Economic Production Quantity (EPQ) model with Imperfect Quality Items Produced

• Main Authors: Bi-Yu Wu, 吳碧玉
• Other Authors: Yuan-Shyi Peter Chiu
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/12730518659920285294

碩士 === 朝陽科技大學 === 工業工程與管理系碩士班 === 91 === This study examines the problem of random defective rate on the economic production quantity (EPQ) model with backlog permitted. One of the unrealistic assumptions of classic finite production model is that it assumes manufacturing facility functions perfectly at all times. However, in most practical settings, due to process deterioration or other factors, defective items are generated. In this paper, random defective rate is considered and all defective items are assumed not repairable. Because of the random scrap rate, it follows that the cycle length of production is not a constant. The renewal reward theorem is employed to cope with the variable cycle length. Disposal cost per scrap item is included in cost analysis, an optimal production quantity that minimizes the expected overall costs for the imperfect quality EPQ model is derived, where backlog is permitted. Two extended models are developed to consider different inventory situations. One is that when backorder is not permitted versus our main model which allows backlogging. The other considers that when all defective items are reworked and repaired for the EPQ model with shortage not permitted. Sensitivity analysis in our study includes judgment on whether to allow backorders or not, and determination on whether to rework the defective items or not, in terms of minimizing overall inventory costs. Numerical examples are provided to demonstrate their practical usages.