John B. Jensen

Machine dedication and process flexibility in a group technology environment

Abstract This study investigates changes in inventory and customer service performance of a job-shop that desires to adopt a Group Technology (GT) philosophy in its shop floor operations. Simulation methodology is pursued to explore tradeoffs in shop performance between the routing flexibility of non-dedicated machines in a functional job-shop and the setup efficiency of dedicated machines in shops that have machine cell layouts. Further, traditional and GT-based scheduling procedures are investigated in these different shops to determine the conditions under which a GT philosophy may be profitably employed only in layout decisions, only in scheduling decisions, or in both layout and scheduling decisions. Results from this study show that shop layout choice is not a simple decision that can capitalize either on the high routing flexibility of the functional job-shop or on the setup efficiency advantages of a cell shop. The tradeoffs between routing flexibility and setup efficiency must be made carefully. The impact of demand variability on performance is also dependent on the type of layout. In general, product volume variability more adversely affects the performance of functional job-shops, while product mix variability has greater impact on the performance of cell shops. Finally, sensitivity analysis is performed to show that maintaining balance between the utilization of machines is a major determinant of performance, and consequently the best layout.

Improving the application of quality conformance tools in service firms

Explains that, as global competition changes the expanding service sector, quality will play an increasingly pivotal role in both attracting and retaining service customers. Reveals that research into service quality has addressed two important dimensions: promoting quality through the design of improved service systems; and searching for reliable instruments for measuring service quality. Proposes a procedure to help the service provider interpret service quality data to improve the service delivery system. Additionally, evaluates a two‐step control chart procedure for evaluating service operations using SERVQUAL type instruments.

The impact of resource flexibility and staffing decisions on cellular and departmental shop performance

Abstract Shop floor control researchers have begun to compare the shop performance advantages of varying forms of resource flexibility. Two major streams of shop floor control research, dual resource constrained shop scheduling (DRC) and group technology (GT), are converging as the literature documents that different forms of resource flexibility aid shop performance in different ways. For example, the DRC literature shows that a small amount of worker flexibility, in the form of cross-training, may be all that is required for superior shop performance. However, the GT literature demonstrates that restricting machines from processing individual part families reduces overall shop effectiveness. Not only does it appear that diverse forms of resource flexibility may be used to alter shop performance in different ways, it may also be that environmental characteristics play a role in arbitrating the performance-improving strength of different forms of flexibility. Studies that have jointly investigated machine and labor flexibility have generated very different conclusions. In this paper we examine the performance advantages of machine and labor flexibility over a wide and realistic set of assumptions and shop floor decisions. We evaluate shop floor control within three different shop configurations at four different levels of staffing. Results indicate that the conclusions of previous studies regarding the choice between labor and machine flexibility are relatively insensitive to a group of labor assignment rules, somewhat more sensitive to changes in demand variability, and very sensitive to staffing levels. Further, this study demonstrates that under several sets of conditions, promoting labor flexibility to the exclusion of machine flexibility provides excellent performance.

FAMILY-BASED SCHEDULING OF SHOPS WITH FUNCTIONAL LAYOUTS

Simulation studies of job shop scheduling have typically assumed that either setup times are zero (subsumed within the processing time), or that every part has such a unique setup that no setup advantages can be gained by better scheduling policies. These studies also assume that the shop has exactly one copy of every machine. Some researchers have proposed heuristics that explicitly consider setup times and parallel machines in the context of a one stage shop with static arrivals. In contrast, family-based scheduling centred around setup time reduction has been credited with achieving economic savings in batch production industries where GT is employed. We motivate this study by the case of an existing realworld semi-conductor testing facility that has family setups, parallel machines and dynamic job arrival. Using this setting, we investigate whether benefits can still be obtained by using a family-based scheduling philosophy in those environments which do not permit the physical creation of cellular la...

