36 research outputs found

    Integrated Batching and Lot Streaming with Variable Sublots and Sequence-Dependent Setups in a Two-Stage Hybrid Flow Shop

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    Consider a paint manufacturing firm whose customers typically place orders for two or more products simultaneously: liquid primer, top coat paint, and/or undercoat paint. Each product belongs to an associated product family that can be batched together during the manufacturing process. Meanwhile, each product can be split into several sublots so that overlapping production is possible in a two-stage hybrid flow shop. Various numbers of identical capacitated machines operate in parallel at each stage. We present a mixed-integer programming (MIP) to analyze this novel integrated batching and lot streaming problem with variable sublots, incompatible job families, and sequence-dependent setup times. The model determines the number of sublots for each product, the size of each sublot, and the production sequencing for each sublot such that the sum of weighted completion time is minimized. Several numerical example problems are presented to validate the proposed formulation and to compare results with similar problems in the literature. Furthermore, an experimental design based on real industrial data is used to evaluate the performance of proposed model. Results indicate that the computational cost of solving the model is high

    Optimal streaming of a single job in a two-stage flow shop

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    Cataloged from PDF version of article.Lot streaming is moving some portion of a process batch ahead to begin a downstream operation. The problem to be considered in this paper is the following: a single job consisting of U units is to be processed on two machines in the given order. Given a fixed number of possible transfer batches between the two machines, the problem is to find the timing and the size of the transfer batches (or, sublots) so as to optimize a given criterion. The schedules can be evaluated based on job completion, sublot completion, or item completion times. In the single job lot streaming problem, minimizing job completion time corresponds to minimizing the makespan, for which formulas for optimal sublot sizes are available. In this paper, the results for the sublot and item completion time models are presented. 0 1998 Elsevier Science B.V. All rights reserved

    Lot streaming in open shops

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    Cataloged from PDF version of article.We study lot streaming in shops in which the order the jobs are to be processed is immaterial. For a single job case, the properties of the optimal routing is determined. For the multi job case, two machine shops are analyzed. It is shown that lot streaming will improve makespan only if there is a job with large processing times. We show that there can be at most one such job and derive the optimal sublot sizes and their sequence. c 1999 Elsevier Science B.V. All rights reserved

    Production Scheduling

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    Generally speaking, scheduling is the procedure of mapping a set of tasks or jobs (studied objects) to a set of target resources efficiently. More specifically, as a part of a larger planning and scheduling process, production scheduling is essential for the proper functioning of a manufacturing enterprise. This book presents ten chapters divided into five sections. Section 1 discusses rescheduling strategies, policies, and methods for production scheduling. Section 2 presents two chapters about flow shop scheduling. Section 3 describes heuristic and metaheuristic methods for treating the scheduling problem in an efficient manner. In addition, two test cases are presented in Section 4. The first uses simulation, while the second shows a real implementation of a production scheduling system. Finally, Section 5 presents some modeling strategies for building production scheduling systems. This book will be of interest to those working in the decision-making branches of production, in various operational research areas, as well as computational methods design. People from a diverse background ranging from academia and research to those working in industry, can take advantage of this volume

    Lot streaming in hybrid flow shop scheduling

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    Production planning and scheduling play significant roles in manufacturing system operations and different techniques have been used to enhance their performance. Lot streaming has been studied for decades and is shown to accelerate production flow. This research deals with lot streaming in hybrid flow shops. Multiple products are processed in a multi-stage hybrid flow shop with non-identical machines. Sublots can be constant or consistent and intermingling is not allowed. Setups are attached and sequence independent. The problem is to simultaneously determine product sequence and sublots sizes so that the makespan is minimized. The model presented in this thesis is a mixed integer linear programming formulation for solving this problem. Several variations of the model are presented to incorporate different problem settings such as exploitation of variable sublots in the single product problem. Numerical examples are presented to validate the proposed model and to compare it to similar example problems in the literature. Furthermore, an example of a lot streaming problem in a general multi-stage hybrid flow shop is concerned and discussions and analysis are presented. Keywords . Production planning; Scheduling; Lot streaming; Hybrid flow shop; Integer programmin

