Welding is one of the most critical stages of both industrial production and small business. We should not forget about their importance in the aspect of even a banal homestead. In all these cases, not only the operational reliability of the finished product, but also the safety of the people who use it often depends on the quality of welding.
Particularly reliable and high-quality
welding is semi-automatic welding machines, performed in an inert gas environment. Do you know
how to cook semi-automatic? Today we’ll talk about this.
General concepts
In general, this process is one of many varieties of classical electric arc welding. Since its resistance is much higher than that for the electrode, most of the energy is released into the space near the arc, melting the surface to be welded and the electrode itself, as a result of which a so-called weld pool is formed.
After the connection cools down and crystallizes, a weld is formed, which at this stage of technological development is considered the most reliable way of joining metal parts.
Semi-automatic welding basic principles
Unlike classical arc welding, in the process under consideration, two things are of predominant importance: the electrode (welded wire) and the inert gas that protects the weld pool. Before cooking semi-automatic, it is very advisable to buy the latter in sufficient quantities.
The latter circumstance is extremely important. The fact is that they try to save the weld by all available methods from interaction with oxygen during the work: firstly, otherwise, a lot of scale will form, and the joint surface becomes far from ideal. Secondly, a huge amount of oxides appears in the weld metal itself, which extremely negatively affect the quality of the finished joint. That is why argon and carbon dioxide are widely used in welding.
Schematic description of the welding process
To learn how to cook semiautomatically, you need to imagine the main principles of its work.
In the process of welding, the electrode (wire) passes through the nozzle of the torch, where it melts due to the high temperature of the arc. Since the welding wire is fed continuously, it is possible to achieve a constant quality and speed of the process. Direction and speed are manually selected. The welder himself also has to monitor the continuity of the electrode feed. In the international classification, such a process is referred to as GMAW (gas metal arc welding). Distinguish welding in an inert or active gas.
The latter is used in cases where the properties of the metal do not allow to achieve any special characteristics of the weld. Here's how to cook semi-automatic.
What equipment is required for this?
The set of equipment should include the welding machine itself, a source of welded current, a device for feeding wire, as well as a gas cylinder. Devices of this type are available both in portable versions and in the form of a chassis for use in the field. Since it is difficult to learn to cook a semiautomatic device of this type, only specialists who have passed the necessary instruction are allowed to work.
What are the characteristics of conventional equipment of this type?
- Amperage from 40 to 600 A.
- On the welding arc itself, the voltage is from 16 to 40 V.
- The speed of the fastened section can reach 2 cm per second.
- For various purposes and materials, a wire is used, the thickness of which is from 0.5 to 3 mm.
- 30 to 250 mm of electrode is consumed per second.
- Inert gas consumption can reach 60 liters in one minute. The minimum value is the consumption of three liters in one minute.
- Up to 100 liters of inert or active gas are placed in one welding cylinder.
Preferred feed mechanisms
Semi-automatic welding machines differ greatly in the arrangement of the mechanism for feeding the electrode welding wire, so this point should be considered in more detail. In the most common version, the push type is used: it greatly simplifies the design of the burner, but in this case the length of the gas supply hose is limited to a maximum of three meters. It is better to use a pulling structure: the length of the hose in this case can reach 20 meters.
Before buying a welding machine, you should pay close attention to the torch. Since the nozzle is the element that wears out almost the fastest, it should be made as high quality as possible. Please note that during welding you need to constantly clean it from adhering pieces of scale. It is very necessary to monitor the condition of the tip, as in case of damage, the welding quality drops sharply.
Important! Before you cook stainless steel semiautomatically, buy replacement kits. Stainless steel takes up a lot of wire and inert gas. For its welding, a powerful electric arc is required , the metal is very hot, the nozzle wears out quickly.
What materials should be used in the work?
As we already said, the wire can be used from 0.5 to 3 mm thick. The thinner it is, the better the burning of the arc, the deeper the penetration of the material being welded. Note that you can use an electrode thicker than 3 mm, but for each "extra" millimeter there must be 100 additional amperes.
Inert gases can be used both in pure form and in mixtures. The average gas flow rate is easy to calculate, knowing the average speed of passage of the treated area and the specific consumption of consumables, which can be found in the manuals for welding specialists.
A bit about current and voltage
Of course, the current strength depends on the thickness of the material being welded, as well as on the diameter of the wire used. The greater the thickness, the deeper the penetration of the material and the overall productivity is less. The higher the voltage, the deeper the penetration of the metal. But you need to remember that this increases the volume of burnt material and scale, and the width of the seam increases significantly. The voltage is set by amperage. More information should be sought in the instructions for the welding machine.
