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Balancing and Sequencing of Parallel Mixed-Model Assembly Lines
(Taylor & Francis Ltd, 2010) Özcan, Uğur; Çerçioğlu, Hakan; Gökçen, Hadi; Toklu, Bilal
In this paper, a simulated annealing approach is developed for the parallel mixed-model assembly line balancing and model sequencing (PMMAL/BS) problem which is an extension of the parallel assembly line balancing (PALB) problem introduced by Gokcen et al. (2006). In PALB, the aim is to balance more than one assembly line together. Balancing of the lines simultaneously with a common resource is very important in terms of resource minimisation. The proposed approach maximises the line efficiency and distributes the workloads smoothly across stations. The proposed approach is illustrated with two numerical examples and its performance is tested on a set of test problems. The computational results show that the proposed approach is very effective for PMMAL/BS.
Balancing of mixed-model two-sided assembly lines
(PERGAMON-ELSEVIER SCIENCE LTD, 2009) Ozcan, Ugur; Toklu, Bilal
This paper presents a new mathematical model and a simulated annealing algorithm for the mixed-model two-sided assembly line balancing problem. The proposed mathematical model minimizes the number of mated-stations (i.e., the line length) as the primary objective and minimizes the number of stations (i.e., the number of operators) as a secondary objective for a given cycle time. In the proposed simulated annealing algorithm, two performance criteria are considered simultaneously: maximizing the weighted line efficiency and minimizing the weighted smoothness index. The proposed approach is illustrated with an example problem, and its performance is tested on a set of test problems. The experimental results show that the proposed approach performs well. (c) 2008 Elsevier Ltd. All rights reserved.
Balancing Parallel Two-Sided Assembly Lines
(Taylor & Francis Ltd, 2010) Özcan, Uğur; Gökçen, Hadi; Toklu, Bilal
Two-sided assembly lines are usually designed to produce large-sized products such as automobiles, trucks and buses. In this type of production line, both left-side and right-side of the line are used. In parallel assembly lines, one or more product types are produced on two or more assembly lines located in parallel to each other. Both production lines have several serious practical advantages. For this purpose, in this paper, two or more two-sided assembly lines located in parallel to each other are considered and a tabu search algorithm which combines the advantages of both types of production lines is developed. To assess the effectiveness of the proposed algorithm, a set of test problems are solved. The proposed algorithm is illustrated with two examples, and some computational properties of the algorithm are given.
Balancing Two-Sided Assembly Lines with Sequence-Dependent Setup Times
(Taylor & Francis Ltd, 2010) Özcan, Uğur; Toklu, Bilal
Two-sided assembly lines are often designed to produce large-sized products, such as automobiles, trucks and buses. In this type of production line, both left-side and right-side of the line are used in parallel. In all studies on two-sided assembly lines, sequence-dependent setup times have not yet been considered. However, in real life applications, setups may exist between tasks. Performing a task directly before another task may influence the latter task inside the same station, because a setup for performing the latter task may be required. Furthermore, if a task is assigned to a station as the last one, then it may cause a setup for performing the first task assigned to that station since the tasks are performed cyclically. In this paper, the problem of balancing two-sided assembly lines with setups (TALBPS) is considered. A mixed integer program (MIP) is proposed to model and solve the problem. The proposed MIP minimises the number of mated-stations (i.e., the line length) as the primary objective and it minimises the number of stations (i.e., the number of operators) as a secondary objective for a given cycle time. A heuristic approach (2-COMSOAL/S) for especially solving large-size problems based on COMSOAL (computer method of sequencing operations for assembly lines) method is also presented. An illustrative example problem is solved using 2-COMSOAL/S. To assess the effectiveness of MIP and 2-COMSOAL/S, a set of test problems are solved. The computational results show that 2-COMSOAL/S is very effective for the problem.
A fuzzy goal programming model for the simple U-line balancing problem with multiple objectives
(TAYLOR & FRANCIS LTD, 2008) Toklu, Bilal; Oezcan, Ugor
A fuzzy goal programming model for the simple U-line balancing (SULB) problem with multiple objectives is presented. In real life applications of the SULB problem with multiple objectives, it is difficult for the decision-maker(s) to determine the goal value of each objective precisely as the goal values are imprecise, vague, or uncertain. Therefore a fuzzy goal programming model is developed for this purpose. The proposed model is the first fuzzy multi-objective decision-making approach to the SULB problem with multiple objectives which aims at simultaneously optimizing several conflicting goals. The proposed model is illustrated using an example. A computational study is conducted by solving a large number of test problems to investigate the relationship between the fuzzy goals and to compare them with the goal programming model proposed by Gken and Apak (Gken, H. and Apak, K., European Journal of Operational Research, 171, 577-585, 2006). The results of the computational study show that the proposed model is more realistic than the existing models for the SULB problem with multiple objectives and also provides increased flexibility for the decision-maker(s) to determine different alternatives.
