##  [Material Requirements Planning](/material-requirements-planning-0) 

 Definition

A rule-based, bill-of-materials–driven method for computing the quantities and timing of component purchases and production orders required to meet dependent demand. MRP converts end-item production schedules into net material requirements by using the product structure (BOM), current on‑hand inventory, scheduled receipts, lead times and lot‑sizing rules; it produces planned orders and order release recommendations but does not, by itself, perform finite-capacity scheduling or replace master production scheduling.

 

 

 

 

 

 





## Principle

Principle

Translate independent end-item demand into time-phased dependent requirements through the bill of materials and schedule order receipts so that materials are available when needed, subject to lead times and lot-sizing rules.

 

 

 

 

 





## Demonstration

Demonstration

Illustrative scenario → A manufacturer must deliver 100 units of Product A on date D. BOM shows each A needs two Bs and one C. Current inventory: 50 Bs, 10 Cs. Lead times: B = 2 weeks, C = 1 week. Recognition → Planner inputs the master schedule, BOM, inventory and lead times into MRP. Action → MRP explodes demand, nettings inventory, and creates planned orders for Bs and Cs with release dates aligned to lead times. Consequence → Purchase orders and shop orders are timed to produce or procure the shortfall so components arrive before assembly on D.

 

 

 

 

## Misapplication

Misapplication

Treating MRP outputs as a guaranteed, executable shop schedule without checking capacity or ignoring inaccurate BOM/lead-time data. This error treats planned order recommendations as directly actionable work orders, conflating material planning with finite scheduling.

 

 

 

 

 





## Consequence

Consequence

Proper use yields time‑phased purchase and production plans that reduce stockouts of dependent parts and clarify procurement timing; misuse (bad data or ignoring capacity) produces excessive work in progress, late orders, or stock imbalances.

 

 

 

 

## Reversal

Reversal

When production is driven by high variability, very short lead times, or pull‑based methods (e.g., Kanban) and when capacity constraints dominate, MRP’s push, deterministic assumptions fail and a pull or finite‑scheduling approach may be more appropriate.

 

 

 

 

 





## Boundary

Boundary

Clearly within → Multi‑level assemblies with dependent demand where BOM, lead times and inventory are defined. Boundary case → Low-volume, engineer‑to‑order products where lot‑sizing and lead‑time variability reduce MRP accuracy. Clearly outside → Independent demand retail items managed by single‑level reorder points without BOM explosion.

 

 

 

 

 





## Semantic Tension

Semantic Tension

Push/planned material control (MRP) versus pull/flow control (Just‑in‑Time/Kanban); material timing recommendations versus capacity/finite scheduling constraints.

 

 

 

 

 





## Synthesis

Synthesis

MRP is a deterministic planning layer that converts product schedules into material actions; its value depends on accurate BOM and lead‑time data and on integration with capacity controls to convert plans into feasible production sequences.