Evaluating sequences for paced, mixed-model assembly lines with JIT component fabrication

Evaluation measures of mixed-model assembly lines are examined. The squared deviation from linear component usage and related measures are often cited due to their apparent consistency with the goals of a just-in-time fabrication shop. This paper develops a different statistic which more directly measures deviations from linear component usage. It is shown that, for the environment studied, sequencing methods developed to achieve linear component usage, are not always better than purely random sequencing when the actual time of component use is measured. Next the sequencing procedures are compared, based on their ability to achieve desired production targets. It is shown that the sequencing method which smooths assembly times on the simulated assembly line, as well as methods which perform well based on the traditional measure of linear component use, achieve the highest levels of production. It is concluded that, in the environment studied, direct measures of system productivity are more useful than measures of linear component usage.