Repetitive Manufacturing with the Production Process Model (PPM) 
Purpose
In this process, you use an R/3 System along with the APO system. You use Repetitive Manufacturing with the Production Process Model if you are a pure make-to-stock manufacturer and produce large quantities of the same product using the same production process in unlimited lots. This means production is planned and executed with no reference to the sales order. The planned independent requirements are created in Demand Management in the R/3 System or in Demand Planning in APO (APO Demand Planning). Incoming sales orders are delivered from warehouse stock and the sales order quantities consume the planned independent requirements quantities according to the selected planning strategy. Planning is based on these two requirements (sales order quantities and planned independent requirements).
APO is purely used as a planning tool and production control, inventory management and cost accounting are executed in the R/3 System.
If you use this kind of Repetitive Manufacturing, create the production master data (routing, material BOM and production version) in the R/3 System. You transfer this master data to APO. APO then uses this data to create a Production Process Model. You then use this same master data for planning in APO. Here, lead time scheduling is carried out.
You can use this planning process if you use APO along with an SAP R/3 System (from Release 3.1H) or a Discrete Industries System.
The disadvantages of using this process are listed below:
Prerequisites
Checklist for Setting Up the System Landscape. For more information, refer to the documentation
Integration of APO and R/3.
Process Flow
The following diagram shows the planning process in Repetitive Manufacturing using the production process model:
You can also plan the lower BOM levels in a separate planning run.

In APO, you should only plan components to be planned using MRP. All components planned using consumption-based planning methods are planned in the R/3 System. You can also plan externally procured components in APO. This makes sense, for example, if you have to take the capacity of your vendor into account when planning. The component Collaborative Procurement is provided to support external procurement activities.

Every change to a planned order is automatically passed on to the R/3 System.