What is a BOM bill of materials

Key Components of a Bill of Materials

A typical BOM includes:

BOM level: BOM level refers to the hierarchy of components in the BOM. Top level is usually indicated by 0 or 1, with subassemblies and components going down from there.
Part number: Each part or component will have a unique part number.
Part name: The name of the part.
Phase: The stage of the product lifecycle the part is in (design, prototype, production, etc.)
Description: A brief description of what the part is.
Quantity: The number of parts required.
Unit of measure: The measurement in which the part is being quantified (each, inches, feet, etc.)
Procurement type: Whether the part is made in-house or is a purchased part.
Reference designators: Other names and descriptions of the part, if applicable.
BOM notes: Any additional notes about the part or assembly.

Here is a sample BOM in table format:

BOM Level	Part Number	Part Name	Description	Quantity	Unit of Measure	Procurement Type
0	1234-A	Bicycle	Mountain bike	1	Each	Make
1	5678-B	Frame	Aluminum alloy frame	1	Each	Buy
1	9012-C	Front Wheel	26 inch wheel	1	Each	Buy
2	3456-D	Spokes	Stainless steel spokes	32	Each	Buy
2	7890-E	Rim	Aluminum rim	1	Each	Buy
2	1234-F	Tire	Rubber tire	1	Each	Buy
1	5678-G	Rear Wheel	26 inch wheel	1	Each	Buy
2	9012-H	Spokes	Stainless steel spokes	32	Each	Buy
2	3456-I	Rim	Aluminum rim	1	Each	Buy
2	7890-J	Tire	Rubber tire	1	Each	Buy
1	1234-K	Handlebars	Aluminum handlebars	1	Each	Buy
1	5678-L	Seat	Padded seat	1	Each	Buy
1	9012-M	Pedals	Aluminum pedals with straps	2	Each	Buy
1	3456-N	Chain	Metal chain	1	Each	Buy

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Types of BOMs

There are several different types of BOMs that a company may use depending on the complexity and the stage of the product.

Engineering BOM (EBOM)

An engineering BOM is created during the design phase by the engineering team. It defines the product as it is designed. The EBOM is not typically used directly in manufacturing, but is instead used as the basis for other BOMs.

Manufacturing BOM (MBOM)

A manufacturing BOM is created by the manufacturing team based on the EBOM. It defines the product as it is manufactured and includes any changes that have been made to the design to ease manufacturing. The MBOM is used on the manufacturing floor to build the product.

Sales BOM (SBOM)

A sales BOM is a simplified version of the EBOM or MBOM that is used by the sales team. It only includes information that is necessary for sales and customer service, such as part descriptions and quantities.

Service BOM

A service BOM is used by the service team to repair or service a product. It includes all the assemblies and parts that can be replaced or repaired.

Importance of BOMs

BOMs are critical to the manufacturing process for several reasons:

Procurement: The BOM is used to plan and purchase the correct materials in the right quantities. This helps avoid shortages or excess inventory.
Production Planning: The BOM is used to plan the manufacturing of the product, including the order of assembly and any special instructions.
Cost Control: By having an accurate BOM, a company can accurately track the cost of materials and labor for a product. This helps with profitability analysis and pricing.
Quality Control: The BOM provides a checklist to ensure that all necessary parts are included in the final product.
Collaboration: The BOM serves as a central document that can be shared between engineering, manufacturing, sales, and service teams to ensure everyone is working from the same information.

BOM Best Practices

To get the most out of your BOMs, follow these best practices:

Keep BOMs up to date: As changes are made to the product design, make sure the BOM is updated to reflect those changes.
Use a consistent naming convention: Use a consistent naming convention for parts and assemblies to avoid confusion.
Include all necessary information: Make sure the BOM includes all necessary information, such as part numbers, descriptions, and quantities.
Review and approve changes: Have a process in place to review and approve any changes to the BOM.
Integrate with other systems: Integrate your BOM with your ERP, MRP, or PLM system to ensure consistency and accuracy across your organization.

BOM Software

Managing BOMs can be complex, especially for products with many parts and assemblies. BOM software can help streamline the process. Some features to look for in BOM software include:

Easy creation and editing of BOMs
Integration with CAD and other design software
Version control and change management
Ability to share and collaborate on BOMs
Integration with ERP, MRP, and PLM systems

Some popular BOM software options include:

Autodesk Fusion 360
Dassault Systèmes SOLIDWORKS
Siemens Teamcenter
Oracle Agile PLM
SAP PLM

Frequently Asked Questions (FAQ)

1. What is the difference between a BOM and a parts list?

A parts list is simply a list of parts, while a BOM is a hierarchical list that shows the relationships between parts and assemblies. A BOM also typically includes more information, such as quantities and procurement type.

2. How do I create a BOM?

To create a BOM, start by listing all the parts and assemblies needed to make your product. Then, organize them into a hierarchical structure, with the top level being the finished product. Add in any necessary information, such as part numbers, descriptions, and quantities.

3. What is the difference between an EBOM and an MBOM?

An engineering BOM (EBOM) is created by the engineering team and defines the product as it is designed. A manufacturing BOM (MBOM) is created by the manufacturing team and defines the product as it is actually manufactured, including any changes made for manufacturability.

4. How often should I update my BOM?

Your BOM should be updated anytime there is a change to the product design or the manufacturing process. It’s important to keep your BOM as up to date as possible to avoid confusion and errors.

5. Can I have multiple BOMs for the same product?

Yes, it’s common to have multiple BOMs for the same product, such as an EBOM, MBOM, and SBOM. Each BOM serves a different purpose and is used by different teams within the organization.

Conclusion

A bill of materials (BOM) is an essential tool in the manufacturing process. It serves as a central source of information for all the parts and assemblies needed to make a product. By creating and maintaining accurate BOMs, companies can improve procurement, production planning, cost control, and quality control.

To get the most out of your BOMs, follow best practices such as keeping them up to date, using consistent naming conventions, and integrating with other systems. Consider using BOM software to streamline the process and ensure accuracy.

By understanding and effectively utilizing BOMs, you can improve your manufacturing process and ultimately deliver better products to your customers.

Published by Prototype PCB Assembly on April 28, 2024April 28, 2024

Key Components of a Bill of Materials