Short answerA bill of materials (BOM) lists every component, material and quantity needed to make a product. The engineering BOM (EBOM) reflects design intent, the manufacturing BOM (MBOM) reflects how it is built, and the service BOM (SBOM) reflects how it is maintained. Material-level BOM data now feeds Digital Product Passport and PPWR reporting.
Key takeaways
- Most manufacturers maintain at least 3 BOM views of one product: EBOM in PLM, MBOM in ERP or MES, and SBOM for after-sales service and spare parts.
- Change control typically follows a two-step process: an Engineering Change Request (ECR) proposes and assesses a change, and an Engineering Change Order (ECO) approves and releases it with an effectivity date.
- PPWR (EU) 2025/40 and ESPR (EU) 2024/1781 require material composition, weights and recycled content, data that only exists reliably at BOM line level.
One product needs several BOM views
A single product has several valid BOMs because each function sees it differently. Engineering structures the product by function and design ownership. Manufacturing structures it by assembly sequence, work centre and consumables. Service structures it by replaceable units. Forcing one structure on all three creates workarounds and errors.
| BOM type | Owner | Typical system | Content focus |
|---|---|---|---|
| EBOM | Engineering | PLM | Parts, revisions, design materials, CAD links |
| MBOM | Manufacturing | ERP or MES | Assembly steps, phantom items, packaging, consumables, plant variants |
| SBOM | Service | PLM, ERP or service platform | Spare parts, field-replaceable units, interchangeability |
| Packaging BOM | Packaging technology | PLM | Primary, secondary and tertiary packaging components and materials |
The EBOM to MBOM conversion step deserves explicit design. Common approaches include manual restructuring in ERP, guided restructuring in PLM with transfer to ERP, and associative MBOMs that stay linked to the EBOM. Linked approaches reduce errors during later changes but need more configuration effort.
Configurable BOMs manage variant complexity
A configurable BOM, also called a 150% BOM, holds every possible option in one structure with rules that resolve it into a buildable 100% BOM. This suits products with many options, such as machinery, vehicles, furniture and electronics. Rules usually express inclusions, exclusions and dependencies between features.
The main trade-off is governance. Configurable BOMs reduce duplication sharply, yet a rule error affects every derived variant. Organisations typically assign a dedicated product configuration role and test rules against a set of reference configurations before release.
Configurable BOMs also complicate compliance reporting. Material totals, recycled content and substance declarations differ per resolved variant, so reporting must run on the 100% BOM of each sellable configuration. PLM suites handle this in different ways, from pre-calculated variant BOMs to on-demand resolution. Buyers with high variant counts should test this explicitly, using a real product family with dozens of options and at least one restricted material.
Change control keeps BOMs trustworthy
Controlled change is what separates a BOM from a spreadsheet. A typical flow runs as follows:
- Problem report or change request raised by engineering, quality, service or a supplier
- ECR: impact analysis covering affected parts, cost, stock, tooling, compliance and suppliers
- Change board review with engineering, manufacturing, quality and sourcing
- ECO: approval, release of new revisions and an effectivity date or serial range
- Transfer to ERP and downstream systems, followed by implementation and verification
Compliance impact should be a standard ECR field. Replacing a plastic grade or a coating can change recyclability class, substance declarations and recycled content claims. Teams that add this check avoid publishing outdated data to labels and catalogues. The wider module context is described in what is PLM.
Material-level BOM data feeds DPP and PPWR
Regulators now ask questions that only a detailed BOM can answer. The Packaging and Packaging Waste Regulation (EU) 2025/40, applicable from 12 August 2026, depends on packaging composition, component weights, recyclability and recycled content. ESPR (EU) 2024/1781 enables Digital Product Passports that will require composition, substances of concern and repairability data for priority product groups.
These attributes exist at BOM line level: each component, its material, its mass and its supplier declaration. Aggregating them upwards produces product-level totals such as total plastic weight or recycled content share. Without line-level data, teams estimate, and estimates rarely survive an audit.
Typical attributes to add to BOM lines include:
- Material type and grade, with a controlled material library
- Net mass per unit, with unit of measure
- Recycled content percentage and evidence source
- Substances of concern, with CAS number and concentration where relevant
- Supplier and declaration reference with validity date
The data structure for packaging is detailed in the packaging data model, and passport requirements in the Digital Product Passport explained.
Start with the BOMs that regulators will ask for first
A phased approach keeps effort manageable. Packaging BOMs come first for most consumer goods companies because PPWR already applies. Product groups named in the ESPR working plan, such as textiles, furniture, steel and aluminium products, follow. Enriching an existing BOM with material and mass data typically takes an estimated 0.5 to 2 hours per item when supplier declarations are available, and considerably longer when they are not. Suites with strong BOM and compliance modules are listed in the PLM vendor overview.
Frequently asked questions
What is the difference between an EBOM and an MBOM?
An EBOM reflects design intent: functional parts, revisions and materials as engineered. An MBOM reflects how the product is actually built: assembly sequence, plant-specific items, consumables and packaging. The EBOM usually lives in PLM and the MBOM in ERP or MES.
What is the difference between an ECR and an ECO?
An Engineering Change Request proposes a change and documents its impact on parts, cost, stock and compliance. An Engineering Change Order approves the change, releases new revisions and sets an effectivity date. Many organisations add a change notice step to communicate it.
Why does BOM data matter for the Digital Product Passport?
Passport requirements under ESPR delegated acts include composition, substances of concern and recyclability information. These values are calculated from component materials and masses. Accurate BOM lines with material and supplier data are therefore the most reliable source for passport content.