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Requirement Planning Logic

In DemandCaster, there are two discrete requirement planning calculation sections:

  1. During an items lead time
  2. Beyond an items lead time

During an items lead time, the basis of the replenishment order is the items Order Point. The Order Point is the level of inventory needed to accommodate an items projected demand over the lead time plus the additional needed to accomodate any demand or supply variation.

This article covers how the order point is calculated, provides an explanation of the basic replenishment order calculation, and outlines all the planner action notifications and rules that follow to illustrate the urgency of and timing of a planned order.

Basic Order Point Logic

The order point is managed in the Order Point Calc Analytic and is calculated by adding the forecast during the lead time plus the safety stock. A user may also enter their own order point or upload the value from their ERP.

The video Basic Order Quantity and Replenishment Logic and the article Basic Order Quantity and Replenishment Logic provide a detailed overview the logic.

Requirement Plan Basics

Once the order point is calculated, the items replenishment is then determined by comparing the items lead time availability against its calculated order point (sometimes called future free).  If the net availability is greater than the order point, then the item does not need to be ordered to cover lead time demand.  If the net availability is less than the order point, a quantity up to a specified level is ordered (Order Up To).

Availability is calculated as: On Hand + On Order - Allocations (over the lead time)

The following table illustrates all the associated calculations. We have excluded allocations for the sake of simplicity.

Note: An item that is make or purchase to order has a reorder point of 0 (no forecast or safety stock) and a suggested order will not be issued unless there are physical customer orders that are greater than the items on hand and on order during the lead time or at any time during the planning horizon.

Requirement Plan Basics

Required Planning Parameters

Based on the above mentioned parameters, it is very important that a number of critical variables be correctly defined by item. Below are the critical data related requirements that you should review to assess if the settings are correct in DemandCaster. All these settings may be modified directly in DemandCaster and should be reviewed at least monthly to assure accuracy. If these are incorrect, DemandCaster may over or understate the companies inventory requirements as compared to reality. As a starting point, all item values are pulled directly from the ERP system but can be overwritten as described in the Data Settings and Recommendation article.

  1. Lead Time: This can be reviewed in the Lead Time Analytic. This is how long it takes from the time you place an order to receive the order (not cycle time or production time). A lead time that is too short or too long may under or overstate the items reorder point. Other lead times such as order lead time and transfer lead time, if available, should be reviewed as well. We often see items with a lead time of 0. A 0 lead time assumes immediate availability of a replenishment order and no safety stock. This is the number one reason why unusual suggested orders are created.
  2. Make versus Purchase Policy: This establishes if an item is purchased versus manufactured. These can be viewed in the Stocking Analysis. An item that is set as purchased (Buy) will not explode its requirements through its bill of material. Only manufactured items explode their requirements.
  3. Maintain in inventory versus build or purchase to stock: This is the determination of what should be maintained in inventory (stocked) versus made / purchase to order. This is a company specific decision that has significant cost and service implications because inventory, purchasing, and manufacturing decisions are made using this information. These can be viewed in the Stocking Analysis. A standard rule of thumb is if an item can be procured or produced faster than your commitment to ship to your customer (assuming capacity is available), then the item should not be stocked.
  4. Bill of Material (BOM): The is the structure of a finished goods assembly. It is important that these are structured correctly in order to pass down forecasts and plans through to components . You can view the BOM structure in item plan screen and where used in the General Item Analysis tab. It is very important that a bill of material have the correct unit of measure conversions through the bill to assure the explosions to components are correctly translated.
  5. On hand quantities: If these are incorrect you may over or under order your inventory. You can view current on hand inventories in the Classification Analytic or in the Item Options tab.
  6. Active and inactive items: A user has the option to deactivate or disable items. This means that the item is no longer visible.
  7. Customer, production, purchase order statuses: Assuring that these orders are properly showing that they are open, closed, or planned has a direct effect on the requirement plan.
  8. Distribution and manufacturing network relationships (if DRP is enabled): Proper source and destination location relationships need to be correctly defined.
  9. Consumption Type: Consumption types are different models that consume on hand and on order inventory as well trigger reorder quantities during the lead time and beyond.

Requirement Planning Due Date and Bucketing Logic

DemandCaster default requirement planning bucket size is a week. Suggested orders are defaulted to a specific day of the week set in system settings. AS an option, when managing short lead times (less than 14 days), you may opt for daily requirement planning buckets. This is a much more finite and precise requirement planning approach.

DemandCaster's week is based on a Sunday to Saturday date where Sunday is the first day of the week and Saturday is the last day of the week.

Planner Action / Requirement Planning Rules - During Lead Time

Based on all the aforementioned calculation and parameters, the requirement planning logic runs as follows:

  1. During Lead the order point rules apply. Each order item is reviewed to assess if the net available is either over or under the order point during the lead time. If the net available is less than the order point, a suggested order is created in the planner action and includes the following information by item and location (if applicable):
    1. Quantity
    2. Need by date
    3. Order by date
  2. Based on the above, DemandCaster will illustrate urgency using the following messages.
    1. Urgent: The item is either stocked out or at risk of going negative during the lead time. There is no open order to expedite during the lead time so a new order must be entered and brought in at the date suggested in order to avoid stocking out.
    2. Expedite: A current open order needs to be expedited to prevent the item from stocking out or breaching the safety stock during the lead time.

A detailed explanation of the Planner Action messages are provided in the article What do the different Planner Action statuses mean?

Planner Action / Requirement Planning Rules - Beyond Lead Time

  1. The planned replenishment orders are scheduled by week using the safety stock level as the reorder trigger. When the order is triggered, the planner action includes the following information by item and location (if applicable):
    1. Quantity
    2. Need by date
    3. Order by date
  2. The following messages also accompany each line to illustrate what action should be take:
    1. Normal: A new order is required to maintain stock at or above safety stock by the end of the lead time and each planning period beyond the lead time.
    2. Exp. Future Order: Orders that are in the planning horizon beyond the lead time are suggested to be expedited to an earlier date in order to prevent a potential stock out or breach of safety stock.
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