Capacity requirements planning (CRP) is a technique used to calculate the workload for different machines and production groups based on an existing manufacturing plan from material requirements planning (MRP). CRP is a total capacity requirements calculation, meaning that it includes all records and all shop order requisitions that have been generated. Ultimately, the goal of CRP is to help you verify that the manufacturing plan is feasible, i.e., whether there is enough capacity to fill all shop orders. This allows you to determine when production orders should be implemented. With CRP, you can analyze resource requirements for a shorter period than is possible with resource planning.
CRP considers all existing shop order requisitions, regardless of their origin. They can be entered manually, generated from order point proposals, created in connection with MRP, or generated from the master schedule. The system generates shop order requisitions originating from the master schedule when it performs Level 1 calculations. These calculations consider demand up to the planning time fence. CRP also considers the fixed and variable master schedule proposals that are located outside the planning time fence. Furthermore, it considers unreleased dynamic order processing (DOP) orders that are entered or generated manually. When DOP orders are created, they use specific routings revision and alternate numbers. When the system calculates the CRP load per work center, it verifies the DOP revision routings and alternate numbers. If these numbers are valid, they are either considered as CRP load on the work center or not considered at all.
Using the resource requirements and information about the capacity of various work centers, the system performs a detailed CRP calculation. This calculation does not consider maximum capacity. The calculation begins with a current operation list for the standard part and works backward. The system verifies that the workload is planned only for days that are included in the shop calendar. Only workdays should exist in the shop calendar. Weekends and holidays are not counted in MRP. CRP also considers CBS overlap values either in units or as a percentage entered in operation level for CBS sites and Advance Planning Board enabled sites.
Once you have confirmed the capacity requirements calculation, the system copies all the information needed for the calculation from the MRP results. The needs that arise from master schedule proposals lying outside the planning time fence are also included in the calculation. Because the information is copied, you can continue working while the system performs CRP. If any basic data changes, such as operations for a part or capacity of work centers, you must redo the calculation. Otherwise, the results will be incorrect.
At any time, the CRP process will have one of three statuses shown below.
| Status | Description |
| Calculation in Progress | The calculation begins. The system verifies that you have access to the specified sites and that no other calculations will interfere with CRP. The system automatically cancels CRP if MRP, master scheduling, another CRP session, or any combination of these is running. |
| Reading in Requisition | The calculation starts. The system deletes any information from the previous CRP for the sites that will be processed. The system then analyzes shop order requisitions and plans the capacity of each work center. This type of operation scheduling uses backward planning from the due date. The system does not consider whether other shop order requisitions affect the same work center the same day. Finally, the system maps out master scheduling requirements beyond the planning time fence that will generate shop order requisitions. This is similar to the process used for existing shop order requisitions. |
| Calculation Complete | The system displays the CRP results in a query window, including total workload per day and work center. |