Plasma cutting with your own hands from the inverter - make a homemade plasma cutter
Factory device for plasma cutting. Our task: make an analogue with your own hands
It is not so difficult to make a functional plasma cutter with your own hands from a serial welding inverter., as it may seem at first glance. To solve this problem, it is necessary to prepare all the structural elements of such a device:
- plasma cutter (it is also called a plasmatron);
- welding inverter or transformer, which will act as a source of electric current;
- compressor, by means of which the air stream will be created, required for the formation and cooling of the plasma flow;
- cables and hoses for integration into one system of all structural elements of the device.
General scheme of plasma cutting
Plasma cutting, including homemade, successfully used to perform various works as in production, and at home. Such a device is indispensable in those situations, when you need to perform accurate, thin and high-quality cut of metal blanks. Some models of plasma cutters by their functionality allow you to use them as a welding machine. Such welding is performed in a protective argon gas environment.
Gas hose and return cable for plasma cutting
When choosing a homemade plasmatron power supply, it is important to pay attention to the current, which such a source will be able to produce. Inverter is most often chosen for this purpose, which provides high stability of the plasma cutting process and allows you to save more energy. Differing from the welding transformer in compact dimensions and light weight, the inverter is more convenient to use. The only disadvantage of using inverter plasma cutters is the difficulty of cutting them with very thick workpieces.
ABIPLAS plasma torch burner and its components
When assembling a homemade device for plasma cutting, you can use ready-made schemes, which are easy to find online. Online, in addition, there is a video on making a plasma cutter with your own hands. Using when assembling such a device ready-made scheme, it is very important to strictly adhere to it, and pay special attention to the conformity of structural elements to each other.
Plasma cutting schemes on the example of the APR-91 device
As a donor in the consideration of the basic electrical circuit, we will use the plasma cutting machine APR-91.
The scheme of the power unit (click to enlarge)
Plasma cutter control scheme (click to enlarge)
Oscillator circuit (click to enlarge)
Elements of the self-made device for plasma cutting
First, what you need to find to make a homemade plasma cutter, Is a power source, in which an electric current with the necessary characteristics will be formed. Inverter welding machines are most often used in this capacity, due to a number of their advantages. Due to its technical characteristics, such equipment provides high stability of the formed voltage, which has a positive effect on the quality of cutting. It is much more convenient to work with inverters, which is explained not only by their compact size and low weight, but also ease of setup and operation.
The principle of plasma cutting
Thanks to compactness and small weight plasma cutters on the basis of inverters can be used when performing works even in the most hard-to-reach places., which is excluded for bulky and heavy welding transformers. A huge advantage of inverter power supplies is that, that they have high efficiency. This makes them very economical devices in terms of electricity consumption.
In some cases, a welding transformer can be a power source for plasma cutting, but its use threatens significant electricity consumption. That should also be taken into account, that any welding transformer differs in big dimensions and considerable weight.
The main element of the device, designed for cutting metal with a jet of plasma, there is a plasma cutter. It is this piece of equipment that ensures the quality of cutting, as well as the effectiveness of its implementation.
The shape and size of the plasma jet depends on the diameter of the nozzle
To form the air flow, which will be converted into a high-temperature plasma jet, a special compressor is used in the design of the plasma cutter. Electric current from the inverter and air flow from the compressor are fed to the plasma cutter via a cable-hose package.
The central working element of plasma cutting is the plasmatron, the design of which consists of the following elements:
- nozzles;
- channel, on which the air stream moves;
- electrode;
- insulator, which simultaneously performs the function of cooling.
The design of the plasma cutter and recommendations for its manufacture
First, what to do before making a plasmatron, - is to choose the appropriate electrode for him. The most common materials, of which electrodes are made to perform plasma cutting, is beryllium, thorium, zirconium and hafnium. Refractory oxide films are formed on the surface of these materials when heated, which prevent the active destruction of the electrodes.
