Welding is an art. Professional welders are valued almost worth their weight in gold everywhere: they are not enough not only for domestic needs, but also for industry. This is largely due to the fact that not every specialist knows all the technological aspects of complex production operations.
For example, not even all enterprises know how to cook semi-automatic. This topic is dedicated to our article.
General concepts
A semiautomatic welding machine is now called a device by which electric arc welding is performed. Its feature is that the role of the electrode is a steel wire, which is continuously fed into the device during welding. The mechanism is semi-automatic because the welder manually performs continuous wire feed.
Automata classification
Semi-automatic welding devices are classified by the type of protection of the weld :
- apparatus for welding metal submerged arc;
- semi-automatic systems for welding in an inert gas environment;
- machines where special flux-cored wire is used as electrodes.
Note that submerged arc welding machines have not been used in domestic industry for quite some time now, as they cook semi-automatic machines of this type only according to old technologies, which are rarely found in developed industrial countries. Semi-automatic welding machines are much more common and convenient, the technological process of which involves the use of neutral gases. In particular, flux-cored wire is most often boiled that way.
In addition, there is a classification according to the type and characteristics of the wire used in the work:
- machines that use a solid steel electrode;
- solid aluminum wire welding systems;
- universal models (allows the use of both types of electrodes).
Welding machines are also divided by the nature of their mobility:
- Stationary models are widely used in the heavy metallurgical industry.
- Their antipodes are portable varieties that only one person can transport.
- A reasonable alternative to both of the above options are mobile modules that can be transported on a special car chassis. Since they cook semi-automatic machines of this type in the field, the apparatus is equipped with the most “tenacious” components.
It should be borne in mind that modern industry produces hundreds of models of semi-automatic welded systems, which can vary significantly in their characteristics. With their help they connect not only steel, but also aluminum and other metals. In the workshops of automobile plants, similar mechanisms are involved in the production of bodies.
Semiautomatic welding modes
Since the welder who works with such equipment has to deal with several types of metals every day, manufacturers have introduced various modes of welding semi-automatic in their products. Among them, an experienced specialist will be able to choose the one that is ideal for each particular case. Let's look at their main varieties:
- A mode with a short circuit of a welding arch and without it.
- Large, medium and small droplet species.
- Modes with and without spraying flux.
The use of one type or another depends both on the type of metal being welded and on the purpose of a particular part. To make it easier for welders to navigate, there is also a more detailed classification:
- cyclic welding when a short arc is used;
- point type;
- pulse welding ;
- option with jet movement of the welded metal;
- welding subject to continuous circular metal transfer.
If carbon dioxide is used (see above), then in practical conditions the pulse-arc mode is most often chosen. As a rule, the current is constant, reverse polarity. In this case, the melting rate of the metal is not too high, but the welding arc is much more stable, and the resulting seam is much stronger.
What should be included?
The apparatus set should include a transformer for power, a torch and a mechanism for supplying a welded wire, cables and sleeves for supplying inert gas, as well as a computerized system for controlling welding processes. The electrode is automatically fed into the zone of technological operations, which distinguishes these mechanisms from fully mechanical counterparts. The welder performs all other activities manually.
Advantages of semi-automatic welding machines
- A huge advantage is the fact that you can weld a metal whose thickness does not exceed 0.5 mm.
- Rust and even quite serious contamination of the welded metal are not an obstacle to the quality of work.
- The cost of work (in comparison with other types of welding) is very low, since the cost of basic consumables is low.
- It is important that using a semiautomatic device on copper wire, galvanized steel parts can be connected, and the coating itself will remain completely intact.
Technology Weaknesses
- If it is not possible to use an inert gas, the metal begins to “boil” quite strongly, and the spray of scale will scatter a decent distance.
- A sufficiently strong radiation comes from the open arc, so this point should also not be forgotten.
Where are semi-automatic machines most often used
Despite some negative features, semi-automatic machines are intensively used in the car repair business. Most often, this technology is used in welding steel and aluminum. Argon is preferably used as the inert gas. In addition, steel is often welded in carbon dioxide.
A bit about the feed mechanism
We have already mentioned why devices of this type are semi-automatic. Since the welder, by the nature of his work, will be forced to constantly work with a mechanism that feeds an electrode (wire) into the working area, it will be useful to learn about all the existing types of such devices. To date, there are three of them:
- Drawing varieties.
- Push type feed mechanisms.
- Universal modifications: a wire for welding by a semiautomatic device in this case can be any.
