Spot Welding: Acquisition

Spot welding is the process of welding parts that are joined in one or at several points. It is indispensable when connecting parts that are small in size. The strength properties of such welding are determined by the size and structure of the welded point.

These parameters depend on many factors. From the contact surface of the electrodes, the current strength, the period of its passage through the parts, the compressive stresses, and also the quality of the surfaces of the welded discs.

Spot welding allows for about a minute to make about 600 solder.

It is indispensable when combining very thin parts of electronic devices, sheet steel in the automotive industry, aircraft construction, shipbuilding and other areas of industrial production.

Spot welding is a modified contact welding. Proceeding from this, the thermal effect of the current, according to the Joule-Lenz law, and the compressive stress of the connected parts are placed in the core of its technology.

When welding parts, the electric current passes through them, and at the contact points of the part-detail, maximum heating occurs. This is due to the maximum level of electrical resistance.

Under the influence of electric current the metal heats up and melts, and this serves as the source of the formation of the base of the welded point. The diameter of this point can be in the range from 4 to 12 mm.

Spot welding has two modes - soft and hard.

With a soft mode, the workpieces are heated gradually with a small current. This welding mode is time-consuming. Its main advantage is low power consumption, when compared with more severe modes. Small network loads. They are insignificant in power, which means that the welding machines used are cheaper.

Soft mode is used for welding steel, prone to subsequent heat treatment.

In the hard mode, the welding time is minimal, however, such values as the current strength and the compressive pressure of the electrodes are much larger than when the docking mode is soft.

The hard mode is used for welding copper and aluminum compounds, as well as steel with a high percentage of alloying to maintain corrosion resistance.

The best option for a home craftsman is homemade spot welding. It can be made from improvised materials.

From an old electrical appliance remove the Sh-shaped transformer. We release it from the bracket and divide the transformer into two parts. The primary winding is done at 220 V.

When it is wound, it is bandaged with a cloth of their cotton. Then cover with KS-521 varnish.

Then a secondary winding is made. Its parameters are determined in each case individually. It is made mainly of copper wire.

On the winding ends put on the tips for their protection. That's ready spot welding. Equipment for it must be done, taking into account the requirements of technical progress.

Electrodes for spot welding, as a rule, are made of copper, and sometimes of bronze or from substitutes for these metals.