    Lot streaming in flow shops

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    Ankara : The Deparment of Industrial Engineering and the Institute of Engineering and Sciences of Bilkent Univ., 1994.Thesis (Master's) -- Bilkent University, 1994.Includes bibliographical references.Lot streaming is permitting partial transfer of processed portions of a job to downstream machines, thus allowing ovelapping operations. The primary motivation is to improve the measures of performance by the quick movement of work in the shop. In this thesis, we study various forms of the lot streaming problem in flow shops to derive the characteristics of optimal solutions. We first analyze single job lot streaming problems, then extend the results to multi-job problems. When there is a single job, the lot streaming problem is to find the best transfer batch sizes that optimizes the given criterion. We consider three different measures of performance, job, sublot and item completion time criteria. We derive a closed form solution for a special case of job completion time criterion. Under sublot completion time criterion, when the first machine has the largest processing time, we show that partial transfers of equal size are optimal. We propose two polynomial time algorithms for the problem in which only two transfer batches are permitted between each consecutive machines for sublot and item completion time criteria. In multi-job lot streaming problems, the sequencing and lot streaming decisions must be considered simultaneously. For multi-job problems we investigate the hierarchical application of lot streaming and sequencing decisions.Topaloğlu, EnginM.S

    Lot streaming in multi stage shops

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    Ankara : The Department of Industrial Engineering and the Institute of Engineering and Sciences of Bilkent Univ., 1994.Thesis (Master's) -- Bilkent University, 1994.Includes bibliographical references.In this thesis, a number of lot streaming problems in flow, open and job shops are investigated. Lot streaming is the process of splitting a job to allow for overlapping of its operations on various machines resulting in shorter completion times. When there is a single job, the problem is to find the size of the transfer batches (“sublots”) which minimizes a given performance measure (e.g., makespan, mean flow time). Multi-job problems are harder, since sequencing and sizing decisions must be made simultaneously. Most of the current research in lot streaming is concerned with minimum makespan problems in flow shops. In this study, other performance measures and shop structures are also analyzed. Optimal sublot sizes are derived for the single job two machine flow shop mean flow time problem. Solution methods are proposed for the minimum makespan problem in open shops both for multiple job and single job cases.Şen, AlperM.S

    A Comprehensive Review of Lot Streaming

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    [[abstract]]"Lot streaming combined lot splitting with operations overlapping is one of the effective techniques used to implement the time-based strategy in today's era of global competition. Therefore, this technique has been studied extensively over the past few decades. In this paper, we first propose a uniquely categorized structure to characterize the existing lot streaming problems in terms of three main dimensions, seven subdimensions. and 17 levels. Then, a notation set is defined to systematically express each existing lot streaming problem by seven ordered elements corresponding to the seven subdimensions. Based on the classification structure and the defined notation set, a comprehensive survey is presented to make up for the lack of a literature review on this subject. The objective is to help the reader gain a clear understanding of the evolution of previous research on lot streaming. This paper concludes with some constructive suggestions for future research directions.[ABSTRACT FROM AUTHOR] Copyright of International Journal of Production Research is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.Copyright applies to all Abstracts.

    Cost Models for Lot Streaming in a Multistage Flow Shop

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    [[abstract]]Lot streaming is a technique used to split a processing batch into several transfer batches. In this way, overlapping operations can be performed in different manufacturing stages, and production can be accelerated. This paper proposes two cost models for solving lot streaming problems in a multistage flow shop. The purpose is to determine the optimal processing batch size and the optimal number of transfer batches that minimize the total annual cost in each model. In the first model, a more complete and accurate method is developed to compute the costs of raw materials, work-in-process, and finished-product inventories. The total cost includes the setup cost, the transfer batch movement cost, the three-type inventory holding cost, and the finished-product shipment cost. The second model contains not only the four costs in the first model, but also the imputed cost associated with the makespan time. The total annual cost functions in both models are shown to be convex, and two solution approaches are suggested. An experiment consisting of three phases was conducted to explore the effect on the optimal solution when changing the value of one parameter at a time. The results indicate that three parameters have significant effects on the optimal solution
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