How to Structure an Effective Bill of Material (BOM)

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A BOM is essentially a complete list of all the items and plans that are required to build a product. It serves as the foundation for the design, planning, procurement, and manufacturing of products.  Essentially a Bill of Material is the design, ordering, building, and maintenance plan for a product.

Given the scope of information needed in a bill of materials, it requires multi-department and cross-functional planning. This can include design, engineering, purchasing, materials management, sales, and manufacturing.

Types of BOMs

It's important to note that based there are different BOM types and structures, each including varied function-specific details. There are three main types of BOMs: 

•     Engineering bill of materials (EBOM): EBOMs define the product design, component structure and its assembly. Including, the part name, part number, alternative and substitute part numbers, subassemblies, part revision, quantity, specifications or features of the product. 

•     Manufacturing bill of materials (MBOM): MBOMs include the parts, assembly and packaging information needed to manufacture a product. Outlining details need to meet a scheduled product delivery including, component and subassembly requirements.

•     Sales bill of materials (SBOM): SBOMs include details of the pricing of the product. It includes the sales order for both the finished product and components.

Other types of BOMs include: 

•     Configurable Bill of Materials: Identifies the materials and components, including any labeling or packaging requirements, needed to manufacture a product specific to a customer design specification.  

•     Production Bill of Materials: Are used as the foundation for production and include the components, production process, and assembly instructions for a finished product.

•     Assembly Bill of Materials: This BOM lists the assembly and sub-assembly items needed for product production.

BOM Configuration

Most BOMs include the part number, name, description, quantity, specification, cost, availability, and other procurement details. There are two main BOM structures, Single-level and Multi-level BOMs. Each is created for use at various stages of the product development lifecycle. 

A Single-level bill of materials is a flat list of parts and the quantity required to make the product. This BOM structure is simple and quick to create but not the best for troubleshooting. Since there are no assembly or sub-assembly and component relationships detailed in this BOM it makes it difficult to determine what part needs replacement in case of product failure.  

A Multi-level Bill of Materials is a hierarchical BOM that includes more details for the product manufacturing. It not only lists the part information (names, numbers, descriptions, quantity, costs) but it also includes the relationship between components, assembly, and sub-assembly. Making it easier to troubleshoot and identify issues arising with the product design and production.

Structuring an Effective BOM

An effective BOM helps companies minimize supply chain risks ensuring effective manufacturing. By tracking and planning component requirements, identifying and pricing all the materials and ensuring inventory control companies can mitigate shortages, component obsolescence and other supply chain or production disruptions. 

To create an effective BOM, 

•     Determine the type, goal, and data needed within your BOM. 

•     Create a cross-departmental centralized BOM, determining individuals responsible for updating the information to ensure accuracy.

•     Identify component and supply chain risks such as supplier dependencies and part availability. 

•     Refine and keep track of any changes to your supply chain. 

•     Track revisions to your BOM. 

While the concept of a Bill of Material is straightforward, creating and managing BOMs can become complicated, especially for products composed of hundreds or thousands of parts. Changes to parts, suppliers or design have to be tracked within large sets of data. 

Having access to data on your BOM will help you assess your supply chain risks, strengthen your BOM and achieve your production goals.