Assessing Effectiveness of Supply Chain Collaboration: An Empirical Study

Even though collaboration has obtained increasing popularity in the supply chain (SC) arena, its effectiveness has not been measured empirically at a national level. In this paper, we refine, validate, and then employ an instrument that measures (1) the extent of information sharing, joint planning, goal congruence, personal interaction, and trust between SC partners and (2) manager perception of the effectiveness of this collaborative relationship. These factors along with several firm- specific variables that the literature has suggested (i.e., number of employees, annual sales revenue, percent of partners involved in collaboration, years in collaboration, and length of current agreement) are used to explain the effectiveness of SC collaboration using regression analysis.

Shop Performance Implications of Using Cells, Partial Cells, and Remainder Cells*

This paper considers the application of cellular manufacturing (CM) to batch production by exploring the shop floor performance trade-offs associated with shops employing different levels of CM. The literature has alluded to a continuum that exists between the purely departmentalized job shop and the completely cellular shop. However, the vast majority of CM research exists at the extremes of this continuum. Here, we intend to probe performance relationships by comparing shops that exist at different stages of CM adoption. Specifically, we begin with a hypothetical departmentalized shop found in the CM literature, and in a stepwise fashion, form independent cells. At each stage, flow time and tardiness performance is recorded. Modeling results indicate that, depending on shop conditions and managerial objectives, superior shop performance may be recorded by the job shop, the cell shop, or by one of the shops between these extreme points. In fact, under certain conditions, shops that contain partially formed cells perform better than shops that use completely formed cells. Additional results demonstrate that in order to achieve excellent performance, managers investigating specific layouts need to pay especially close attention to changes in machine utilization as machine groups are partitioned into cells.

Learning and labour assignment in a dual resource constrained cellular shop

Recent studies have shown that in a cellular shop that benefits from learning due to repetitive processing, limitations attributable to routing flexibility can be more than offset. Moreover, the shop can respond more quickly to changes in demand than a job shop. This study examines the impact of labour assignments in a dual constrained cellular shop in which processing times decrease with operator task repetition. Results indicate that in the presence of operator learning, shop performance is significantly affected by the flexibility permitted in labour assignments. Moreover, the sensitivity of performance to labour assignments is significantly impacted by staffing levels and the magnitude of learning effects.

Trane/Ingersoll Rand Combines Lean and Operations Research Tools to Redesign Feeder Manufacturing Operations

Trane U.S. Inc., a brand of Ingersoll Rand, is a leading global provider of indoor comfort systems and services. It provides service, parts, and financial solutions to commercial and residential customers worldwide. In this paper, we showcase results of combining classic lean techniques, such as value stream mapping, with operations research analytics, including statistical and simulation modeling, to dramatically improve the manufacturing of a problematic feeder component assigned to a dedicated manufacturing process. We first used value stream mapping to visualize the process and develop an overall lean strategy for the manufacturing cell. We then used regression analysis to express the relationship between numerous product attributes and improvement opportunities. Finally, we developed simulation models to assess the effectiveness of process changes on cell performance under a wide range of demand and processing conditions prevalent at the plant. Process improvement recommendations presented to Trane management included 1 a redesigned material strategy, 2 a new cell layout, and 3 a one-piece product flow. In combination, these improvements facilitate a 13 percent throughput improvement, 50 percent cycle-time reduction, and higher cell efficiency that led to projected recurring savings of more than

Evaluating the shop-wide performance effect of pooling synergy with analytical models

700,000 per year.

Snider Tire Optimizes Its Customers-Stores-Plants Transportation Network

This paper explores some simple queuing-based spreadsheet tools that provide information to managers interested in forming cells. These interim models can help the practicing manager build powerful insights. Specifically, we demonstrate that work in process inventory (WIP) requirements as well as cycle time performance can be easily obtained for individual cells as well as relatively complicated shop arrangements. To illustrate the usefulness of this spreadsheet approach, this paper contrasts a spectrum of shops and documents the performance effect due to a loss of pooling synergy.