Heuristics and Lower Bounds for the Simple Assembly Line Balancing Problem Type 1: Overview, Computational Tests and Improvements

Assigning tasks to work stations is an essential problem which needs to be addressed in an assembly line design. The most basic model is called simple assembly line balancing problem type 1 (SALBP-1). We provide a survey on 12 heuristics and 9 lower bounds for this model and test them on a traditional and a lately-published benchmark dataset. The present paper focuses on algorithms published before 2011. We improve an already existing dynamic programming and a tabu search approach significantly. These two are also identified as the most effective heuristics; each with advantages for certain problem characteristics. Additionally we show that lower bounds for SALBP-1 can be distinctly sharpened when merging them and applying problem reduction techniques

Implementation of Work Sharing Technique to Improve Line Efficiency in Sewing Section: A Case Study

This paper focuses on analyzing the garment processes and operation bulletin for a particular sewing line in Mahadi Fashion (PVT) Limited. The production rate of the existing layout was not close to the target. The target was 175 pieces per hour but actual production was 138 pieces per hour. So we analyzed the layout and found out the bottleneck area. Then we rearranged the workload by work sharing and reduced manpower. By doing so, actual production was 160 pieces per hour, which is near to the target, and line efficiency increased to 77%, where the existing sewing line layout was 55%. After reducing the bottleneck in sewing line capacity, we achieved 160 pieces per hour against the 138 pieces in the existing layout

Balancing straight and U-Type assembly lines with stochastic process times

Cataloged from PDF version of article.In this thesis, we study the problem of assembly line balancing with stochastic task process times. The research considers both the well-known straight line balancing problem and U-line balancing problem where the line is paced, with no buffer inventories between stations. The objective is to minimize a two component cost function where the cost terms come from cost of manning the line and cost of finishing the incomplete units off the line. Cost is measured by an existing exact method for straight line balancing and a heuristic cost measurement method is developed for U-line balancing. The key idea in the core of this research is a task's marginal desirability for assignment at a given station. This idea is embedded in a beam search heuristic for solving both the straight line and U-line balancing problem. Extensive computational experiments and simulation experiments are made with well-known problems in the literature under the assumption of normally distributed task processing times. The quality of the solutions found by beam search for the straight-line balancing problem is compared to an existing method in literature. A simulation model of the assembly design is constructed and sample results from the U-line balancing problem are tested against the simulation results. The algorithm presented in this thesis improves the objective function by up to 24 percent.Şekerci, HalilM.S

A new model for supply chain network design with integrated assembly line balancing decisions

Supply chain network design aims at the integration of the different actors of a supply chain within a single framework in order to optimise the total profit of the system. In this paper, we consider the integration of line balancing issues within the tactical decisions of the supply chain, and we offer a novel model and a solution approach for the problem. The new approach decomposes the problem into multiple line balancing problems and a mixed integer linear model, which is easier to solve than the previously available non-linear mixed integer formulation. The results show that the new method is able to solve previously studied models within a fraction of the reported running times, and also allows us to solve larger instances than those reported in earlier works. Finally, we also provide some analysis on the influence of the cost structure, the demand and the structure of the assembly process on the final configuration of the assemblies and the distribution network.Postprint (author's final draft

An efficient genetic algorithm application in assembly line balancing.

The main achievement of this research is the development of a genetic algorithm model as a solution approach to the single model assembly line balancing problem (SMALBP), considered a difficult combinatorial optimisation problem. This is accomplished by developing a genetic algorithm with a new fitness function and genetic operators. The novel fitness function is based on a new front-loading concept capable of yielding substantially improved and sometimes optimum solutions for the SMALBP. The new genetic operators include a modified selection technique, moving crossover point technique, rank positional weight based repair method and dynamic mutation technique. The moving crossover point technique addressed the issue of propagating best attributes from parents to offspring and also supports the forward loading process. The new selection technique was developed by modifying the original rank-based selection scheme. This eliminates the high selective pressure associate with the original rank-based technique. Furthermore, the modified selection technique allows the algorithm to run long enough, if required, without premature convergence and this feature is very useful for balancing more complex real world problems. The repair technique included in this model repairs a higher proportion of distorted chromosomes after crossover than previous methods. Moreover, a third innovative feature, a moving adjacent mutation technique, strengthens the forward loading procedure and accelerates convergence. The performance of the front-loading fitness function currently outperforms the published fitness functions and fifty-four published test cases generated from sixteen precedence networks are used to assess the overall performance of the model. Encompassing the new genetic algorithm concepts, forty-four test problems (81%) achieved the best solutions obtained by published techniques and twenty-four problems (44%) produced better results than the benchmark Hoffmann precedence procedure, the closest non-genetic algorithm method. The superiority of the genetic model over other heuristics is identified in this research and future developments of this genetic algorithm application for assembly line balancing problems is evident

Hybrid metaheuristics for the accessibility windows assembly line balancing problem level 2 (AWALBP-L2)

This paper addresses an assembly line balancing problem in which the length of the workpieces is larger than the width of the workstations. The problem differs from traditional variants of assembly line balancing in the sense that only a portion of the workpiece, or portions of two consecutive workpieces, can be reached from any workstation. Consequently, at any stationary stage of the cycle, each workstation can only process a portion of the tasks, namely, those which are inside the area of a workpiece that is reachable from the workstation. The objective is to find a (cyclic) movement scheme of the workpieces along the line and a task assignment to stationary stages of the production process, while minimizing the cycle time. We propose three hybrid approaches of metaheuristics and mathematical programming - one based on simulated annealing and the other two based on tabu search, relying on different neighborhood definitions. The two former approaches make use of a classical neighborhood, obtained by applying local changes to a current solution. The latter approach, in contrast, draws ideas from the corridor method to define a corridor around the current solution, via the imposition of exogenous constraints on the solution space of the problem. An extensive computational experiment is carried out to test the performance of the proposed approaches, improving the best results published to date.Postprint (author's final draft