A genetic algorithm for the stochastic mixed-model U-line balancing and sequencing problem
(TAYLOR & FRANCIS LTD, 2011) Ozcan, Ugur; Kellegoz, Talip; Toklu, Bilal
Mixed-model assembly lines are widely used to improve the flexibility to adapt to the changes in market demand, and U-lines have become popular in recent years as an important component of just-in-time production systems. As a consequence of adaptation of just-in-time production principles into the manufacturing environment, mixed-model production is performed on U-lines. This type of a production line is called a mixed-model U-line. In mixed-model U-lines, there are two interrelated problems called line balancing and model sequencing. In real life applications, especially in manual assembly lines, the tasks may have varying execution times defined as a probability distribution. In this paper, the mixed-model U-line balancing and sequencing problem with stochastic task times is considered. For this purpose, a genetic algorithm is developed to solve the problem. To assess the effectiveness of the proposed algorithm, a computational study is conducted for both deterministic and stochastic versions of the problem.
Multiple-criteria decision-making in two-sided assembly line balancing: A goal programming and a fuzzy goal programming models
(PERGAMON-ELSEVIER SCIENCE LTD, 2009) Ozcan, Ugur; Toklu, Bilal
Two-sided assembly lines are especially used at the assembly of large-sized products, such as trucks and buses. In this type of a production line, both sides of the line are used in parallel. In practice, it may be necessary to optimize more than one conflicting objectives simultaneously to obtain effective and realistic solutions. This paper presents a mathematical model, a pre-emptive goal programming model for precise goals and a fuzzy goal programming model for imprecise goals for two-sided assembly line balancing. The mathematical model minimizes the number of mated-stations as the primary objective and it minimizes the number of stations as a secondary objective for a given cycle time. The zoning constraints are also considered in this model, and a set of test problems taken from literature is solved. The proposed goal programming models are the first multiple-criteria decision-making approaches for two-sided assembly line balancing problem with multiple objectives. The number of mated-stations, cycle time and the number of tasks assigned per station are considered as goals. An example problem is solved and a computational study is conducted to illustrate the flexibility and the efficiency of the proposed goal programming models. Based on the decision maker's preferences, the proposed models are capable of improving the value of goals. (C) 2008 Elsevier Ltd. All rights reserved.
A new hybrid improvement heuristic approach to simple straight and U-type assembly line balancing problems
(SPRINGER, 2009) Oezcan, Ugur; Toklu, Bilal
This paper presents a new hybrid improvement heuristic approach to simple straight and U-type assembly line balancing problems which is based on the idea of adaptive learning approach and simulated annealing. The proposed approach uses a weight parameter to perturb task priorities of a solution to obtain improved solutions. The weight parameters are then modified using a learning strategy. The maximization of line efficiency (i.e., the minimization of the number of stations) and the equalization of workloads among stations (i.e., the minimization of the smoothness index or the minimization of the variation of workloads) are considered as the performance criteria. In order to clarify the proposed solution methodology, a well known problem taken from literature is solved. A computational study is conducted by solving a large number of benchmark problems available in the literature to compare the performance of the proposed approach to the existing methods such as simulated annealing and genetic algorithms. Some test instances taken from literature are also solved by the proposed approach. The results of the computational study show that the proposed approach performs quite effectively. It also yields optimal solutions for all test problems within a short computational time.
