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 Prioritized Equal Distribution

Use

You use the prioritized equal distribution procedure to plan individual production lines or simple line networks (without groups of alternative lines). The procedure distributes the orders with the characteristics (for which you defined restrictions) evenly over the planning horizon. In the distribution, the procedure gives priority to the orders whose characteristic values are the most common in the given quantity of orders.

Integration

You can carry out this procedure by:

  • Integrating it in a procedure package for the model mix planning run in Customizing for Model Mix Planning.

  • Accessing it from interactive sequencing.

The procedure is defined in the function module /SAPAPO/SEQH_BS02_CALL and uses the table /SAPAPO/SEQC_BSV.

Parameters

The procedure can take into account all restriction categories except block restrictions. When you call up the procedure, you can determine which restriction categories should be taken into account and up to which weight. For example, you can determine that only quantity restrictions weighted with priority 4 or higher should be taken into account.

You can save the parameters in a processing profile in Customizing for model mix planning, or you can enter them every time you call up the procedure.

Note Note

Note however, that the prioritized equal distribution interprets all selected restrictions as hard . The procedure cannot differentiate between hard and soft restrictions.

The procedure can only take into account the maximum quantity when using quantity restrictions . Minimum quantities are ignored.

End of the note.

See also:

Restriction Categories

Including Restrictions in Planning

Features

. You can use this procedure as follows:

  • You can use this procedure based on either requirements or orders. This depends on the setting of the Planning Basis of the Horizon in the procedure package. You can choose between the setting requirement-oriented or order-oriented .

  • If you want to produce a smaller number of variants in lots, you can create planned orders with lot size 1 in the short-term horizon for the planned orders with a lot size greater than 1. Then the individual products are distributed equally to create an evenly-spread assembly load. To achieve this, you must choose the setting order-oriented with lot size 1 or requirements oriented with lot size 1 as the planning basis of the horizon in the procedure package.

  • If you produce highly-configurable products, you can use the procedure in the medium to short-term to create a temporary sequence in this horizon. For the short-term, you can then use a more complex procedure such as the genetic algorithm, and thus improve the quality of the sequence.

  • If you have used the LP procedure to create period packages for a line network (with groups of alternative lines) in the medium-term horizon, you can use the prioritized equal distribution in the short-term horizon to split the period packages into planned orders with lot size 1 and to sequence these orders.

Activities

This procedure calculates the requirements or the orders for every period of the planning horizon. Then the system loads all periods in succession up to 100%. If in one period, there are not enough requirements or orders, the system transfers requirements or orders from the following period for every product using the same proportion (in percent) as was calculated for the first period. If too many requirements or orders exist in a certain bucket, the excess requirements or orders are added to the requirements/orders in the following period.

The system proceeds as follows when scheduling orders/requirements:

  1. The prioritized equal distribution starts at the beginning of the planning horizon and calculates all existing requirements or orders per period and their relevant characteristics. The characteristics for which you have defined restrictions are relevant.

  2. The system calculates the priority of each relevant characteristic by dividing the occurrence of the characteristic by the number of products. It also takes a note of this priority for all other iterations.

  3. The system calculates the prioritization of every requirement or order, by adding up the priorities of its relevant characteristics.

  4. It schedules the order with the highest priority in the period, as long as all the restrictions are respected.

    • If the order does not fulfill the restrictions, it checks the order with the next highest priority.

    • If none of the orders in the period fulfill the restrictions, the system checks the orders from the following period (day or shift) and brings these forward.

    • If no orders in the planning horizon fulfill the restrictions, the system schedules the order with the highest priority.

      Note Note

      As the prioritized equal distribution regards all restrictions as hard, each restriction which cannot be respected is also a hard restriction violation. The system does not cancel the procedure, but still schedules the orders.

      End of the note.

  5. After it has scheduled a requirement/order, the system recalculates the priorities. In addition, it adds the priority determined in step 2 to the priority of the requirement/order for each characteristic. In the first iteration, the priorities of the characteristics double. However, for the characteristics that occurred in the last order scheduled, the system subtracts the number 1.

  6. The system repeats steps 3 to 5 until all requirements/orders have been scheduled in a period.

Example

Initial sizes:

  • Number of products: 100

  • Occurrence of characteristic A: 50

  • Occurrence of characteristic B: 40

  • Products without characteristics: 30

  • Restrictions are not taken into account here.

It follows that:

  • Priority of characteristic A = 50/100 = 0.5

  • Priority of characteristic B = 40/100 = 0.4

First iteration:

  • If an order contains characteristic A and characteristic B, it has priority 0.9

  • If an order only contains characteristic A, it has priority 0.5

  • If an order only contains characteristic B, it has priority 0.4

  • If an order does not contain any characteristics, it has priority 30/100 = 0.3

    An order with characteristics A and B is therefore scheduled first.

Second iteration

The system determines the priorities of the characteristics again, by adding the priority determined above to each characteristic and subtracting one from the scheduled characteristics:

  • Characteristic A was scheduled in the first iteration: priority = 0.5 + 0.5 – 1 = 0

  • Characteristic B was scheduled in the first iteration: priority = 0.4 + 0.4 – 1 = -0.2

    This results in the following priority for the orders:

  • If an order contains characteristic A and characteristic B, it has priority -0.2

  • If an order only contains characteristic A, it has priority 0

  • If an order only contains characteristic B, it has priority -0.2

  • If an order does not contain any characteristics, it has priority 0.3 + 0.3 = 0.6

    An order without characteristics is therefore the next to be scheduled.

The next iterations follow the same schema.