摘要:

The paper develops a complex simulation model (written in GPSS) that comprises a range of different shop management decision areas such as job sequencing, overtime usage, machine speed variations and alternate machine selection. A suboptimal scheduling procedure is proposed which takes into account trade-offs between machining and delay cost on one hand, and computer time on the other hand. The efficiency of the heuristic is studied by means of model assumptions referring to real-world characteristics in the engineering industry environment.

ISSN:0020-7543    

DOI:10.1080/00207548908942607

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Although many companies have found JIT manufacturing to be a very effective manufacturing strategy, few models have been developed which can help direct JIT efforts. This article discusses some of the problems with modelling JIT manufacturing, it describes some simple models of inventory costs in a JIT system and it uses these models to evaluate alternative inventory-cost reduction strategies in a printed circuit board (PCB) assembly system.

ISSN:0020-7543    

DOI:10.1080/00207548908942608

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper examines the order review/release (ORR) function and its impact on the operation of the shop floor. A source of disagreement between practitioners and researchers, ORR is an important element of any shop floor control system. This paper attempts to provide a better understanding of this element by presenting a framework for ORR. This framework not only identifies the important dimensions of ORR but also new dimensions for research. The paper also explores the relationship between ORR and job dispatching through a simple computer simulation model. The results indicate that the ORR, while reducing time spent in queue on the shop floor, does not always reduce the total time spent in the system.

ISSN:0020-7543    

DOI:10.1080/00207548908942609

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

In this paper we present heuristics and analytical models for the order batching problem. Orders are batched into tours such that the total travel time is minimized. Four heuristics are developed for the order batching problem, for which no exact solution exists. All heuristics are based on the time-saving criterion of combining two or more orders in a single tour rather than processing them one order at a time. Among the heuristics that are presented, the SL algorithm has the best performance. An analytical model is developed to estimate the travel time of the S/R machine as a function of the number of locations to be visited and the physical specifications of the structure. Expressions for upper and lower bounds for travel time are presented.

ISSN:0020-7543    

DOI:10.1080/00207548908942610

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Material requirements planning (MRP) systems have become a dominant method in production scheduling and inventory control over the last decade. An MRP is a very complicated information system. It needs to be updated frequently in order to reflect unplanned events, such as machine breakdowns, that exist within or outside the production system. However, the resultant frequent disruption of open orders is a major operational problem of MRP systems, which is generally referred to as 'system nervousness'. MRP system nervousness is caused by various operating variables and environmental factors. The purpose of this paper is to evaluate the impact of operating environments, external or internal, on MRP system nervousness. Several studies have addressed the effectiveness of alternative strategies for reducing MRP system nervousness in a number of operating environments. In this study, a factory simulation is used as an experimental vehicle to investigate the impact on M R P system nervousness of various factors, such as the tightness of capacity utilization and the lot-sizing algorithm used. Based on this study, a set of guidelines is presented which allow MRP users to select an appropriate dampening strategy to cope with system nervousness in face of their operating environments.

ISSN:0020-7543    

DOI:10.1080/00207548908942611

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A flexible manufacturing cell (FMC) has become of major interest recently as a new machining unit for low-volume, variety production. However, set-up operations for workpieces have not yet been automated in the usual FMC. In this paper, the design and scheduling problems for FMC with automatic set-up equipment are discussed. The FMC consists of a machining centre, an industrial robot, a loading-unloading station and an index-pallet changer. First, the design and control system of the FMC is explained. Then a scheduling algorithm is developed to achieve the minimum total production time in order to operate the FMC effectively. As this FMC has finite buffer spaces on the index-pallet changer, this model can be regarded as a two-machine flow-shop problem with finite buffer spaces. Next, an algorithm for determining the optimum number of buffer spaces is constructed to design the FMC using the results of scheduling. Finally, a numerical example is given for demonstrating the effectiveness of the proposed algorithms.

ISSN:0020-7543    

DOI:10.1080/00207548908942612

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

One of the difficulties associated with the application of graph theory to the facilities layout problem is the conversion of the dual graph into a block layout. This paper presents a procedure to address this problem. The procedure exploits the similarities between the graph-theoretic approach and computerized layout-construction procedures, and also resolves some of their differences. It considers the faces of the dual graph one by one and places them in the block layout adjacent to each other in a manner consistent with the adjacencies specified by the dual graph, The procedure is independent.of the manner the maximal planar weighted graph is developed.

ISSN:0020-7543    

DOI:10.1080/00207548908942613

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Among the models developed to form machine cells in group technology applications, those based on the similarity coefficient method (SCM) are more flexible in incorporating the manufacturing data into the machine cells formation process. SCM is the application of clustering techniques to the machine cells formation problem. When SCM is used to form the machine cells, some bottleneck machines are not initially assigned to proper cells. These machines should be reexamined and be reassigned to their proper cells in order to reduce the number of intercellular moves. This problem is referred to as 'improper machine assignment' and is the subject of discussion in this paper.

ISSN:0020-7543    

DOI:10.1080/00207548908942614

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper presents a model for obtaining the optimal buffer space size in two-stage machining systems. It is shown that the optimal buffer space size is the one necessary to keep the critical machine running even when there are tool failures and subsequent tool changes on the non-critical machine. An analytical expression for the optimal buffer space size is derived when tool failures follow a Markovian process and the objective function is the minimization of the unit cost. A simulation mode! is developed for obtaining the optimal buffer space size when tool failures follow a non-Markovian process. It is shown that the optimal buffer space size depends on the expected delay time per part due to tool failures on the non-critical machine (which depends on the probability of tool failure on the non-critical machine during machining on the critical machine), on the labour and the buffer space cost, and on the tool-change time. The model can be extended to cover the case of two or more identical parallel machines per stage and the case of multi-stage machining systems.

ISSN:0020-7543    

DOI:10.1080/00207548908942615

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

This paper considers the ability of the existing aggregate planning approaches to model the type and range of planning variables currently used in industrial planning. From this stems the initiative to present a goal-search approach to aggregate planning, which has the ability to model across a wider range of real-world planning and environmental conditions. The validity of the approach is checked by comparing it against other prominent planning approaches. Finally the goal-search performance is demonstrated through considering variable worker productivity, profit and multiple goals.

ISSN:0020-7543    

DOI:10.1080/00207548908942616

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor