EBOM, MBOM and SBOM: Managing Bills of Materials

Short answer

A bill of materials (BOM) lists the parts, materials and quantities that make up a product. The engineering BOM (EBOM) shows the product as designed, the manufacturing BOM (MBOM) shows how it is built in a specific plant, and the service BOM (SBOM) shows which parts can be replaced in the field. PLM keeps these views linked and traceable.

Key takeaways

The EBOM is organised by function and design, the MBOM by assembly sequence and plant, and the SBOM by serviceable units.
Each view adds or removes items: the MBOM adds consumables and packaging, the SBOM groups parts into spare kits.
Linking the views in PLM makes change impact visible across design, production and service.
In software and cybersecurity, SBOM also means software bill of materials, a separate concept now required by the EU Cyber Resilience Act.

What is in each BOM view?

View	Answers	Organised by	Typical additions or removals
EBOM	What is the product as designed?	Function, system, CAD structure	Includes all designed parts, excludes process materials
MBOM	How is it built in plant X?	Assembly sequence, work centres	Adds glue, labels, packaging, phantom assemblies; may flatten design subassemblies
SBOM (service)	What can be replaced in the field?	Field replaceable units	Groups parts into kits, adds service tools, removes non-serviceable parts

Other views exist. A costing BOM groups items for quotation, and a sales or configurable BOM holds options for order entry. The three above are the core views that most PLM systems manage.

Worked example: an industrial pump

EBOM. The design team structures the pump into a motor assembly, pump housing, impeller, shaft and seal kit, and a control unit with a PCB and firmware. Each line has a part number, revision and quantity, and maps closely to the CAD assembly.

MBOM. The plant in Poland builds the pump differently. The seal kit is not a subassembly on the line, so its parts are flattened into the housing operation. The MBOM adds thread locker, two labels, a pallet and a carton. The motor arrives as a purchased unit, so its internal parts drop out. A second plant in Mexico has its own MBOM because it buys the control unit pre-assembled.

SBOM. Field service needs a seal kit, an impeller and a control unit as replaceable units, plus a special puller tool. The shaft is not serviceable, so it does not appear.

Why should the views be linked?

When an engineer changes the impeller material, three things need checking: which plants build it, whether spare part stocks need updating and whether service manuals change. If the views are separate spreadsheets or separate ERP records, these questions are answered manually and often late. When PLM links each MBOM and SBOM line back to its EBOM source, it can show the impact automatically during engineering change management.

Linked views also support reconciliation reports. These flag EBOM parts that no MBOM consumes, or MBOM lines with no engineering source.

Where should each BOM live?

The EBOM belongs in PLM. The MBOM can sit in PLM or ERP, and the trade-offs are covered in PLM vs ERP. Vendors with strong manufacturing process planning, such as Siemens Teamcenter, Dassault 3DEXPERIENCE and Aras Innovator, support EBOM to MBOM restructuring with side-by-side editors. Cloud BOM tools such as OpenBOM and Arena focus on fast, collaborative BOM editing for smaller teams. The SBOM often moves to a service lifecycle or ERP service module after release.

How are variants handled?

Configurable products would need thousands of separate BOMs without variant logic. PLM systems use a 150% BOM (also called a super BOM) that contains every possible option, with rules that filter it to a specific configuration. For example, a pump available with three motor sizes and two seal materials has six combinations from one structure. Rules can sit on BOM lines as option codes or in a separate configurator. Keep option logic in one place, because duplicated rules in PLM and ERP drift apart quickly.

The other SBOM: software bill of materials

In software and cybersecurity, SBOM means software bill of materials: a machine-readable list of software components and dependencies. The EU Cyber Resilience Act, Regulation (EU) 2024/2847, requires manufacturers of products with digital elements to draw up an SBOM as part of technical documentation. Most of its obligations apply from 11 December 2027. Common formats are CycloneDX and SPDX.

For connected products, the PLM record increasingly links hardware BOMs to the firmware and software SBOM. That link is part of the wider digital thread. It lets a vulnerability in a software library be traced to the affected hardware revisions and serial numbers in the field.

Practical rules for BOM governance

One part number per form, fit and function. Change the number when interchangeability breaks.
Define who owns each view and who may edit it.
Release BOMs through change orders, never by direct edit after release.
Run reconciliation between views before each release.
Plan BOM cleansing early in PLM data migration.

Frequently asked questions

What is the difference between an EBOM and an MBOM?

The EBOM describes the product as designed, structured by function and usually mirroring the CAD assembly. The MBOM describes how a specific plant builds it, structured by assembly sequence. It adds process materials such as adhesives, labels and packaging, and may flatten or regroup design subassemblies. One EBOM can have several MBOMs, one for each plant or production method.

What is a 150% BOM?

A 150% BOM, also called a super BOM or overloaded BOM, contains every option and variant a product can have in one structure. Configuration rules filter it to a 100% BOM for a specific order or model. This avoids maintaining thousands of separate BOMs for configurable products and keeps engineering changes in a single place.

Is a service BOM the same as a spare parts list?

They are closely related. A service BOM is a structured view of the product showing field replaceable units, kits and service tools, linked to the engineering source. A spare parts list is often a flat commercial extract of it, with prices and stock data. Keeping the service BOM linked in PLM means engineering changes flag which spare parts are affected.

Sources

Reviewed 16 October 2026 by the PLM Vendors editorial team. Regulatory dates and vendor details change; check the sources for the latest position.