摘要:

A just-in-time (JIT) buyer demands frequent deliveries of small lots of certain products. However, there is a perception among the suppliers that participation in a JIT delivery system is economically disadvantageous for them. To test this conjecture, a generalized inventory model is developed for a supplier who has to meet a deterministic demand at fixed intervals. The generalized total cost model developed here is found to be a piecewise convex function. A simple algorithm is developed to compute the optimal batch size. When production uptime and cycle time are each equal to an integer multiple of the shipment interval, a perfect matching of shipment size occurs, and for such a situation, the generalized model specializes to more traditional inventory models. The solution approach for such models becomes much easier. It is found that, under certain conditions, the total cost decreases linearly with reduced shipment size and the suppliers benefit from this. Economic impact of ordering and setup costs reduction are also investigated.

ISSN:0020-7543    

DOI:10.1080/00207549208942936

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The problem of grouping printed circuit boards (PCBs) for simultaneous assembly on electronic assembly machines is an extension of the set-covering problem. A general approach based on cluster analysis and measure of similarity between PCBs is suggested as a basis of PCB grouping. The approach is independent of the specific similarity measure used. We show that, due to the analogy between this problem and the problem of machine cell formation in group technology, similarity measures developed for the second problem are useful as building blocks in a general framework that solves the PCB grouping problem.

ISSN:0020-7543    

DOI:10.1080/00207549208942937

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Most existing FMS performance measures assume the existence of some correlation between maximum profit and system performance. In this article the ‘contribution to profit per unit time’ is adopted as a direct measure of system performance. A simple system having one machining centre, for handlingndifferent products is described, which operates under four different production environments. In each case, relationships are developed which enable the scheduler to implement a decision-making procedure that maximizes the contribution to profit per unit time.

ISSN:0020-7543    

DOI:10.1080/00207549208942938

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper presents a structure for an integrated CAD/CAM system in wireframe models than can be simultaneously used for product design and manufacture of prismatic components. A feature-driven, process-based design methodology, which derives its basis from traditional geometry-based design, feature-based design, deterministic and expert heuristic manufacturing knowledge, is proposed. This methodology provides an integrated modelling environment for automation of downstream manufacturing applications such as process planning and NC code generation. Representation of features in the design database is not limited to geometry alone but includes material, tooling and machine specifications and is based on a process-to-geometry mapping. Research shows that informational completeness of a CAD database depends on application; and for manufacturing tasks, the vocabulary of the process describing the means of making a part should be mapped directly to the feature-based geometry. This effort answers key issues in integrating CAD and CAM in the most widely used wireframe modelling systems.

ISSN:0020-7543    

DOI:10.1080/00207549208942939

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Many researchers have suggested methods for developing manufacturing cells (machines cells/part families). However, few of these methods have addressed the possible (in actuality, highly probable) existence of exceptional elements in the solution. Exceptional elements are bottleneck machines and exceptional parts that span two or more manufacturing cells. This paper presents a mathematical programming model that deals with exceptional elements. An initial solution is developed using any of the numerous cell formation procedures. Any exceptional elements that can be eliminated by changing the design or the process plans of the parts are eliminated. Then, the mathematical programming model is solved to determine how best to deal with the remaining exceptional elements. The mathematical programming model considers three important costs: (1) intercellular transfer; (2) machine duplication; and (3) subcontracting. The model is an optimizing model that can recognize possibly advantageous mixed strategies ignored by previous approaches.

ISSN:0020-7543    

DOI:10.1080/00207549208942940

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Automated printed circuit board assembly is a complex process where accuracy is a critical issue. This paper discusses the quantitative effects of linear and angular errors present in such a system on the successful assembly of through-hole components that have been properly registered. Both additive and statistical error compounding methods are illustrated. Mathematical models developed in this study can be used to determine the relative effects of critical system parameters and tolerances on proper insertion of the component into the pc board. Optimal design and control specifications can therefore be obtained for an efficient and successful assembly system.

ISSN:0020-7543    

DOI:10.1080/00207549208942941

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Facet point drills have been favoured for CNC machining, yet their geometry has not been standardized so far. In this paper, a possible geometry of facet point drill has been analysed and a preferred method of specification, which uniquely describes the point geometry, is established along with the point sharpening method. Based on acceptable grinder criteria a range of values of the specified features which can be used to successfully produce this type of drill point have been proposed. A mechanics of cutting model for drilling thrust and torque prediction has been developed and used to compare the thrust and torque values with those produced by the plane flanked facet point drills studied earlier.

ISSN:0020-7543    

DOI:10.1080/00207549208942942

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

In this paper, an on-line dispatching algorithm is proposed for the FMS scheduling problem. The algorithm uses various priority schemes and relevant information concerning the load of the system and the status of jobs in the scheduling process. This information is organized into hierarchical levels. The scheduling decision process is hierarchical in the sense that different decision criteria are applied sequentially to identify the most appropriate part and the machine to be served. The algorithm schedules the jobs on a machine or an automated guided vehicle (AGV) one at a time as the scheduling decision is needed (or as the status of the system changes). Performance of the proposed algorithm is compared with several machine and AGV scheduling rules by using the mean flow-time and the mean tardiness criteria. Simulation results indicate that the proposed algorithm produces significant mean flow-time and mean tardiness improvements over existing scheduling rules for a variety of experimental conditions.

ISSN:0020-7543    

DOI:10.1080/00207549208942943

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

As more US firms turn to global manufacturing, not only to meet the competitive challenges brought on by the economic globalization of the past 20 years but also to take advantage of the unique opportunities created by global markets, logistics will increasingly be viewed as strategically critical to the firm's competitive succcess. While much of the impetus for the development of co-ordinated global manufacturing strategies has historically originated from the desire to reduce production costs to compete with lower-cost foreign competitors, the emergence of large trading blocks has created an additional incentive for global manufacturing. Indeed, the added incentive of gaining access to global markets is now a pervasive argument in the decision to establish global manufacturing operations. Regardless of the reason for undertaking a global manufacturing strategy, the key to achieving success rests on the firm's ability to effectively co-oordinate its worldwide operations so that the overall manufacturing network performs as a cohesive conversion system. Logistics competence provides this essential co-ordinating mechanism.

ISSN:0020-7543    

DOI:10.1080/00207549208942944

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The initial stage in the implementation of cellular manufacturing involves the determination of part families and machine cell (PF/MC). We developed a new heuristic for PF/MC formation that provides a variety of PF/MC alternatives. In addition, we developed a simulation model of a group technology (GT) system using the new heuristic and compared this to that of a traditional process layout (TPL) system. We used performance criteria such as: machine utilization, queue length, flow time, etc. The simulation experiment included a TPL shop, an original GT shop, and an alternative GT shop, each with different part demand distributions.

ISSN:0020-7543    

DOI:10.1080/00207549208942945

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor