Effects of Imperfect Quality and Defective Items on Economic Production Lot Size

The classical EPQ model has been used for a long ti me and is widely accepted and implemented. Nevertheless, the analysis for finding an economic lot size has based on a number of unrealistic assumptions. A common unrealistic assumption in using EPQ is that all units produced are of good quali ty. The classical EPQ model shows that the optimal lot size will generate minimum ma nufacturing cost, thus producing minimum setup cost and inventory cost. However, this is only true if all products manufactured in the process are assumed to be of good quality (i.e. all products are within the specification limits). In rea lity this is not the case, therefore, it is necessary to consider the cost of im perfect quality items, because this cost can influence the economic lot size. Ma ny studies and recent papers have indicated that there is a significant relation ship between economic production lot size and process/product quality. However, their models included either the imperfect quality items (not necessarily de fective) which are to be sold at a discounted price or defective items which can be reworked or rejected. The aim of this paper is to provide a framework to integrate three different sit uations (discounted pricing/rework/reject) into a single model. 100% inspection is performed in order to distinguish the amount of good quality items, imper fect quality items and defective items in each lot. In this paper, a mathematica l model is developed, and a numerical example is presented to illustrate the sol ution procedures. It is found that the economic production lot size tends to inc rease as the average percentage of imperfect quality items and defectives (rejec ted items) increases.

An Inventory Model of Production with Level Dependent Demand Allowing Few Defective Items

This paper considers a model regarding the products with finite life which allows defective items in reproduction and causes a small amount of decay. The market demand is assumed to be level dependent linear type. The model has also considered the constant production rate which stops after a desired level of inventories and that is the highest level of it. Due to the market demand, defective item and product’s decay, the inventory reduces to the zero level where again the production cycle starts. With a numerical search procedure, the proof of the proposed model has been shown. The objective of the proposed model is to find out the total optimum inventory cost, optimum ordering cost and optimum ordering cycle.

Statistical Analysis of Defective Items of Pharmaceutical Wholesale Enterprises

Objective To provide some references and suggestions for promoting the healthy development of pharmaceutical wholesale enterprises,improving the scientific supervision level of the drug regulatory department and ensuring the quality of drugs in the circulation.Methods Retrieving the items on the official websites of the national and provincial drug regulatory departments from 2017 to 2019 that didn’t meet the requirements of the 2016 edition of the Good Supplying Practice in pharmaceutical wholesale enterprises under various inspections,the defective items were summarized and analyzed,and further study of the changes of defective items was conducted.Results and Conclusion 908 pharmaceutical wholesale enterprises had definite defective items,and 218 items violated the Guidelines for On-site Inspection of the Good Supplying Practice,with a cumulative frequency of 3874 defects.Defective items with high-frequency mainly occurred in storage and maintenance,facilities and equipment,personnel and training,general rules and sales.The average defect frequency in each pharmaceutical wholesale enterprises increased year by year,but the proportion of serious defective items decreased significantly.It is recommended that based on improving drug quality,pharmaceutical wholesale enterprises should strengthen personnel training to enhance their awareness of quality responsibility.Besides,the drug regulatory department should increase inspection and crackdown on illegal business operations and the deception of pharmaceutical wholesale enterprises.

Two-echelon imperfect production supply chain with probabilistic deterioration rework and reliability under fuzziness

This paper develops an integrated fuzzy two-layer supply chain for manufacturersand retailers with defective and non-defective types of products. The manufacturerproduces up to a specific time, including both faulty and non-defective items, andpost-screening only the non-defective item sends to the retailer. The strategy of theretailer is to do the screening of items received from the manufacturer.Subsequently, the perfect quality items use to fulfill the demand of thecustomer, and the defective items are reworked. The retailer considers thatcustomer demand is time and reliability dependent. The proposed supply chainconsiders probabilistic deterioration for the manufacturer and retailers. Theoptimum solution of the given model is evaluated for both the cases of crispand fuzzy environments on the strategies such as production rate, unitproduction cost, idle time, screening, rework, etc. Managerial insights and theeffect of parameters on the optimal inventory under fuzziness are presented.