The i4s was designed to directly address the biggest challenges to welding modern high-strength steels. Because these metals are rigid and sensitive to heat, it is important to deliver the right amount of power at the right time to avoid weak welds. Too much heat applied too quickly results in a ring of brittle metal around the weld nugget, reducing the tear-out strength of the joint.
In order to create the strongest weld possible, the i4s uses a unique system to regulate the true energy delivered to the weld, ensuring smooth and consistent nugget growth. Using a combination of thickness and resistance measurements, the welder calculates the total amount of heat energy needed to create a solid joint. The unit’s central processor then adjusts current several thousand times per second to ensure that weld power remains stable even in the presence of adhesives, paint, or contaminants on the metal.
This precise control is especially important at the start of the weld since UHSS metals often have very high electrical resis- tance between the weld surfaces. Trying to force even moderate currents through the metals at early on can lead to almost instantaneous blowout. The i4s solves this issue by constantly monitoring thermal power even during preheat, reducing current if the measured power rises above a limit that is safe for the metal. Once the weld joint is clean and good contact is detected, current is allowed to rise and the weld continues until the energy target is reached. By accounting for all energy added during all stages of the weld, the i4s can accurately gauge when the weld is complete and cut off current before over- heating of the metal can occur.