Group Technology exploits similarities in product and process design to meet the diversity of customer demand in an economic way. In this paper we consider one of the implementations of this concept -family-based dispatching. Intrinsic to family-based dispatching is the grouping of similar types of products for joint processing. In this way the number of set-ups may be reduced. Consequently, lead-time performance of the shop can be improved. We extend existing rules for family-based dispatching by including data on upcoming job arrivals. Typically, this type of data resides in the minds of the operators, or is stored in a shop-floor control system. Its availability allows for (1) better estimates of the composition of a process batch for a family, (2) the consideration of families for which no products are available at the decision moment, and (3) the possibility to start set-ups in anticipation of future job arrivals. The potential of including forecast data in decision-making is demonstrated by an extensive simulation study of a single-machine shop. Results indicate the possibility of significant improvements of flow time performance.

This paper reviews prior research in the area of virtual manufacturing cells. A virtual manufacturing cell (VMC) is a group of resources that is dedicated to the manufacturing of a part family, though this grouping is not reflected in the physical structure of the manufacturing system. Distinguishing such groups in the production control system offers the possibility of achieving the advantages of cellular manufacturing in non-cellular manufacturing systems. The advantages may include improved flow performance, higher efficiency, simplified production control, and better quality. The paper reviews the previous publications on virtual manufacturing cells, to determine the methods and scope of present research. This results in a comprehensive framework which identifies the underlying principles of VMCs and classifies the different VMC concepts. It is shown that virtual manufacturing cells can significantly improve the performance of manufacturing systems. Based on the comprehensive review, many future research issues and high-impact research areas are also identified.

International audienceIn many practical instances, the choice whether to apply family-based dispatching or not can be decided per machine. This paper explores the impact of the location of family-based dispatching, load variations between machines, and routing of jobs on the flow time effect of family-based dispatching. These factors are explored in small manufacturing cells with and without labour constraints. An industrial case motivates the study. A simulation study is performed to assess the impact of these effects. The results show that shop floor characteristics such as routing and load variation impact the decision where to locate family-based dispatching in manufacturing cells without labour constraints. By contrast, the effect of family-based dispatching is much less vulnerable to shop floor characteristics in cells with labour constraints. Since workers are the bottleneck in these cells, it becomes less important at what machine the set-up time involving a worker is reduced. In general, there seems to be a trade-off between the positive effect of applying family-based dispatching at a (bottleneck) machine and the possible negative effect of the more irregular job arrivals at subsequent machines. The results further indicate that family based dispatching is more advantageous in cells with labour constraints than in cells without labour constraints, when both types of manufacturing cells have comparable machine utilisations

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