On the shape of protective capacity in a simple line

Abstract

The design of a simple production line in which serially arranged workers can work independently of one another assuming inventory is presented. Traditional thought indicates that the output of such a line is determined by the slowest station. Traditional thought maintains that a balanced line is best, Goldratt (1984) says that a balanced line is inefficient because of statistical fluctuations and dependent resources. The present study presents a simulation of a 10-station line in which the capacity of station 10 is held constant while additional capacity is gradually added to stations 1–9. Station 10 is thus called the constraint, while stations 1–9 are non-constraints. The shape of the extra (or protective) capacity at non-constraints was varied from a flat pattern to patterns that increased from 1 to 9 and decreased from 1 to 9. Four random patterns were also tested. It was found that increasing non-constraint capacity increased the output of the line, and that the flat protective capacity pattern slightly bettered the performance of the other patterns.