TABLE OF CONTENTS Planning in an MS is the process of determining tentative plans that specify what the MS should produce and what it should purchase in production periods in the near future. Note that this definition can be considered a simplified one because every activity in an MS that requires a plan for some future period, e.g., maintenance, or staff scheduling, needs planning as well. Here, however, the aspects relevant to production (and to some extent to inventory) management are stressed. The set of production periods over which a plan is defined is known as the planning horizon. During a planning process in an MS, future decisions related to the planning horizon must be taken. This decisional process results from an aggregation of decision variables, objectives, and constraints characterizing the decisions. Aggregation is a key term when considering planning: decisions are made by viewing time, production resources, and products as aggregate elements.
The first purpose of planning is to establish the level of production for the MS products for the time periods composing the planning horizon. The detail of this decision is generally coarse because aggregate categories of products are considered. The definition of a plan for finished product and material inventories is also linked to such decisions, where the term material denotes any kind of raw material, component, or semifinished product required for the finished product. In this case, the levels of inventories must be determined for the different periods of the planning...
