What are the factors that affect the contact resistance of intermediate frequency spot welding machines?

If there are oxides or dirt on the surface of the workpiece and electrode of the intermediate frequency spot welding machine, it will directly affect the contact resistance. Contact resistance is also affected by electrode pressure, welding current, current density, welding time, electrode shape, and material properties. Let’s take a closer look below.

The influence of electrode pressure on the strength of solder joints always decreases with the increase of electrode pressure. While increasing electrode pressure, increasing welding current or extending welding time can compensate for the decrease in resistance and maintain the strength of the solder joint unchanged.

The main causes of current changes caused by the influence of welding current are voltage fluctuations in the power grid and impedance changes in the secondary circuit of AC welding machines. Impedance variation is due to changes in the geometric shape of the circuit or the introduction of different amounts of magnetic metals in the secondary circuit.

The current density and welding heat are significantly affected by the current flow through the already welded solder joints, as well as increasing the electrode contact area or the size of the solder joints during convex welding, which can reduce the current density and welding heat.

The influence of welding time can be achieved by using high current and short time, as well as low current and long time, in order to obtain a certain strength of the solder joint. The influence of electrode shape and material properties will increase with the deformation and wear of electrode ends, resulting in an increase in contact area and a decrease in solder joint strength.