What is a Bill of Materials (BOM)?
A bill of materials (BOM) is a comprehensive list of items, parts, assemblies, drawings, documents, and other materials needed to create a product. It includes information related to each item’s required quantities, specifications, and quality. Think of it as a recipe used to build a final product.
To better understand, check out what a bill of materials (BOM) looks like for a bicycle:
Part Number | Description | Quantity | Unit of Measure | Procurement Type | Notes |
|---|---|---|---|---|---|
FRAME-001 | Aluminum Frame | 1 | Piece | Purchased | Size: 18 inches |
WHEEL-002 | Alloy Wheel (700c) | 2 | Piece | Purchased | Includes rim and spokes |
TIRE-003 | Rubber Tire (700x28c) | 2 | Piece | Purchased | Tubeless ready |
BRAKE-004 | Disc Brake Set | 1 | Set | Purchased | Hydraulic, front and rear |
CHAIN-005 | Bicycle Chain | 1 | Piece | Purchased | 116 links, 10-speed |
GEAR-006 | Derailleur Gear Set | 1 | Set | Purchased | 10-speed, Shimano compatible |
HANDLE-007 | Handlebar (Flat) | 1 | Piece | Purchased | Aluminum, 600mm width |
SEAT-008 | Saddle | 1 | Piece | Purchased | Padded, ergonomic design |
PEDAL-009 | Pedal Set | 1 | Set | Purchased | Alloy, non-slip surface |
BOLT-010 | M6 Bolt | 10 | Piece | Purchased | Stainless steel |
NUT-011 | M6 Nut | 10 | Piece | Purchased | Stainless steel |
MANUAL-012 | Assembly Instruction Manual | 1 | Document | In-house | Includes step-by-step guide |
DRAWING-013 | Bicycle Assembly Diagram | 1 | Drawing | In-house | CAD file, PDF format |
To better understand, check out what a bill of materials (BOM) looks like for a bicycle:Simply put, a BOM provides a detailed outline of everything manufacturers need to build a product. It is used across a wide range of industries, such as manufacturing, construction, engineering, software development, and more. It ensures that the finished product fulfills the targeted quality standards.
Benefits of Using a BOM
The benefits of the bill of materials (BOM) extend beyond just listing components. A well-structured BOM offers many benefits, as follows:
Ensure Material Availability
BOM provides a complete list of components and their right quantities. Your inventory management software can keep an eye on the stocks listed in BOM and send you alerts when they are low. This ensures that the right quantity of materials is always available.
Predictable Delivery Processes
BOM is a key to better planning and predictable delivery processes. It clarifies what are the required inventory levels, the process, and the manufacturing time. All the steps and functions become clear, which leads to a better estimation of the exact time to manufacture.
Reduce Waste
BOM also helps reduce waste. One of the financial burdens companies face is inventory carrying costs. They purchase excess inventory, which never gets used. With BOM, you know what you want in the exact quantity. This reduces waste and leads to efficient spending on inventory.
Effective Planning
The BOM details all the components needed to manufacture finished products. This enables efficient production planning and reduces unnecessary delays.
Quality Assurance
BOM also serves as a document to ensure quality assurance. The team can use the BOM to verify that the correct materials and components are used in manufacturing. It helps track defects and maintain compliance with quality and industry standards.
What to Include in a Bill of Materials
The purpose of a bill of materials (BOM) is to include all the essential details needed to proceed with the manufacturing process efficiently. It lists many items, each having various components. Below is a complete list of what to include in a BOM:
BOM Level
Assign a number to each component or assembly to indicate its position in the bill of materials (BOM) structure. This numbering system helps anyone familiar with the BOM layout to quickly understand its organization.
Part Number
Each component or assembly should have a unique part number for easy identification and reference. Manufacturers often choose between an intelligent/non-intelligent numbering system, but it’s crucial to ensure that there are no duplicates for the same part.
Part Name
Give each part or assembly a distinct name. This makes it easier to recognize and differentiate between components.
Phase
Document the current phase of each part in its lifecycle. For example, you can use a term like “In Production” for parts that are in production. Similarly, you can use “Unreleased” or “In Design” from new components. This classification is especially useful during new product introductions (NPI) to track progress and also set realistic timelines.
Description
Include a comprehensive description of each component to help distinguish similar parts and make identification more straightforward for everyone involved.
Quantity
Specify the number of parts needed for each assembly or subassembly. It guides decisions related to purchasing and manufacturing processes.
Unit of Measure
Define the unit of measurement for each part when it is purchased or used. Common units include each, inches, feet, ounces, or drops. This helps confirm that correct quantities are ordered/delivered.
Procurement Type
Record the procurement method for each part, such as off-the-shelf or custom-made. This will assist in purchasing and manufacturing activities.
Reference Designators
For products that include printed circuit board assemblies (PCBs), reference designators that specify the part’s location on the board are essential. This avoids confusion and saves time during assembly.
BOM Notes
Add any additional notes that might be relevant to those using the BOM. These notes give everyone the same understanding and expectations.
6 Questions to Ask Before Creating a Bill of Materials
To create a complete and effective bill of materials (BOM), you should first answer a few important questions as follows:
Q1. What are you building?
If you can’t visualize the final product and its function, you don’t need a BOM yet. Ensure you have the product design, materials list, final testing, and Gerber file ready. This will guide component selection.
Q2. What information will you include?
Other than essential components, you should also consider adding consumables, preferred manufacturers, replacement options, and descriptors like color and shape for accuracy.
Q3. Will you include consumables in your BOM?
Some manufacturers hesitate to document items like wires, glues, fasteners, etc. However, if they are not in the BOM, they might be overlooked in production.
Q4. How will you attach files to your BOM?
You should link essential documents, such as CAD drawings and work instructions, directly to the relevant components. This will prevent doubts and ensure smooth manufacturing.
Q5. Who will use the BOM?
Your BOM should be detailed enough for all stakeholders, even those you may never interact with. This will ensure clarity throughout the product life cycle.
Q6. How will you track BOM revisions?
Since BOMs evolve during design, you have to compare versions, navigate component hierarchies, and track changes linked to engineering change orders (ECOs).
How to Create a Bill of Materials
There are many ways to create a bill of materials (BOM). You can use spreadsheets or dedicated inventory management software. The latter is the best option to create BOM, as it provides better accuracy, automation, and integration. That’s where C2W Inventory steps in.
C2W Inventory is a powerful, cloud-based inventory management software. It provides a complete inventory management solution, which includes an automated warehouse, purchase, sales order, and manufacturing management. Furthermore, you get an easy-to-navigate dashboard that provides real-time insights on stock levels.
C2W Inventory facilitates beyond just inventory tracking; it’s a comprehensive platform designed to handle all aspects of bill of materials management for different manufacturers.
BOM Types for Different Manufacturing Models
Before we discuss how C2W Inventory helps create BOM, let’s first clarify the two main types of BOM and the role of C2W Inventory:
1. Traditional Manufacturing BOMs
- Engineering BOM (EBOM): Outlines the product’s design perspective, detailing raw materials, specifications, tolerances, and standards.
- Assembly BOM (ABOM): Lists all components required to assemble the finished product. It is a simpler format than a full MBOM.
- Service BOM (SBOM): Provides a list of serviceable parts, replacements, and supersessions for maintaining assets like machinery or equipment.
2. Kitting and Bundling BOM
It is used to combine items into kits and bundles sold as a single SKU:
- Kitting: Groups related items (e.g., a smartphone kit with a phone, case, and earbuds).
- Bundling: Sells identical items together (e.g., a 3-pack of ketchup bottles).
The difference between kitting and bundling is in the type of items combined. Kitting groups different but related products into a single package while bundling groups the same products in bulk quantity into a single package.
To learn more about kitting and bundling, check out our previous blog about it.
Create a BOM in the C2W Inventory System
The C2W Inventory System supports both traditional manufacturing and kitting/bundling. Here’s how to use it:
Step 1:
Add Finished Products and Components
Enter all raw materials, sub-assemblies, and finished goods into the system. For instance, add Aluminum Frame, Alloy Wheels, and Disc Brake Set for a bicycle.
Step 2:
Add the Bill of Materials(BOM)
Link components to the finished product (e.g., 1 frame + 2 wheels + 1 brake set = 1 bicycle). Specify quantities, units of measure, and other details.
Step 3:
Create a
Manufacturing Order
Step 4:
Complete the Manufacturing Order
After production, finalize the order to update inventory levels.
That’s all! This way, you can use C2W Inventory to create BOM and help streamline operations. To learn more, watch our step-by-step tutorial video on how to use C2W Inventory for different BOM scenarios.
Best Practices for Creating a BOM
The benefits of BOM are only achievable if you create a top-notch BOM with the correct details. In this perspective, below are a few best practices for creating a BOM:
- Organize Hierarchically: Structure the BOM with the finished product at the top, followed by sub-assemblies, components, and raw materials.
- Assign Unique Part Numbers: Ensure each item has a distinct identifier to prevent confusion and facilitate easy tracking.
- Include All Components: Document every necessary item, including consumables like adhesives and fasteners, to avoid omissions during production.
- Maintain Version Control: Clearly label and track BOM revisions to monitor changes and maintain inventory accuracy over time.
- Attach Supporting Documents: Link relevant files, such as CAD drawings and work instructions, to specific components for comprehensive guidance.
- Define Access Permissions: Limit editing rights to authorized personnel to maintain data integrity and prevent unauthorized modifications.
- Use Descriptive Part Names: Provide clear and concise names for each part to enhance understanding across all departments involved.
- Plan for Modularity: Design the BOM to accommodate easy customization or scalability by organizing components into sub-assemblies.
- Review and Update: Assess and revise the BOM to reflect design changes, process improvements, or material substitutions.
- Implement a BOM Management System: Utilize specialized software to automate processes, enforce best practices, and ensure consistency.
Wrapping Up
Bill of materials (BOM) is an essential activity to create an extensive list of components, raw materials, and instructions to construct a complete product/service. A well-crafted BOM can lead to high-quality finished products with proper material planning, reduced production errors, and efficient cost management. So, it’s not a choice to create or skip BOM but a necessity to have smooth manufacturing and supply chain operations.
