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Sampling inspection is one of preventive quality methods for decreasing waste of time and cost, but should be along with other quality control approaches to effectively enhance product quality. Determination of optimum process mean tends to reduce the bias of the central tendency of process characteristic from its target, and has been an important topic in quality system design. Pulak and Al-Sultan developed a single sampling rectifying inspection model to determine the optimum process mean, based on maximization of the expected total profit per item. Since setting the economic specification limits for process characteristic is considered a short-term approach for quality assurance and, on the other hand, quality investment is a long-term approach for process improvement, in the present paper, a modified product inspection model, which is modified from Pulak and Al-Sultan's work, is firstly presented to simultaneously determine the optimum process mean and economic specification limits, based on maximization of the expected total profit per item. Then, quality investment is integrated into this modified model to obtain the optimum quality investment level. [ABSTRACT FROM AUTHOR]

In 2009, Darwish developed a single-vendor single-buyer supply chain model with process mean integration for determining the optimal process mean, production lot size, and number of shipment of product to buyer. Taguchi proposed the quadratic quality loss function for measuring the product quality and redefines the product quality as the loss of society when the product is shipped and sold to the customer. The quality cost of conforming products is excluded in Darwish’s model, which is inconsistent with Taguchi’s quality concept. In this paper, the author presents a modified Darwish’s model with quality loss for obtaining the optimal process mean, number of shipment, and production lot size. The numerical results show that the modified model has larger process mean and expected total relevant cost of product, smaller production lot size, and same number of shipment than those of original one. The original Darwish’s model will underestimate the expected total relevant cost of product because he doesn’t consider the quality loss of conforming products. [ABSTRACT FROM PUBLISHER]

Chung and Hou develop a deteriorating production system with allowable shortage for determining the optimal production run time. The rework cost of the defective products is included in their model. However, they did not consider the quality cost of non-defective products. In this study, the author proposes a modified Chung and Hou’s model for obtaining the optimal production process parameters (process quality level and production run time) under the minimization of the expected total relevant cost of product per unit time. Taguchi’s asymmetric quadratic quality loss function is used for measuring the product quality. [ABSTRACT FROM PUBLISHER]

In 2000, Roan et al. developed an imperfect production system including raw material procurement cost and finished product cost for determining the optimal process mean, production run size, and raw material order quantity, in which the quality cost of conforming products was not included. Taguchi proposed the quadratic quality loss function for measuring the product quality and redefined the product quality as the loss of society when the product is shipped and sold to the customer. In the present paper, the model developed by Roan et al. is modified with quality loss for obtaining the optimal parameters associated with raw material and production process. Numerical results show that our modified model leads to larger process mean, larger raw material order quantity, higher expected total relevant cost of products, smaller production run size, and smaller number of order quantity of the raw material satisfying each production run than those from the original model, which indicates that the original model given in Roan et al. may underestimate the expected total relevant cost of products due to ignoring the quality loss of conforming products. [ABSTRACT FROM PUBLISHER]

In this paper, the author proposes a modified Kapur and Wang's model with unequal target value and specification center. The economic specification limits and process mean are determined by minimizing the expected total quality loss per unit product under the specified process capability index value. The process capability indices Cpm and Cpmk correlated with Taguchi's quadratic quality loss function are considered. The 100% inspection is executed before the product shipped to the customer. Taguchi's asymmetric quadratic quality loss function is applied in evaluating the product quality. The numerical results show that the modified model with specified Cpm value has smaller specification tolerance, larger process mean, and smaller expected total cost per unit product than those of the modified model with specified Cpmk value. [ABSTRACT FROM AUTHOR]

Chen and Liu [‘Procurement Strategies in the Presence of the Spot Market-an Analytical Framework’, Production Planning and Control, 18, 297–309] presented the optimum profit model between the producers and the purchasers for the supply chain system with a pure procurement policy. However, their model with a simple manufacturing cost did not consider the used cost of the customer. In this study, the modified Chen and Liu's model will be addressed for determining the optimum product and process parameters. The authors propose a modified Chen and Liu's model under the two-stage screening procedure. The surrogate variable having a high correlation with the measurable quality characteristic will be directly measured in the first stage. The measurable quality characteristic will be directly measured in the second stage when the product decision cannot be determined in the first stage. The used cost of the customer will be measured by adopting Taguchi's quadratic quality loss function. The optimum purchaser's order quantity, the producer's product price and the process quality level will be jointly determined by maximising the expected profit between them. [ABSTRACT FROM AUTHOR]

Abstract: The maximum expected profit model between the producers and the purchasers is an important objective for the supply chain system. The producer’s profit needs to consider the problem of sales revenue and manufacturing cost. The purchaser’s profit needs to consider the problem of order quantity and used cost of customer. How to get a trade-off between them should be an important topic. presented the optimum profit model between the producers and the purchasers for the supply chain system with pure procurement policy. However, their model with simple manufacturing cost did not consider the used cost of customer. In this study, the modified Chen and Liu’s model will be addressed for determining the optimum product and process parameters. The authors propose a modified Chen and Liu’s model with indirectly measurable quality characteristic under the single stage screening procedure. The surrogate variable with high correlation with indirectly measurable quality characteristic will be directly measured. The used cost of customer can be obtained by adopting Taguchi’s quadratic quality loss function. The optimum purchaser’s order quantity, the producer’s product price, and the process quality level will be jointly determined by maximizing the expected profit between them. [Copyright &y& Elsevier]

Abstract: In this study, the authors first address the formulation of modified Pulak and Al-Sultan’s model with quality loss and inspection error for determining the optimum process mean based on maximizing the expected profit per item. Then the modified Ladany and Shore model with integrating quality and reliability is formulated for determining the optimum expected lifetime and warranty period of product based on maximizing the total expected profit. [Copyright &y& Elsevier]

Economic selection of process parameters has been an important topic in modern statistical process control. The optimum process parameters setting have a major effect on the expected profit/cost per item. There are some concerns on the problem of setting process parameters. Boucher and Jafari (1991) first considered the attribute single sampling plan applied in the selection of process target. Pulak and Al-Sultan (1996) extended Boucher and Jafari's model and presented the rectifying inspection plan for determining the optimum process mean. In this article, we further propose a modified Pulak and Al-Sultan model for determining the optimum process mean and standard deviation under the rectifying inspection plan with the average outgoing quality limit (AOQL) protection. Taguchi's (1986) symmetric quadratic quality loss function is adopted for evaluating the product quality. By solving the modified model, we can obtain the optimum process parameters with the maximum expected profit per item and the specified quality level can be reached. [ABSTRACT FROM AUTHOR]

This article explores the problem of designing a CSP-1 plan with the specified average outgoing quality limit (AOQL), the acceptable quality level (AQL), and the limiting quality level (LQL) value. By adopting the regret-balanced criterion under the producer's and consumer's interests of quality, we can design the optimal CSP-1 plan. [ABSTRACT FROM AUTHOR]