The complementary nature of manufacturing goals by their relationship to throughput time: A theory of internal variability of production systems

Abstract This study argues that major manufacturing goals are compatible due to their relationships with internal throughput time which, in turn, depends upon estimated parameters. Further, this study argues that a large percentage of the internal throughput time is caused by variable move, queue, or preventive maintenance policies that introduce uncertainty into the manufacturing system, requiring internal buffer inventories to accumulate in the queue and increase throughput time. The increase in throughput time decreases production performance by creating higher inventories and lower productivity and a general decrease in the manufacturing performance. The results of this study suggest that internal variability of throughput time is caused by both variability of move times and processing time. Further, processing variability can be improved by lower rework time and lower down time, both of which may be achieved by systematic preventive maintenance programs. The results also suggest the protection of the “technical core” from demand variations is necessary for modern just‐in‐time systems. Further, they suggest that if the technical core is not protected, internal buffer queues may develop and further worsen system performance by increasing costs and decreasing on‐time delivery. This study's results support common practitioner concern about quality and its relationship to the success of just‐in‐time systems. In short, this study provides a theoretical base that justifies the results of other studies and practitioners' experiences with modern production facilities.