billOfMaterials

Bill of materials, often abbreviated as BOM, is a comprehensive list of the raw materials, sub-assemblies, components, parts, and the quantities required to manufacture a final product. It may include part numbers, descriptions, units of measure, reference designators, and sourcing information. A BOM serves as the authoritative record for material requirements, supporting manufacturing planning, procurement, cost estimation, and inventory control.

Different BOM types reflect different perspectives in product development and production. An engineering bill of materials (EBOM) represents the product structure from a design viewpoint. A manufacturing bill of materials (MBOM) translates the EBOM into what must be built and procured on the shop floor, often incorporating assembly steps, sub-assemblies, and sequencing. A service or spare-parts bill of materials covers components required to repair or maintain products in the field. Some organizations maintain configurable or modular BOMs to accommodate variants and options.

BOMs are typically hierarchical, forming a multi-level bill of materials that connect assemblies to sub-assemblies and parts. Each line item includes fields such as quantity per assembly, unit of measure, part number, description, and reference designator. BOMs are versioned and time-stamped to reflect design changes, with linkage to change orders and effectivity dates. Effective management of BOM data is essential to avoid discrepancies during procurement, manufacturing, and service.

They are commonly managed within enterprise resource planning (ERP) and product lifecycle management (PLM) systems and integrated with material requirements planning (MRP) to compute material needs. BOMs support cost roll-ups, supplier selection, pricing, lead times, and production scheduling. They also enable BOM explosion for planning at the component level and can underpin configuration management for product variants.

Maintaining accurate BOMs is a core part of product data management, requiring governance, change control, and regular auditing to ensure alignment with design intent and manufacturing capabilities.