What are the reasons for the electrode sticking during the welding process

1. The working surfaces of the two electrodes are not parallel.

When the working surfaces of the two electrodes are not parallel, it will cause the electrode working surfaces to partially contact the part, resulting in an increase in the contact resistance between the electrode and the part, and a decrease in the current of the welding circuit. 

When the current is concentrated at the local contact point and the current density at the contact point is greater than the current density of the electrode working surface during normal welding, the temperature of the contact point rises to the welding temperature between the electrode and the part, resulting in the fusion of the electrode and the part. 

2. Roughness of the electrode working surface

The electrode working surface does not fit perfectly with the part. Only some protruding parts come into contact with the part. This situation will also cause the two electrode working surfaces to be not parallel, resulting in the sticking of the electrodes. 

3. Insufficient electrode pressure

The contact resistance is inversely proportional to the pressure. Insufficient electrode pressure leads to an increase in the contact resistance between the electrode and the part, resulting in an increase in the resistance heat at the contact area, causing the temperature at the contact surface between the electrode and the part to rise to the soldering temperature, thereby forming a fusion connection between the electrode and the part. 

4. The water pipe connected to the cooling outlet of the welding gun is reversed or the cooling water circulation is blocked.

If the water pipe connected to the cooling outlet of the welding gun is reversed or the cooling water circulation is blocked, the electrode temperature will rise, which may cause the electrode to fuse and connect with the part during continuous spot welding. 

All of the above four situations are likely to cause the electrode to fuse and connect with the part, resulting in the phenomenon of electrode sticking. So, how can we prevent the occurrence of this electrode sticking phenomenon? 

(1) Polish the electrode tips to ensure that the working surfaces of the two electrodes are parallel and there are no rough defects on the surfaces. The welding procedure can be selected as the polishing procedure (without current output), and the parallelism of the two electrode working surfaces can be observed by using an air welding gun.

(2) In the polishing state, perform 5 to 10 welding passes with the air welding gun, and press the working surfaces of the two electrodes to increase the contact area within the specified electrode head diameter range and improve the surface hardness.

(3) Heat the working surfaces of the electrodes with an oxygen-acetylene flame to form an oxide layer (oxidation zone) on the electrode working surfaces. This can increase the melting point of the electrode working surfaces and destroy the welding properties between the electrode and the part.

(4) Apply the red lead prepared by the welder to the electrode working surfaces to disrupt the welding properties between the electrode and the part.

(5) Adjust the electrode pressure and use welding parameters with high pressure, large power supply, and short power-on time.

(6) Regularly clean the cooling water pipes to ensure the flow rate of the cooling water. 

All of the above are measures that can solve the problem of electrode sticking that occurs during the welding process.