2003 Volume 53 Issue 6 Pages 456-465
A method for designing flexible mixed-product lines is presented. The word "flexible" means product-mix flexibility. A flexible mixed-product line is capable of executing various production plans. Each production plan represents the quantity scheduled to assemble each product type within a time specific period. This design method consists of a new algorithm imitating the fission of living beings and has been created to solve design problems where search trees branch out. The algorithm is called the "fissiparous algorithm" and could be an evolutionary algorithm. Conventional evolutionary algorithms change chromosomes randomly or according to probabilistic rules. But the fissiparous algorithm does not change chromosomes in this manner. This algorithm changes the chromosomes of each individual in the population by a power accelerating the evolution. A chromosome is a string of the order numbers discriminating tasks (elemental works). This design method searches out a solution to the design problem by assigning tasks in the chromosome to each workstation and selecting a kind of "station condition." Station condition is a set of production factors (e.g., worker, robot, equipment or those complex and tools) capable of performing the tasks assigned to each workstation. This design method requires the following data and information. (1) The product types to be assembled on the same line. (2) The various production plans to be executed. (3) The precedence diagram of each product type and the combined precedence diagram. The types of station conditions capable of performing each task and performance times are written in the diagram. A station ability to perform a task determines the task performance time. This design method adopts the goal of minimizing the number of workstations to execute each production plan within a time specific period. The validity of this method was confirmed by solving problems.
