The master schedule is the detailed planning process that tracks production performance and compares it to the customer orders that have been placed. The master schedule is the next planning step after sales and operational planning.
The master schedule determines when specific product groups are created, when sales orders are executed, and which manufacturing capacities are still available for new customer requirements.
The master schedule is further scheduled in the Material Requirements MRP system, which calculates the quantity and timing of the purchase and production orders required to meet the master schedule.
Master Schedule Record
The master schedule record depends on your company’s planning systems and specific products, but contains a lot of required information. The record should contain the projected demand, the number of posted purchase orders, the estimated inventory, the production quantities, and the quantity available for promises.
The master plan set is displayed over a period of time called the planning horizon. This can take a few days to several months, depending on the finished item.
Complex finished products such as aircraft, custom conveyor systems, had a lead time of months, while products that can be manufactured and delivered within a few days have a short planning horizon.
Master schedule link with ATP
The master schedule not only provides information about the time and size of the required production quantities, but also provides the marketing department with information that can be used when they are on final delivery dates with customers need to work together.
When sales take orders from customers, they can offer them final delivery dates based on the quantity of the Available-to-Promise (ATP) warehouse.
The ATP is calculated as the difference between the posted sales orders and the quantity that the manufacturing department has planned. When the sales team accepts a new order, the quantity available for the promise is reduced by the amount specified on the sales order. Therefore, the next order may require that the customer be assigned a final delivery date based on the available promise quantity.
The ATP quantity is not a real number, but an estimated number based on customer contracts and estimated production. When a customer calls to cancel an order or the manufacturing department schedules a new run, the available quantity changes to shorten delivery dates.
However, the opposite is true if the customer calls to change the sales order to a larger quantity, or the manufacturing department does not produce the planned number of parts. An inventory promise that is available is associated with each main scheduling quantity because the main scheduling quantity indicates the time and size of new finished goods that can be assigned to fulfill future sales orders.
Time fences
Changing the master schedule for any reason can be costly for the company, as the additional production can cause delays in delivery to customers. Reducing the number of sales orders can result in no raw materials being used and inventory costs in inventory.
To manage the master schedule, a company can freeze a certain period of time, the so-called Demand Time Fence. This is the number of periods from the current period in which very few or no changes can be made to the master schedule.
The number of periods can be determined based on the costs associated with changes to the master plan. If it is extremely expensive to make changes, the demand time limit can be several weeks. However, if the adjustment cost of the main schedule is low, the demand time limit can be one or two days.
Therefore, if changes are made outside the demand timeframe, they are less costly for the company, but still incur some costs.
This period is called the planning time fence. During this number of periods, the master scheduler can:
- Make changes to the schedule
- Consider customer requirements
- Consider manufacturing changes
