# 12.1 Demand and Available Inventory along the Time Axis

### Intended learning outcomes: Explain the projected available inventory and its calculation. Describe scheduling and cumulative projected available inventory calculation. Produce an overview on operating curves for stock on hand.

Both long-term management of resources, as outlined in Section 5.2.2, and stochastic materials management allow the demand for an item to be regarded as a scalar variable, that is, as a total, because the exact time at which the demand arises is either not relevant or was not the object of the estimate. What is estimated is the requirement quantity over a given time period. Thus, the shorter the selected period, the greater the scatter. At this level of inaccuracy, it is more sensible to assume that demand is uniformly distributed across the entire period.

However, when the exact point in time at which demand will occur within the customer tolerance time is known, it makes sense to utilize this information. Instead of relying on the order point technique (see Section 11.3), which only takes stock levels into account, you can now also consider future demand and deliveries.

Time phasing is a technique that divides the future time axis into time periods and considers stock levels for any desired point in the future ([ASCM22]).
Time bucket is the chosen period for time phasing. It contains all relevant planning data summarized into a columnar display (for example, a weekly or monthly time bucket).
Time-phased order point (TPOP) is a concept that was used in the early version of the MRP (material requirements planning) technique as described in Section 12.3.2.

Considering time periods makes the technique easier to teach and learn. Also, calculation of the technique by hand is such a time-consuming procedure that it makes sense to produce a rough calculation according to time periods. This also held in the early days of ERP software, when access to the data media was very slow. Today, however, software packages produce calculations that are accurate at the event level.

The projected available inventory calculation described below forms the basis for deterministic materials management.

## Course section 12.1: Subsections and their intended learning outcomes

• ##### 12.1 Demand and Available Inventory along the Time Axis

Intended learning outcomes: Explain the projected available inventory and its calculation. Describe scheduling and cumulative projected available inventory calculation. Produce an overview on operating curves for stock on hand.

• ##### 12.1.1 Allocated Quantities, and the Projected Available Inventory

Intended learning outcomes: Disclose the concept of allocated quantities. Explain projected available inventory and its components. Disclose planning-related events and their effect on available inventory.

• ##### 12.1.2 Projected Available Inventory Calculation

Intended learning outcomes: Differentiate between the spreadsheet representation and the graphical representation (or inventory curve) of the projected available inventory calculation.

• ##### 12.1.3 Scheduling and Cumulative Projected Available Inventory Calculation

Intended learning outcomes: Explain scheduling projected available inventory calculation (spreadsheet and graphical representation). Describe the cumulative projected available inventory calculation (graph) or store throughput diagram.

• ##### 12.1.4 Operating Curves for Stock on Hand

Intended learning outcomes: Explain the derivation of an operating curve for stock on hand from the store throughput diagram.

## Course 12: Sections and their intended learning outcomes

• ##### Course 12 – Deterministic Materials Management

Intended learning outcomes: Produce an overview on demand and available inventory along the time axis. Describe deterministic determination of independent demand. Explain in detail the deterministic determination of dependent demand (Material Requirements Planning, MRP). Differentiate various lot sizing techniques. Disclose how to analyze the results of the MRP.

• ##### 12.1 Demand and Available Inventory along the Time Axis

Intended learning outcomes: Explain the projected available inventory and its calculation. Describe scheduling and cumulative projected available inventory calculation. Produce an overview on operating curves for stock on hand.

• ##### 12.2 Deterministic Determination of Independent Demand

Intended learning outcomes: Present the customer order and distribution requirements planning (DRP). Disclose the consumption of the forecast by actual demand.

• ##### 12.3 Deterministic Determination of Dependent Demand

Intended learning outcomes: Describe characteristics of discontinuous dependent demand. Explain material requirements planning (MRP) and planned orders. Disclose the determination of the timing of dependent demand and the load of a planned order.

• ##### 12.4 Batch Sizing, or Lot Sizing

Intended learning outcomes: Explain combining net requirements into batches. Differentiate between different batch-sizing policies.

• ##### 12.5 Analyzing the Results of Material Requirements Planning (MRP)

Intended learning outcomes: Present projected available inventory and pegging. Produce an overview on action messages.

.

.

• ##### 12.8 Scenarios and Exercises

Intended learning outcomes: Calculate projected available inventory. Determine net requirements and planned release using the MRP technique. Differentiate between order point technique and MRP technique.

.

.