Title: The effect of inspection errors on the optimal batch size in reworkable production systems with scraps

Authors: Alireza Haji, Sharam Shadrokh Sikari, Ramin Shamsi

Addresses: Department of Industrial Engineering, Faculty of Industrial Engineering, Sharif University of Technology, Azadi Ave., P.O. Box 11155–9414 Tehran, Iran. ' Department of Industrial Engineering, Faculty of Industrial Engineering, Sharif University of Technology, Azadi Ave., P.O. Box 11155–9414 Tehran, Iran. ' Department of Industrial Engineering, Mazandaran University of Science and Technology, Babol, Iran

Abstract: The objective of this paper is to provide a framework to integrate the existence of products with imperfect-quality items, inspection errors, rework and scrap items into a single Economic Production Quantity (EPQ) model. To achieve this objective, a suitable mathematical model is defined and the optimal production lot size that minimises the total cost is obtained. Sensitivity analysis is carried out for this model. The sensitivity analysis results indicate that the model is very sensitive to defective proportions and type 1 errors of inspection. Nowadays, given the progress made, inspection errors are often ignored. But the findings of this study show that the values of EPQ and total cost are very sensitive to type 1 errors of inspection. If the existence of such errors is ignored, then the obtained results will differ considerably from the optimal outcome. This will impose additional costs to the system.

Keywords: economic production quantity; EPQ; rework items; scrap items; imperfect quality items; optimal production lot size; batch sizes; sensitivity analysis; defective proportions; type 1 inspection errors; costs; production management; advanced production systems; production design; mathematical modelling.

DOI: 10.1504/IJPD.2010.029993

International Journal of Product Development, 2010 Vol.10 No.1/2/3, pp.201 - 216

Available online: 03 Dec 2009 *

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