Professional Application of Statistical Process Control in Manufacturing Quality Management at Dangote Industries

Statistical process control (SPC) provides quantitative tools for monitoring manufacturing quality, detecting process deviations, and reducing defect rates in industrial settings. This study examines the professional application of SPC methods in quality management at Dangote Industries, Nigeria's leading manufacturing conglomerate operating across the South West and North Central zones. Production line quality data from the Obajana cement plant, Kogi State, were obtained for 12 months. Xbar-R control charts, process capability indices (Cp, Cpk), and CUSUM charts were constructed for key quality parameters including cement compressive strength and fineness. Western Electric rule violations were used to identify special cause variation. Process capability analysis revealed Cpk values below 1.33 for two of six monitored parameters, indicating insufficient capability. Control chart analysis identified 14 out-of-control signals over the 12-month period, 9 of which were attributable to raw material quality variation from a specific limestone quarry. CUSUM charts detected a sustained mean shift in clinker temperature five days before a major process failure, demonstrating early warning value. The study provides a professional SPC implementation blueprint for Nigerian industrial manufacturers and recommends real-time SPC software integration, SPC-trained quality engineers on each production shift, and supplier quality audit protocols to address upstream material variation. Keywords: statistical process control, control charts, manufacturing quality, Dangote, process capability