Capacity Requirements Planning and Rough-Cut Capacity Planning
Two levels of capacity check
Rough-cut capacity planning (RCCP) tests the MPS against key resources before MRP runs. Its three techniques are capacity planning using overall factors (historical hours-per-item ratios), capacity bills (BOM-based hours per MPS item, untimed), and resource profiles (hours spread over time using lead-time offsets). CRP then takes planned order releases from MRP, applies routings to work centres, and produces a period-by-period load profile.
Calculating load
Load per order = setup time + (run time per unit × quantity). Sum across all orders routed to the work centre. Compare with available capacity: hours per shift × shifts × days, adjusted by utilisation and efficiency, and sanity-checked against demonstrated capacity. Overload means the plan is infeasible as dated; options are overtime, extra shift, subcontracting, rescheduling, or changing the MPS.
Infinite vs finite
RCCP and CRP are normally infinite-loading exercises: they expose the gap, they do not resolve it. Finite scheduling constrains sequence and quantity. Queue time absorbs some variation but not sustained overload - when a work centre is chronically overloaded, lead times grow and MRP's fixed lead times become fiction.
Worked example
An order for 200 units on a work centre with setup 2.0 hours and run time 0.10 hour per unit: load = 2.0 + (200 × 0.10) = 22.0 hours. The centre offers 40 hours per week with 25 already committed, leaving 15. The order overloads the week by 7 hours, so it must be split, covered by overtime, or moved. CRP's job is to flag it, not to fix it.
Traps
Confusing RCCP (MPS, key resources, families) with CRP (MRP, all work centres, components). Omitting setup time from the load. Treating lead time as fixed when queueing is the real constraint.