Knowledge that Transforms

We consider an important topic from the traditional quality literature‐the impact of conformance quality of a manufactured product on the preventive maintenance costs to downstream users of this product. Folk wisdom supports the notion that higher conformance quality translates into lower maintenance costs (as well as other components of life‐cycle costs) for these users. We examine this proposition in some detail on the basis of a failure‐time model that relates conformance quality to reliability. We consider both repairable and nonrepairable items that are maintained by a block‐replacement or a minimal‐repair strategy. In addition to maintenance cycles and costs, we discuss the value of information to the user as to the actual production quality, and the value of inspection.

This study addresses the problem of replanning frequency for a rolling horizon master production schedule (MPS) in a process industry environment under demand certainty. The major contribution of this paper is the demonstration of how the appropriate replanning frequency for a MPS can be determined under the conditions of minimum batch‐size production restrictions in a rolling planning horizon setting. In addition, the problem environment for this study is an actual MPS operation that includes features such as multiple production lines, multiple products, capacity constraints, minimum inventory requirements, and multiple goals. Actual data from a paint company are used to determine the appropriate replanning frequency for a rolling horizon MPS. Results indicate that a 2‐month replanning frequency was the best at this firm because of the significant cost savings it provided when compared to actual company performance and the other replanning intervals.

Kramer and Lee recently addressed a common due window scheduling problem with earliness and tardiness penalties, where earliness and tardiness penalty factors are constant and the common window size is given. They showed that the problem is polynomial when the location of the due window is a decision variable. For the case where the location of the due window is given, the problem is also polynomial when the latest due date is greater than or equal to the makespan, and they proposed a pseudopolynomial dynamic programming algorithm to find an optimal schedule when the latest due date is less than the makespan. In this note we address the problem for the case where the location of the due window is given. Specifically, we show that the problem is polynomial if the window location is unrestricted, and present a more efficient dynamic program algorithm to optimally solve the problem if the window location is restricted. The concepts of unrestricted and restricted window locations are defined in this note.

Focus in the manufacturing plant is generally deemed to be an important element of success in manufacturing strategy. Yet, little work has been completed in the measurement of plant focus and a dearth of empirical evidence exists to support the broad popularity of this concept. This paper presents a plant focus measurement approach and reports the results of a field study that uses a site visit research design to apply the focus measure to a multi‐industry sample of manufacturing plants. Regression analysis is used to study the relationships between the plant focus variable and the environmental variables of plant size, number of product lines, plant age, number of processes, and type of processes. Although highly intuitive, these relationships have undergone very little empirical study in the literature. Our study provides evidence of a strong logarithmic relationship between our plant focus measure and the number of product lines. Support is also demonstrated in that our measure of plant focus is linked to the number and type of manufacturing processes. However, the variables of plant age and plant size do not appear related to the plant focus measure. The literature‐based multicriteria focus measure can be used by managers and researchers as an objective, formal, and generalizable approach for assessing plant focus, for identifying areas in the plant that detract from focus, and for tracking focus improvement efforts over time.

Today's markets are characterized by time and product quality‐based competition. Companies must compete through their ability to manage the whole cycle of product realization and delivery, from the initial concept through to delivery and support at the customer. They must do this through managing an integrated company, not a set of separate functions. This paper addresses the issue of how companies should develop operations strategies for engineering and manufacturing combined. It uses field research into 15 engineering companies to develop the concept of the manufacturing system mission, and proposes strategic choices for manufacturing, engineering and linked functions.

The main advantage of deep lane storage systems compared with conventional high bay warehouses is seen in a better space utilization, because products are stored in channels one pallet behind the other. However, for deep lane storage systems the last‐in‐first‐out principle holds and direct access to pallets is lost apart from the last pallet entering a channel. To operate deep lane storage systems effectively, namely, providing high throughput rates even at times of high storage rack utilization requires a sophisticated operational planning system. We will describe a totally new concept consisting of five modules for storage and retrieval assignments, as well as for a reorganization of storage location occupations.

Paralleling the increased interest in cellular manufacturing in recent years, a large number of studies have emerged that focus on the relative performance of cell systems and the functionally organized systems they replace. This paper is an analysis of studies that use model‐based, controlled experimentation to seek answers to the questions of if, when, and why cellular layouts outperform their functional counterparts. Twenty‐four model‐based studies are analyzed with respect to their definitions of cellular versus functional layouts, the experimental factors that have been investigated, the results concerning relative performance, and the findings' relevance to layout choice. We conclude that although the comparative studies have been very valuable in their efforts at identifying the factors that embody the essence of cells and shape performance improvements, most of the basic findings are known from past research. Furthermore, the studies' findings cannot assist practitioners in making specific choices between existing layouts and alternative cell systems. However, the totality of the findings reinforce our knowledge of how work systems in general can be designed and organized to reduce throughput time, and can also be used to identify environments and conditions for which conversions to cells may have more or less potential.

Engineering changes in the design of a product, while attractive from a marketing viewpoint (in terms of increased sales opportunities, matching competitors innovations, etc.) cause disruptions in the manufacturing function of a firm. These disruptions include delays or backorders in the delivery of both committed‐orders and forecast‐demands of existing products, increased capacity requirements that could result in greater use of subcontracts, higher component inventories, and obsolescence of certain components. In this paper, we establish how the marketing opportunities and manufacturing costs associated with engineering changes can be managed so as to enhance the firm's profits over a planning horizon. Using an optimization model, we show that an enhanced product with increased marketing opportunities may not immediately replace the existing product; it may be phased in over a period of time. We further illustrate how the firm's overall profit, and the mechanics of phasing out the old product and phasing in the new product, are affected by factors such as the manufacturing lead time of the new product, its market attractiveness as compared to the old product, capacity availability, subcontracting premiums, and backorder costs. We develop several insights that allow managers to quickly establish whether an engineering change would be desirable and discuss a multitude of options that may be used to further enhance their desirability. Finally, we show that if the phase out period of the old product is set arbitrarily, rather than optimally, the result may be a substantial reduction in overall profits.

After a decade of updating and modernizing U.S. manufacturing with advanced management techniques (AMTS), competitive results have been generally disappointing. Industrial managers under pressure have relied on AMTS to solve their problems, but in this era of ever more intense and fast‐moving competition, this has generally proven inadequate. Competitors abroad have moved ahead just as vigorously and usually earlier in applying AMTS such as JIT, TQM, and MRP, so the result has been “competitíve gridlock.” Simultaneously, industry is full of misfits between manufacturing policies and strategy, as AMT‐driven managers make and change policies piecemeal. The mediocre results of this conventional, operational mindset demonstrate that sheer productivity improvement or other conventional performance objectives seldom build unique competitive advantage. Winning in competition today requires a different management approach, one which is focused on establishing competitive superiority. Basic structural redesign is the key to clear competitive advantage, but its rare practice signals the presence of problems in the skills, attitudes, and premises of many industrial managers. Rather than continuing the common practice of relying on available AMTS, a new breed of industrial managers is needed, equipped with a breadth of skills which encompass all the functional areas of production and who are business‐ and strategy‐rather than narrowly operation‐ and functionally‐oriented.

In this survey we review methods to analyze open queueing network models for discrete manufacturing systems. We focus on design and planning models for job shops. The survey is divided in two parts: in the first we review exact and approximate decomposition methods for performance evaluation models for single and multiple product class networks. The second part reviews optimization models of three categories of problems: the first minimizes capital investment subject to attaining a performance measure (WIP or lead time), the second seeks to optimize the performance measure subject to resource constraints, and the third explores recent research developments in complexity reduction through shop redesign and products partitioning.