MRP, MRP II, and ERP answer different planning questions
Material requirements planning calculates what material is needed and when. Manufacturing resource planning, commonly called MRP II, extends that logic into capacity, labor, schedules, and execution feedback. ERP coordinates those manufacturing decisions with the wider business, including purchasing, sales, inventory, quality, costing, and finance. The boundaries overlap by product, so evaluate the inputs, outputs, owners, and exception response rather than relying on a label.
| Planning layer | Primary question | Core inputs | Typical output | Feedback needed |
|---|---|---|---|---|
| MRP | What material is needed, and when? | Demand, BOM, inventory, lead time | Planned purchase and production orders | Receipts, issues, shortages, changes |
| MRP II | Can the manufacturing plan be executed? | MRP inputs plus routing, labor, work centers, calendars, capacity | Feasible schedules and resource plans | Completion, downtime, scrap, actual time |
| ERP | How does the plan affect the enterprise? | Manufacturing data plus customers, suppliers, quality, cost, and finance | Coordinated business transactions and records | Cross-functional status and reconciliation |
Start with the inputs that make a plan credible
An MRP calculation can be mathematically correct and still be operationally unusable. Demand dates may be stale, inventory may include material that is unavailable, BOM quantities may not match the released revision, and lead times may reflect a policy rather than actual supply behavior. Before comparing software, define who owns each input and how its accuracy is checked.
Capacity adds another layer. A routing may list the correct operations but omit setup behavior, alternate resources, labor constraints, preventive maintenance, tooling, outside processing, or shift calendars. MRP II becomes useful when those constraints influence the plan and when actual production results return quickly enough to change the next planning decision.
- Separate customer orders, forecast demand, safety stock, and replenishment policy.
- Confirm revision, effectivity, yield, scrap, substitute, and make-or-buy rules in the BOM.
- Define usable inventory by location, status, lot, quality hold, and allocation.
- Record lead-time assumptions and the evidence used to maintain them.
- Assign owners to routing standards, calendars, work centers, labor, and tooling constraints.
Close the loop with production evidence
A plan loses value as soon as the floor changes and the system does not. Completions, partial quantities, scrap, downtime, material substitutions, queue time, and outside-process delays affect both material and capacity. Decide which events change availability, which trigger replanning, and which require human review.
The planner should see the cause of an exception, not only a new late date. A shortage caused by a rejected lot needs a different response from a shortage caused by an unposted receipt. A capacity conflict caused by planned maintenance differs from one caused by an inaccurate cycle standard. Preserve that evidence so the planner can choose a response and explain its tradeoff.
Planning automation does not remove planner judgment
Rules can calculate dates and quantities. People still decide how to handle competing customers, constrained tools, uncertain suppliers, overtime, substitutions, and risk. The operating model must show where approval is required.
Evaluate one constrained order from demand through close
Use a representative order with multiple BOM levels, a purchased constraint, a shared work center, an inspection step, and a credible schedule disruption. Load the same known inputs into each candidate process. Record the planned material, capacity, start dates, promise date, exception messages, and transactions required to keep the plan current.
Then change one condition at a time. Delay a component, place a lot on quality hold, reduce a machine calendar, report partial completion, or increase scrap. The useful test is whether the system identifies the affected work, preserves the reason, supports an owned decision, and reconciles the resulting inventory, schedule, cost, and customer date.
| Test | Evidence to retain | Failure signal |
|---|---|---|
| Initial plan | Inputs, assumptions, dates, quantities, constraints | Output cannot be traced to source data |
| Material delay | Affected orders, allocation rule, response | Planner relies on an offline shortage list |
| Capacity loss | Resource impact, alternatives, approval | Schedule moves without explaining the constraint |
| Execution feedback | Event time, quantity, reason, recalculation | Floor status and plan disagree |
Choose planning depth that matches the operating problem
A stable, low-variety replenishment environment may not need the same planning depth as a make-to-order plant with shared resources, multi-level structures, variable yields, and frequent change. More model detail also creates more master data to govern. Add a constraint only when it materially changes a decision and has an accountable owner.
DELMIAWorks is documented by Dassault Systèmes as combining manufacturing ERP and MES in one shared database. That architecture is relevant when planning depends on production, quality, inventory, and financial transactions staying connected. It does not replace a fit review. The specific planning rules, configuration, interfaces, and commercial scope still need to be verified for the intended release.
Build the planning-input register before the demo
Record each planning question, required input, source, owner, exception evidence, and status. Use the same register to compare the current process and candidate systems.
Frequently asked questions
What is manufacturing resource planning?
Manufacturing resource planning, or MRP II, extends material planning into capacity, labor, scheduling, and production feedback. It tests whether the material plan can become an executable manufacturing plan.
What is the difference between MRP and MRP II?
MRP focuses on material quantities and timing. MRP II adds manufacturing resources and closed-loop feedback, including work centers, labor, calendars, schedules, and actual production results.
Is MRP II the same as ERP?
No. MRP II centers on manufacturing planning and resource coordination. ERP extends the transaction model across the wider business, although modern manufacturing ERP products may include both sets of capabilities.
What data should be checked before evaluating MRP II?
Check demand, BOMs, revisions, inventory status, lead times, routings, work centers, calendars, labor, tooling, yield, scrap, order policy, and the production events used to update the plan.
References and method
- Dassault Systèmes DELMIAWorks, current vendor architecture and manufacturing scope
- DELMIAWorks advanced planning and scheduling course profile, vendor planning and scheduling training scope
- IBM: Enterprise resource planning, general ERP category context
- The tables, diagrams, selection questions, and downloadable register are Morphos 3D guidance. Verify product configuration, interfaces, validation requirements, and commercial packaging for the exact release and operating environment.
Map the planning decision before selecting the tool
Use one constrained order to expose the required inputs, feedback, owners, and exception paths. Then test whether the manufacturing system keeps those decisions connected.