An assembly line is a flow-oriented production system where the productive units performing the operations, referred to as stations, are aligned in a serial manner. The work pieces visit stations successively as they are moved along the line usually by some kind of transportation system, e.g., a conveyor belt. An important decision problem, called Assembly Line Balancing Problem (ALBP), arises and has to be solved when (re-) configuring an assembly line. It consists of distributing the total workload for manufacturing any unit of the product to be assembled among the work stations along the line. The assignment of tasks to stations is constrained by task sequence restrictions which can be expressed in a precedence graph. However, most manufacturers usually do not have precedence graphs or if they do, the information on their precedence graphs is inadequate. As a consequence, the elaborate solution procedures for different versions of ALBP developed by more than 50 years of intensive research are often not applicable in practice. Unfortunately, the known approaches for precedence graph generation are not suitable for the conditions in the automotive industry. Therefore, we describe a detailed application of a new graph generation approach first introduced by Klindworth et al. [1] that is based on learning from past feasible production sequences. This technique forms a sufficient precedence graph that guarantees feasible line balances. Experiments indicate that the proposed procedure is able to approximate the real precedence graph sufficiently well to detect nearly optimal solutions even for a real-world automotive assembly line segment with up to 317 tasks. In particular, it seems to be promising to use interviews with experts in a selective manner by analyzing maximum and minimum graphs to identify still assumed relations that are crucial for the graph’s structure. Thus, the new approach seems to be a major step to close the gap between theoretical line balancing research and practice of assembly line planning.
Manufacturing Process Planning is the systematic development of the detailed methods by which products can be manufactured in a cost-efficient manner, while achieving their functional requirements. An assembly line is a flow-oriented production system where the productive units performing the operations, referred to as stations, are aligned in a serial manner. The work pieces visit stations successively as they are moved along the line usually by some kind of transportation system, e.g., a conveyor belt. An important decision problem, called Assembly Line Balancing Problem (ALBP), arises and has to be solved when (re-) configuring an assembly line. It consists of distributing the work tasks among the work stations along the line due to changes in task requirements for planned production. The assignment of tasks to stations is constrained by task sequence restrictions which can be expressed in a precedence graph. However, most manufacturers usually do not have precedence graphs or if they do, the information on their precedence graphs is inadequate. As a consequence, the elaborate solution procedures for different versions of ALBP developed by more than 50 years of research are often not applicable in practice as not all constraint information is known. This is a common problem in automotive final assembly. In this work we describe a novel precedence generation technique that is based on system-learning from past feasible production sequences. This technique forms a sufficient precedence graph that guarantees feasible line balances. Experiments indicate that the proposed procedure is able to approximate a precedence graph generated by an expert sufficiently well to detect nearly-optimal solutions even for a real-world automotive assembly line segment. Thus, the application of system learning seems to provide a simple and practical way to implement Decision Support Systems to make assembly line planning more efficient.
Line balancing is a very resource-intensive and time consuming process which is highly reliant on the experience and expertise of a few employees. Line balancing is made even more complex due to the high level of option content in premium automobiles. The current phase of this study involves hands-on training on the automotive assembly line, precedence relationship mapping of all the tasks involved on a pilot assembly line, identification of constraints, and development of a strategy to manage option content and constraints. The second phase will include the generation of an optimal line balance through optimization on expected station utilization. The current line balancing process relies significantly on the experience level of the utility workers and team leaders. Although initially labor intensive, the precedence mapping exercise and option coding strategy will facilitate the development of a decision support system to aid the human decision-maker in making data-driven decisions about work distribution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.