Lean Manufacturing Principles and 5S Methodology for Waste Identification and Elimination in a Manufacturing Unit: A Semi-Quantitative FMEA-Based Framework and KPI Audit System with a Numerical Illustration

Abstract

Manufacturing units face continuous pressure to cut costs, shorten lead time, and improve quality without new capital equipment. Lean manufacturing meets this pressure by removing non-value-adding activity, yet small and medium-sized enterprises (SMEs) often lack an objective way to decide which waste to tackle first. This paper presents a diagnostic, prioritisation, and audit framework that combines lean principles and the 5S methodology with a Waste Priority Number (WPN = S × O × D) adapted from Failure Mode and Effects Analysis (FMEA). The framework comprises (1) semi-quantitative WPN scoring, (2) a Pareto loss accounting model, (3) a distinction between overproduction as a root cause and inventory as its buffering consequence, and (4) a Key Performance Indicator (KPI) audit suite. A hypothetical numerical illustration, set in a CNC machining and assembly unit, shows how the framework is applied and read; all values are assumed, and no plant data were collected. In the illustration, overproduction, defects, and waiting rank highest (WPN = 60, 60, and 48) and account for 77.6% of the assumed monthly waste cost, and an assumed 12-week programme of Kanban, Single-Minute Exchange of Die (SMED), Poka-Yoke, autonomous maintenance, and 5S lifts Overall Equipment Effectiveness (OEE) from 61.2% to 78.7%. These values are not empirical findings, and validation in real plants is the next step. The framework links qualitative lean principles with quantitative shop-floor audits.