Modified Economic Manufacturing Quantity Model Research Articles

Process mean and production quantity settings by considering modified economic manufacturing quantity model

In this article, the author proposes a modified economic manufacturing quantity (EMQ) model with deteriorating production process. Assume that the two independent quality characteristics of the product are normally distributed with known process standard deviation for a period of time. Consider the unstable production process with positive shift and an age-dependent positive drift while process variance increases. The bivariate quality loss function is applied to evaluate the product quality. The process mean and economic manufacturing quantity are jointly determined by minimizing the total expected cost of product per unit time. A solution procedure is devised to find the optimal solution for modified EMQ model and the sensitivity analysis of key parameters is conducted to investigate the effect on the optimal solution.

The joint determination of specification limits, process mean, and economic manufacturing quantity

This study proposes a modified economic manufacturing quantity (EMQ) model with deteriorating production process. Assume that the quality characteristic of the product is normally distributed. Consider the unstable production process with positive shift and an age-dependent positive drift while process variance increases. The target value of product characteristic is considered to be equal to its specification center and Taguchi’s symmetric quadratic quality loss function is applied to evaluate the product quality. The specification limits, process mean, and EMQ are jointly determined by minimizing the total expected cost of product per unit time under the specified process capability index Cpm value. A solution procedure is devised to find the optimal solution for modified EMQ model and the sensitivity analysis of key parameters is conducted to investigate the effect on the optimal solution. Numerical results show that the expected total cost of product per unit time is significantly influenced by the process capability index, the quality loss coefficient, the production rate, the demand rate, and process standard deviation.

The Modified Economic Manufacturing Quantity Model Based on Inspection Error, Quality Loss, and Shortage

AbsractIn 1996, Pulak and Al-Sultan presented the problem of determining the optimum process mean for a product with the one-sided specification limit under the rectifying inspection plan. However, they didn't consider the quality loss within the specification limit. The inspection is perfect and the non-conforming items of the accepted lot aren't eliminated or replaced by the conforming ones in their model. Traditional economic manufacturing quantity (EMQ) model addressed that the perfect production for product. However, there possibly exists the defective product in the manufacturing process. Hence, it is necessary to consider the quality loss of product in the modified EMQ model. In this study, the author integrates the modified Pulak and Al-Sultan's model with inspection error and quality loss into the Cardenas-Barron's production lot model with shortage for determining the economic manufacturing quantity, shortage and optimum process mean.

Issuing for perishable inventory management with a minimum inventory volume constraint

We study a perishable inventory system that requires to maintain a minimum inventory volume at all times, where the minimum amount in the constraint is significant with respect to regular market demand and the traditional Economic Manufacturing Quantity (EMQ) models do not suffice. The problem is motivated by applications in homeland security, which are related to the management of pharmaceuticals in the Strategic National Stockpile (SNS) for emergency preparedness. We use a modified EMQ model to represent the system and consider the issuing policy given a fixed ordering quantity, as well as the joint ordering and issuing policy problem. We aim to maximize the profit of the system under a linearly-decreasing price structure assumption. We first present the optimal issuing policy with a given ordering quantity for this modified EMQ model. Then we demonstrate that maximizing the revenue of the ordering policy with FIFO (first-in, first-out) and LIFO (last-in, first-out) issuing policies can be formulated as a non-convex non-smooth unconstrained optimization problem. The properties of both problems (e.g. optimizing issuing policy with a fixed ordering quantity and optimizing ordering policy with a fixed issuing policy) is analyzed and an efficient exact algorithm is presented to solve the joint ordering and issuing problem. We show that the LIFO issuing policy is optimal with a linearly-decreasing price structure that deteriorates with the age of the item.

ECONOMIC PRODUCTION RUN LENGTH AND WARRANTY PERIOD FOR PRODUCT WITH WEIBULL LIFETIME

Traditional economic manufacturing quantity (EMQ) model addressed the perfect production for product. However, there possibly exists the defective product in the production process. In this paper, we present a modified EMQ model with shortage based on considering the product revenue and the inventory cost. The economic production run length, the maximum shortage level, and the optimal warranty period are simultaneously determined for obtaining the maximum expected total profit per year. The numerical example and the sensitivity analysis are further provided for illustration.

The determination of economic production run length and manufacturing target by considering quality loss function

Traditional economic manufacturing quantity (EMQ) model assumes that the perfect production for product. However, there possibly exists the defective product in the production process. In 1996, Chen and Chung presented the quality selection problem to the imperfect production system for obtaining the optimum production run length and target level. In 1998, Wu and Tang proposed the optimum manufacturing target based on Taguchi’s quadratic quality loss function. In this paper, we further integrate Chen and Chung’s and Wu and Tang’s models in the modified EMQ model for obtaining the optimum production run length and manufacturing target. The normal, uniform, and triangular quality characteristics are considered in the modified EMQ model. The asymmetric quadratic and linear quality loss functions are adopted for measuring the product quality. The numerical example and sensitivity analysis of parameters are provided for illustration.

Optimum production run length and warranty period setting for the imperfect production system

Traditional economic manufacturing quantity (EMQ) model addressed that the perfect production for product. However, there possibly exists the defective product in the manufacturing process. Hence, it is necessary to consider the production process state in the modified EMQ model. Chen and Chung presented the quality selection problem to the imperfect production system for obtaining the optimum production run length and target level. Ladany and Shore proposed the problem of determining optimal warranty period of product in relation to the manufacturer’s lower specification limit. In this paper, we further integrate Chen and Chung’s and Ladany and Shore’s models in modified EMQ model for obtaining the optimum production run length and warranty period of product for the imperfect production system.

THE OPTIMUM SELECTION OF IMPERFECT QUALITY ECONOMIC MANUFACTURING QUANTITY AND PROCESS MEAN BY CONSIDERING QUADRATIC QUALITY LOSS FUNCTION

ABSTRACT In this paper, we present a modified economic manufacturing quantity (EMQ) model under the imperfect product quality. Taguchi's quadratic quality loss function is adopted for measuring the product quality. The modified EMQ model denotes the total loss to the society which includes the producer's loss and the customer's loss. The total inventory cost of the modified EMQ model includes the set-up cost, the holding cost, and the product cost. The perfect and imperfect reworks of product are considered in the modified EMQ model, respectively. By solving the modified EMQ model, we can obtain both the optimum combination of EMQ and process mean in order to have the minimum total loss of society.

Integrating an EMQ model and product quality

In this paper we further extend Chen and Wang's study concerning a CSP‐1 plan applied to the economic manufacturing quantity (EMQ) model with imperfect quality. Adopting the backorder assumption for shortages, the modified total inventory cost includes the setup cost, the holding cost, the backordering cost, the inspection cost, and the internal and external failure cost. By solving the modified EMQ model, we not only obtain the required level of product quality but also determine the minimum of the total inventory cost.