How to learn to cook: tips from a professional welder

Recommendation points

• Preparation for welding
• What needs to be completed
• How to prepare parts
• What current to set
• With what polarity to connect the electrode holder and ground
• Working with a welding arc

This is a small workshop on manual arc welding. In the article, we tried to pay attention to the most common problems and questions faced by a novice welder..

Thinking about purchasing a welding machine “for a house, for a summer residence”, many inhabitants refuse this venture, since they doubt that they will be able to independently master the wisdom of electric arc welding. Everyone knows that highly qualified welders are creators, a separate caste of artisans. Meanwhile, the reality is that the domestic construction application of welding in the overwhelming majority of cases does not require a special weld quality, and welded joints, in fact, simply replace collapsible bolt / screw assemblies. At the same time, of course, a novice master should not undertake welding, for example, a water pipe or a loaded floor truss, because the consequences can be very unpleasant.

The best way to learn how to cook is to enroll in the appropriate courses. It is also useful to just work with an experienced master for a while in order to visually, in real time, observe his actions, torment him with questions and adopt basic techniques. But even this is not necessary, basic theoretical training may be enough to go out and start learning on your own. Especially if, when choosing a welding power source, you preferred inverters, which at the moment are the most practical and forgive a beginner a lot. We have already discussed the selection of welding equipment in the article “How to choose a welding inverter. Professional advice ”. Next, we will talk about the most common type of welding – manual electric arc (MMA), designed to connect parts made of carbon structural steel using piece coated electrodes.

Preparation for welding

What needs to be completed

Equipment

Welding is a rather harmful process for humans, so the craftsman must take care of his protection. You need to start with clothes. On sale are fire-resistant suits of the welder, as well as various capes, aprons, etc. Hands are protected separately; for these purposes, special leggings, mittens or gloves are required. Don’t forget about shoes, which must be tall to be covered with trousers and heat resistant to withstand hot sparks. The most important thing is eye protection. For this, so-called light filters have been developed, which, being installed on a mask, are able to protect the eyes from harmful radiation, but allow you to clearly see the weld pool. They are numbered and separated by shading. The shading of the filters is selected according to the working conditions (arc intensity). Many masters are very fond of masks with light filters of the “chameleon” type. Some of the equipment, usually a mask or gloves, may be included by the device manufacturers, but these devices are not always of normal quality..

High voltage wires

In addition to the welding machine itself (welding current source), it is necessary to have wires to transfer power to the electrode holder and the earth clamp (ground terminal). These are special copper conductors of large cross-section, designed for a certain current strength – the greater the current, the larger the wires, and the higher the current they are designed for. In domestic conditions, where relatively low-power inverters are used, conductors designed for currents up to 200 A, 2.5-4 meters long, are quite suitable. These wires are usually included, but sometimes you need to buy them separately.

Carrying

To connect the inverter to the network (in addition to a reliable grounded 25 A socket, powered by a high-quality machine), you almost always need a carrier. The cross-section of each of its conductors should not be less than 2.5 mm². Its length can be up to fifty meters, but the shorter it is, the more accurate the current will be at the output. In any case, the extension cord must be completely unwound from the reel to prevent overheating..

Auxiliary tool

When welding, angle grinder (“grinder”) always comes in handy, better and “big” and “small”. As accessories, you should stock up on both cutting and grinding abrasive discs. A metal brush is needed to clean the parts. A hammer is required to remove the slag. In order to reliably fix the parts to be welded together, it is very convenient to use metal clamps; due to temperature hazards, plastic clamps will not work. Let’s immediately mention the scaffolds, which outright beat any stepladder. They are needed in order to fully control the welding process in place and will serve as a workplace if you weld parts “on the table”.

Electrodes

The classification of electrodes for MMA welding is very extensive. We can solve most of the problems with the help of such popular brands as ANO, OZS, MP, which are well suited for DC welding of an inverter. As for the diameter of the rod, then our size is “two” and somewhat less often – “three”. One golden rule should be understood: the diameter of the electrode is selected according to the thickness of the metal of the parts to be welded, and the welding current is selected from the diameter of the electrode. This is the main, basic criterion, although the chemical composition of the metal, the shape of the edges, the type of connection of parts, the position of the weld in space are also taken into account..

