| # Capacity CTP check The capacity CTP represents what you can produce in addition to the standard ATP, taking the free capacity of critical work centers into account. Component CTP and capacity CTP can be seen as Build to Promise. LN calculates the CTP quantity from the free capacity of a work center and based on the number of hours required to manufacture one additional end item. Example ATP of A =10. CTP of work center WC-1 = Three hours. 0.5 hours of WC-1 is required to produce one piece of A. If LN performs an ATP check and a capacity-CTP check for item A, the result is 16 (ATP of A + additional CTP of WC-1). Enabling capacity CTP checking To enable capacity CTP checking for the end item: Select the Capacity CTP check box in the Items - Planning (cprpd1100m000) session. Select the Critical in CTP and Maintain Resource Master Plan check boxes for the resource (work center) in the Resource (cprpd2100m000) session. LN uses the resource master plan to calculate the capacity CTP of a resource. Therefore, you must always select the Maintain Resource Master Plan check box when you define a resource as critical in CTP. Otherwise, LN will not calculate the capacity CTP during CTP checks. Combined component CTP and capacity CTP - single level If you use both component CTP and capacity CTP, the most restrictive one, available components or available capacity, is leading. Example End item A is manufactured in work center WC-1 using component B. ATP of A = 10. ATP of component B = Six pieces. CTP of work center WC-1 = Seven hours. One piece of component B and one hour of WC-1 is required to produce one piece of A. If LN performs a component CTP check and a capacity CTP check for item A, the result is 16 (CTP of component B limits WC-1). Combined component CTP and capacity CTP - multiple periods If you combine component CTP and capacity CTP, LN checks the components and capacity independently from each other, based on cumulative quantities. This implies that the critical capacity is not necessarily available at the same time as the critical component. Example The following example illustrates this limitation. t is the time for which LN performs a CTP check for end item A. The offset for the required component B and capacity WC-1 is three periods. Therefore, the component and capacity are required no later than time (t-3). The cumulative capacity CTP of work center WC-1 on t-3 is seven. The free capacity of seven hours that creates the cumulative CTP is not on t-3, but earlier on t-4. Component B has cumulative ATP of six pieces on t-3 and zero pieces on t-4. Component B is required to perform the operation on work center WC-1. In this situation, the CTP check shows that you can produce six pieces to be delivered on t, although the exact work center (t-4) and component (t-3) availability do not fall in the same period. In fact, LN calculated the CTP with the cumulative CTP figures only (the cumulative capacity CTP and the cumulative ATP of the component). LN does not take the relationship between the component and the capacity into account. In this case, LN indicates that you can promise the sales order on time t. After you run the order planning, the work center WC-1 is overloaded on t-3, but the total capacity load over all periods matches the available capacity. This situation is the result of working with cumulated quantities over multiple periods. This calculation method is considered correct, because Enterprise Planning is an infinite capacity planning tool. To perform order promising against finite capacity and consider all relationships between work centers and materials, you must use Order Promising Server. Combined component CTP and capacity CTP - multilevel If you defined multiple critical components and capacities on various levels of a bill of material in the same branch, each level adds a particular quantity to the total quantity you can promise to the customer. Example End item A is manufactured in work center WC-1, using component B. Component B, in turn, is manufactured in work center WC-2 using component C. Item B is a component. Therefore, on the CTP tab of the Items - Planning (cprpd1100m000) session, you must select the Critical in CTP check box. At the same time, item B is also a product. Therefore, you must also select the Component CTP and the Capacity CTP check boxes. ATP of A = 10. ATP of component B = Six pieces. CTP of work center WC-1 = Seven hours. ATP of component C = Four pieces. CTP of work center WC-2 = Three hours. On both levels, you need one piece of a component and one hour of work in a work center to produce a product. If LN performs a component CTP check and a capacity CTP check for item A, the result is as follows:
Multilevel CTP calculation
Level | ATP
--- | ---
Level 0 | 10 (ATP of A)
Level 1 | 6 (CTP of component B limits WC-1)
Level 2 | 3 (CTP of WC-2 limits component C)
Total | 19
Combined component CTP and capacity CTP - multiple branches in the BOM If you check various branches in the bill of material, the most restrictive branch determines the available quantity. Example You have a second component D on level 1, in addition to component B. ATP of D is zero The branch of D restricts the complete branch of B. Therefore, the total available quantity is 10 (ATP of A). |