Getting started
As in other cases, which in one way or another relate to work with welding machines, first you will need to correctly configure all your equipment. First, you should choose the current strength, being guided by the thickness of the metal being welded and the instructions attached to the device. As a rule, the documents have a special table in which the welding technology is described in detail. Note that with a low welding current, the operation of the apparatus leaves much to be desired.
Guided by the same instruction, set the required feed rate of the electrode to the working area. It can be adjusted by appropriately selecting interchangeable gears for the gearbox. Be sure to check the current strength and voltage before starting work!
If you intend to weld some important technological product, be sure to check the correctness of all the settings displayed on any test sample. Accordingly, according to the test results, a final adjustment should be made (if necessary). If you have set up the welding machine correctly, the best evidence of this is a smooth and stable welding arc.
Can I cook semi-automatic without inert gas?
Without a doubt, using inert gas, welding work is carried out with the highest quality. But only for individuals who rarely use welding, buying a whole gas cylinder is not economically feasible. Is semi-automatic welding possible without gas?
An excellent alternative is flux or flux cored wire. In this case, it is made of a steel tube into which a flux is pressed. When it burns out, a local zone is formed above the welding site, protected by its vapors. Note that in this case, direct current must be used.
This is how semi-automatic welding without gas is performed.
Cook steel products
First, set the switch to the “Forward” position, which is responsible for supplying the electrode (wire). Then fill the existing funnel with flux. Important! The holder must be set in such a way that the feed end of the funnel is exactly in the welding zone, as otherwise the flux will go in the wrong place and you will observe a huge amount of fun scattering.
We open the shutter on the flux tank, after which we begin to lightly strike the electrode at the place of welding, while simultaneously pressing the "Start" button. After that, an arc will appear. You can start to work.
And how is aluminum welding performed semiautomatic?
Cook aluminum parts
Aluminum is a metal that, from the point of view of welders, is very complex. On its surface there is a rather thick layer of amalgam, which not only interferes with conventional metal welding, but also recovers extremely quickly after any contact with oxygen. Therefore, it is advisable to know all aspects of this work well, since otherwise you simply will not be able to make a reliable and high-quality seam on metal.
This is how aluminum is welded semi-automatically.
Semi-automatic arc welding
Just note that with this method of work, only aluminum wire is allowed, which is used as an electrode. Note that because of its softness, it often forms loops in the current collector, and therefore you will have to use their special models, designed specifically for the use of aluminum.
Most often, argon welding is used (it is more convenient to work with a semiautomatic device in this environment), and special attention should be paid to the quality of gas. The pressure is the most difficult to choose: it should be sufficient for reliable protection of the weld pool, but at the same time not exceed the limit values, since in this case air suction begins to appear .
What are the challenges facing the welder?
- First you need to thoroughly clean all parts of parts intended for welding from dirt and paint.
- Residues of dirt must be cleaned with chemical solvents.
- As we already said, you should first make a test seam, as the equipment settings may not be too successful.
- It is very important to choose the right current strength and voltage: a weak current simply will not break the amalgam. In addition, you need to be very careful in protecting the weld pool.
All other operations are no different from the above activities.
In which environment is it best to weld car body parts?
Based on the experience of leading enterprises, we would strongly recommend that you use only a semiautomatic device for welding aluminum in carbon dioxide during body repair. This approach has many advantages, which we will discuss below.
Firstly, the real zone of thermal deformation of the material is very small, which makes it possible to weld even narrow parts without problems, without fear of losing their appearance. Even if the part has already been painted, the pigment burns out locally, and the size of the damage is small. This provides an excellent opportunity to save on finishing painting and preparing parts for it.
Even welding with a semi-automatic stainless steel will be performed very quickly and with a minimum amount of waste.
The melting speed of the wire with this method is very high. This provides for excellent labor productivity and high quality work. The latter circumstance is all the better because the seam is extremely accurate and high-quality. In addition, you do not have to desperately calculate the fractions of millimeters by joining parts: there are very few losses in the metal, so that even very small parts can be welded reliably.
Even those joints that are composed of elements of different thicknesses will delight the quality of the welded joint. It should be added that carbon dioxide is cheap, and welding by an inverter semi-automatic machine is quickly mastered even by not too experienced employees.
Technology for welding vertical joints
It is not by chance that we brought this topic into a separate paragraph. The fact is that the heat in this case rises from the bottom up, which prevents high-quality welding. Therefore, all vertical seams are cooked strictly from top to bottom. The torch should be directed slightly upward, since in this case the heat necessary for the weld pool is much better held. Note that you need to weld as quickly as possible, since you will need to prevent the occurrence of leaks of molten metal. Be sure to hold the electrode at the front edge of the bath.
Here's how to cook semi-automatic. Good luck with your work!