8.3 Lean Quality Foundations: 5S & Visual Factory

Quality cannot exist in chaos. 5S is not a housekeeping methodology; it is a foundational quality discipline designed to make abnormalities immediately visible. If the standard state is not obvious, deviations cannot be detected.

8.3.1 The 5S Protocol for Quality

• Sort (Seiri): The rigorous removal of unneeded items. "Red Tagging" campaigns must be used to identify and remove obsolete tools, fixtures, and materials that clutter the workspace and hide defects.
• Set in Order (Seiton): "A place for everything." Shadow boards for tools ensure that if a torque driver is missing, it is visually obvious immediately, preventing un-torqued screws.
• Shine (Seiso): Cleaning is inspection. The act of wiping a reflow oven sensor or a stencil frame is a calibration check, not a janitorial task.
• Standardize (Seiketsu): Creating consistent color codes and labeling across the facility (e.g., Red Bins = Defect, Green Bins = Good, Yellow Bins = WIP).
• Sustain (Shitsuke): The audit rhythm that prevents regression.

8.3.2 Visual Controls

• The 5-Second Rule: A supervisor walking past a station must be able to assess the status (Running/Down, Ahead/Behind, Quality Good/Bad) within 5 seconds without asking the operator.
• Andon Lights: Automated status towers (Red/Amber/Green) on SMT machines provide instant line-of-sight status to the floor management.

Final Checklist