A metal is considered thin if its thickness is no more than 5 mm. Today, such material is widely used in various fields, so sooner or later everyone who has a summer cottage faces its welding. Sheet metal welding has some features that both a professional welder and a novice should know. Therefore, further will be considered how to weld thin metal with their own hands.
Any careless movement when welding thin sheet metal can lead to burning of the material being processed.
Difficulties in welding thin sheet metal
The main problem with the connection of thin metal by electric welding is that any careless movement of the welding machine can lead to burning of the material being processed, that is, there may be an unplanned through hole in it. On the other hand, excessive caution can lead to insufficient strength of the connection and the occurrence of lack of penetration.
Another difficulty is that the welding process is performed at low currents, and if even a little increase the distance from the electrode to the metal, then the arc immediately ends. Therefore, to carry out such work it is necessary to have certain skills and abilities that will allow the welder to choose the working current, the feed rate of the electrodes and the length of the arc.
The scheme of welding thin metal using inverter welding.
It should be noted that when connecting a thin metal, not all welding methods are equally well suited - there are certain connections that are used most often, and those that are recommended to be used only in extreme cases. At the same time, the thickness of the material being welded and the spatial location of the seam are of great importance. In a word, there are a lot of difficulties that may arise during welding. The main thing is to be able to analyze all the moments and overcome any difficulties with the least amount of time and effort.Back to table of contents
Requirements for welding sheet metal
Of great importance when performing such welding work is the thickness of the electrode used and the value of the operating current. These 2 parameters are directly dependent on the thickness of the metal. For the initial choice of the electrode thickness and operating current, you can use the table below.
|The thickness of the workpiece, mm||2||3||4-5||6-8||9-10|
|Electrode section, mm||2||3||3-4||four||4-5|
|Operating current, A||50-60||110-120||110-160||140-160||140-300|
If necessary, make a ceiling or vertical joint, it is recommended to use electrodes with a cross section of not more than 4 mm. If there is a cutting edge or you need to close the gap between the parts, the root seam can be created with a welded wire with a diameter of 2-3 mm.
When working with thin metal, it is equally important to choose the type of electrodes used. For welding with a small current, it is necessary to use electrodes with such a coating that allows for easy excitation of the arc and its durability.. Also, such electrodes should melt slowly, giving a flowing metal.Back to table of contents
Thin sheet metal welding methods
One of the two methods of welding thin sheet material is continuous welding of the entire weld, in which the electrode is conducted along the entire weld without separation from the metal.
Small thickness metal can be welded by manual arc welding or semi-automatic. For beginners it is better to use a semi-automatic device, since it is much easier to work with them. But not every household has such equipment, so metal joints are usually made by manual arc welding.
There are 2 ways to weld thin metal:
- continuous welding of the entire weld;
- spot welding.
In the first case, the electrode is conducted throughout the seam without separation from the metal. This method is usually used when you need to create ceiling joints. It is very important to carefully monitor that the root of the seam is well boiled, but the metal itself is not burned. If you drive the electrode too quickly, the root of the seam will not evaporate, and the seam itself will be placed over the joint. If, however, to lead slowly, then there is a high probability of burning the workpiece.
The second method involves extinguishing the arc during welding. This method is the most optimal solution when welding thin-sheet metal. In this case, the value of the operating current is set slightly more than usual, so that the root of the seam is well boiled.Back to table of contents
When performing welding, you may need the following tools and materials:
- welding machine;
- scissors for metal;
- degreasing agent.
Before welding metal, it is necessary to properly prepare it for these works. It is very important to thoroughly clean the place of the future compound from various contaminants: rust, paint, grease, anti-corrosion coating, etc. The presence of these contaminants will result in a poor quality weld. This is because:
- impurities do not conduct electricity well;
- some substances emit gases upon thermal exposure, which leads to the splashing of the liquid metal in all directions;
- the emitted gases make the seam porous;
- during the work possible strong smoke.
After the metal is cleaned, you can proceed to fixing the welded surfaces next to each other. For this purpose, various clamps, clamps, clamps, levers, coupling angles, temporary fasteners on screws, bolts, etc. are used.Back to table of contents
Thin metal welding technology
Welding of sheet metal can be done overlap or end-to-end. Vertical seams are recommended to be carried out in the butt method, and horizontal ones - with overlap.
Weld overlap. First, the prepared sheets are adjusted on each other in such a way that throughout the seam the overlap width is at least 4-6 mm. With the help of fasteners it is necessary to ensure a tight fit of the top blank to the bottom. The gap between the sheets should not be, because otherwise during the welding work will burn the top sheet.
Then select the electrode with the most optimal cross section and set the required value of the operating current.
Before welding the workpiece itself, it is recommended to practice on an unnecessary piece of metal of similar thickness.
This will help to choose the operating current without damaging the product. After that, grab the sheets in several places. Sticking is carried out by small suture jumpers with a step of 5-10 cm. For this, electric welding is carried out with periodic arc extinction. The continuous arc time will depend on the operating current and the thickness of the workpiece. For example, for a sheet with a thickness of 1 mm, it should be no more than 3 s.
After sticking, it is possible to perform welding with a continuous weld, periodically moving the electrode to a new joint zone. This will avoid strong warping of the material. This is especially true if the connection length is large enough (more than 25 cm). Start cooking at one end, then go to the other end, and then move to the center.
Butt-welding In this case, it is necessary to achieve a minimum clearance between the welded blanks. To perform butt-welding, you need to use an auxiliary metal lining, which is installed under the junction. Further welding process is carried out in the same way as in the first case.