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Four stages of welding time for intermediate frequency spot welder [DCS02]

Dec 20,2023

We know that there is a complete course for Spot Welder to finish each welding joint. The course can be divided as pre-pressure, welding, holding, resting total four stages. Each stage lasts a certain time, namely pre-pressure time, welding time, holding time, and resting time. These four stages are indispensable to the quality of spot welding.

DCS02 resistance spot welding 2

Pre-pressure time

Pre-pressure is the stage when the electrode compacts the workpieces to increase the contact area prior to spot welding.

The pre-pressure time is the time between the beginning of the electrode pressure on the workpieces and the beginning of the electrification. During this time, the electrode must apply the necessary welding pressure to the workpieces in order to ensure that the welded workpieces in close contact. If the pre-pressure time is too short, not waiting for the two workpieces close contact when it begins to electrify, burning through phenomenon may occur in spot welding process because the contact resistance is too large.

Welding time

The welding time refers to the time when the current passes through the electrode in the process of spot welding, which is an important link in the welding process.

When welding, the electric current flows through the electrode, which makes the welding place produce strong resistance heat. The metal at the place where the heat is most concentrated melts first. Meanwhile, the molten metal is surrounded by the metal ring in the unmelted and plastic state around, which keeps molten metal from spilling out.

Holding time

Holding time is the time between the start of a power outage and the electrode lifting. Under the action of pressure, the liquid metal in the plastic ring crystallizes and forms a weld nugget.

If the electrode is raised when the welding current is broken and the liquid metal in the Nugget does not have time to crystallize, then the volume shrinkage of the nugget metal can not be replenished due to the solidification of the liquid metal in the closed plastic ring, the weld nugget will form shrinkage or loose tissue. Obviously, the strength of the weld nuggets with shrinkage or loose structure is very low, so it is necessary to hold this period of time.

Resting time

The resting time is the time between the electrode being raised from the workpiece and the beginning of the next cycle of pressure.

The resting time has to meet the time for workpiece movement, positioning and the mechanical action of the welder. Subject to these conditions, the shorter the time, the better.

IF welding machine 3