For welding, a variety of equipment is used, but a welding semi-automatic has become popular today, which has the necessary performance, quality of work, and convenience.
The welding semiautomatic device is the electrotechnical device intended for welding process with use of an electrode.
Before buying, you need to decide how to choose a semi-automatic welding machine. We will have to take into account numerous parameters, to decide in which gas environment the work will be carried out.
Welding gas mixtures
When choosing a welding machine, it is necessary to take into account in which gas environment the work will be carried out. For example, an inert gas (argon) must be used for the MIG welding method, and an active gas (carbon) is suitable for MAG.
All types of gases that are used for welding machines can be divided into 2 large groups:
The list of source gases used to obtain gas mixtures.
- Gas compounds that actively react with metals. These include carbon dioxide, nitrogen, oxygen.
- Inert gases, for example, helium, argon.
The easiest option is to use carbon dioxide, it will be the cheapest. But in this case, the quality of the seam suffers; it cannot be called completely bad, but additional cleaning after work is necessary, otherwise the seam will rust. For a semiautomatic device, it is recommended to use a mixture of two gases - this is a composition that consists of 20% carbon dioxide and 80% argon. Pure argon is used for non-ferrous metals, and when using a tungsten electrode it is best to take a mixture of 90% argon and 10% hydrogen.
Pure nitrogen as a protective medium is used for welding bronze parts, brass. There are models that can work without gas, but then it becomes necessary to use a flux. It is important to immediately determine under what conditions the work should be conducted, whether there are requirements for the gaseous environment.Back to table of contents
Criterias of choice
To choose a welding machine of semi-automatic type, it is necessary to pay attention to various parameters. The selection criteria include:
An important indicator when choosing a welding machine is the voltage value of the electrical network.
- load capacity of the electric supply medium;
- the choice of material to be welded, it may be stainless steel, low carbon steel, aluminum, non-ferrous metals;
- thickness of the metal being processed;
- requirements for the quality of welding;
- the quality of the weld, taking into account its length, width, position in space;
- intensity of equipment operation.
Choosing a welding machine, it is necessary to pay attention to the voltage of the electrical network. It is important to accurately determine which machine can be used for work. For example, for single-phase networks, only those devices that can work with networks from 220 V with a load up to 16 A are suitable. will not work normally.Back to table of contents
What should be the welding current
When choosing any unit it is important to consider the current. This indicator determines at what values the equipment will not overheat, how thick the metal can be boiled. When a semi-automatic welding machine is selected, certain indicators must be taken into account. For example, if the welded metal has a thickness of up to 5 mm, then it is possible to take equipment with a current of 150-200 A. A diameter of 0.8-1 mm is allowed for wire. But with a greater thickness of welded parts, the value of the rated current will increase to 250 A, the wire for work is used with a diameter of 1.2-1.6 mm. In more detail, the choice of device for welding under the conditions of use of carbon dioxide will be based on the following values:
Electrode selection table depending on metal thickness and current.
- With a metal thickness of 0.8-1 mm, a wire diameter of 0.7-0.8 mm will be needed. The welding current should be 50-80 A.
- With a metal thickness of 1.5-2 mm, a wire diameter of 0.8-1.2 mm will be needed. Welding current should be equal to 90-200 A.
- With a metal thickness of 3 mm, the wire diameter will be 1.2-1.4 mm, welding current - 200-380 A.
- With a metal thickness of 4 mm, the wire diameter will be 1.2-1.6 mm, welding current - 200-350 A.
- When the thickness of the metal is 8 mm, it is necessary to use a wire diameter of 1.2-2.5 mm. The welding current should be 300-450 A.
Some experts recommend to provide a reserve of 50 A. This will allow you to use the device for metal with a greater thickness, if necessary. In order to choose a semi-automatic welding machine, you need to take into account the duration of the load. This is necessary so that the equipment does not overheat during operation. Such values are always indicated by the manufacturer, but usually the duration of the load is 60%. This is quite enough for quality work.Back to table of contents
Current source and function
Important indicators when using the welding machine are the function and current source. All semi-automatic devices have a main mode, i.e. the ability to carry out welding due to mechanized wire feed. But there are other modes, universal devices. An important additional mode is MMA. In some cases, it may be necessary to manually feed the wire, if such an activity is assumed, then it is necessary to choose a unit with the proper mode.
Attention should be paid to what power source will be used during operation.
Functions of automatic welding machine.
All semi-automatic welding machines can be divided into inverters and current rectifiers. Functions such as pulse welding, hot start, anti-sticking, are possible only for inverters, and they are not provided for rectifiers. But the latter are more reliable. If you only need to perform a certain type of activity for which such functions are not needed, it is better to choose rectifiers. Their cost is lower, the purchase will be more profitable.
When a welding machine is selected, attention should be paid to the type of torch. Different can be the length of the sleeve, workmanship, availability and type of cooling. For example, if the work is supposed to be intensive, then it is necessary to choose the liquid, air type of cooling.Back to table of contents
Current adjustment and digital display
When choosing, you must immediately determine which regulator is needed. There are models with a smooth or stepped regulator. On this depends the exact selection of the mode of operation. Smooth adjustment is preferred when fine tuning is required. Step more convenient, allows you to quickly set up the device.
The digital display function is not mandatory, but it is important if usability is put in one of the first places. It is through this display that the voltage, current, selected function are immediately visible. It must be remembered that the cost of such equipment will be higher.
How to choose a welding machine? Attention should be paid to certain parameters on which welding quality, safety, and comfort will depend. For simple homework, an expensive professional device does not make sense, and the price is high.