Closed-Loop MRP — Manufacturing Glossary

Closed-Loop MRP is an enhanced material requirements planning system that adds feedback from capacity planning and shop floor execution back into the planning process. Unlike basic MRP, which generates plans without verifying feasibility, closed-loop MRP validates that plans are achievable and adjusts them based on actual production results.

At User Solutions we have spent 35+ years helping manufacturers move beyond open-loop planning. Closing the MRP loop is one of the fastest ways to eliminate the gap between what the plan says and what the shop floor actually delivers.

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How Closed-Loop MRP Works

Basic MRP follows a one-directional flow: the master production schedule drives BOM explosion, which generates planned orders. Closed-loop MRP adds critical feedback steps:

1. Master Production Schedule (MPS) defines what to produce and when.
2. MRP explosion calculates material requirements from the Bill of Materials.
3. Capacity Requirements Planning (CRP) checks whether sufficient machine and labor capacity exists to execute the plan.
4. If capacity is insufficient, the planner adjusts the MPS or adds capacity (overtime, outsourcing).
5. Order release sends feasible work orders and purchase orders to the shop floor and suppliers.
6. Execution feedback — actual production completions, scrap rates, and delays — flows back into the system.
7. MRP re-plans based on updated reality.

The "loop" is this continuous cycle of plan, check capacity, execute, measure, and re-plan.

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Closed-Loop MRP Example

A mid-size machine shop runs MRP weekly. The MPS calls for 500 machined housings next week across three CNC work centers.

Without closed-loop: MRP generates planned orders for 500 units and releases them. But Work Center 3 is already loaded at 95% capacity from existing orders. The new work pushes it to 140% — jobs pile up, overtime explodes, and three customer deliveries slip.

With closed-loop: After MRP explosion, CRP flags that Work Center 3 is overloaded by 45%. The planner sees the overload report and takes action:

• Shifts 80 housings to an alternate CNC with available capacity
• Moves 50 housings to the following week
• Approves 8 hours of Saturday overtime for the remainder

The adjusted plan is feasible. At week's end, the shop reports that actual output was 465 units (93% of plan) due to an unplanned tool break. Closed-loop MRP absorbs this feedback, automatically adjusting next week's schedule to recover the 35-unit shortfall.

The result: capacity is respected, delivery promises are realistic, and deviations are corrected quickly instead of compounding.

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Why Closed-Loop MRP Matters for Scheduling

Plans become executable. The biggest failure in manufacturing planning is generating schedules that ignore capacity. Closed-loop MRP prevents this by validating every plan against real constraints before releasing orders.

Feedback prevents drift. Without feedback, small deviations — a machine breakdown here, a quality reject there — accumulate until the plan bears no resemblance to reality. The feedback loop catches deviations early and corrects them.

Scheduling accuracy improves over time. Each feedback cycle refines planning parameters: lead times, scrap rates, and run times get more accurate. Scheduling tools like Resource Manager DB leverage this improved data to produce increasingly reliable schedules.

Customer promises become trustworthy. When you know your plan is capacity-checked and continuously updated, you can quote delivery dates with confidence. Manufacturers running closed-loop systems consistently achieve 90%+ on-time delivery rates.

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Related Terms

• Capacity Requirements Planning (CRP) — The capacity validation step that makes MRP "closed-loop."
• Manufacturing Resource Planning (MRP II) — The evolution of closed-loop MRP that adds financial and business planning.
• Regenerative MRP — A full MRP recalculation method often used within closed-loop systems.

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FAQ

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This term is part of the Manufacturing Glossary. For a deep dive into material planning, see our MRP Guide.