Application of Green Lean Six Sigma (GLSS) through DMAIC Approach: A Case of Walia Steel Industry (WSI)
| dc.contributor.advisor | Yitagesu Yilma (PhD) | |
| dc.contributor.advisor | Birhanu Tolosa (Mr.) Co-Advisor | |
| dc.contributor.author | Seble Negash (PhD) | |
| dc.date.accessioned | 2025-08-15T20:11:47Z | |
| dc.date.available | 2025-08-15T20:11:47Z | |
| dc.date.issued | 2025-06 | |
| dc.description.abstract | In today’s manufacturing world, producing high-quality products while reducing waste and environmental harm is increasingly critical. This study explores the application of Green Lean Six Sigma (GLSS) an integrated framework combining Lean principles, Six Sigma methodologies, and sustainability practices within the Walia Steel Industry (WSI), a major steel profile manufacturer in Ethiopia. The research applies the DMAIC (Define, Measure, Analyze, Improve, Control) approach to assess and address rising product defects, which increased from 2.34% in 2022/23 to 3.06% in 2023/24, alongside growing material waste and emissions. A mixed-method case study was employed, drawing on production records, interviews, and observational data. Analytical tools such as Pareto charts, Material Flow Analysis (MFA), simplified Life Cycle Assessment (LCA), fishbone diagrams, and the 5 Whys method were used to identify and analyze key defects in CHS, RHS, SHS, and LTZ products. Root causes were traced to poor machine calibration, substandard raw materials, and inadequate storage conditions. The process capability assessment revealed a DPMO of approximately 10,213, corresponding to a Sigma level of 2.6 for without 1.5σ shift and 3.8 for with 1.5σ shift. MFA projected 149.83 tons/year of material waste, while LCA estimated this waste contributes approximately 45 tons of CO₂e emissions annually. Additionally, Lean wastes particularly Defects, Waiting, Motion, and Overprocessing were conceptually mapped using the TIMWOOD framework, based on qualitative observations. As a result, the study proposes a tailored GLSS-based conceptual framework designed to reduce defects by an estimated 46.7%, potentially lowering CO₂e emissions by 21 tons/year. The framework integrates Lean waste reduction, Six Sigma quality control, and Green sustainability tools across all DMAIC phases. This research fills a critical gap in the literature by demonstrating how GLSS can be applied in developing country contexts like Ethiopia to drive operational efficiency and environmental performance. The findings offer a scalable model for sustainable manufacturing applicable to similar industrial settings.ment. | |
| dc.identifier.uri | https://etd.aau.edu.et/handle/123456789/6771 | |
| dc.language.iso | en_US | |
| dc.publisher | Addis Ababa University | |
| dc.subject | Green Lean Six Sigma (GLSS) | |
| dc.subject | DMAIC | |
| dc.subject | Defect Reduction | |
| dc.subject | Sigma Level | |
| dc.subject | Sustainable Manufacturing | |
| dc.subject | Material Flow Analysis (MFA) | |
| dc.subject | Life Cycle Assessment (LCA) | |
| dc.title | Application of Green Lean Six Sigma (GLSS) through DMAIC Approach: A Case of Walia Steel Industry (WSI) | |
| dc.type | Thesis |