Imagine stepping into a manufacturing plant where every component, material, and process is perfectly aligned to produce a product with precision and efficiency. This is the power of BOM (Bill of Materials), a fundamental concept in the manufacturing industry that structures the items and materials needed to fulfill a product’s purpose.
In this blog post, we will explore the importance of BOM in manufacturing, break down the different types of BOMs, and discuss the challenges organizations face in managing them. We’ll also dive into how Nora IPLM can help streamline BOM management, maintaining accuracy, synchronization, and efficiency across departments and systems.
What Is BOM Management?
BOM management is the process of creating, organizing, maintaining, revising, and sharing the complete product structure throughout its lifecycle. It ensures that parts, assemblies, materials, quantities, revisions, documents, and related product information remain accurate and accessible to the teams that design, manufacture, source, and service the product.
In PLM, BOM management goes beyond maintaining a parts list. It connects the BOM with CAD data, documents, revisions, engineering changes, suppliers, configurations, workflows, and downstream systems so teams can work from controlled product information.
What Is BOM Management?
BOM management is the structured process of creating, organizing, revising, validating, releasing, and maintaining the product structures used throughout the product lifecycle. It keeps parts, assemblies, quantities, revisions, documents, configurations, suppliers, engineering changes, and manufacturing information connected to the correct product definition.
Effective BOM management is not simply maintaining a parts list. It establishes a controlled method for answering:
- What makes up the product?
- Which revision is current?
- Where is each component used?
- What changed between releases?
- Which product variants use this component?
- How does the engineering BOM relate to manufacturing?
- Which BOM should downstream systems use?
BOM vs. BOM Management: What Is the Difference?
A Bill of Materials is the structured definition of what makes up a product. BOM management is the ongoing process used to keep that structure accurate as the product changes.
| BOM | BOM Management |
Purpose | Defines product components and structure | Controls that structure throughout the lifecycle |
Typical data | Parts, assemblies, quantities, attributes | BOM data plus revisions, changes, approvals and relationships |
Focus | What the product contains | How product structure is created, changed, released and shared |
Lifecycle | Represents a product structure at a point in time | Maintains product structure as it evolves |
A Practical BOM Management Method
There is no single universal BOM methodology used by every manufacturer. However, effective BOM management usually follows a controlled lifecycle from product definition through manufacturing release.
A practical BOM management method can be organized into seven steps:
1. Define the product structure
Start by defining the hierarchy of:
- finished product
- assemblies
- subassemblies
- parts
- purchased components
- raw materials where applicable
The structure should represent clear parent-child relationships rather than an unstructured parts list.
2. Standardize item and BOM data
Define consistent rules for:
- part numbers
- item names
- descriptions
- quantities
- units of measure
- item types
- revisions
- lifecycle states
- make-or-buy classification
- supplier or manufacturer references
Standardized data makes comparison, search, integration and automation more reliable.
3. Connect supporting product information
A BOM should remain connected to the information that defines and explains the product.
Depending on the organization, that can include:
- CAD files
- drawings
- specifications
- documents
- requirements
- suppliers
- projects
- configurations
- engineering changes
This turns the BOM into a connected product structure rather than an isolated spreadsheet.
4. Control revisions and changes
When an item or structure changes, preserve the previous approved definition rather than overwriting it.
Use revision control, baselines and engineering change workflows to understand:
- what changed
- why it changed
- which BOMs are affected
- who approved it
- which downstream structures require action
5. Validate the BOM
Before release, check whether the structure is complete and consistent.
Typical checks include:
- correct revisions
- valid quantities
- missing attributes
- obsolete components
- duplicate parts
- incomplete relationships
- configuration or effectivity errors
- missing supplier or manufacturing information
6. Release the right BOM for its purpose
Different teams may require different product structures.
Engineering may work with an EBOM, while Manufacturing may require an MBOM organized around how the product is actually built.
The goal is not to force one BOM to serve every function. It is to keep the different views controlled and traceable.
7. Synchronize downstream systems
Once a product definition is approved, the appropriate released information can move to ERP, manufacturing, procurement or other downstream systems.
Future changes should follow the same controlled process so downstream teams do not work from outdated structures.
Multiple BOMs in an Organization
Contrary to the common perception that BOMs are solely used for manufacturing, especially by business units utilizing MRP/ERP systems, BOMs play a broader role. They are involved in various business activities before and after the manufacturing phase. In reality, there is no single BOM in an organization; instead, multiple BOMs manage different materials and structures to serve the unit’s purpose.
Some of the widely used BOM types include:
- EBOM (Engineering BOM)
- MBOM (Manufacturing BOM)
- PBOM (Production BOM)
- SBOM (Service BOM)
Additionally, there are more specialized BOMs like Costing BOM and Purchasing BOM. Other related structures include BOP (Bill of Process) and BOR (Bill of Resources), which, while not typical BOMs, define the overall manufacturing process alongside MBOM.
From a data management perspective, a global or enterprise BOM is crucial. It gathers multi-disciplinary definitions under one structure to ensure better integrity of complex products.