Roughly, for metal with a thickness of 1.5 to 3 mm, you need to take an electrode with a diameter of 2–2.5 mm. With a triple, metal is boiled up to 5 mm in thickness – and this will be our limit, more massive parts will not be subject to us, since the electrode simply does not warm up the metal of the parts. The intra-house network will not pull electrodes of 4 mm (the current is close to 200 A, and the load approaches 5 kW – the machine will turn off), and its capabilities are rarely needed. About what amperage to set, read below.

How to prepare parts

Seam processing

The joint area of ​​the two parts, where the weld will form, should be cleaned of dirt and moisture, and rust should be removed from the edges with a metal brush, the remnants of paint and varnish compositions (the metal is cleaned a couple of centimeters from the joint until it shines). If the thickness of the parts exceeds 3 mm, then it is recommended to remove the chamfer from the edges, which allows you to achieve good welding of the metal array.

Orientation of parts

It is easiest to carry out manual arc welding if the weld bead is on a horizontal surface (welding “in the down position”). With this method, it is most convenient to control the weld pool. Gravity acts on the melt from top to bottom without moving it, it helps the filler metal of the electrode to transfer into the weld created by the user. That is why, if possible, it is better for a beginner to cook on the table, and only then assemble the enlarged parts “on the spot”.

The vertical position is more difficult, but it is common, with this method of orientation, you have to cook either vertically or horizontally on a vertical plane. In the first case, the seam is most often led from the bottom up, but for thin metal it is better to move from top to bottom – this way it warms up less and there is less danger of burning. And the peculiarity of the second type of welding (horizontally on a vertical surface) is that the weld pool is “pulled” perpendicular to the force of gravity, therefore, so that the metal does not flow out, the amount of melt (the size of the weld pool) should be minimal, the arc is kept as short as possible.

Ceiling welding, for obvious reasons, is the most difficult and low-productivity, it is better for a non-professional not to take on it.

It should also be noted that when welding, parts can be positioned relative to each other in various ways. From this, several types of welding are distinguished: butt, overlap, corner, tee. Butt welding is performed with an “almost straight” electrode, in the other three types the electrode will be tilted, since you need to weld two parts located in mutually perpendicular planes. There is a problem: for example, if the corner joint of the parts is placed on the table in the usual way, then in the section we see the letter L, that is, the lower edge will fall more into the zone of the weld pool due to gravity. That is why it makes sense to arrange the parts “in a boat” (section in the form of V), then both edges will weld well.

What current to set

We have already said that the welding current is selected depending on the thickness of the electrode. First you need to keep in mind that only the lower current limit is technically limited. For example, using a two to get a good seam, you need to put the current switch on 70-80 or more amperes (the higher, the sooner the electrode will burn out). For a three, a current from 100 to 140 A is suitable, a four – 160 A. First, try a current slightly higher than the minimum, and, if necessary, raise its value. There is a good way to know if you have chosen the right power mode: the sound of welding should resemble a crackle, and not a gurgle or hum..

With what polarity to connect the electrode holder and ground

The inverter operates on direct current, therefore it allows you to connect high-voltage wires in two positions, a “plus” or “minus” can be applied to the electrode or ground. If the electrode has a plus (reverse polarity), then it heats up more, and if there is a minus (direct polarity), then the part. Reverse polarity is used more often and is typical for traditional welding. Straight polarity is used to weld sheet metal at a high rate with special electrodes.

Working with a welding arc

After completing all the preparatory work, you can start training. Make yourself as comfortable as possible, sit down better, lean on the table, hold the electrode clamp with both hands. Next, we will consider the basic movements and techniques at the simplest one – welding in the lower position, butt-weld parts, electrode two, sheet metal (or plates), straight edges without chamfers, straight single-layer seam. Items will go roughly in the order of work, but some actions are carried out simultaneously. Each item does not necessarily represent an action, it is an important point to pay attention to.

1. Ignition. For the arc to appear (ignite), you should perform a striking motion with the electrode along the part, as if with a match. You need to scratch in the direction of the seam so that the workpiece is not damaged. The electrode itself must be slightly tilted relative to the vertical (about 30 degrees).

