Kaizen, or continuous improvement, is a basic tenet of lean manufacturing. It says, in effect, that less-than-optimal is never acceptable. The concept can be applied to every major assembly process, including resistance spot welding.
Spot welding involves generating heat at the interface of the parts to be joined by passing an electrical current through the parts for a set amount of time and pressure. Engineers obtain a strong weld by carefully determining the best combination of time, force and current.