Why are medium frequency spot welding machines replacing ordinary AC spot welding machines now? Let's take a look at the difference between a medium frequency spot welding machine and a regular AC spot welding machine.
1. Welding time
A 50Hz power grid with a welding time adjustment resolution of 20ms. The time adjustment resolution of the intermediate frequency inverter DC welding machine can reach 0.25ms (4kHz inverter frequency), with high control accuracy. The response speed of feedback control for intermediate frequency inverter welding machine is significantly accelerated, and the output stability is good.
2. Welding speed
Due to the influence of zero crossing current, the heating time of the AC spot welding machine is relatively long. The intermediate frequency inverter resistance spot welding machine has DC output, centralized heating, and shortened welding time.
3. Energy saving effect
The AC spot welding machine operates at 50Hz, with high transformer losses, low welding machine power factor, and high circuit losses. The transformer of the intermediate frequency inverter welding machine operates at a high frequency (1-4kHz) with minimal loss, and the DC output improves the power factor, resulting in significant energy-saving effects.
4. Equipment volume and weight
The transformer iron core of the AC spot welding machine is relatively large, and the equipment is bulky under the same power conditions. The transformer of the intermediate frequency inverter DC resistance spot welding machine is greatly reduced, and the equipment is relatively lightweight.

There are many types of intermediate frequency spot welding machines, each with its own characteristics and working principles. During spot welding, flat steel bars with cleaned surfaces are stacked together and placed between two electrodes. The foot pedal is pressed to make the intersection of the two steel bars tightly contact, and the circuit breaker is also in contact. When the power is turned on, a large amount of resistance heat is generated at the intersection of the steel bars in a short period of time, and the steel bars are quickly heated to their melting point and in a molten state.