The electrode feed rate is set based on the characteristics of the material and the required strength of the seam. Welding time depends both on the thickness of the material being joined and on the expected width of the seam. At high speeds, therefore, we strongly recommend that you make only narrow joints, since with wide joints you will get disgusting articulation quality and a large amount of scale.
About gas consumption
The thicker the wire, the more inert gas is consumed to protect the surface of the material being welded. It is possible to lower the consumption by pressing the nozzle of the burner more tightly to the working surface, or by tritely reducing the speed of welding parts. Attention! If you overdo it at a speed (increasing it for the sake of increasing productivity), the nozzle tip can go beyond the weld pool, undergoing accelerated oxidation and collapsing from this.
Correct work with electrodes
The stability of the welding process largely depends on the release and flow rate of the electrode wire. The larger the outreach, the less stable the arc becomes. In addition, in this case, a huge amount of material goes into scale. This is largely due to the fact that the zone of the weld pool is sharply reduced, the tip and the material itself begin to oxidize at an accelerated rate. If the overhang is unnecessarily small, visibility during welding is sharply reduced.
Aluminum cooking
And how to cook aluminum semi-automatic? Aluminum is a chemically inert metal, as there is a thick amalgam on its surface. To burn it, you need a powerful arc. As an electrode, a thin aluminum wire is used. It is imperative (!) To use an inert gas, since at the slightest oxygen supply the amalgam is instantly restored.
Important Tips
If you are cooking thin metal, then the seam must be kept from top to bottom. The seam must be made as thin as possible, since in this case its thickness is approximately the same on both sides. If you make an overly wide joint, you are unlikely to be able to avoid burning through the material. To avoid damage to the material, we recommend increasing the welding speed, while reducing the welding current voltage.
In the event that you are cooking the material on a lining base, ensure that it is pressed as tightly as possible. The fact is that the arc very strongly heats the metal, as a result of which its sheets of small thickness begin to bend strongly due to thermal deformation. To reduce the manifestations of this physical effect, bend the joints towards the lining. Since it can be difficult to cook semiautomatically in this way, make several test seams before work.
If the metal to be welded is more than 1.5 mm in thickness, we advise you to work on weight. At the same time, we recommend placing the electrode in a vertical position, directing it precisely to the bath. When welding metal with a thickness of 1.3 to 2 millimeters, select the modes so that the seam is obtained in a maximum of one pass. Before you cook the machine semi-automatically, be sure to fit the parts to each other, mark the front of the work: the body is easy to spoil, so you need to work very carefully.
If the gaps between poorly fitted parts are too large, we recommend proceeding as follows: also conduct welding from top to bottom, conduct experiments with power fluctuations, and also stop working from time to time, allowing the finished sections to get stronger. Once again, we remind you: before you cook semi-automatically, it is advisable to fit the parts to each other. You will spend quite a bit of time, but the welding process will go much faster.
We cook metal without using inert gases
All of the above is true for welding metals in an inert gas environment. But what to do in the case when you simply do not have the opportunity or means to buy cylinders, how to cook semiautomatically without gas? Especially for these cases, manufacturers produce special varieties of electrode wire.
In its manufacture, two technologies can be used: pressing flux into a thin metal tube or incorporating its components directly into the electrode metal.
Why is such a wire good? The thing is in physics: when an electric arc discharge begins to melt it, a cloud of those compounds that are part of the flux forms around the weld pool. Thus, the classic inert gas is replaced, since the burnt flux protects the material being welded is not much worse.
Here's how to cook semi-automatic without gas.
A bit about safety
Our article would not be complete if we did not mention the safety requirements. Recall that the TB during electric arc welding requires the creation of at least a ten-meter protective zone around the work site. If the distance is less, then those present are seriously at risk of severe burns to the retina. To learn more about specific regulations and rules, you should carefully read the instructions for your equipment.
The specialist must use individual protective equipment, carefully check all available equipment before starting work. It is strictly forbidden to start welding if at least one mechanical or electrical malfunction is detected. Always remember that welding is a source of increased risk of fire.
Since semi-automatic welding is often done indoors, remove all combustible material from the work area.
findings
In conclusion, it must be said that the welding quality is really high only if the surface of the parts is thoroughly cleaned of dirt and grease before work. In addition, the correct configuration of the equipment plays a huge role: if you overdo it with power, you can burn through the sheets of iron. Decide to do the work more slowly - there is a high probability of sloppy wide seams and the appearance of a large amount of scale.
The latter not only takes the metal of the part itself. As we said above, the scale contributes to the speedy wear of the nozzle of the torch and other important parts of the welding machine. It is very important to remember this before you cook the machine semiautomatically: the metal of the body is not particularly thick, and therefore it can burn through.