TABLE OF CONTENTS Hartmut Stadtler
Darmstadt University of Technology, Department of Production & Supply Chain Management, Hochschulstra e 1, 64289 Darmstadt, Germany
An indispensable part of an ERP system, Material Requirements Planning, also plays an important role in APS, because it
generates replenishment orders (production orders) for uncritical components and parts (operations) in a multi-stage production environment (Sect. 11.1 and 11.2) and
provides access to a transactional ERP system and thus can initiate the execution of orders.
The typical tasks of purchasing are to analyse procurement markets, to negotiate the terms of trade with potential suppliers and finally to select suppliers and to place replenishment orders. Here, we are interested in the way APS can support the selection of suppliers and the decisions on order sizes, taking into account the specific cost functions of suppliers, which often allow for quantity discounts (Sect. 11.3). This may apply to input materials for production, indirect materials and articles of merchandise.
Material Requirements Planning (MRP) is regarded as the core engine of an ERP system, which calculates time-phased plans of secondary demands for components and parts based on a time series of primary demands (usually finished products). Time-phased secondary demands are a prerequisite for generating production or replenishment orders so that demands for finished products can be met in time with as little work-in-process and inventory as possible.
Although most appealing, this logic suffers from the ignoring of available capacities. Consequently, production orders may result in overloaded capacities and thus infeasibilities.
