On the MILP model for the U-shaped assembly line balancing problems

Fattahi, Ali; Türkay, Metin

doi:10.1016/j.ejor.2014.10.036

Cited by 21 publications

(9 citation statements)

References 6 publications

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“…Equation (4) states that if a task is assigned to a workstation, then the predecessor of this task must be already assigned to this workstation or to a previous one. The SLBP and ULBP are represented by the same model except for the precedence constraints [26]. In the former, a task is assigned to a worstaion after all its predecessors, while in the later a task is assigned after all its predecessors or sucessors.…”

Section: Problem Formulationmentioning

confidence: 99%

Combining Line Balancing Methods and Discrete Event Simulation: A Case Study from a Metalworking Company

Mirzaei

Nejad²,

Fernandes

2021

Int J Ind Eng Manag

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In this study, we consider a real-life Line Balancing Problem (LBP) at a metalworking company. Based on the concerns of the company's managers, the number of workstations is considered as the main performance criteria for line balancing, while line efficiency and smoothness are considered as the second and the third performance criteria. Two alternative line configurations, i.e., the straight line and the U-shaped line, are considered in the study as a company request. The Grouping Evolution Strategy (GES) algorithm, as one of the novel and powerful method in the literature, is used at a first step, assuming deterministic task times. At a second step, discrete event simulation is used to analyse the impact of stochastic' times on the dynamic behaviour of the two line configurations in terms of throughput time and throughput rate. Results of this study are expected to contribute to both research and practice in the context of line balancing.

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Section: Problem Formulationmentioning

confidence: 99%

Combining Line Balancing Methods and Discrete Event Simulation: A Case Study from a Metalworking Company

Mirzaei

Nejad²,

Fernandes

2021

Int J Ind Eng Manag

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“…On the other hand, as the proposed study addresses the balancing problem for SRCUAL, relevant literature about Utype assembly line balancing problem (UALBP) is also covered (Miltenburg and Wijngaard, 1994;Sparling and Miltenburg, 1998). Research on UALBP using optimization techniques such as branch and bound algorithm (Ogan and Azizoglu, 2015), MILP (Urban, 1998;Fattahi and Turkay, 2015), integer programming (Fattahi et al, 2014) and goal programming (Gokcen and Agpak, 2006;Toklu and Ozcan, 2008) has been flourishing. Because of the fact that metaheuristic methods can yield a satisfactory solution quality by providing diversity in solution search in a reasonable time, some attempts have been made to solve UALBP via metaheuristics such as genetic algorithm (Cheng et al, 2013), particle swarm optimization (Chutima and Kid-Arn, 2013), immune co-evolution algorithm (Liu et al, 2010), ant colony optimization (Sabuncuoglu et al, 2009) and simulated annealing (Erel et al, 2001).…”

Section: Literature Reviewmentioning

confidence: 99%

A novel optimization approach for segmented rabbit chase oriented U-type assembly line design: an application from lighting industry

Çevikcan

Durmuşoğlu

2020

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Purpose Rabbit chase (RC) is used as one of the most effective techniques in manufacturing systems, as such systems have high level of adaptability and increased productivity in addition to providing uniform workload balancing and skill improving environment. In assembly systems, RC inspires the development of walking worker assembly line (WWAL). On the other hand, U-type assembly lines (UALs) may provide higher worker utilization, lower space requirement and more convenient internal logistics when compared to straight assembly lines. In this context, this study aims to improve assembly line performance by generating RC cycles on WWAL with respect to task assignment characteristics of UAL within reasonable walking distance and space requirement. Therefore, a novel line configuration, namely, segmented rabbit chase-oriented U-type assembly line (SRCUAL), emerges. Design/methodology/approach The mathematical programming approach treats SRCUAL balancing problem in a hierarchical manner to decrease computational burden. Firstly, segments are generated via the first linear programming model in the solution approach for balancing SRCUALs to minimize total number of workers. Then, stations are determined within each segment for forward and backward sections separately using two different pre-emptive goal programming models. Moreover, three heuristics are developed to provide solution quality with computational efficiency. Findings The proposed mathematical programming approach is applied to the light-emitting diode (LED) luminaire assembly section of a manufacturing company. The adaptation of SRCUAL decreased the number of workers by 15.4% and the space requirement by 17.7% for LED luminaire assembly system when compared to UAL. Moreover, satisfactory results for the proposed heuristics were obtained in terms of deviation from lower bound, especially for SRCUAL heuristics I and II. Moreover, the results indicate that the integration of RC not only decreased the number of workers in 40.28% (29 instances) of test problems in U-lines, but also yielded less number of buffer points (48.48%) with lower workload deviation (75%) among workers in terms of coefficient of variation. Practical implications This study provides convenience for capacity management (assessing capacity and adjusting capacity by changing the number of workers) for industrial SRCUAL applications. Meanwhile, SRCUAL applications give the opportunity to increase the capacity for a product or transfer the saved capacity to the assembly of other products. As it is possible to provide one-piece flow with equal workloads via walking workers, SRCUAL has the potential for quick realization of defects and better lead time performance. Originality/value To the best of the authors’ knowledge, forward–backward task assignments in U-type lines have not been adapted to WWALs. Moreover, as workers travel overall the line in WWALs, walking time increases drastically. Addressing this research gap and limitation, the main innovative aspect of this study can be considered as the proposal of a new line design (i.e. SRCUAL) which is sourced from the hybridization of UALs and WWAL as well as the segmentation of the line with RC cycles. The superiority of SRCUAL over WWAL and UAL was also discussed. Moreover, operating systematic for SRCUAL was devised. As for methodical aspect, this study is the first attempt to solve the balancing problem for SRCUAL design.

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“…Although many researchers have presented the mathematical models for U-shaped assembly line such as Urban and Chiang (2006), Fattahi and Turkay (2015) and Li et al (2017d). However, none of the models report the considered RUALBP or is able to tackle robot assignment.…”

Section: Mathematical Modelmentioning

confidence: 99%

Mathematical models and migrating birds optimization for robotic U-shaped assembly line balancing problem

Janardhanan

Ashour

et al. 2019

Neural Comput & Applic

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Modern assembly line systems utilize robotics to replace human resources to achieve higher level of automation and flexibility. This work studies the task assignment and robot allocation in a robotic U-shaped assembly line. Two new mixed integer programming linear models are developed to minimize the cycle time when the number of workstations is fixed. Recently developed migrating birds optimization (MBO) algorithm is employed and improved to solve large-sized problems. Problemspecific improvements are also developed to enhance the proposed algorithm including modified consecutive assignment procedure for robot allocation, iterative mechanism for cycle time update, new population update mechanism and diversity controlling mechanism. An extensive comparative study is carried out to test the performance of the proposed algorithm, where seven high-performing algorithms recently reported in the literature are re-implemented to tackle the considered problem. The computational results demonstrate that the developed models are capable to achieve the optimal solutions for small-sized problems, and the proposed algorithm with these proposed improvements achieves excellent performance and outperforms the compared ones.

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On the MILP model for the U-shaped assembly line balancing problems

Cited by 21 publications

References 6 publications

Combining Line Balancing Methods and Discrete Event Simulation: A Case Study from a Metalworking Company

Combining Line Balancing Methods and Discrete Event Simulation: A Case Study from a Metalworking Company

A novel optimization approach for segmented rabbit chase oriented U-type assembly line design: an application from lighting industry

Mathematical models and migrating birds optimization for robotic U-shaped assembly line balancing problem

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