Technique for welding thin metal with an electrode: equipment features

Both professionals and beginners often have questions about how to properly weld thin metal with an electrode. The whole problem is that welding sheet metal causes some difficulties due to its thickness (0.1-0.3 mm), due to which deformation may occur during operation. Let's consider the basic requirements of the operating rules and technology of welding on sheet steel and the selection of the thinnest electrodes for the job.

Features of welding thin metal with an electrode

Welding sheet metal using a conductor, although a popular process, is quite complex and requires a special approach. The thing is that one awkward movement of the conductor and the metal can be damaged, that is, burned through, since it is less than 0.4 millimeters thick. At the same time, an insufficiently tight fit of the electrode can lead to poor-quality connection of the material being welded.

Welding thin metal with an electrode is carried out at low current, so it is necessary to strictly maintain the distance between the product and the conductor so as not to lose the arc. In a word, you need to study and train for a long time on how to weld thin metal in order to fully experience the whole process and learn how to hold the arc.

One of the features is special preparation for thin metal, for better adhesion. That is, the parts must be cleaned as efficiently as possible from oil, paint, dirt and dust for better bonding. It should be borne in mind that not all types of seams and not every technology are suitable for welding steel sheets.

Formation of a standard welding seam using an inverter

It is necessary to connect parts during welding so as not to change the speed of movement of the electrode, otherwise it will not be possible to form an even seam. The liquid state of the weld is much lower than the main part of the metal.

The resulting arc is capable of capturing the entire base metal, moving the entire pool to its original place, forming a welding seam. The welder's job is to position the weld in a straight line with the metal. By creating zigzags and describing arcs with your hands, you can easily create an even seam.

The entire welding process depends on the quality of the electrode.

In such cases, it is necessary to constantly keep in mind the dimensions of the location of the weld. It is worth trying and positioning the bath strictly in a circle. A uniform rocking motion creates a seam, but you must watch for it to form at one edge of the metal plate and then control its formation at the top of the tub.

By directing the electrode closer to the metal workpiece, a raised seam is formed. Most welders achieve a flat weld and movement of the pool by significantly changing the angle of the electrode. The best option: control the angle of inclination within 45-90° to form an ideal seam and control the bathtub.

Requirements and technology for welding sheet metal

Welding thin sheet metal has a number of requirements that are recommended to be met to obtain a high-quality result:

• electrodes for welding thin metal should be selected in accordance with the thickness of the work product. If the thickness of the part is no more than 3 mm, a conductor should be used with a diameter of 3-4 millimeters. To do this, you need the thinnest welding electrode;
• in order to avoid deformation of parts, it is necessary to select the appropriate current strength for welding steel sheets of small diameter;
• Welding of thin-sheet steel should be done with electrodes with a special coating, which will melt slowly and make it easy to initiate and hold an arc, without spattering drops of metal.

Particular attention must be paid to the choice of electrode. To weld sheet metal, you need to choose special conductors that provide slow melting and allow you to better hold the arc. Both alternating and direct current can be used for operation. It is best to choose universal electrodes for welding thin metal with an inverter. Experts recommend giving preference to “C”.

Regarding the technology of work, it is better to weld thin products overlapping, this way there is less chance of burning through the metal.

If it is necessary to butt weld sheet metal, then before processing it must be fixed in such a way that they do not move during work. When heated and cooled, metal tends to expand and contract. In this regard, difficulties may arise, especially for a novice welder.

Tools and materials

In the case of gas welding, the most justified solution would be to choose acetylene technology. In this case, the only additional components you will need are wire and flux. To influence the intensity of the fire, a special reducer is used. Gas welders use:

• special welding tables;
• cylinders with gas obtained at the plant and/or gas generators;
• hoses for supplying gaseous components;
• accessories for assembling welded products;
• other tools that they deem necessary for themselves.

For manual arc welding, the following is required:

• apparatus;
• electrodes;
• power wires;
• special transformers;
• protective masks, gloves and shields;
• slag hammer;
• magnetic square;
• trolleys for devices;
• standardized samples for ultrasonic flaw detection;
• welding compounds;
• collet holders.

