A bill of materials, also called a BOM, is a planning document used to structure and identify the materials and steps that are required to build a product or assemble products together for shipping.
While a BOM may be used in many different industries, in fulfillment a BOM is used to list out the components that are needed for a special project like kitting products in a certain way, or assembling materials to be placed in a package in a specific order.
A BOM is not to be confused with work instructions. The bill of materials includes only the materials needed for the project. Work instructions (also called pictorials) include the step-by-step instructions on how those materials should be put together.
Why Use a BOM?
A fulfillment provider may get a request from one of their customers to assemble a specific grouping of products for a promotion or sale. Using product bundles is complex operationally but a huge value-add for customers, not to mention that bundles increase average order value. The fulfillment provider will need to get detailed work instructions from the customer on how they want the products assembled.
Once the 3PL has all information, they will create a BOM for their internal workers to be able to collect all the materials necessary build each of these product bundles. If a BOM is not created, the workers doing assembly are likely to forget a component.
Here are a few other benefits of using a BOM for assembly in fulfillment:
- Vetting a BOM with the customer will verify exactly what they intend for the project.
- A BOM helps organize the planning of a project build by centralizing the materials list.
- For companies that rely on supply chain partners, a BOM helps provide effective revision control throughout the new product development and introduction process
- Workers who have a BOM to follow will be able to work faster and more efficiently.
- The use of a BOM will help reduce waste, which also saves money.
A quick note about automation in relation to using bills of materials. When creating a bill of materials, it’s critical to make sure it is error free. Most modern 3PLs will use an enterprise resource planning (ERP) tool to help build and track BOMs. An ERP will be able to automate any revisions or changes. By adding automation BOMs can be processed in a way that reduces discrepancies, errors, and helps production move more quickly.
Components of a BOM
The BOM structure must be clear and detailed. Information is presented in a hierarchical way, so the functionality of the instructions can be followed to execute the project appropriately.
Each bill of materials will vary considerably depending on the specific project, but there are some key components that need to be included. This is a centralized place for your project information, and it will be used as a reference by other departments and workers, so clarity is key.
Some key identifiers that need to be included are:
- Part number — this is usually the way a warehouse will track components, including it is the fastest way to specifying which components need to be included.
- Part name — often this helps the floor workers verify that the part numbers listed are correct. If they pick a part number that looks like a camera lens, but the part name says “camera strap” they’ll know to stop and ask which is correct.
- Unit of measure — how many of the items are needed? This clarifies that question.
- Final product — in assembly projects, naming the final product that will come out of the build is important.
Are There Different Types of BOMs?
Yes! Many industries use bill of materials to build products or assemble projects. The two main types of BOMs are manufacturing and engineering. Here is a breakdown of a few different types of BOMs.
Manufacturing Bill of Materials (MBOM)
Manufacturing BOMs are typically used either within the manufacturing process or assembly and subassemblies of products needing to be shipped to customers. A BOM is essential in materials requirement planning (MRP)
Configurable Bill of Materials
Sometimes used in manufacturing or assembly, a configurable BOM is a type of manufacturing bill of materials, used to customize or finalize finished products or goods. It will include any labeling, packaging, or specification needed to meet a customer order. This could mean placing a specific color case on a mobile phone or labeling a product with specific stickers that are retailer specific.
Engineering Bill of Materials (EBOM)
Designed to help the development stage of a product, an engineering BOM defines the design and use of a product. EBOMs are more often used to build a product from components as specified by an engineer. It might include the raw materials needed as well as how those individual parts should fit together as the product was intended to be built and assembled. An EBOM is a technical document that can include figures and drawings from the engineers.
Sales Bill of Materials (SBOM)
A bill of materials that lists products as ordered by a customer is called a Sales Bill of Materials. The name comes from the “sales order” that necessitates a list of what should be included in the order.
In a single-level BOM, each part that will make up the product or asset is shown once, along with the quantity needed. It is essentially like a shopping list.
Used for subassemblies where components and raw materials are made into a final product, and then assembled together for shipping, a multi-level bill of materials details the exact ways each sub-assembly should go. These must have a very hierarchical BOM structure.