What Is EBOM vs MBOM (Engineering BOM vs Manufacturing BOM)?
Also known as: EBOM, MBOM, engineering bill of materials, manufacturing bill of materials
Definition
The engineering BOM (EBOM) lists parts as the designer structured the product. The manufacturing BOM (MBOM) restructures that list to match how it is built: assemblies, consumables, packaging, phantom levels and the plant where it is made.
EBOM vs MBOM (Engineering BOM vs Manufacturing BOM) Explained
Design engineers build the EBOM in CAD or PLM around function: assemblies as the product is designed to work. The shop floor needs a different shape. It adds fasteners, adhesives, labels and packaging, removes drawing-only items, and creates sub-assemblies that match real build stages and stockable kits.
The MBOM is what ERP planning reads. MRP explodes the MBOM to generate purchase and work orders, and costing rolls up from it. If an EBOM is loaded to ERP unchanged, MRP often plans phantom or non-physical items that nobody builds, and misses consumables that do get issued.
Handling differs by system. Infor LN keeps engineering and production BOM concepts separate in Engineering Data Management and Manufacturing. SyteLine has a single job-order BOM per item, so many sites keep the EBOM in PLM and publish an MBOM. NetSuite uses assembly item BOMs with revisions. The recurring problem is keeping the two aligned after each ECO.
Some companies also keep a service BOM, which is a third view for spare parts. The same part appears differently in each view by design.
Why It Matters
- Planning from an unconverted EBOM produces wrong shortages and excess purchases.
- Cost rollup is only as good as the MBOM, so margin reporting depends on it.
- Engineering changes must propagate to the MBOM or the floor builds stale structures.
- Multi-plant companies need one EBOM with several plant-specific MBOMs.
In Practice
A pump EBOM shows motor, housing, impeller and seal kit, 4 lines. The MBOM adds 12 fasteners, thread locker, a test fixture step item, a carton and a label, and groups motor and housing into a phantom sub-assembly built in one cell. The 4-line EBOM becomes about 20 MBOM lines, none of which engineering needed to draw.
Frequently Asked Questions
Why can't I just use the EBOM in ERP?
It reflects design structure, not build structure. MRP would plan the wrong sub-assemblies and miss consumables, packaging and process materials.
How is an EBOM converted to an MBOM?
Usually in PLM or a conversion tool: restructure levels, add process materials, set plant and effectivity, then publish to ERP. Many small companies do it manually.
Does every company need both?
Not always. Simple build-to-print shops may use one BOM. The split matters once design and production are separate teams or plants.
Related Terms
BOM (Bill of Materials)
A BOM (bill of materials) is the structured, hierarchical list of components, sub-assemblies, and quantities required to produce one unit of a parent item, and it is the primary input MRP explodes to calculate material requirements.
Multi-Level BOM
A multi-level BOM lists a finished product and each of its sub-assemblies and components in nested levels, so you can see the full structure from the end item down to raw material, rather than only the immediate children.
PLM (Product Lifecycle Management)
Product lifecycle management (PLM) is software that manages product definition data from concept through design, release and retirement: CAD models, engineering BOMs, documents, revisions and change approvals, then hands released data to ERP for production.
Engineering Change Order (ECO)
An engineering change order (ECO) is the formal, approved document that authorizes a change to a part, bill of materials, drawing or routing, defines when it takes effect, and says what happens to existing stock and open orders.
Go Deeper
ERP-PLM Integration Guide
ERP-PLM integration guide: sync engineering BOMs, item masters, ECOs, and CAD documents between PLM and Infor SyteLine or LN without duplicate data entry.
SyteLine BOM Management & Optimization with AI
Optimize SyteLine Bill of Materials with AI. Automated BOM validation, cost rollups, and engineering change management for Infor CloudSuite Industrial.
Working with EBOM vs MBOM (Engineering BOM vs Manufacturing BOM) in a live environment? Our engineers do this every day - and our AI agents automate most of it.