Basic methods of joining thin sheet metal

Welding of sheet metal can be carried out using both manual arc welding and semi-automatic welding. Both of these methods are widely used for joining small parts whose metal thickness is no more than 3 millimeters.

Experts recommend semi-automatic welding of thin metal, since the equipment copes with this task better when operating at low current. In this way, deformation of the product can be avoided.

Welding of steel sheets can be carried out in several ways:

• intermittent method or spot method, in which you can weld thin metal with an inverter without risk. Dots are simply placed on the product and thus the two parts are fastened. This method requires some skill, since the master must move the conductor very quickly before the metal has time to cool.
• continuous welding of sheet metal throughout the entire seam. For this method, it is better to set the welding machine to a low current, no more than 60A. In addition, you need to choose a certain speed for moving the electrode, since with fast movement the product will not have time to fuse, and with slow movement, holes may form in it.

There are two main methods for welding sheet metal:

1. Working with consumable electrodes. For this, it is better to use conductors with a diameter of no more than 2 millimeters. The optimal size is considered to be 1.6 mm. The main task of the master is to control the prevention of overcooking, so as not to burn the part. The conductor must be guided at a moderate speed so that the alloy turns out to be of high quality, and at the same time a hole does not form in the metal. At the moment of adhesion of materials, it is necessary to ensure complete penetration of the steel edges, but not to burn through it. Here, welding thin-sheet steel involves instantaneous melting of the edges and the inability to maintain full control over the creation of the weld pool. That is, with this method, it is important to carefully guide the electrode so as not to burn through the material. To do this you need to train for a long time.
2. Welding thin metal with an inverter using a non-melting electrode. This method, in turn, is also divided into two types:

• method of melting and joining the edges of parts;
• method using filler wire.

This method involves connecting parts without adding additional material. That is, the electrode does not melt, but only melts the edges of the parts and connects them together. This technique makes it possible to work with the thinnest steel sheets.

Preparatory work

When performing welding work, you may need the following tools and materials:

• welding machine;
• electrodes;
• metal scissors;
• fasteners;
• sandpaper;
• degreaser.

Before welding metal, you need to properly prepare it for this work.

In this case, it is very important to thoroughly clean the site of the future connection from various contaminants: rust, paint, grease, anti-corrosion coating, etc. The presence of these contaminants will lead to a poor quality weld.

This is because:

• contaminants do not conduct electricity well;
• some substances emit gases when exposed to heat, which leads to splashing of liquid metal in all directions;
• the gases released make the seam porous;
• Heavy smoke may occur during work.

After the metal is cleaned, you can proceed to securing the surfaces to be welded next to each other. For this purpose, various clamps, clamps, clamps, levers, clamping angles, temporary fastenings with self-tapping screws, bolts, etc. are used.

Features of working with galvanized steel

Galvanized steel is a thin metal that is coated with zinc. When working with it, you need to take several features into account. First, the parts must be carefully prepared, clearing the coating down to clean steel. If this is not done, then the connection will not work. Since zinc has a completely different melting point compared to steel.

The galvanized layer can be removed with a wire brush or sandpaper. Some people use an abrasive wheel for this. All work with zinc is prohibited from being carried out indoors, since its evaporation is very harmful to the body.

When the material is fully cleaned to pure steel, the process of joining the parts can begin. When working with galvanized pipes, to obtain a high-quality and reliable seam, two passes with different electrodes will be needed. The first seam is welded with rutile-coated electrodes, for example, MR-3, ANO-4, OZS-4. In this case, movements must be made smooth and small. The top facing seam should be made wider. Its width is approximately equal to three conductor diameters. Here it is important not to rush and cook well. For this purpose, electrodes with a basic coating are used (for example, UONI-13/55, UONI-13/45, DSK-50).

In conclusion, it is worth noting that welding sheet metal is a delicate and painstaking task, requiring the welder to have certain skills in the work. Thin metal can be welded semi-automatically or manually. The first method is a little easier, because manual welding with a thin electrode requires the fulfillment of a number of conditions in order for the seam to be strong and of high quality.

An important point is the type of soldering. Butt welding of sheet metal can only be carried out if the welder is a true professional and correctly calculates the current strength in order to make the connection correctly. Otherwise, it is necessary to choose overlapping soldering. This reduces the risk of through penetration of products. With the inverter method, it is important to set the current strength correctly. Then you will get an even and correct seam.

