摘要:

A model is presented for jointly determining the profit-maximizing number of workstations and interstation buffer capacities for stochastic unpaced lines. Several important implementation issues are discussed and system sensitivities examined, providing the line designer with new and important tools and insights.

ISSN:0020-7543    

DOI:10.1080/00207549408956983

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper studies the effects of work-in-process (WIP) inventory on the simultaneous determination of the optimal production batch sizes of the single product and its component parts, where the component parts, processed in manufacturing cells, are assembled into the product. We develop a procedure to simultaneously find the optimal lot size for the product and its component parts and the total relevant cost. The effect of setup reduction is considered. A numerical example demonstrates that, in the lot size computation, the WIP inventory costs and the relationship between the product and its component parts should all be taken into account.

ISSN:0020-7543    

DOI:10.1080/00207549408956984

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Carousels have been used in industries for many years. In addition to being one of the most efficient storage alternatives for order picking, they are also very economical. The purpose of this study is to help engineers in obtaining a storage carousel design that satisfies the storage requirements, space constraints and throughput requirements at the minimum cost. A three phase approach is used in the proposed design procedure. Phase I eliminates the alternatives not meeting the storage requirements and space limitations. In phase II, simulation is utilized to obtain the throughput of each feasible design realized in phase I. Hence, the alternatives which do not satisfy the throughput requirements can be eliminated at this step. Finally, the total cost of all the qualified alternatives from phase II are computed in phase III and the alternative with the minimum cost is recommended to the designers. A case study is also analysed to verify the proposed design procedure.

ISSN:0020-7543    

DOI:10.1080/00207549408956985

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Nearly all of the literature on part type selection for flexible manufacturing systems has focused on maximizing throughput. We present an approach for part type selection in which meeting due dates is the primary objective. The approach is based on the idea of using information from the solution of an approximate, aggregate scheduling problem as the basis for determining release priorities. The need for the approximation and aggregation arises because the exact machine configuration (partitioning of identical machines into groups, and loading of tools) cannot be decided until the parts are selected. We develop and evaluate several different policies for setting release priorities in a context where the approximate, aggregate schedule is constructed using list scheduling (dispatching) rules. The results indicate that using information from such a schedule to set release priorities performs far better than using simpler procedures.

ISSN:0020-7543    

DOI:10.1080/00207549408956986

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The challenge of improving performance in the job shop can be met in a number of ways. We can rely on variance control to reduce variances created either in the planning system (through uneven or fluctuating loads) or on the shop floor (through varying processing times for released batches). We can rely on Order Review/Release (ORR). Finally, we can turn to one of the various dispatching rules that are available. Each option has been previously examined. However, this study examines all of these options simultaneously within the context of a simulated simple job shop. Based on a regression analysis of the data generated, several interesting results are uncovered. First, the results show that the presence of variance control at both the planning and shop floor levels can greatly enhance the effectivess of ORR. This result partially helps resolve the controversy surrounding ORR. Second, the results show that Shortest Processing Time (SPT), while extremely effective in an uncontrolled environment, reacts adversely to the presence of variance control. Finally, if used effectively, variance control can greatly reduce the need for complex dispatching rule.

ISSN:0020-7543    

DOI:10.1080/00207549408956987

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

To integrate CAD and CAM of 2½ D prismatic machining parts, part descriptions in low-level format, such as Boundary Representation, are typically interpreted into forms of high-level features, such as pockets and virtual pockets, to facilitate process planning and tool path generation. A recognition procedure is required to transform the low-level data into machinable pocket definition. For complex depression volume where pocket interactions occur, current feature recognition algorithms do not adequately recognize the pockets such that the complex depression volume can be transformed into individual pockets machinable by current pocket milling techniques. Furthermore, in a complex depression, there may exist multiple equally valid set of pockets to describe the same total removable volume. The problem of recognizing multiple interpretations of pockets from part description in Boundary Representation (Brep) is presented in this paper. The algorithm presented in this paper first uses volume decomposition to decompose the total removable volume into small blocks of machinable volume. Then based on machining strategies of 2½D pockets, the small blocks are reconnected in a systematic way to reconstruct pocket volumes and generate multiple interpretations. The result provides multiple sets of pockets, and hence shows that there are multiple ways to machine a part with interacting pockets. Sample results demonstrating the implementation and the capabilities of the algorithms are discussed.

ISSN:0020-7543    

DOI:10.1080/00207549408956988

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The focus of this study is on investigating worker assignment policies in dual resource constrained (DRC) job shops which include features such as the presence of heterogeneous resources and worker transfer delays between different departments. Previous studies on DRC systems have not modelled a shop which includes these design features simultaneously, although both of them would be present in many actual DRC environments. Several worker assignment policies that can be expected to work well in such environments are proposed and tested. Results indicate that in most DRC shops that have heterogeneous resources and finite transfer delays, decentralized assignments which delay the transfer decisions improve system performance. Additionally, two different task selection rules are shown to be very robust in giving good performance across a wide range of DRC environments modelled in the study.

ISSN:0020-7543    

DOI:10.1080/00207549408956989

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The use of redundant manipulators in assembly stations, where a number of pick-and-place tasks needs to be performed, is examined in this paper. The aim is to obtain optimum values for the location of the robot in the workstation, the sequence of tasks and the configuration of the robot at each task location, such that the total travel time is minimized. The location of the robot and the optimal configurations, for a given sequence of tasks, is obtained by formulating and solving a constrained nonlinear optimization problem using the sequential quadratic programming method. A near-optimum sequence of travel is then obtained using simulated annealing. The proposed techniques are illustrated using three numerical examples.

ISSN:0020-7543    

DOI:10.1080/00207549408956990

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Hierarchical Production Management uses different decision levels and handles a different model at each of these levels. The model of the top level leads usually to a continuous flow control problem under finite capacities. Here we study the problem of minimizing in-process inventory cost under finite capacity constraints and for a continuous time varying demand. The multi-product problem is examined. We finally propose a numerical application to illustrate the analytical results.

ISSN:0020-7543    

DOI:10.1080/00207549408956991

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Since Muth (1973) it has generally been accepted that the throughput of production lines with variable processing times depends primarily on the first two moments of the processing time distribution. However, several recent studies have suggested that differences in higher moments may lead to significant differences in throughput. In order to shed light on this question, we examine the applicability of the two-moment approximation over a variety of types of lines (both serial and assembly) and a variety of processing time distributions. We find significant differences in throughput (on the order of 5%) even among commonly used probability distributions, and large differences (as large as 28%) among highly skewed and kurtotic distributions. We also find that the differences among distributions generally increase with the number of stations in the line and with the coefficient of variation of processing times.

ISSN:0020-7543    

DOI:10.1080/00207549408956992

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor