eBOMs

An Engineering Bill of Materials (EBOM) is a structured list of the components, subassemblies, and materials required to realize a product according to its engineering design. It expresses the design intent and is typically derived from CAD and product data management (PDM/PLM) systems. An EBOM is usually organized hierarchically into assemblies and parts, and includes part numbers, descriptions, units of measure, and quantities per assembly. It may also record design attributes such as material, finish, tolerances, and whether parts are standard or custom.

The EBOM is distinct from a Manufacturing Bill of Materials (MBOM), which specifies how the product is built on the shop floor, including manufacturing steps, routing, and process-specific parts. The EBOM provides the engineering perspective, while the MBOM reflects production requirements. A mapping or reconciliation between EBOM and MBOM is common, enabling downstream planning and ensuring design changes are reflected in manufacturing plans.

Lifecycle and governance: EBOMs are created during concept or detailed design phases and evolve through design changes. They are managed within PLM or PDM systems, with revision control and configuration management to maintain traceability. EBOMs can support multiple configurations or variants of a product, each with its own design-accurate bill of materials.

Uses and benefits: EBOMs support design reviews, cost estimation, sourcing alignment, and change impact analysis. They help ensure BOM integrity across design changes, support compliance and traceability, and provide a design-centric view for engineering teams. EBOMs also serve as a baseline for downstream processes in procurement and, when reconciled with MBOM, for manufacturing planning.