What is the Bill of Materials (BOM)?

Before starting the manufacturing process for any product, a critical document must be prepared containing all possible information needed to create the required finished product successfully. This document is the Bill of Materials (aka the BOM). It must provide a comprehensive list of all the components and raw materials that the final product requires and must also include unambiguous instructions for the assembly process of the product. The BOM also serves as a central resource for the manufacturers, allowing them to proceed confidently and assuredly. Manufacturers can ensure they have all the necessary materials and instructions for production by preparing a comprehensive Bill of Materials. This helps them streamline the manufacturing process and minimise potential errors.

What are the Advantages of Using a Bill of Materials?

Companies that adopt lean production techniques based on continuous improvement can benefit from BOMs. It helps make the manufacturing process precise and effective. Preparing a BOM has several benefits, as listed below:

• Plan your raw material purchases.
• Track and plan material requirements
• You can know the estimated material cost
• Manage inventory
• With the help of BOM, you can stay alert to material shortages, expediting charges, and planned and unplanned downtime. 
• Beneficial in controlling a budget
• Stay on schedule
• Maintain records
• Reduce Waste
• It helps in identifying the cause of product failure.
• It helps in identifying the faulty component. 
• You can find a vulnerability in the software components.
• It can help in improving supply chain security.

Who Uses a Bill of Materials (BOM)?

Every manufacturer creating products for any industry started their manufacturing process by creating a bill of materials for the specific product. For example, the engineering department creates an engineering bill of materials (MBOMS). The following teams use the Bill of Materials.

• Material procurement team or sourcing materials. 
• The manufacturing or production team or department includes contact manufacturing partners, design, engineering and mechanical teams. 
• Assembly team or department
• Operations Team

Structure of Bill of Materials

The two types of BOM representation that are most frequently used are single-level and multi-level BOMs.

• Single Level BOM – This is a simple list that includes the quantity needed for each assembly or subassembly for the product that is being displayed. It is simple to create this bill of materials. However, this BOM is inappropriate for complicated products because it doesn’t define the relationship between assemblies and sub-assemblies. A single-level BOM makes it challenging to identify the defective element when a new product fails.

• Multilevel Bills Of Materials – Creating this BOM requires more labour, but it provides more information, particularly on the parent and child parts of the product. A multilayer BOM’s product structure demonstrates the connections between assemblies, sub-assemblies, and parent and child items.

Content Of Bills Of Material (BOM)

A bill of materials provides detailed information about a product’s engineering, design, document management, manufacturing, purchasing, and contract manufacturers. Below is a list of the typical particulars included in a bill of materials:

• BOM Level: A unique identification number assigned to each part or assembly to show its position in the hierarchy of the BOM for easy understanding of the BOM structure.
• Part Number: An assigned number for each part or assembly for reference and identification purposes.
• Part Name: A unique name given to each part or assembly.
• Phase: Records the stage of the lifecycle at which each part and product is currently at.
• Description: A detailed description of each part to distinguish it from other similar parts and identify specific parts conveniently.
• Quantity: The number of parts required for each assembly or subassembly.
• Unit Of Measurement: The unit of measurement used for each part, such as inches and feet.
• Procurement Type: The method of purchasing each part, whether off-the-shelf or made-to-specification.
• Reference Designators: Used in printed circuit board assemblies (PCBAs) to indicate where the part fits on the board in the BOM.
• BOM Notes: A section that captures other important notes for everyone’s understanding and clarity about the BOM and product, such as a list of alternate suppliers.

Types Of Bills Of Material

A bill of materials (BOM) combines all the information required to build a final product. There are three main types of BOMs:

1. Manufacturing: A manufacturing bill of materials (aka MBOM) is a detailed list of all the parts and components required to create a finished product that is ready for shipping. The MBOM explains how all the pieces fit together and provides information on the necessary work to be done on each component before assembly. It helps manufacturers keep track of everything they need to make a product and ensure that they don’t miss anything critical.
2. Engineering: An Engineering bill of materials (aka EBOM) lists the assemblies and components created by the engineering department. It shows a mechanical or a technical product diagram showing the component structure from a functional perspective.
3. Sales: Before a product is assembled, its specifics are described in a sales bill of materials (SBOM) during the sales stage. The completed goods list and the materials needed to make them must appear separately in the sales order documents in an SBOM. Instead of being maintained as an inventory item, the final product is controlled as a sales product.

Other types of BOMs include the following:

• Configurable BOMS – They are used in industries with multiple options and highly configurable products. Configurable bills of material are designed to meet unique customer specifications and identity-building materials, labelling, and packaging materials. 
• Production BOMs – It is a structured list of all components and subassemblies used to produce a parent item. It is the basis of the production order.  
• Assembly BOMS – The Assembly Bill of Materials (Assembly BOM) is a document that lists all the components and parts required to assemble a finished product. 
• Software BOMS – They list the components of a piece of software which may consist of a mix of commercial and open-source products. SBOMS enable developers to ensure disparate software components work together, are up to date and are protected from vulnerabilities.

How To Ensure An Effective Bill Of Material Management? 

To ensure that the production process is as efficient as possible, a custom manufacturer must include all relevant information in the BOM. After several iterations and involving numerous teams, a final bill of material is produced. While utilising a spreadsheet to construct a BOM is one option, the optimal method for managing BOMs is to use an enterprise resource planning (ERP) system. BOM needs constant observation throughout its whole existence. As a result, many evaluations and modifications are needed to produce high-quality output.

To create an effective BOM without the manual effort involved, try BUSY Inventory Management Software.