How is Statistical Process Control (SPC) applied in manufacturing?

SPC uses statistical methods to monitor and control processes. Key elements include: Control charts (X-bar R charts for variables, p-charts for attributes), Process capability indices (Cp, Cpk - target Cpk > 1.33), Upper/Lower control limits (UCL/LCL at +/-3 sigma), and Rules for detecting out-of-control conditions (Western Electric rules). SPC helps identify process variations before they cause defects, distinguishes between common cause and special cause variation, and enables data-driven process improvement. It is fundamental to Six Sigma and lean manufacturing.