T he complexities of getting materi-al ordered, manufactured and delivered overload most supply chain management (SCM) systems. The fact is, most systems are just not up to han-dling all the variables up and down the supply chain. For years, it was thought that it was enough for manufacturers to have an MRP or ERP system that could help answer fundamental questions such as: What are we going to make? What do we need to make the products? What do we have now? What materials do we need, and when? What re-sources/capacity do we need and when? Manufacturers need to know a lot more today to have a truly effective supply chain. There are a number of fundamental weaknesses in the old system logic. Many planning and scheduling systems in use today assume that lead times are fixed, queues do not change, queues must exist, capacity is infinite and backward scheduling logic will produce valid load profiles and good shop floor schedules. These assumptions are totally illogical, and following them causes many schedule compliance problems. An effective fix is first to streamline operations and then to apply predictive, preventive forms of advanced planning and scheduling. SCM involves two flows. Infor-
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