Secondary effects of this characteristic include materials management, and resource planning. Materials management activities are influenced by core acquisition activities since replacement lot sizing is dependent on the expected volumes and condition of cores. In the event replacement parts are not available, excess cores may be cannibalized for needed replacement parts. Inventory control and management techniques should be developed specifically for cores since many re-manufacturing firms report that excess cores require costly storage space, and that disposal costs may be high. Finally, production decisions with respect to staffing and scheduling are dependent on core acquisitions and timing. When new parts production co-exists with re-manufacturing using shared resources, this information becomes even more crucial since resource contention becomes more pronounced