<![CDATA[Sodium sulfate is a critical raw material in the glass industry that is highly susceptible to caking defects during storage due to its hygroscopic nature. This study aims to analyze the occurrence of caking defects and develop improvement strategies for the sodium sulfate storage system in the logistics department of PT XYZ. The Six Sigma approach was implemented through the DMAIC framework, integrated with Failure Mode and Effect Analysis (FMEA) and a proportion control chart (p-chart). Based on September 2025 operational data, 71 out of 294 received tons experienced caking defects, yielding an average defect proportion of 24.15%. A DPMO value of 241,500 indicated a process capability of 2.20 sigma, which falls below industrial quality standards. The p-chart revealed that the process was statistically unstable. Root cause analysis identified five contributing factors: material, environment, method, human resources, and measurement. FMEA highlighted the most critical risks as high warehouse relative humidity (RPN 448), inadequate inspection procedures (RPN 336), three-tier stacking (RPN 288), and excessive storage duration (RPN 150). Proposed improvements include humidity control, enhanced inspection procedures, two-tier stacking limitation, and FIFO system implementation to reduce storage-related defects and improve overall operational quality performance.]]>
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