Determining the Optimum Process Mean Under Quality Loss Function

The setting of a process mean for a manufacturing process which frequently produces scrap and rework, can significantly affect profitability. Optimal mean setting is a methodology by which the process mean is adjusted to maximise profit. This paper studies the dynamics of the problem and investigates the possibility of applying different process means to each rework iteration, to further maximise profit. A proof is given confirming there is only one optimal mean that applies over all rework iterations in the single feature case. However, applying similar reasoning to a dual feature case led to the development of a new optimal mean setting methodology which outperformed the existing approach in terms of the maximum expected profit.

Section: Literature Reviewmentioning

confidence: 99%

Improving profitability of optimal mean setting with multiple feature means for dual quality characteristics

Dodd

Scanlan

Marsh

et al. 2015

“…In the area of quality loss functions, most researchers consider the case where a single quality characteristic is present [5][6][7][8][9]. In general, products are judged by more than one quality characteristic.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the product quality level under multiple L-type quality characteristics

Chan

Ibrahim

Lochert

2004

One of the most critical issues encountered in the area of quality engineering is the selection of an appropriate quality loss function to relate key quality characteristics of a product to its quality performance. The loss function can be used to evaluate the quality loss in terms of monetary units that enables managers to quantify unobservable costs. It aids manufacturers to evaluate quality improvement projects more rigorously, hence, the choice of paths for quality enrichment depends on the type of loss function. Although several multivariate quality loss functions have been proposed, these models only considered the-nominal-thebest (N-type) quality characteristics. The effect of other types of quality characteristics was not addressed. In this paper, a cost model is proposed to evaluate the quality level of a product with multiple the-larger-the-better (L-type) quality characteristics. An example with two quality characteristics is given to illustrate the application.

Determining the optimum process mean for a mixed quality loss function

Chen

2005

In 1999, Wen and Mergen adopted the step loss function of a product to balance the costs of out-of-specification occurrences and to determine the optimum process mean. They considered a normal quality characteristic and assumed a known standard deviation for the process in their model. This paper proposes a modified Wen and Mergen [1] model with a mixed quality loss function to determine the optimum process mean. The quality loss of the product per item includes a quadratic loss within specifications and an out-of-specification piecewise linear loss.