Integrated SPC‐based scheme utilising variable control charts and Cpm ratio to improve manufacturing quality of empty hard gelatin capsules

Quality control and improvement at the process level is a vital activity for the achievement of quality in products and services. This paper presents a three‐phase scheme based on statistical process control methodology that employs variable control charts and process capability indices for quality improvement. The control charts employed are X‐bar, s and the exponentially weighted moving average. The centred process capability ratio (Cpm) is employed for process capability assessment. The scheme accounts for both short‐term and long‐term changes in process performance and it is designed for a structured and less‐complex implementation of control charts and process capability assessment. The proposed scheme has been implemented to the manufacturing process of empty hard gelatin capsules as a case study. This implementation has led to an expected reduction in the number of defective capsules by 29% relative to the stage before implementation.