Interchangeable nozzles for plasmatron
Some of the above materials may emit compounds that are hazardous to human health when heated, which must be taken into account, choosing the type of electrode. So, when beryllium is used, radioactive oxides are formed, and the evaporation of thorium when combined with oxygen produces hazardous toxic substances. Absolutely safe material, from which electrodes for a plasmatron are made, is hafnium.
For the formation of a plasma jet, due to which the cutting is performed, corresponds to the nozzle. Its manufacture should be given serious attention, as the quality of the workflow depends on the characteristics of this element.
The structure of the nozzle of the plasma burner
The nozzle is the most optimal, whose diameter is 30 mm. The accuracy and quality of the cut depends on the length of this element. However, the nozzle should not be made too long, because it contributes to its rapid destruction.
As mentioned above, a compressor must be present in the design of the plasma cutter, which forms and supplies to the nozzle air flow. The latter is necessary not only for the formation of a jet of high-temperature plasma, but also for cooling the elements of the device. The use of compressed air as a working and cooling medium, as well as the inverter, generates operating current by force 200 A, allows you to effectively cut metal parts, whose thickness does not exceed 50 mm.
Choice of gas for plasma cutting of metal
To prepare the plasma cutting machine for work, the plasmatron must be connected to the inverter and the air compressor. A cable hose package is used to solve this problem, which is applied as follows.
- Cable, on which electric current will be given, the inverter and the plasma cutter electrode are connected.
- The compressed air supply hose connects the compressor outlet and the plasmatron, in which of the incoming air flow will be formed a jet of plasma.
Features of plasma cutting
To make a plasma cutter, using an inverter for its manufacture, it is necessary to understand that, how such a device works.
After turning on the inverter, electric current from it begins to flow to the electrode, which leads to the ignition of the electric arc. Arc temperature, burning between the working electrode and the metal tip of the nozzle, is about 6000-8000 degrees. After the arc is ignited, compressed air is supplied to the nozzle chamber, which passes strictly through an electric discharge. The electric arc heats and ionizes the air flow passing through it. As a result, its volume increases hundreds of times, and it becomes capable of conducting electric current.
With the help of a plasma cutter nozzle, a plasma jet is formed from the conductive air flow, whose temperature is actively rising and can reach 25-30 thousand degrees. Plasma flow rate, due to which the cutting of metal parts is carried out, at the exit of the nozzle is about 2-3 meters per second. At that moment, when the plasma jet is in contact with the surface of the metal part, electric current from the electrode begins to flow through it, and the original arc goes out. New rainbow, which burns between the electrode and the workpiece, called cutting.
A characteristic feature of plasma cutting is that, the processed metal melts only in that place, where it is affected by plasma flow. That is why it is very important to do so, so that the plasma exposure spot is strictly in the center of the working electrode. If you ignore this requirement, then you can face it, that the air-plasma flow will be disturbed, so, the quality of the cut will deteriorate. In order to comply with these important requirements, use special (tangential) the principle of air supply to the nozzle.
It is also necessary to monitor this, so as not to form two plasma streams at once instead of one. The emergence of such a situation, which leads to non-compliance with the regimes and rules of the technological process, may cause the inverter to fail.
Plasma cutting parameters of different metals (click to enlarge)
An important parameter of plasma cutting is the speed of air flow, which should not be too large. Good quality of a cut and speed of its performance provides speed of an air stream, equal to 800 m / sec. The current strength, coming from the inverter device, should not exceed 250 A. Performing work in such modes, that fact should be taken into account, that in this case the air consumption will increase, used to form plasma flow.
It is easy to make a plasma cutter yourself, if you study the necessary theoretical material, watch the training video and choose all the necessary elements correctly. If you have such a device in your home workshop, assembled on the basis of a serial inverter, can be qualitatively performed not only cutting, but also plasma welding with their own hands.
If you do not have an inverter, it is possible to collect a plasma cutter and on the basis of the welding transformer, but then have to come to terms with its large size. in addition, plasma cutter, made on the basis of a transformer, will have not very good mobility, as it is difficult to move it from place to place.