EBOM vs MBOM: What Is the Difference?
The Engineering Bill of Materials (EBOM) describes the product from the engineering perspective.
It typically reflects:
- engineering assemblies
- designed parts
- CAD-related structure
- engineering quantities
- controlled revisions
- product configuration
The Manufacturing Bill of Materials (MBOM) describes how the approved engineering definition will actually be built.
Manufacturing may need to:
- reorganize engineering assemblies
- introduce manufacturing-specific items
- add consumables or raw materials
- create intermediate assemblies
- use alternates or equivalents
- apply plant-specific structures
- define date or unit effectivity
- support different manufacturing configurations
This means an MBOM should not simply be an uncontrolled copy of the EBOM.
The two structures should remain traceable so teams can answer:
- Which MBOM implements this engineering component?
- Which plants are affected by an engineering revision?
- Has a changed EBOM item been implemented in manufacturing?
- Which manufacturing structure still requires review?
Nora IPLM supports EBOM-to-MBOM transformation while maintaining relationships between the engineering and manufacturing definitions. Manufacturing teams can regroup, relocate, split or merge engineering content, add manufacturing-specific items, manage plant-specific structures, variants, effectivity and alternates, and validate manufacturing readiness before release.
Common Types of BOMs and Their Purpose
| BOM type | Primary purpose | Typical users |
|---|---|---|
| EBOM – Engineering BOM | Represents the product as designed by engineering | Engineering, design, product development |
| MBOM – Manufacturing BOM | Represents the product as it will actually be manufactured | Manufacturing engineering, production planning |
| PBOM – Production BOM | Supports operational production and execution requirements | Production, ERP, operations |
| SBOM – Service BOM | Represents serviceable components and replacement structures | Service, maintenance, aftermarket |
| Configurable / 150% BOM | Contains the possible components and rules required to derive product variants | Engineering, configuration, sales engineering |
| Costing BOM | Organizes product structure for cost analysis | Finance, sourcing, engineering |
| Purchasing BOM | Provides material information required for procurement | Procurement, supply chain |
*The important BOM-management challenge is not simply creating these structures. It is maintaining traceability and synchronization between them as the product changes.
Autodesk likewise separates EBOM, MBOM and service BOM concepts, while Siemens emphasizes connected multi-domain BOMs, configuration and historical product structures.
What Information Should a Well-Managed BOM Include?
The exact fields vary by product and organization, but a controlled BOM typically contains more than part names and quantities.
- Part or item number and description
- Quantity and unit of measure
- Parent-child assembly relationships
- Revision and lifecycle status
- CAD files, drawings, specifications, and supporting documents
- Make/buy or sourcing information where required
- Supplier or manufacturer relationships
- Effectivity, configuration, and variant rules
- Change history and approval status
- Relevant compliance, material, cost, or manufacturing attributes
Synchronizing BOMs
When multiple BOMs exist for the same product, synchronization is critical. BOMs with incorrect information, outdated revisions, or out-of-sync structures can lead to costly problems. Examples include:
- Supplying incorrect materials to production lines in JIT/JIS environments.
- Sending outdated design data to mold suppliers.
- Missing long-lead items due to incomplete information.
- Incorrect cost calculations resulting in financial losses.
Practical BOM Management Examples
Example 1: Component Obsolescence
A manufacturer discovers that a motor used in three machine models is being discontinued.
With controlled BOM management, the team can:
- identify where the motor is used
- review affected assemblies and end products
- evaluate a replacement
- create the required item revision
- update affected EBOMs
- determine which MBOMs require changes
- route the change for approval
- release the replacement downstream
Without connected BOM management, teams may have to search spreadsheets, CAD assemblies, emails and ERP records manually.
Example 2: Moving From Engineering to Manufacturing
Engineering releases a drive assembly containing:
- motor
- gearbox
- coupling
- housing
- fasteners
The engineering structure is organized around product design.
Manufacturing instead needs:
Station 10 – Housing preparation
Station 20 – Motor and coupling assembly
Station 30 – Gearbox installation
Manufacturing may also add:
- consumables
- packaging
- manufacturing kits
- plant-specific components
The resulting MBOM can look different from the EBOM while remaining traceable to it.
This is exactly the type of EBOM-to-MBOM transformation Nora IPLM supports. Nora IPLM
Example 3: Managing Product Variants
A manufacturer offers the same machine with:
- two motor options
- three voltage configurations
- two control packages
- regional component requirements
Maintaining a separate static BOM for every possible combination quickly creates duplication.
A configurable BOM can instead maintain a reusable product structure with options, rules and effectivity so the appropriate product definition can be derived for each configuration.
EBOM to MBOM: Why BOM Transformation Matters
An Engineering BOM (EBOM) represents the product from the engineering and design perspective, while a Manufacturing BOM (MBOM) organizes the product according to how it will be built. The structures may therefore differ even when they describe the same finished product.
Managing the transition from EBOM to MBOM is important because manufacturing may need assembly sequencing, production-specific components, packaging, consumables, or other information that is not represented in the engineering structure. PLM helps preserve the relationship between these views so an engineering change can be evaluated against the corresponding manufacturing structure rather than relying on disconnected BOM copies.
