How "overstaffing" at bottleneck machines can unleash extra capacity

Using simulation, Headway Technologies predicted that increasing staffing among a group of already lightly loaded machine operators - "overstaffing" would significantly improve throughput of its factory. This was counterintuitive since the operators already had significant idle time. Yet time studies confirmed that bottleneck equipment for which these operators were responsible was spending over 22% of its uptime idle solely due to lack of an operator. Analysis showed how this could be so: production equipment has a frequent and unpredictable need for operators, yet the operators must spend time away from the equipment tending to other demands of their jobs. A method of estimating, the cost of this operator-induced throughput loss is described. The result shows how extremely profitable the hiring of extra operators is in such situations. A means of estimating the most profitable level of staffing is also described, along with several alternative solutions for reducing operator absences.