Paralel montaj hattı dengeleme problemleri için bir tavlama benzetimi yaklaşımı
(2009) Çerçioğlu, Hakan; Özcan, Uğur; Gökçen, Hadi; Toklu, Bilal
Birden fazla montaj hattına sahip imalat sistemlerinin örneklerine Sanayide oldukça yaygın olarak rastlanmaktadır. Bu hatların ürettikleri ürünlerin birbirinin aynı ya da benzeri oldukları ve çevrim zamanlarının birbirine eşit ya da yakın oldukları görülmektedir. Bundan dolayı da, Gökçen vd. (2006), üretim sisteminin verimliliğinin ve kaynak kullanımının artırılması için, paralel bitişik hatların bazı istasyonlarının iş yüklerinin birleştirilmesini önermişlerdir. Birden fazla hattın ortak bir şekilde dengelendiği bu problem, Paralel Montaj Hattı Dengeleme Problemi (PMHDP) olarak isimlendirilmiştir. PMHDP’nin ana amacı en az istasyon sayısına (veya operatör sayısına) ulaşılmasıdır. Bu çalışmada PMHDP için, tavlama benzetimi (TB) tabanlı bir yaklaşım geliştirilmiştir. Çalışma temel olarak Gökçen vd. (2006) çalışmasını ele alarak geliştirilmiştir. Önerilen yaklaşım, sayısal bir örnekle açıklanmış ve bu yaklaşımın performansı Gökçen vd. (2006) çalışmasındaki test verileri üzerinde denenmiştir. Yapılan hesaplama çalışmalarında, 95 test problemi için önerilen yaklaşım, 47 tane optimalliği kanıtlanmış sonucu yakalamış ve Gökçen vd. (2006) çalışmasından iyi 6 tane sonuç bulmuştur.
Paralel Montaj Hattı Dengeleme Problemleri İçin Bir Tavlama Benzetimi Yaklaşımı
(2009) Çerçioğlu, Hakan; Özcan, Uğur; Gökçen, Hadi; Toklu, Bilal
Production systems which has more than one assembly line is widely seen in industry. These lines produce same or similar products, and their cycle times are generally considered similar. So, Gökçen et al. (2006) suggested to combine workload of some stations on parallel consecutive lines, in a convenient way, for improving the resource utilization and the efficiency of the production system. This common balancing of more than one assembly line is named Parallel Assembly Line Balancing Problem (PALBP). The major aim of PALBP is to obtain minimum number of stations (or operators). In this paper, a simulated annealing (SA) based approach is developed for PALBP. This paper is built directly on the study of Gökçen et al. (2006). The proposed approach is illustrated with a numerical example and its performance is tested on data set taken from Gökçen et al. (2006). In the computational studies, for 95 test problems, the proposed approach found 47 proven optimal solutions and 6 solutions superior to Gökçen et al. (2006).
A SIMULATED ANNEALING APPROACH FOR PARALLEL ASSEMBLY LINE BALANCING PROBLEM
(GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2009) Cercioglu, Hakan; Ozcan, Ugur; Gokcen, Hadi; Toklu, Bilal
Production systems which has more than one assembly line is widely seen in industry. These lines produce same or similar products, and their cycle times are generally considered similar. So, Gokcen et al. (2006) suggested to combine workload of some stations on parallel consecutive lines, in a convenient way, for improving the resource utilization and the efficiency of the production system. This common balancing of more than one assembly line is named Parallel Assembly Line Balancing Problem (PALBP). The major aim of PALBP is to obtain minimum number of stations (or operators). In this paper, a simulated annealing (SA) based approach is developed for PALBP. This paper is built directly on the study of Gokcen et al. (2006). The proposed approach is illustrated with a numerical example and its performance is tested on data set taken from Gokcen et al. (2006). In the computational studies, for 95 test problems, the proposed approach found 47 proven optimal solutions and 6 solutions superior to Gokcen et al. (2006).
A Tabu Search Algorithm for the Parallel Assembly Line Balancing Problem
(2009) Özcan, Uğur; Çerçioğlu, Hakan; Gökçen, Hadi; Toklu, Bilal
In a production facility there may be more than one straight assembly line located in parallel. Balancing of parallel assembly lines will provide the flexibility to minimize the total number of workstations due to common resource. This type of problem is called as parallel assembly line balancing (PALB) problem. In this paper, a tabu search based approach is proposed for PALB problem with aim of maximizing line efficiency (LE) (or minimizing number of stations) and minimizing variation of workloads (V). This study is based on the study of Gökc ?en et al. [1]. The proposed approach is illustrated on a numerical example and its performance is tested on a set of well-known problems in the literature. This study is the first multi objective parallel assembly line balancing study in the literature.
A tabu search algorithm for two-sided assembly line balancing
(SPRINGER LONDON LTD, 2009) Ozcan, Ugur; Toklu, Bilal
Two-sided assembly lines are often used at the assembly of large-sized high-volume products, such as cars, trucks, and buses. In this type of a production line, the left side and the right side of the line are used in parallel. This paper presents a tabu search algorithm for two-sided assembly line balancing. The line efficiency and the smoothness index are considered as the performance criteria. The proposed algorithm is illustrated with two numerical example problems, and its performance is tested on a set of test problems taken from literature. The performance of the proposed algorithm is compared to the existing approaches. The computational results show that the proposed algorithm performs well.

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