Control and Lean Fundamentals
The Control phase locks in the gains so improvements do not erode over time, using monitoring, standardization, and clear reaction plans. Lean fundamentals such as waste elimination and 5S support a stable, capable process.
Control charts and stability
Control charts plot a metric over time with statistically derived control limits to separate routine common-cause variation from special-cause signals. Reacting only to genuine signals avoids tampering that can increase variation.
Process capability
Capability indices compare the voice of the process to the voice of the customer. Cp equals the tolerance width divided by six standard deviations, while Cpk also accounts for centering; a Cp or Cpk of 1.33 is a common capability target.
Lean waste and 5S
Lean targets eight wastes, often summarized as overproduction, waiting, transport, overprocessing, inventory, motion, defects, and unused talent. The 5S method (Sort, Set in order, Shine, Standardize, Sustain) builds an orderly, visual workplace that helps sustain results.