2. Control of an arc, formation of a weld pool. As soon as the arc has flared up, we bring it to the beginning of the seam and wait for the metal to melt. First, a red spot appears under the electrode within 2–3 seconds, this is the flux burning. Then you can observe the appearance of a yellow-orange spot, on which you can see ripples – this is the metal melted.

3. The position of the electrode when forming the weld pool. The electrode is positioned almost vertically, slightly tilted towards the direction of the seam (25–40 degrees). A distance of about 3 millimeters must be maintained between the electrode and the parts, usually for this they touch the metal of the workpieces to be welded.

4. Seam formation, weld pool control. So, a sign of the appearance of a weld pool is the appearance of an orange spot with a trembling surface. From the beginning of the ignition of the arc, the bath (molten metal) appears in 2-3 seconds, and we have to move the electrode one or two millimeters in the direction of our seam. Then again we wait for the appearance of the orange spot, now it will take less than a second. So gradually, millimeter by millimeter, and we move.

5. Position, type of movement of the electrode when forming a seam.

First, you must always keep the correct slope. If the electrode is tilted too much, the arc will push the weld pool back with its flow, making the seam high, making it difficult to heat the metal. A more vertical electrode presses with an arc on the bath, spreading it out. Thus, the tilt of the electrode can be used to manipulate the seam height, the seam is considered more correct, which is flush in height with the surfaces to be welded. However, it should be noted that with a significantly tilted electrode, it is easier to visually monitor the state of the weld pool..

Second, do not forget to maintain the arc gap. The fact is that the electrode is consumed, and it must be constantly lowered, as they say: “dip” into the weld pool. If the electrode is not brought as close as possible, then there will be no metal to form a weld, and a large gap will make the arc unstable. Too frank contact of the electrode with parts will cause a short circuit, and protection will work on the inverter. Take the height as a reference when, when the electrode is tilted, you touch the parts only with the electrode coating.

Third, it is better for a beginner to choose a straight-line type of movement of the electrode, in extreme cases – with small circular (around the bath) and at the same time translational movements. We form the so-called “scales”, which overlap each other by about half. The best seam is with fine scaly. By the way, you will learn all kinds of zigzags and eights later, they are needed to work with thick metal.

Fourth, the speed of movement. Failure to observe this parameter often results in the main welding defects – lack of penetration or burns. It is impossible to give numerical solutions. Monitor the condition (color) of the area under the electrode, move smoothly, do not overexpose. Stop and view the finished seam pieces. The thinner the electrode, the less it heats up the metal, and the slower it is driven. Obviously, in borderline situations (when the parts can be welded with both three and two), it is better for a beginner to use a thinner electrode and lead it slower. As you improve your skills, increase the current and use a thicker electrode.

6. Control of the weld pool is carried out visually. Look at the tub and the seam behind, not the arc itself. Examine your seam so that it is of the same thickness and width (the optimal width is from 0.8 to 1.5 of the electrode diameter) with a minimum of defects (GOST 30242-97). In domestic conditions, many welding defects are eliminated without problems by additional welding, but only after the seam has cooled down and cleaned of slag. For a beginner, it is probably best to work with a substantially tilted electrode to better see the weld pool. Note that at first you should not try to weld the seam with one arc, stop and consider the geometry (section) of the resulting seam: scale / tubercle – good; ball on a leg – low current; burn-through and craters – high amperage, slow electrode trajectory.

7. How to finish welding. At the end of the seam, do not remove the electrode immediately, but make a small circle in place, bringing in metal, otherwise a crater will remain at the point where the arc breaks off. Tear off the electrode by light striking. After welding, the slag, when it has cooled down and turned black, is removed from the seam with a hammer and a stiff brush. With correct welding, it bounces off in large flakes, and there are no slag inclusions in the weld metal.

This article, of course, cannot claim to be a comprehensive guide, but we tried to answer some frequently asked questions from novice welders. I would also like to say that before starting training, carefully read the recommendations of the manufacturer of your welding machine and electrodes, as well as carefully study the safety rules for welding. And you will succeed.