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The 10 Types of BOMs Explained

In our last post, we focused on the advantages of automated BOMs vs. manual spreadsheet-based systems. Today, we’re going to drill down a little further into types of BOMs (Bills of Materials) so that you have a better understanding of some of the available options.

BOMs are a comprehensive list of raw materials or assemblies required for production. While there are many types of BOMs, some of which are unique to specific business sectors, the following 10 types of BOMs stand out as the most common for manufacturing and engineering industry:

1. Manufacturing Bill of Materials (mBOM)

The manufacturing BOM (mBOM) is employed when a business needs to show all the parts and assemblies required to build a finished product. Parts that require processing prior to assembly must also be included in the mBOM. The document contains information that is disseminated to all the integrated business systems involved in ordering parts and building the product, including enterprise resource planning (ERP), materials resource planning (MRP) and, in some cases, manufacturing execution system (MES). This is the most common type of BOM for a manufacturing company.

The mBOM depends on the accuracy of the quantities of parts ordered during the manufacturing process. This helps ensure that the purchasing department can maintain the optimal schedule for ordering the necessary parts and negotiate the best possible price from applicable vendors.

Bill of Material (BOM) Explained

2. Engineering Bill of Materials (eBOM)

The engineering BOM (eBOM) is developed during the product design phase and is often based on Computer-Aided Design (CAD) or Electronic Design Automation (EDA) tools. The document usually lists the items, parts, components, subassemblies and assemblies in the product as designed by the engineering team, often according to their relationships with the parent product as represented in its assembly drawings. And it’s not unusual for more than one eBOM to be associated with one finished product.

3. Service BOM

The Service BOM (often developed by engineers during the design phase) typically includes a list of all the parts, installation steps and repair instructions that service technicians use when installing or servicing a product onsite at the customer’s place of business.

4. Sales BOM

Unlike other types of BOMs, a Sales BOM provides details of a finished product prior to its assembly during the sales phase. In a Sales BOM, both the finished product and the components appear as separate items in the sales order document. In addition, the parent item will be listed only as a sales item, not as an inventory item and the children will be listed as sub-items.

5. Assembly Bill of Materials

An assembly BOM is similar to a Sales BOM in which the parent item is listed as a sales item and not an inventory item. However, a notable difference is that unlike the Sales BOM, only the finished product appears in the sales document; the children do not appear as sub-items. Also, Assembly BOMs can be either single-level or multi-level, which we will explain, below.

6. Production BOM

A Production BOM often serves as the foundation for a production order. It lists the components and subassemblies that comprise a finished product, as well as prices, descriptions, quantities and associated units of measure. During the production process, physical components can be converted into actual finished products. With a fully automated BOM system, component needs, cost, and materials availability can be automatically added to work orders, thus ensuring that raw materials are properly allocated to products.

7. Template Bill of Materials

A Template BOM is a highly flexible form of BOM that can be used for either Production or Sales BOMs, usually with the parent items displayed first and then the components below. One can update the quantity of those components, swap them out and replace them with other components or delete them in the BOM or on the sales order.

8. Configurable BOM (cBOM)

A Configurable BOM contains all the components required to design and manufacture material to a customer’s specific requirements. The cBOM is often used in industries that have highly configurable products such as job shops, heavy machinery and industrial machinery.

9. Single-Level BOM

A single-level BOM is typically used for products whose constructions are not complex and do not include subassemblies. Typically, this document contains a total count of all the parts used in the construction of a product and those parts are listed in part number order. The structure of this type of document only allows for one level of children in components, assemblies and material.

10. Multi-Level BOM

In contrast to a single-level BOM, a multi-level BOM tends to be used for more complex constructions and thereby includes subassemblies, often broken down into further levels of subassemblies. In this document, each item number (either a raw material or labor) must associate with a parent item, except at the top-most level.

If you are a manufacturer with complex production processes – utilizing BOM software integrated with an ERP solution must be a serious consideration. We can assist you in the discovery and evaluation process, contact us or read our resources to learn more.

BOM Manufacturing ERP Demo