Development and Implementation of a Quality Management Framework for CNC Machining Operations in Engineering Workshops in Anambra State

CNC machining workshops in the industrial clusters of Nnewi and Onitsha in Anambra State, South East Nigeria, are increasingly being engaged for precision component manufacturing for the automotive and consumer goods sectors, yet few operate formal quality management systems that could ensure consistent dimensional and surface quality output. This study presents the development and implementation of a quality management framework for CNC machining operations tailored to the operational context of small and medium-sized engineering workshops in Anambra State. The framework integrates dimensional measurement protocols, statistical process control using X-bar and R control charts, tool wear monitoring procedures, and a documented non-conformance and corrective action process. The framework was piloted at three CNC machining workshops in Nnewi over a four-month implementation period. Pre-implementation process capability indices for representative turning and milling operations were measured between Cpk 0.72 and Cpk 0.91, indicating processes below the minimum acceptable Cpk of 1.33. Following implementation and process adjustments guided by SPC data, Cpk values improved to between 1.18 and 1.41. Customer rejection rates for machined components decreased by 47 percent over the pilot period. A workshop quality manual and standard operating procedure documentation were developed as deliverables for each participating workshop. The study provides a practical and scalable quality management model for Nigerian engineering workshops transitioning toward formal quality certification. Keywords: quality management, CNC machining, statistical process control, engineering workshop, Anambra State