Increasingly, flexible manufacturing systems are being employed to allow the same equipment to produce a variety of different products, depending on demand. The key to the economic success of these systems is keeping changeover time to a minimum. Short changeover times mean more average production per hour and a smaller economical lot size. The time spent changing over a machine is part of what is called planned downtime. Planned downtime, if left unmanaged, can become a real sap on overall productivity.