Work centre scheduling is typically designed to meet a range of objectives with the balance of these objectives being determined by the strategy of the organisation. The five common objectives are:
1. Meet due dates: Delivering the product to the customer on the date promised.
2. Minimise lead time: Minimise the time that the product is in production to minimise inventory levels and respond to customer demand quickly.
3. Minimise setup time or cost: Grouping product in economic batch quantities to minimise the expense of setup to change between products.
4. Minimise work-in-process inventory: Often as part of a lean operations approach.
5. Maximise machine utlisation: To get the most out of expensive equipment.
This video examines some of the issues that schedulers with Southwest Airlines have to deal with:
http://operationsandsupplychain.wordpress.com/2011/06/02/week-5-scheduling/