摘要:

In this paper, a systematic methodology to enhance the effectiveness and efficiency of the product development process under a Concurrent Engineering (CE) environment is presented. The concepts adopted by this methodology are analogies to the total productivity enhancement concepts employed in Just-In-Time (JIT).

ISSN:0020-7543    

DOI:10.1080/00207549508930167

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Sensitivity analysis of performance measures, like through-put or utilization, with respect to system parameters, such as service time parameters or buffer sizes, leads to improving and optimizing the performance of a given system. For a sample system from the world of manufacturing, we discuss various methods for estimating the sensitivity of the steady-state through-put. We compare the application of the finite difference estimator (where the sensitivity is estimated with the help of two independent simulation experiments) with the application of the infinitesimal and finite perturbation analysis (where the sensitivity is estimated with only one simulation experiment). Numerical examples are given to illustrate the practical aspects of the application of these methods.

ISSN:0020-7543    

DOI:10.1080/00207549508930168

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The situation of a family of items sharing a piece of production equipment is considered. Known level demand rates are assumed. The items are scheduled in a cyclic fashion where the production cycles through all of them every T units of time. There are shelf life limits for each of the items. I deal specifically with the situation where the cost-minimizing T leads to the violation of one of the shelf life constraints. Removing the infeasibtlity by simultaneously adjusting T and the production rate of the item concerned is shown to be at least as good as adjusting just one of these parameters.

ISSN:0020-7543    

DOI:10.1080/00207549508930169

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Learning curve theory has been an important consideration for capacity planning and bid preparation since the 1940's. Constraint theory is a relatively new approach to managing manufacturing systems. This paper examines the implications each of these theories has for the other. Several important relationships are identified using a deterministic simulation of a simple production line which is influenced by learning and the presence of a system constraint. The rate of improvement of several measures of system performance follows the learning rate, but because of the role played by the constraint, other measures of performance actually get worse.

ISSN:0020-7543    

DOI:10.1080/00207549508930170

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We deal with the problem of tool management in FMSs that are provided with a tool carrier. The paper reports on a procedure to determine how many copies of the various types of tools should be present and describes a simulation study that investigates the possibility of reducing the investment in tools by sharing the tools among several machining centres. The performance of the FMS is measured by the fraction of time that machining centres are unable to work because the tool required for the next imminent operation is not present in the tool magazine of the machining centre. These waiting times depend on the selection of tools available at the central tool magazine and on the tool management policy. The paper shows that by a proper management of the tool transport system it is possible to obtain savings in tooling while preserving the performance of the FMS.

ISSN:0020-7543    

DOI:10.1080/00207549508930171

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We describe the method of verification and manual and automatic editing of the NC code. A new method was proposed to find out the errors quickly and to edit the errors easily. Both wireframe display of tool path and solid display of machined part are used to detect the motion command errors and auxiliary command errors in NC code. The Z-map method was used for the shaded image display and the comparing the CAD data and CAM data. Using the verification result, the NC program was edited manually without returning to the programming stage. In addition, an automatic editing was proposed to overcome the limit of manual editing. The method was implemented as a software in an IBM/PC with the MS-Windows.

ISSN:0020-7543    

DOI:10.1080/00207549508930172

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We present a realistic cell formation problem in the design of cellular manufacturing systems which includes three important features. First, when multiple units of a machine type are considered due to processing time requirements, the model accounts for assigning the units to different cells if such an assignment contributes to reducing material handling costs. Second, the model accounts for the possibility of performing two or more nonconsecutive operations of a part on the same machine. Finally, the model allows for splitting the lot into two if the total workload required of a part's operation on a machine exceeded its daily unit capacity expressed in manned hours. We refer to this feature as ‘lot splitting’. Consequently, the operation required of each split lot of the part can be performed on a separate unit (machine). The model formulated for the problem falls into the class of generalized quadratic binary programming models. As the problem is shown NP-hard in the strong sense, a higher level heuristic algorithm based upon a concept known as tabu search is presented. Results obtained from solving an example problem demonstrate the application of the proposed algorithm when either of the two features—lot splitting or nonconsecutive operations, exist. The applicability of the proposed algorithm has further been extended to solving a test problem consisting of both features—lot splitting and non-consecutive operations. The results obtained show a reduction of ⩽ 50% in total moves (material handling costs) between the initial solution and the final best solution.

ISSN:0020-7543    

DOI:10.1080/00207549508930173

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We consider finite-buffered fork/ join queueing networks under the so-called ‘blocking before service’ mechanism. For such networks with exponential servers, Ammar and Gershwin (1989) showed some throughput equivalencies between different network configurations. We show that their result also holds even when service time distributions are general, using the sample path argument. Additional equivalencies are also suggested along with a remark on a multi-server case.

ISSN:0020-7543    

DOI:10.1080/00207549508930174

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Artificial intelligence has been claimed to yield revolutionary advances in manufacturing. While most of the survey papers about artificial intelligence in manufacturing have been focused on knowledge-based expert systems, fewer attentions have been paid to neural networks. However, neural networks are able to learn, adapt to changes, and can mimic human thought processes with little human interventions. They could be of great help for the present computer-integrated manufacturing and the future intelligent manufacturing systems. This paper presents a state-of-the-art survey of neural network applications in manufacturing. The objective of this paper is to update information about the applications of neural networks in manufacturing, which will provide some guidelines and references for the research and implementation.

ISSN:0020-7543    

DOI:10.1080/00207549508930175

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In sheet metal fabrication, bending is used in order to obtain rigidity and to obtain a part of desired shape and function. In analysing a sheet metal part, an important consideration is how to unfold the part after a bending operation or series of bending operations. The unfolding process is the first major step in process planning for generating NC paths for a sheet metal blank. This paper addresses the problem of determining whether or not a part can be unfolded. A graph-based approach using the face-edge of the sheet metal part is at the heart of the algorithm presented here. Using this algorithm one can determine which faces are unfoldable and which cannot be unfolded. This algorithm can be used to help facilitate the process of NC path generation. It also sheds some light on the kind of design practices that make a part easily unfoldable or otherwise.

ISSN:0020-7543    

DOI:10.1080/00207549508930176

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor