Getting the Most from Your WELDA WELD TECH Closed Loop Resistance Welding Power Supply

One of the keys to manufacturing success is simply to know your equipment so you can maximize its usage. Today’s post focuses on eight key features found on AMADA WELD TECH’s closed-loop resistance welding power supplies: what they are, where to find them, how they work, and when to use them.

1. Closed loop control – At a high level, resistance welders are either “open-loop” or “closed-loop.”
   • Open-loop welders provide no feedback during the weld; they just supply the programmed energy regardless of any process variation. This can lead to variation in weld quality. Example power supplies include most AC welders and some capacitive discharge welders.
   • Closed-loop welders, on the other hand, use current, voltage, or power feedback to precisely control the energy delivered to the parts. This ability to accurately control weld energy is a key factor in overcoming problems associated with process variation and the rapid changes in resistance that happen during the weld. Examples include high frequency inverters and linear DC power supplies.When to use the different power supplies depends on the process, its sensitivity to variation, and the budget. For safety critical parts, we always recommend closed loop power supplies to get consistent results.
2. Feedback modes – Most of our closed-loop resistance welding power supplies feature three feedback modes: constant current, constant voltage and constant power.
   • Constant current (kA):
     • Delivers the same current for each weld
     • Voltage and power will vary based on resistance
   • Constant voltage (V):
     • Voltage is held constant for each weld
     • Current and power will vary based on resistance