Rules for welding steel and zinc

Metal that is welded using zinc is coated with a thin layer of zinc alloy. When working with it, you need to first prepare the parts for processing.

This is the first and most important feature of the metal. If you do not clean the spray, the connection will be weak. Zinc has different temperatures at which it melts.

The zinc layer can be removed using sandpaper. Some craftsmen use a wheel for grinding. If you work with this metal, it is prohibited to be indoors.

Upon receipt of clean material, craftsmen begin to weld the structure. Zinc requires careful treatment. This way you will get a reliable seam.

You need to make a couple of passes using different types of electrodes. The first compound is obtained using oxide deposition. Models MP 3, OZS 4, AHO 4 are suitable for this.

Your actions should be slow. The facial connection is made wide. Its dimensions correspond to the three sizes of the mediator.

Welding technique

Welding thin-sheet iron requires proper approach of the edges of the plates to each other. Butt joints often result in burn-throughs and are only suitable for experienced welders. If possible, it is worth placing the plates overlapping. This will create some basis for the deposited metal, and will not allow burning through the entire product. In this case, the electrode is directed primarily to the bottom plate, since a different position will lead to undercuts on the top side.

When joining into a butt, the edges are not cut. There is no need for a gap either. It is necessary to bring the ends of the parts together as tightly as possible and tack. Low current strength and thin electrodes make the work much easier. You can then cook it in several ways:

• Set the current to low and quickly sew the seam without oscillating movements, strictly along the connection line.
• Raise the current a little higher, but conduct the seam with an intermittent arc, giving the metal time to cool before the next “portion” of the additive.
• Cook using the methods described above, but using a special substrate to maintain a heated area and avoid sagging. A metal table will not work here, since the product may be partially welded to it. A good alternative would be a graphite backing.
• To prevent severe deformation, apply stitches in a checkerboard pattern, or in small sections (100 mm each). With the latter method, it is necessary to finish the next seam at the beginning of the previous one. This will allow the product to be heated evenly along its entire length and minimize deformation.

Welding is carried out with a short arc, which allows you to quickly form a seam and avoid overheating of the area. Increasing the distance between the end of the electrode and the surface visually prevents burning of the plates, but does not contribute to the formation of a welding bead. The electrode is held towards itself at an angle of 45 degrees, or tilted to the side. Right angles should be avoided as this leads to burns.

Alternative Methods

A reliable alternative to an inverter is the use of semi-automatic devices for connecting thin metal elements . The use of wire allows you to increase productivity due to the absence of pauses for replacing electrodes. The range of consumables allows you to choose the ideal option for a particular case.

The disadvantage of a semi-automatic machine is the increased requirements for the qualifications of the worker - a novice welder is not able to master all the skills of working with this equipment in a short period of time.

Problems of thin-walled products

The technology of welding thin metal with coated electrodes requires attention to detail and precision in work from the performer .
Beginners should not start joining thin-sheet products without sufficient experience in welding elements of medium thickness. Training centers produce specialized literature that can facilitate this task. Difficulties in work are caused by the following reasons:

1. Danger of burns . This is the most common mistake made by novice welders who cannot select the optimal operating parameters and speed of the electrode.
2. Poor welding of the seam . Another problem for inexperienced specialists, the reason for which follows from the first. Trying to avoid burns, the operator chooses the electric arc speed too high. This leads to the fact that the melt zone does not have time to warm up properly. As a result, the connection does not have the necessary strength and tightness.
3. Swells . They appear on the reverse side of the connection. It is noteworthy that on the outside of the seam there may be no visual defects, while on the opposite part of the product numerous protrusions may form, which are caused by subsidence of the molten metal under the influence of gravity.
4. Surface deformation. The metal has high thermal conductivity. The thin-sheet surface heats up very quickly, and overheating is fraught with a change in the structure at the molecular level: around the contact zone, the metal expands under the influence of temperature, while in other areas the surface is cold. As a result, the surface of the workpiece is deformed.

When doing work at home, it is possible to straighten the surface with hammers with a rubber striking part. Otherwise, welding is not performed in a continuous strip, but alternating in a certain sequence of places where the seam is applied.