Application of Continuous Improvement Principles for Scrap Reduction in Assembly Lines: The Case of Electrolux S.p.A.

This thesis presents the improvement project carried out in the new Genesi assembly area of the Electrolux plant located in Susegana (TV), which produces built-in refrigerators and freezers. During the first months of 2025, the plant experienced a substantial increase in scrap levels along the assembly lines, generating significant non-quality costs due to material losses, inefficiencies and rework activities. The aim of this work is therefore to understand the causes of scrap and implement corrective actions capable of reducing waste and enhancing the stability of the production process. The project followed the principles of Continuous Improvement, Lean Management and Total Quality Management (TQM), developed in an Industry 4.0 environment, but placed strong emphasis on practical activities performed on the shop floor. The work began with an analysis of scrap data for the two families of semi-finished products most affected: cabinet and cabinet prefoam, using data from the internal system for scrap declaration. A complete revision of scrap reasons, used during declarations to specify the causes, was carried out to improve accuracy and support more precise analyses. A second activity concerned the application of the 5S methodology to scrap-related areas, including zones used as temporary buffer for units awaiting rework or reintegration into the assembly line. These areas were redefined and organized; standardization and visual management tools were implemented to reduce misclassification, avoid unnecessary accumulation and prevent damage. This directly improved production flow and waste management. Additionally, several structured problem-solving activities were executed following the PDCA cycle framework. Each defect category with significant impact was investigated through root cause analysis using Ishikawa diagrams, 5-Whys and observations on the shop floor. Corrective solutions were implemented, monitored over time and standardized across different processes and working shifts, ensuring long-term sustainability. The activities delivered a concrete and measurable scrap reduction. Considering the two categories included in the project, cabinet and cabinet prefoam, their combined scrap rate calculated on total production was lowered from 2.26% to 1.26%, corresponding to a reduction of approximately 44%. These results led to substantial savings related to material, rework time and productivity, while also improving product quality. Overall, the project highlighted the effectiveness of applying structured Continuous Improvement and TQM-based methods in modern manufacturing environments, confirming their importance for quality enhancement and operational excellence.