摘要:

Issues relating to the bowl phenomenon in unpaced lines have been studied extensively; however, no previous paper has determinedoptimalbowl configurations of mean processing times for a given line length and buffer capacity under realistic operating conditions. We have discovered bowl-shaped configurations that perform better than perfectly balanced lines for systems of at least 30 workstations in length with interstation buffer capacities of up to one unit. Solid evidence confirms an earlier conjecture that the optimal two-level (i.e. flat-bottomed) allocation of mean processing times performs no worse than the optimal multi-level configuration. Information useful to the industrial engineer has been obtained through an examination of the maximum amount of imbalance that still provides some productivity benefit. It has been found that the amount of imbalance in a line can generally be double the imbalance in a optimal bowl and still perform better than the balanced line. This study also contradicts earlier conclusions in that the bowl phenomenon is still appropriate for smaller coefficients of variation and greater buffer capacities.

ISSN:0020-7543    

DOI:10.1080/00207549408956948

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper proposes an algorithm for hoist scheduling problems in a flexible PCB electroplating line where there is no buffer among workstations. Due to its chemical process nature, the processing times have to be controlled within a specified range (i.e. between a maximum processing time and a minimum processing time). The product will become defective if this constant is violated. The objective is to maximize throughput with no defective product. The proposed algorithm schedules jobs entering the system based on the specified range of processing time. A simulation study shows that the proposed algorithm outperforms the basic algorithm that schedules jobs based on the minimum processing times.

ISSN:0020-7543    

DOI:10.1080/00207549408956949

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A heuristic, analytical model is developed to integrate the work in process storage space allocation and block layout planning steps of the facility design process. The model is applicable when identical unit loads are transported by a discrete materials handling system. The model is applied in the context of a ‘CRAFT like’ procedure where the user can reallocate storage space between departments on successive iterations while simultaneously considering materials handling volume distance and dynamically changing storage requirements. The scope of model inputs includes the layout, materials handling system attributes and production parameters. It is shown that the analytical nature of the model and scope of model inputs also allow the user to investigate significantly different production scenarios and materials handling system designs in layout planning. As a result, the model provides greater modelling flexibility than simulation and Petri net modelling in supporting sensitivity analyses in layout design. An example problem is used to illustrate application of the model.

ISSN:0020-7543    

DOI:10.1080/00207549408956950

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Acceptance control charts establish control limits based on specification limits for very capable processes where the mean is permitted to vary. This paper deals with designing such charts when a product has two or more correlated characteristics that must all simultaneously conform to specification limits for the product to be acceptable. We extend past work by solving the general correlated multivariate case, and by allowing a more general hypothesis test. We find the control limits and sample sizes for each characteristic that minimize sampling costs. The problem is a convex nonlinear optimization problem, and optimal solutions are found using multidimensional search.

ISSN:0020-7543    

DOI:10.1080/00207549408956951

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An architecture for structuring and implementing an object-orientated process planning system for manufacturing is described. The primary objective of the architecture is modularity, where modularity is achieved mainly through polymorphism. The manufacturing objects are identified, as is the knowledge they own and the interactions between objects. Process planning is conducted solely with autonomous objects, and manufacturing tools are the primary actors. The architecture and its modularity are demonstrated with two working systems, one for sheet metal and one for turning.

ISSN:0020-7543    

DOI:10.1080/00207549408956952

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper describes a fuzzy set theory based heuristic for the quadratic assignment formulation of the facility layout problem with single/multiple objectives. A heuristic procedure is presented, that involves the assignment of facilities to locations to generate an initial solution and then possibly improving the solution through shifting of facilities as per the scope for improvement identified during the evaluation of the generated solution. The effectiveness of the heuristic, in terms of quality of solution, is illustrated with a numerical example. Finally, a set of examples, previously used by various researchers, are solved and the results are compared with the optimal solution or with the 'best' solution of other known heuristics. The results of comparison indicate that the proposed procedure performs well in terms of quality of solution.

ISSN:0020-7543    

DOI:10.1080/00207549408956953

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper discusses the results of simulation tests for multi-item, single-machine production systems facing stochastic, time-varying demands. Six different heuristics are compared with the objective of minimizing the sum of changeover and inventory costs. Tests are performed to evaluate the effect of the stationarity of the demand process and of the level of forecast errors on the performance of the heuristics tested.

ISSN:0020-7543    

DOI:10.1080/00207549408956954

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In this paper, the accessibility of coordinate measuring machines (CMM) and path generation in dimensional inspection are studied. The objective is to develop an algorithm which can determine all the feasible probe orientations for the inspection of a workpiece using a touch trigger probe. The feasible probe orientations ensure that when the probe tip is in contact with the workpiece there should be no collision with either the touch probe or the probe stylus. The algorithm should be able to handle internal holes and complex surfaces and be capable of extending to multiple surfaces. After solving for the probe orientations, a heuristic method determines the number of probe orientations required to inspect the workpiece. It then picks the optimal probe orientation and creates a collision-free inspection path based on the information for probe orientation.

ISSN:0020-7543    

DOI:10.1080/00207549408956955

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The major objective of engineering change is to redesign product/component parts to perform better or to be produced more efficiently. However, frequent engineering changes contribute to scheduling instability. When a material requirements planning (MRP) system is used as the production planning and inventory control method, scheduling instability becomes the most difficult problem for production planners to deal with. The purpose of this paper is to evaluate the trade-off between frequent engineering changes and resultant cost increments in writing off obsolete items. A simulation experiment is conducted to examine the effect of different frequencies of engineering changes on the performance of a multi-level MRP system under various operating environments. An analysis is also performed to evaluate the sensitivity of base experimental results to changes in important parameters which are held constant in the simulation experiment. Results show that frequent engineering changes indeed deteriorate MRP system performance considerably. Furthermore, an appropriate selection of a lot-sizing rule tends to mitigate the impact of frequent engineering changes. A lot-sizing rule such as part-period balancing consistently generates the least cost increment as engineering changes become frequent.

ISSN:0020-7543    

DOI:10.1080/00207549408956956

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Process planning for assembly requires a computerized representation and analysis of assembled products. In order to recommend a good sequence of assembly operations, the process planner needs to generate all such feasible sequences. This paper presents a methodology to consistently generate all feasible asssembly sequences with consideration for the various combinations of subassembly operations. The methodology is demonstrated on a real product. A practical method to reduce the number of feasible combinations generated is also demonstrated.

ISSN:0020-7543    

DOI:10.1080/00207549408956957

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor