What Is A BOM?

A “BOM” is a critical component of the manufacturing world. It stands for “bill of materials” which is a list of the assemblies, components and parts that are required to make a product. A BOM will also incorporate the instructions needed to gather and use all of the required materials on the list. A BOM is multi-leveled, generally providing a display of all items that are considered to be part of a “parent-child” relationship. Think of it this way. The components are the parents and the children are the sub-components needed to complete the manufacturing of a product. The item number listed on a top-level BOM includes “children” which involve a mix of finished sub-assemblies, various parts and raw materials.

A BOM can be defined as a “recipe”.

A bill of materials contains all of the necessary ingredients that are required for the creation of a final product. It explains what materials to compile and where to buy them. The instructions also clearly outline how to assemble the product from the various parts that are ordered. No matter the industry, all manufacturers of products start the manufacturing process by creating a BOM. As you may have guessed, a BOM is necessary in order to get the job done right. Each bill of materials must be organized, fact-checked and up-to-date. Engineers and manufactures rely heavily on BOMs so that they can create their own special subsets. These subsets are known as EBOMs (engineering bill of materials) and MBOMs (manufacturing bill of materials).

What must be included in an effective bill of materials?

Each BOM has BOM levels. This is where each part is assigned a number in order to determine exactly where it fits in the hierarchy of the bill of materials. Because each part has a number, they can all be referenced and identified quickly. Manufacturers usually use either intelligent or non-intelligent part numbering schemes. Parts are also assigned names in order to help identify each part more easily. The “phase” of each part must also be recorded. This clarifies the stage at which each part is at in its lifecycle. Examples of phases are “In Production”, “Unreleased” or “In Design”. Descriptions of each part are also necessary. This helps manufacturers distinguish between similar-looking parts.

The quantity of each part is also listed in a BOM.

This helps to guide purchasing and manufacturing decisions and activities. A BOM also includes units of measure such as inches, feet, ounces and drops. This helps to ensure the right quantities are procured and delivered to the production line. The procurement type is also included. This documents how each part is purchased or made. For example, is the part “off-the-shelf” or is it “made-to-specification”? A BOM also include reference designators, especially if the product contains PCBAs (printed circuit board assemblies). Reference designators detail where each part fits on the board in your BOM. This both saves time and avoids confusion. Finally, BOM notes help to provide clarification about any of the above in order to keep everyone on the assembly line on the same page. For more information about BOMs and how they are used by Flux Connectivity, please don’t hesitate to give us a call at 1-800-557-FLUX or email us at connect@fluxconnectivity.com.