Optimal Group Maintenance Policies with Continuous and Periodic Inspections

Optimum group maintenance policies for a set of N machines subjected to stochastic failures under continuous and periodic inspections are considered. Under very general conditions it is shown that a control limit policy minimizes the expected cost per unit time over an infinite horizon, when costs are incurred due to loss of production and repair only. It is also shown how to explicitly compute this control limit. When additional costs are incurred due to inspection, a characterization of an optimal periodic inspection/repair policy that minimizes the expected cost per unit time over an infinite horizon is given.