Optimal batch sizing, quality improvement and rework for an imperfect production system with inspection and restoration

This paper incorporates the effect of process inspection and restoration (Ben-Daya and Rahim, 2003) in an imperfect production process while considering three different scenarios (Ojha et al., 2007): 1) single lot of raw material–multiple lot of finished product–multiple delivery of the product, 2) single lot of raw material–multiple lot of finished product–single delivery of the product, 3) single lot of raw material–single lot of finished product–single delivery of the product. A numerical algorithm is proposed, and an illustrative example is provided. The optimal number of inspections, ordering quantities and expected total cost of the illustrative example are evaluated for each of the three models along with a sensitivity analysis to show the impact of the model parameters on the solution. The analysis shows that incorporating the inspection and restoration in the imperfect production process results in larger batch sizes and lower total costs. The implementation of inspection and restoration in imperfect production processes is good in cases of higher percentage of defective items produced (α), as it results in higher savings on total cost. [Submitted 03 October 2007; Revised 22 May 2008; Revised 10 November 2008; Accepted 11 November 2008]