Master Production Scheduling
Master Production Scheduling Overview
Master Production Scheduling is the process of scheduling over time items that are critical in their impact on lower level components or in their requirements for capacity. Items that are master scheduled may be end items, intermediate components, or a pseudo item that represents items grouped for the purpose of planning.
Master Production Scheduling typically occurs in the intermediate time frame. It drives the MRP module of ERP systems which creates manufacturing orders for operations and purchase orders for materials. Master Production Scheduling also considers available inventory and safety stock policies.
Available to Promise (ATP) / Capable to Promise (CTP)
One key output of Master Production Scheduling is the uncommitted portion of a company’s inventory and planned production, commonly known as Available to Promise (ATP). In theory, you should be able to use Available to Promise to make delivery commitments to customers.
Historically, the timing of planned production is determined through a capacity planning process that assumes infinite capacity. As discussed elsewhere on this site, this approach is rife with approximation and error. Therefore, Available to Promise calculations that depends on projecting the completion time of planned production will give poor results. Promising shipment to your customers based on these calculations will lead to longer than anticipated lead times, missed delivery, poor customer service, and unhappy customers.
An alternative to Available to Promise calculations based on capacity planning, are calculations based on Advanced Planning and Scheduling software that incorporate Finite Capacity Scheduling. If actual capacity (machine, tool, labor, material) is finitely considered in the Master Production Scheduling process, projected completion times will be much more accurate, as will the commitments made to customers. The term Capable to Promise (CTP), as opposed to Available to Promise, describes finitely Master Production Scheduled uncommitted inventory and planned production.