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Firm Repetitive Schedules

You can firm part or all of your current repetitive schedules for a repetitive assembly in Oracle Work in Process.

If you firm all your current repetitive schedules for an assembly in Oracle Work in Process, the repetitive planning process considers the current aggregate repetitive schedule to be firm. The sum of all your firm schedules for an assembly is called the firm rate. Rather than calculating an optimal rate for assemblies with firm rates, the repetitive planning process suggests the firm rate for the duration of the firm aggregate schedule.

The following diagram illustrates how your firm schedules influence the repetitive planning process. Notice that the repetitive planning process suggests the firm rate for the duration of the firm aggregate schedule. After the firm period, the suggested rate is increased to address the previous depletion in supply caused by the firm rate being less than the optimal rate. If the optimal rate was less than the firm rate, the repetitive planning process decreases the suggested rate after the firm period in response to the previous build up of supply.

In the example, the repetitive planning process is 10 units short as a result of the firm rate. The optimal rate is 12/day. However, for the duration of the firm schedule, the suggested rate is restricted to 10/day. This creates a shortage of 2/day for 5 days, resulting in a total shortage of 10 units. This increases the total demand in the next planning period from 36 to 46 units. Notice how the firm schedule breaks up two planning periods (Periods 2 and 3) into four smaller planning periods (Periods 2, 3, 4, and 5).

Partially Firm Repetitive Schedules

If you have firmed some, but not all, of your current repetitive schedules for an assembly, the repetitive planning process considers your current aggregate repetitive schedule to be partially firm. The sum of all firm schedules is called the minimum firm rate. If the optimal rate calculated by the repetitive planning process is less than the minimum firm rate, the repetitive planning process suggests the minimum firm rate for the duration of the partially firm aggregate schedule. If the optimal rate is greater than the minimum firm rate, the repetitive planning process suggests the optimal rate. The minimum firm rate acts as the floor for the suggested rates for the duration of your partially firm aggregate schedule.

The following diagram illustrates how your partially firm schedules influence the repetitive planning process. Notice that the repetitive planning process suggests the minimum firm rate for the duration of the partially firm schedule. After the partially firm period, the suggested rate is decreased due to the previous build up in supply caused by the minimum firm rate being greater than the optimal rate.

In the example, the repetitive planning process has a 25 unit surplus as a result of the minimum firm rate. The optimal rate is 10/day. However, for the duration of the partially firm schedule, the suggested rate is restricted to 15/day. This creates a surplus of 5/day for 5 days, resulting in a total surplus of 25 units. This reduces the total demand in the next planning period from 30 to 5 units. Notice how the partially firm schedule breaks up two planning periods (Periods 2 and 3) into four smaller planning periods (Periods 2, 3, 4, and 5).

Implicit Firm Repetitive Schedules

Your repetitive assembly lead times create an implicit firm schedule. Inside the lead time, the repetitive planning process always suggests the current aggregate rate. This is true even if your current aggregate rate is zero. The repetitive planning process assumes an implicit firm schedule inside your assembly lead times on the assumption that any new suggested rates, even if implemented immediately, can only be realized as supply outside the assembly's lead time.

The following diagram illustrates how assembly lead times form implicit firm schedules. Notice that the repetitive planning process suggests the current aggregate firm rate for the duration of the assembly lead time. In the example, the current aggregate rate is 5 per day.

After the assembly lead time, the suggested rate is increased to address the previous depletion in supply caused by the current aggregate rate being less than the optimal rate. Notice how the firm schedule formed by the assembly lead time breaks the first planning period into two smaller planning periods.

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