Spot welding

Spot welding

Spot welding is the method by which a spot can be melted and welded in a material in a very short period of time. This will not affect the other portion of the material. So it requires concentrated energy to a spot that it is welded.

The material is placed together under pressure exerted by electrodes. The sheets are about 0.5 to 3.0 mm. in thickness. Copper alloy electrodes are used to weld two sheets together in a spot. The heat that is obtained is determined by the resistance to the electrodes and the amplitude and duration of the current. If too much or too little energy is used you will not get the desired result.

There are three steps in spot welding. 

In the first step the electrodes and brought to the surface of the metal and a little pressure is applied to it. The second step is when the current from the electrodes is applied for a brief period of time. The third step is when the current is removed and the electrodes are left in place so that the material can cool. According to the material and its thickness, the electrode force, and the diameter of the electrodes, the weld time ranges from 0.01 seconds to 0.63 seconds.

The electrodes come in different shapes and sizes according to different requirements and are generally made of copper or other low resistance alloys.

The two materials that are welded in spot welding are known as workpieces. They must conduct electricity. When the current is removed from the workpiece, the coolant holes in the center of the electrodes cool it. Water or brine solution is generally used as a coolant. Spot welding is used for many different types of applications. It is used in different types of metal sheets. You can see it in buckets.

It is greatly used in the automobile industry. Here the sheet metal is welded to make a car. The work can be completely automated by using robots. It is also used by orthodontists.

It is used to make batteries - nickel-cadmium and nickel metal hydride. The battery cells are joined by spot welding. Thin nickel straps are joined battery terminals.

Care should be taken to see that the surfaces that have to be welded are free of oil and dust.
Be sure to clamp the electrodes tightly.

Resistance spot welding step by step Procedure:

1

The weld sheet metal is cleaned simultaneously and is free of dirt, oxide, grease, and oxide.

2

The electrode tip will be cleaned should this current flow; Otherwise, electrical resistance arises between the work piece and the electrode.

3

On either side of the plate, the electrodes are stick.

4

When pressure is created on the electrode and a particular time period is maintained, the sequence of time before the weld starts is known as.

5

In order to maintain weld time during the process and to weld the current range of 3000 A to 100000 A, it passed the electrode in a time of

6

The transformer bottom phase controls the magnitude of the high possible current.

7

The current is passed from one electrode to another electrode through the workpiece, a small area contact between the work pieces.

8

After the weld time is complete, the current is shut down and the pressure will be maintained.

9

A particular brief time of time is called hold time.

a

So the heated metal freezes and takes the form of a weld.

b

After a short period of time, the pressure is released, then the workpiece is removed.

c

Now water is supplied to the electrode due to the excess heat escaping the electrode.

d

In this welding process, determine the proper welding current and time before welding

If you plan and have all the necessary material ready for spot welding and take the necessary precautions before, during, and after welding is done, you will be able to do it without difficulty.