An Economic Production Inventory Problem with Reworking of Imperfect Items in Fuzzy Environment

Abstract

The classical inventory models are formulated with the assumptions that the items are produced with perfect quality. But in reality, product quality may not always be perfect. Due to machinery fault, unskilled labour fault etc., imperfect quality items may be produced. A proportion of the defective items are assumed to rework at a constant rate. Some of the perfect quality items may deteriorate perish or damage at the time of packaging or transportation and these defective items passes from the manufacturer or supplier to the customers. Customers then return these defective items to the suppliers. In this paper, we formulate a multi-objective imperfect quality inventory model with rework of defective items under the limited storage space restrictions in fuzzy environment. Cost parameters are assumed as fuzzy number with different types of left and right branches of membership functions. Problem is solved by modified geometric programming approach. A numerical example is provided to illustrate the proposed model. Keywords : inventory; nearest weighted interval; best approximationl interval; ranking fuzzy number; geometric programming 2010 Mathematics Subject Classification 90B05