Model Mix Planning

Purpose

You use this component for takt-based, flow manufacturing for configurable products with a high volume of orders, such as engines, for example. In this type of production, different products are often produced together on one production line or a line network.

The aim of Model Mix Planning is to create a production schedule in the medium to long-term planning horizon. Various heuristic procedures are available for dispatching the orders. When planning, the system has to take the delivery dates, available capacities and any existing restrictions into account. The system creates period packageswhich are assigned to the lines on which they are to be processed.

In the short-term planning period, the system uses these period packages to calculate an order sequence with exact start and end times which it does in Sequencing. This order sequence takes restrictions and customer required dates into account and fulfills certain business aims which may include the following, for example:

  • an equal load of the line segments or takts

  • a minimization of restriction violations

  • a minimization of the absolute schedule deviation

You can execute Model Mix Planning to plan individual lines or you can also execute Model Mix Planning for a complete line network . The line network may exist as a series of lines one after the other or also as parallel lines which may be used as alternatives. In this case, Model Mix Planning is executed as multiline planning.

The following graphic shows the creation of period packages for a line network with alternative lines using multiline planning. The orders are assigned to the possible processing paths taking the predefined restrictions into account:

Implementation Considerations

  • Model Mix Planning has been designed to meet the demands posed by large order volumes, such as those in the automotive industry.

  • Model Mix Planning is based on the master data of the integrated Product and Process Engineering (iPPE). As you can only represent a continuous process with iPPE and a Discrete Industries (DI) System , you should currently only use model mix planning with this OLTP system.

See also:

Repetitive Manufacturing with iPPE

Integration

  • Model Mix Planning uses the Optimization component . The data relevant for planning is transferred to be optimized. The optimization uses the optimization procedures defined in the procedure package to determine the best solution and transfers the results back to Model Mix Planning.

  • Model Mix Planning carries out takt-based scheduling using the data from iPPE Line Design and the line resources.

  • The planning of the components required for the orders is integrated in the planning run of Model Mix Planning. Depending on the setting in the product master of the product to be planned, APO calculates the required components either using the rapid planning matrix (see also: Production Planning Using the Rapid Planning Matrix ) or by an individual explosion of the iPPE.When starting Model Mix Planning, you can define whether or not a requirements calculation is to be carried out. If you decide not to calculate the component requirements, you can carry out either a production planning run or a planning run to create the planning matrix after the model mix planning run.

  • If you execute the model mix planning run periodically as automatic planning, you can integrate it as a heuristic in the production planning run of the APO System. Then you can execute a planning run every night in the background, for example.

  • You can also link the APO System to an external system. This means you can transfer the planned order sequence to a production control system, for example. (See also: Transferring Order Sequences to Production ).

Features

Restrictions

Model Mix Planning also uses restrictions when planning the order sequence which means you can define conditions for sequencing. Therefore, restrictions are planning master data:

  • You can define restrictions for characteristic values, combinations of characteristic values, for product numbers as well as for fields in the product master. Here, you usually refer to the availability of machines, work or materials.

  • The system differentiates between six Restriction Categories which you can use according to your business requirements.

  • You create a restriction with reference to a planning version and you assign it to exactly one production line. The restriction is unique as a result of the assignment to a planning version and line.

  • You can group several restrictions in a restriction group.

Model Mix Planning

You can execute planning either automatically in the model mix planning run and manually in interactive sequencing:

Model Mix Planning Run

With the model mix planning run, you can execute automatic planning where you plan various planning horizons with complex procedures in several steps. You can also combine several standard procedures or your own procedures. You can define the number and the length of the horizons as well as the procedures to be used. In the long to medium-term area, you can assign the orders to the lines as period packages , whereas in the short-term area you can execute complex sequencing that takes all restrictions into account and provides exact order start and finish times. The system only uses existing planned orders when planning or depending on your settings it also converts sales orders and planned independent requirements into planned orders.

Interactive Sequencing

You use interactive sequencing in the short-term horizon to process the planning results. You can display the orders in sequence and make any necessary changes. The following functions are available:

  • Change sequence manually

  • Reschedule orders to an alternative line manually

  • Deallocate orders

  • Restart an individual procedure

  • Display restriction violations and order characteristic values

  • Display tracking information for an order

  • Start actions from action control for an order

Constraints

If you execute Sequencing with Model Mix Planning in APO, the system first creates the order sequence for the planning segment. Then, starting from the planning segment, the system executes midpoint scheduling . Here, it calculates times for the preceding and following lines. Therefore, the start and end times are only exact for the planning segment.