Revise Operations planning for Cambridge 9609 (9.3.5)

Demand forecasting is the foundational activity of operations planning. It involves using historical data and market intelligence to estimate future demand for a company's products or services. Accurate forecasts are critical; over-forecasting leads to excess inventory, tying up working capital and risking obsolescence, while under-forecasting results in stock-outs, lost sales, and diminished customer loyalty. Methods range from qualitative techniques, such as the Delphi method or consumer surveys, to quantitative techniques like time-series analysis (e.g., moving averages, exponential smoothing) and causal modelling (e.g., regression analysis). The choice of method depends on data availability, the product life cycle stage, and the required accuracy. This forecast provides the primary input for the Master Production Schedule.

The Master Production Schedule (MPS) translates the aggregate demand forecast into a specific and detailed production plan for finished goods. It specifies exactly which end products are to be made, in what quantities, and on what dates over a given planning horizon. The MPS is not a forecast; it is a definitive statement of production intent. It considers the demand forecast, current inventory levels, and the firm's actual production capacity. An effective MPS provides stability for the production floor, enables valid order promises to customers, and serves as the primary driver for Materials Requirement Planning (MRP). It acts as the crucial link between a business's strategic goals (meeting demand) and its tactical operations (producing goods).

Materials Requirement Planning, often referred to as MRP I, is a computer-based inventory management system designed to ensure that the necessary materials and components are available for production at the right time and in the right quantity. It takes the Master Production Schedule (MPS) and 'explodes' it using two other key data files: the Bill of Materials (BOM), which details all components needed for one finished product, and the Inventory Records File (IRF), which contains data on current stock levels and lead times. By processing these three inputs, the MRP system calculates the net requirements for each component and generates a schedule of purchase orders for suppliers and work orders for internal departments, thereby optimising inventory levels and production flow.

Creating a plan is only half the battle; effective monitoring and control are essential for success. This process involves continuously tracking actual performance against the planned schedules set out in the MPS and MRP. Managers use variance analysis to identify deviations, such as production delays, higher-than-expected scrap rates, or late supplier deliveries. When significant variances are detected, corrective action is required. This could involve authorising overtime to catch up, finding an alternative supplier, or, in more serious cases, revising the MPS itself. This feedback loop ensures that the operations plan remains a realistic and effective tool for achieving business objectives like efficiency, cost control, and on-time delivery, rather than becoming an obsolete document.