Six Sigma DMAIC-Based Analysis of Defect in the Cement Bagging Process: A Case Study at PT Semen XYZ

Abstract

This study evaluates quality performance in the cement bagging process at PT Semen XYZ using a Six Sigma framework with the Define, Measure, Analyze, Improve, and Control (DMAIC) stages. A descriptive quantitative case-study design was applied to production and rejected-bag records from September to November 2025, covering 6,315,978 inspected bags and 4,998 rejected bags. Data were collected through field observation, interviews with personnel in the packer area, and operational documentation. Under the explicit assumption that each inspected bag represents one opportunity for nonconformance, the analysis used defect proportion, defects per million opportunities (DPMO), sigma-level conversion, p control charts, Pareto analysis, a fishbone diagram, and root-cause analysis. The monthly DPMO values were approximately 741, 813, and 819, corresponding to sigma levels of 4.67, 4.65, and 4.64, respectively. These results indicate relatively good quality performance but also a gradual increase in the rejected-bag rate. Among classified defect occurrences, the rotary packer was reported as the leading process location, accounting for 46.87%, while the rotary packer and chute together accounted for 90.82%. Potential causes were mapped using the 5M+1E categories: man, machine, material, method, measurement, and environment. Because the recommended actions were not implemented during the observation period, the Improve and Control stages are presented as proposed improvement and control plans. The proposals prioritize preventive maintenance, material inspection, equipment calibration, operator competency development, procedure refinement, and environmental control.