Upper and lower control limits are calculated to establish boundaries for expected process variation. These limits, often displayed visually on control charts, help determine whether a process is stable and predictable. For instance, if measurements of manufactured parts consistently fall within the calculated limits, the process is considered in control. Exceeding these boundaries signals potential issues requiring investigation and corrective action.
Establishing these boundaries provides a powerful tool for quality control and process improvement. By identifying deviations early, unnecessary costs associated with defects or rework can be minimized. This statistical approach, with roots in the early 20th century, provides a framework for data-driven decisions, reducing reliance on subjective assessments of process stability and enabling proactive interventions. It empowers organizations to consistently deliver products and services that meet specified requirements.
