Component CTP and capacity CTP order-based CTP check

Standard items

To calculate the date on which items are required, LN retrieves the lead-time offsets, as follows:

The bill of material defines the lead-time offset for the components. In addition to this lead-time offset value, the component is also offset with the inbound and outbound lead-time, the safety time, and the extra lead time.
LN multiplies the routing operation times and the required quantity to calculate the lead-time offset for the capacity.

When the required date is determined, the component CTP is calculated online for every bucket as specified in the Component CTP bucket field of the Planning Parameters (cprpd0100m000) session.

However, the capacity CTP is derived from the resource master plan that is based on the plan period buckets as defined in the Scenario - Periods (cprpd4120m000) session. As a result, the lead-time offset for capacity results in a required date that will fall in a resource master plan bucket, after which the available capacity of that bucket is taken.

Note: You can specify the critical materials by selecting the Critical in CTP check box in the Items - Planning (cprpd1100m000) session.

In a multilevel bill of material, you can indicate that only the lowest level components are critical in CTP. The subassemblies need not be selected as critical.

If only the Component CTP check box is selected for the subassemblies in the Items - Planning (cprpd1100m000) session, the CTP check will not calculate their availability. Instead, the CTP checks only perform a lead-time offset for such items based on the information in the bill of material. Next, the CTP check explodes the critical components and checks the availability of components. This enables you to check only the critical materials in the entire product structure.

For capacities, the same concept can be applied. If the Critical in CTP check box is selected in the Work Centers - Planning (cprpd2100m000) session and the Capacity CTP check box is selected in the Items - Planning (cprpd1100m000) session, the resource’s availability will be checked during CTP. This enables you to check only the critical resources in the entire product structure.

Generic items

In case of generic items, the correct materials and capacities must be checked based on the chosen options in the product variant. First, the user configures the product variant in, for example, the sales order. When the user enters the ordered quantity, the CTP for that specific configuration is checked.

The generic bill of material is therefore matched against the chosen options in order to find the appropriate materials and capacities. This action is performed online.

The generic bill of material is exploded, taking into account all constraints, which is precisely the same action as when the customized product structure is created for the generic item. However, this explosion is merely a simulation to find the correct CTP figures. The result of the explosion is not stored.

The lead-time offset is determined in the same way as for standard items. However, instead of the bill of material lead-time offset (LTO), the generic bill of material LTO is used to determine the required date for the components. In addition to this LTO value, the component is also offset with the inbound and outbound lead-time, the safety time, and the extra lead-time.

Customized items

In case of customized items, the ATP and Component CTP are performed first for the customized items, and then for the derived-from item, as illustrated in the following figure:

The ATP of the standard-to-order items does not include the ATP of the related customized items. As a result, if a standard to order item A has a relation to five different customized items, the ATP of all these customized items is deducted from the ATP of item A.

This outcome is logical, because when the ATP is checked for one of the customized items, the ATP cannot, of course, consume ATP of any of the other customized items. ATP can only consume its own ATP and the ATP of the derived-from item.

The ATP of the derived-from item (A) is based on the item’s own transactions and on-hand stock. The item order plan for this type of item enables you to toggle between the item’s transactions and the derived-from item's transactions, including all customized items.

Both options provide the ATP for the derived-from item that is checked for customized items.

Note: This concept of checking ATP/CTP for customized items and the derived-from item is also valid for customized items that are derived from a generic item.