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What Is a Bill of Materials?

Imagine building a house without a blueprint or cooking a complicated recipe without an ingredients list. Without a BOM, manufacturing operations may encounter cost blowouts and production delays.

A BOM, which can also be called a product recipe, displays the raw materials, assemblies and parts necessary to build a finished product. Different types of BOMs define products as they are designed (engineering bill of materials, or EBOM), as they are ordered (sales bill of materials, or SBOM) or as they are built (manufacturing bill of materials, or MBOM).

What is a bill of materials?

A bill of materials, or BOM, is a comprehensive inventory of the components, raw material assemblies and parts that go into making a product. It lists their respective quantities needed to fulfill an order, whether it’s for a single item or an entire batch of finished goods. BOMs are used by companies of all sizes to streamline production processes and minimize errors, especially when they’re tied into materials requirements planning (MRP) or enterprise resource planning (ERP) systems.

Just like your favorite recipes specify each ingredient, a BOM acts as the blueprint for the breakdown of any physical product into its most basic parts and materials. There are a number of different types of BOMs, with each serving specific purposes. For example, an engineering bill of materials (EBOM) is used during the design phase and outlines the components, subassemblies, similar parts and materials required to build a new product based on technical specifications.

A production BOM is used during the actual manufacturing process, and includes those same components but at a higher level in the assembly structure. There are also template BOMs, which are typically used for sales and production and are designed to be flexible. These include parent items, which act as the basis for a sale or production and child items that list sub-assemblies. The choice of which BOM type to use depends on the particular need, such as minimizing inventory inaccuracies or conveying project progress to stakeholders across departments.

What is a BOM’s purpose?

A BOM is a key document for the product development process, used in multiple departments across an organization. It is a critical part of the product’s lifecycle, providing vital information for engineering, manufacturing, sales and material management. It can help streamline product planning and assembly processes by ensuring that the right parts are used and sourced correctly. A BOM also helps manage costs and provides visibility into the supply chain, enabling companies to make smarter purchasing decisions.

BOMs can be structured in a variety of ways, depending on the complexity of the products being manufactured. A simple, single-level BOM is typically used for simpler products that do not require the preconstruction of lower-level subassemblies. A multilevel BOM displays the entire product structure, including parent and child parts, and the relationships between them. It also shows the total amount of materials required for each product, allowing you to identify and anticipate potential production shortfalls before they occur.

A configurable BOM is a special type of BOM that is used to design or manufacture a custom product to specific customer orders. It can be used to add custom labeling or packaging, such as a different color case for a mobile phone, or to incorporate additional features or specifications. A BOM record can also contain supporting documentation, such as CAD drawings and work instructions, to allow the right people to quickly find the information they need.

What is a BOM’s structure?

A BOM is the list of raw materials, components, and sub-assemblies that go into a finished product. It can be used for physical products, such as bicycles or cars, or software-as-a-service (SaaS) projects, like web frameworks or libraries. It is generally tied to a production order that reserves the exact quantity of each component needed to finish a project or assembly. A BOM can also include instructions, routes, and practices that need to be followed during production or construction. It might also include notes that help anyone reading it understand the process, like a list of alternate suppliers or special specifications a component must meet.

Depending on the type of product being manufactured, there are various ways to structure a BOM. The most basic is a single-level BOM, which only includes the components and parts that are required to make the product at hand. This may be sufficient for simpler products, but for more complex ones, a multi-level BOM is usually preferred.

In a multi-level BOM, each sub-assembly is broken down into its component parts and then further into its own subassemblies. The result is a hierarchical breakdown of the product that shows how each part fits into its final assembly and where it is located on the finished product. It is used by engineers during the design phase of a new product.

What is a BOM’s format?

There are multiple types of BOMs, but the most common is a manufacturing bill of materials. It consists of all the items, components, and raw materials required to produce a final shippable product. This type of BOM can be a single-level or multi-level document. It also includes the quantity or volume of each item used to produce the finished product.

Having an accurate BOM can help reduce inventory inaccuracies and production delays. It can also ensure that all the necessary components are in stock at the right time, which can save a company valuable resources. This is especially true for companies that manufacture products in small batches.

A single-level BOM is typically used for products that are not complex in construction and do not contain sub assemblies. This type of BOM usually consists of a total count of the parts used in the product’s construction, listed in part number order. It also typically contains a notes section that provides other information about the product.

An assembly BOM is similar to a sales BOM in that the finished product and its components appear as separate items on a sales document, rather than being grouped together as an inventory stock item. An assembly BOM may be a single-level or multi-level format. This type of BOM can be augmented by a reference designator, which is used to clarify exhaustively how each component fits together in the assembly process.