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What Does an Indented Bill of Materials Mean?

A bill of materials (BOM) is a list of components, sub-components and assemblies that go into the creation of a finished product. It helps prevent issues with production and reduces inventory inaccuracies.

BOMs are used for different purposes and can be categorized as engineering (design) or manufacturing. For those manufacturing businesses with a complex process involving subassemblies, a multilevel BOM is needed.

What is an Indented BOM?

A BOM is a list of the components that make up an assembly or subassembly. BOMs can be used to define products as they are designed (engineering bill of materials), as they are ordered (sales bill of materials), or as they are built (manufacturing bill of materials). BOMs can also be tied to a production order that generates reservations for components in stock and requisitions for those that are not.

A multilevel BOM is a BOM that contains nested lists of assemblies and components in two or more levels. Multilevel BOMs become indispensable once a certain level of product complexity is reached because they allow you to manage the composition of your finished product using a hierarchical structure.

An indented BOM is a special type of BOM that shows the component items and their relationships in an indented structure. Indented BOMs are commonly used for communicating design details with contract manufacturers and partners. They provide a more structured and readable way to communicate design data than simple text files.

Indented BOMs are also useful for managing inventory and reducing manufacturing costs. For example, if you are using material kits to simplify inventory picking, an indented BOM allows you to show just the components that are needed for each individual kit. This can help reduce the amount of time spent opening drawings and orienting new workers on the jobsite.

How do I create an Indented BOM?

In a multilevel BOM, items at different levels of the product structure are indented to indicate their relationship. This can help make it easier to understand and manage the product assembly process.

Multilevel BOMs are often used when a manufacturer produces its own subassemblies as well as the finished products it makes. This can be especially helpful if a company has highly configurable products, or if it uses material kits to simplify inventory picking and inventory management. In an indented BOM, a subassembly can be updated easily because it will only affect the parts that use it—it won’t change higher-level assemblies.

To create an indented BOM, start with a listing of all the raw materials, components, and subassemblies in your product (level 0). Then, break the product down into its individual component and subassembly units by indenting them. Next, add the top-level assembly (level 1), followed by any ancillary materials and then all the subassemblies that make up the final product.

Ensure that the quantity of each item is specified so it can be used as an accurate purchasing asset, and to establish safety stock and reorder points. Also, include notes that might be useful to anyone reading the BOM—such as supplier and contact information, lead times, cost, and part type (Document, Custom, COTS, Sheet Metal, Machined, etc.). Katana’s all-in-one BOM management solution, MRPeasy, allows you to import multilevel BOMs from spreadsheets or CAD software in bulk as CSV files.

What are the benefits of an Indented BOM?

The indented BOM is an effective tool for managing complex products. It helps ensure that third-party contract manufacturers use efficient and accurate production methods, and it lays out a clear plan for how the product is to be built. It also helps manage inventory levels and reduce production delays and waste.

A BOM can be structured in different ways, depending on the type of product you build and how you intend to use it. It can be used to design a product (engineering bill of materials, or EBOM), as it is being built (manufacturing bill of materials, or MBOM), or for service and maintenance purposes (service bill of materials, or SBOM).

Multi-level BOMs, sometimes called indented BOMs, display the relationship (often referred to as parent-child) between components, subassemblies and assemblies by showing them in a hierarchical or “explosion” display. This is the most common format for a BOM.

Single-level BOMs, on the other hand, describe a single assembly. They include all documents and ancillary material required to build that one assembly, such as assembly drawings, test procedures and power cords. They also include the raw material required to build that particular assembly, including any special characteristics or specifications the item must meet. These are the types of BOMs that are most useful when building the actual product.

What are the disadvantages of an Indented BOM?

A multi-level BOM (sometimes called a parent-child BOM) shows the relationship between components, sub-assemblies and assemblies. It also displays the material or subassembly used to make up a higher-level assembly or part — and these are usually indented. These types of BOMs are typically required for complex products.

Creating a BOM for your product requires careful thought and planning to ensure that you include all parts and components that are needed to manufacture the product. For example, it is easy to overlook minor components like glue, tape, labels, or shrink wrap, which can impact your overall cost. Adding these items to your BOM helps you plan for and control inventory, estimate costs, and minimize production delays and waste.

In addition, a multi-level BOM can help you organize your product structure by grouping together similar components. This allows you to streamline sourcing and take advantage of economies-of-scale purchasing.

However, while a multi-level BOM can provide many benefits, it can also be difficult to maintain and manage. To minimize complexity and the time required to maintain a BOM, you may want to consider adopting cloud manufacturing software like Katana. Katana centralizes your business, from sales channels to manufacturing operations, into one intuitive, visual platform, making it easier for you to create and manage BOMs. And importing your BOMs from spreadsheets or CAD software into Katana is fast and easy, saving you time on manual data entry.