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In a private house and in the country, there is always a need to cook something. In order not to turn to the pros on trifles (and not pay them), you can buy an inexpensive welding machine and learn it yourself. To acquire these skills, it is recommended to purchase DC welding machines, and in particular, welding inverters. They are small in size, weigh little, and with their help you can get a high-quality seam even without a lot of experience. No less important, in this category there are good devices at a low price (5-10 thousand rubles). Therefore, welding with an inverter for beginners is the best that the market can offer today.
What is a welding inverter and how does it work
This device was called an inverter because it converts the alternating current of the 220 V network with a frequency of 50 Hz into high-frequency oscillations, and then into direct current. At the same time, the device has a high efficiency: about 85-90%, and even at fairly large loads, the counter “winds” a little. In any case, you will not have to pay crazy bills. The consumption will be slightly higher than without welding, but not by much.
Most inverter welding machines operate from a 220 V household network (there are also machines from 380 V). And this is one of their advantages. Moreover, they practically do not affect it in any way; do not “sit down” tension. As for the neighbors, be calm: they will not know that you are welding. The second important plus is that they can work more or less normally even at low voltage. Of course, you need to look at the characteristics, but at 170 V most of them still allow you to work with a 3 mm electrode. This is very important especially in rural areas where low voltage is the norm rather than the exception.
What else is good for beginners is that the arc with inverter welding is easier to get and hold. And in general, according to many, it cooks from “softer” and its arc is “lighter”. So if you want to learn how to cook, try inverter welding first.
Read about the choice of welding inverters for home and garden.
Inverter Welding Basics
First, let’s look at the design of the welding inverter. We will not consider the “stuffing”, we will examine what is on top and what we will have to use.
This device is a small metal box, which, depending on the power, weighs from 3 kg to 6-7 kg. The case is usually metal, some manufacturers make ventilation holes in it – for better cooling of the “stuffing” (mostly the transformer). There is a belt for carrying, sometimes there is also a handle: the belt is put on the shoulder if the work requires movement.
On one of the panels there is a key or a power switch. In the front part there are power and overheating indicators. There are also knobs for setting voltage and welding current. Also on the front panel there are two outputs – “+” and “-” to which working cables are connected. One cable ends with a clip-pin, which is attached to the part, the second – with an electrode holder. The connector for connecting the power cable is usually located at the back. That’s actually all.
When buying an inverter, make sure that the cables are long enough and flexible enough to make it easier to work with. It is on insufficiently long and rigid working cables that users of the popular brand of Resanta inverter welding machines have the most complaints.
The general principles of working with an inverter welding machine are described in this video.
Inverter welding for beginners
As with any electric welding, the melting of the metal occurs due to the heat of the electric arc. It occurs between the welding electrode and the metal to be welded. To create an arc, they are connected to opposite poles: “+” is served on one, “-” on the second.
When connecting the electrode to the “minus” and the details to the “plus”, the connection is called “direct”. If a “plus” is applied to the electrode, the connection is reversed. Both options are used in welding, but only for metals of different thicknesses: reverse – for welding thin metals; straight – for welding thick metals (more than 3 mm thick). But this is not an immutable rule, sometimes they do the opposite.
What is the reason for this division in practice? The physics of the process. When an arc occurs, the electrodes move from minus to plus. At the same time, they also transfer their energy to a positively charged surface, increasing its temperature. Therefore, the element that is connected to the positive output heats up more. When welding metals of sufficient thickness, they must be well heated so that they fuse and the seam is of high quality. That’s why they are given “+”. Thin metal, on the contrary, can burn out from overheating and a “minus” is attached to it, heating the electrode more strongly, from which more molten metal enters the seam.
It is possible to weld metal correctly with an inverter only if the electrode is well controlled by you. To do this, you need to take the handle correctly. How to do this, see the video.
How a seam is formed during welding
To make the basics of inverter welding clearer, consider what happens when a seam is formed. To begin with, let’s clarify that a welding electrode for welding metals consists of a metal core and a coating – a special coating that closes the welding area from contact with oxygen contained in the air. Read more about electrodes for inverters here.
Now about the actual welding process. An electric arc is formed when the electrode core and metal come into contact (read below how to ignite the arc). At the same time, the coating starts to burn. It partially melts, turning into a liquid state, partially turns into gases. These gases surround the welding zone – the weld pool. They do not allow oxygen from the air to “break through” to the molten metal. That part of the coating, which has passed into a liquid state, covers the molten metal, creating a second layer of protection. After cooling, it turns into slag, which covers the seam with a crust. And at this stage, the slag protects the still hot metal from oxygen.
But slag and protection are far from the only process that takes place and needs to be controlled. When welding, it is necessary to ensure that the junction of two pieces of metal is heated evenly and sufficiently. Both parts should melt at the same distance from the edge. In order for the heating to be uniform, you need to keep the same distance from the tip of the electrode to the part. It is not very easy to do this: the electrode melts during welding, and the particles of its molten metal are transferred by the arc into the seam. Therefore, the electrode holder has to be gradually moved closer to the part. But this is not the end of the electrode welding technique. You also need to “write out” some shapes with its tip – zigzags, circles, Christmas trees, etc. They allow you to make the seam wider and fuse the two parts together. The most common electrode movements are shown in the photo below.
