback during the operation of a self-made semiautomatic device is the limited cable length for connecting the device (no more than 2.5 m).
Types of semi-automatic units
In the open air, non-ferrous metal parts to be welded quickly undergo oxidation, and therefore their connection is difficult. To improve the quality of the weld, it is necessary to protect the weld zone from oxidation. Therefore, to solve certain problems, it is necessary to establish exactly what type the welding machine will be used. Semi-automatic home-made depending on the type of protection of the weld pool is divided:
- welding under a protective flux layer;
- inert gas cloud connection;
- welding process using electrode flux-cored wire.
The most common type of semiautomatic device is the use of protective gas.
Shielding gas properties
To eliminate the negative effect of oxygen on the metals being welded, gas is added to the joint zone, which is able to improve the quality and bond strength of materials. Nitrogen in the air and moisture can cause weld porosity, but oxygen oxidizes the surface. Also, the use of gas provides uniform and reliable ignition of the welding arc.
It is the type of gas used that completely affects the shape and mechanical strength of the weld, the melting speed of the metal and the penetration of the arc, as well as the number of spatter during welding. The composition of the gas mixture has a significant effect on how molten metal flows from the wire to the junction of the surfaces.
Helium and argon are often used for welding non-ferrous metals and aluminum. But the connection of steel surfaces occurs best under the protection of active gases and their mixtures (carbon dioxide), which significantly increase the melting rate and improve the permeability of the electric arc.
Self-made welding semiautomatic device
Before making a home-made semiautomatic device, it is necessary to prepare the following equipment:
- To form a working current of 150A, you need a welding inverter, which can be made from a transformer from a microwave oven.
- A torch that is responsible for dosing the shielding gas at the welding site.
- The feed mechanism is responsible for the continuous flow of the welding wire to the welding site.
- To control the unit, it is necessary to equip an electrical unit with which the current is regulated.
- Using the feed hose, the welding wire is fed to the working surfaces.
- A gas hose is needed to supply shielding gas to the connection area.
- Spool of filler wire.
It is very difficult to make some components yourself (burner, cylinder, hoses), so it is advisable to purchase them in a distribution network.
Transformer alteration
To create a high-quality inverter-semiautomatic device, you can use a transformer from a microwave oven. A home-made semiautomatic device from the inverter is a current transformer with the necessary alterations to obtain the necessary parameters.
In principle, the primary winding remains unchanged. The main changes will concern the secondary winding of the transformer. For these purposes, a copper strip and a winding of heat-insulating paper will be needed, a transformer wire is not suitable for such reconstruction, since it will be very hot at extreme operating conditions.
Three layers of tin are added to the secondary winding, which must be carefully insulated. The ends of the manufactured winding and the existing one must be interconnected.
When deciding to make a home-made semiautomatic device from a welding transformer, you can use the device from the microwave. To do this, you will have to remove the old winding and wind a new one from several turns of thick wire. When working, damage to the enamel must be avoided. Calculations of wire diameter and number of turns are based on the transformer used.
Obtaining a stable voltage at the output of the supply unit is achieved by installing a rectifier bridge, inductor and capacitor. Capacitance is needed to smooth ripple, and the inductor maintains a stable level of operating voltage.
Wire feeder
To get a high-quality and durable weld, the wire must be fed to the soldering place continuously and evenly. For this purpose, the welding semiautomatic device is equipped with a wire feed system.
To make the feed mechanism with your own hands, you need to purchase the following elements:
- Electric motor for shaft rotation.
- Two bearings, one of which is made adjustable (pressure).
- Special guide roller.
- Compression spring.
- The mounting system of the feeding device.
If you use a system unit from a computer for the semi-automatic case, then there is a voltage in its power supply that is suitable for the operation of the electric motor. In the case of manufacturing a separate case, you will have to assemble an autonomous power system.
Since the welding wire is one of the electrodes of the semiautomatic device, the installation of the feed system must be carried out on an electrically insulating material. For these purposes you need:
- On a special plate, make holes for installing the motor shaft, as well as bearings.
- Attach an electric motor to the back of the carrier plate.
- Install bearings above and below.
- A guide roller is put on the drive shaft.
- A clamping spring is mounted on the adjusting bearing.
Cooling system
When constructing a home-made semiautomatic device from a welding inverter, special attention should be paid to the need to cool the secondary winding of the transformer, which can become very hot under heavy equipment load.
The cooling system consists of two fans that are aimed at the transformer winding and operate to extract the heated stream. To improve air circulation, dozens of holes must be made in the semiautomatic device body.
As fans, you can use products from the cooling system of a personal computer.
Additional devices of a semiautomatic device
It is very difficult to make a torch for semi-automatic welding on your own, so experienced welders recommend purchasing industrial gas equipment. And the problem here is not only in the manufacture of the equipment itself, but also in the need to strictly comply with safety requirements.
It is also advisable to use standard shielding gas cylinders. Carbon dioxide containers may be an exception. Fire extinguishers are often used, but it is only necessary to install a special adapter for the gearbox.
The mobility of all semi-automatic equipment is increased by using special trolleys, which can be purchased at the store, but it is also not very difficult to do it yourself. The design of such a device is easy to develop from various metal channels and profile or round pipes.
Safety precautions
Welding work belongs to the increased category of complexity. In order not to harm the welder's health, it is necessary to strictly observe some safety measures:
- Bright light from electric arc welding adversely affects human vision. Therefore, all welding work must be carried out in a protective mask.
- To protect against splashes of molten metal and ultraviolet radiation, which negatively affects exposed skin, gloves must be worn.
- Also, work must be carried out in closed shoes so that the hot metal does not get inside.
- Clothing should not be made of synthetic material in order to avoid melting during welding.
- The room where welding is carried out must be equipped with good ventilation so as not to inhale harmful fumes from welding.
To create a home-made welding semiautomatic device, you do not need the presence of expensive equipment and scarce parts. The main thing is to have knowledge of electrical engineering and the ability to carry out simple carpentry work, and, if desired, you will have an indispensable assistant in the household.