That is, you need to move the electrode from side to side by the width of the seam along one of these trajectories, while monitoring the state of the weld pool, and lower it as the electrode burns out, maintaining the distance to the part constant. This is such a difficult task for those who want to learn how to weld metal. It is easier with a welding inverter – the arc is constant and does not jump, but at first you may not succeed.
This very slow motion video shows the transfer of metal particles from the electrode to the weld pool and how it is formed.
How to learn to weld metal with an inverter
Begin training with the ignition of the arc. To do this, in addition to the apparatus, metal (5-6 mm thick) and an electrode, you will also need a mask and leggings (tight leather gloves) of a welder, as well as thick clothes and boots made of thick leather – to protect against sparks and scale.
Begin work by connecting the welding cables. Then the selected electrode is inserted into the holder (for starters, take MP 3 with a diameter of 3 mm – they ignite easily and cook well). After turning on the power, set the welding current (see table). For an electrode with a diameter of 3 mm, a current of 90-120 A is set. The current during the welding process can be adjusted. If you see that it is not a roller, but just some incoherent stripes, increase it. If, on the contrary, the metal is very liquid and it is difficult to move the weld pool, reduce it. The settings are very dependent on the device and the selected electrode. So try and change. Having set the current, they put on a welder’s mask (it will be easier for beginners to work in a chameleon mask), you can work.
Inverter welding for beginners begins with learning how to strike an arc. There are two methods: hit the part with the tip of the electrode several times or strike it like a match. Both methods work. Whichever is more convenient for you, use it. But for the future, keep in mind that you need to strike along the seam line – so that there are no marks on the product. In order to strike the arc steadily, you will have to practice for a while and burn several electrodes.
When the arc is already ignited without problems, you can move on – master the movements. They do this by laying rollers on thick metal. On a metal plate, draw a line with chalk that will replace your seam. Then you light the arc. In the place where it rested, the metal melts and is covered with a film of liquid slag. This place is called the weld pool. Here you will have to move it along the drawn line. Do this with one of the movements shown in the figure above.
In order for the bath to move, the electrode must be slightly tilted, approximately at an angle of 50-45 °. Some people have more angles, some less. In general, by tilting the electrode, you change the dimensions (width) of the weld pool. You can experiment: there are a lot of different techniques in welding and it is only important that the seam is of high quality, and how you achieve this is up to you, especially since you will work for yourself and for yourself.
There are two main working positions of the electrode: angled forward and angled back. When welding with a forward angle, we get less heat, the seam will be wider. This technique is used when welding thin metals.. Thick ones are welded, as a rule, with an angle back.
But the angle of inclination is not all the parameters that will have to be maintained. There is also the length of the arc. This is the distance from the tip of the electrode to the surface of the part. The average arc is 2-3 mm, the short one is 1 mm or even end-to-end, the long one is 5 mm or more until it breaks off. Practice begins with work on the average length of the arc. Hold up to the metal 2-3 mm. Then the seam will turn out smoother and better: if the gap is too large, the arc starts to jump, the heating of the metal is insufficient, the seam turns out to be smeared, the connection is unreliable. With a short arc, another problem arises – the seam is too convex due to the fact that the heating zone is too small. This is also not good, since undercuts remain – grooves along the seam on the part – reducing the strength of the connection.
Having practiced for some time on laying the rollers with different movements, after the rollers are the same width, the surfacing flakes are approximately the same size, you can try to weld the seams. You can read about the types of seams and joints, as well as their preparation here, or you can watch another lesson “Welding for Dummies”.
All the basics of inverter welding for beginners. All you have left is practice: you need to wear more than one electrode for training. Maybe not even one kilogram. When the hand itself performs all the movements, everything will seem quite simple to you.
To consolidate the acquired knowledge, first try to train your hand a little without an electrode, practicing the movements while holding a pencil in your hand. Also a good option, maybe it will seem more acceptable to you. In this video tutorial on welding with an inverter for beginners, everything is very sensible, simple and accessible. If there are any ambiguities, please review. Understand how to cook with inverter welding. A lot of useful information for beginner welders.
And finally, about some features of the operation of welding inverters. They are very afraid of dust, especially metal. Therefore, it is advisable not to use a grinder next to them and to carry out regular cleaning with a vacuum cleaner inside (after the warranty period has expired). They are not recommended to work in the rain or in wet areas. This is especially true of inexpensive household models. Although they have protection against electric shock, it is better to play it safe.
When choosing electrodes, pay attention to the area of uXNUMXbuXNUMXbits use: they must be suitable for direct current operation. When welding at the highest current or voltage, the operation mode is intermittent. It is indicated for each device in the passport.