Change Management and BOMs
Change Management is essential for maintaining multiple BOMs in sync. Without a unified Change Management platform, it is challenging to keep BOMs integrated and trustworthy. Key aspects include:
- Conducting impact analyses during change requests.
- Maintaining a chain of changes in downstream units.
- Ensuring controlled implementation.
Even with existing change management processes, managing them in a single environment is crucial to avoid issues. A single dashboard for tracking ongoing changes and implementations is vital for success.
Read more about Nora IPLM’s Change Management capabilities: Read now
Configurable BOMs (150% BOM)
As companies aim to deliver more configurable and customizable products, static (100%) BOMs are insufficient. A configurable BOM is flexible, including all product variants and configurable items. It also tracks material history, such as revisions or replacements.
Using static BOMs for 100 product configurations would require maintaining numerous separate items, leading to complex relations. In contrast, a configurable BOM uses a single superstructure with changing effectivities and rules per configuration.
Understanding Different Bill of Materials (BOM) Views
Optimizing how your BOM data is viewed is crucial for efficient product development, manufacturing, and supply chain management.
Here are the essential views of a BOM and their primary applications:
- Flat View: This is a straightforward, single-level list of all components and their quantities needed to build a product.
- Primary Use: Ideal for planning and procurement, as it provides a quick summary of total material requirements for purchasing.
- Where Used (Reverse) View: Instead of breaking down a product, this view shows the inverse. It starts with a specific component and lists all the higher-level assemblies or final products in which that component is utilized.
- Primary Use: Highly valuable for analyzing material usage across multiple products, managing component obsolescence, and assessing the impact of a part change or recall.
- Consolidated vs Multi-instance: These views focus on how quantities of shared components are presented.
- Consolidated: Combines all instances of a particular part into a single line item with a total quantity.
- Primary Use: Favored by procurement for aggregating total material needs to secure bulk discounts or manage inventory.
- Multi-Instance: Lists each occurrence of a part separately, even if it’s the same component used in different sub-assemblies.
- Primary Use: Essential for design and engineering teams to understand the specific placement and context of each part within the product structure.
- Consolidated: Combines all instances of a particular part into a single line item with a total quantity.
- Phantom: Phantom assemblies are logical groupings of materials that are “virtually” assembled but don’t exist as a physical sub-assembly until they are integrated into a higher-level assembly.
- Primary Use: Some departments, particularly manufacturing and production planning, use phantom levels for organizational purposes. Others, like financial or inventory management, may prefer these levels to be consolidated into the parent BOM for simpler tracking.
- Primary Use: Some departments, particularly manufacturing and production planning, use phantom levels for organizational purposes. Others, like financial or inventory management, may prefer these levels to be consolidated into the parent BOM for simpler tracking.
- Diagram View: This offers a visual, often graphical, representation of a product’s entire structure. Unlike flat lists, it uses nodes and connecting lines to clearly show hierarchical relationships between the final product, its sub-assemblies, and individual components.
- Primary Use:
- Clarity for Complex Products: Makes intricate assemblies easy to understand at a glance.
- Understanding Dependencies: Clearly shows how changes to one part affect others in the assembly.
- Enhanced Collaboration: Serves as an excellent communication tool across various departments (e.g., engineering, manufacturing, sales) due to its intuitive visual nature.
- Error Reduction: Helps visually identify structural errors in the BOM before production begins.
- Primary Use:
Integrating BOMs With ERP
PLM and ERP usually manage different parts of the product lifecycle.
PLM typically controls the engineering product definition, including:
- items
- EBOMs
- revisions
- CAD-related data
- documents
- configurations
- engineering changes
ERP typically controls operational information such as:
- inventory
- purchasing
- material planning
- production orders
- cost
- operational supplier transactions
The BOM sent downstream depends on the organization’s manufacturing architecture.
Some manufacturers author and release the MBOM in PLM before publishing it to ERP. Others maintain more of the manufacturing structure directly in ERP.
The important requirement is clear system ownership.
Approved product information should move downstream only after the appropriate review and release process, and subsequent changes should remain synchronized according to defined ownership rules.
Discover How Nora IPLM Transforms BOM Management
Nora IPLM makes BOM management faster, smarter, and more connected, helping teams maintain accuracy and stay aligned from design to production.
Advanced BOM Management
Create, track, and update multi-level Bills of Materials with full control and visibility across every change.
Dynamic Workflows
Automate repetitive steps and approvals so teams can focus on engineering and innovation instead of manual coordination.
Real-Time Analytics
Access live product and component data to make quicker, data-driven decisions and prevent costly mistakes.
By centralizing BOM data, Nora IPLM connects design, engineering, and manufacturing teams in one platform, reducing errors, eliminating silos, and improving collaboration across the entire product lifecycle.
Ready to simplify and scale your BOM management?
Explore how Nora IPLM streamlines every step of your process today.
Managing BOMs in Organizations
Unfortunately, many organizations still rely on Excel spreadsheets to manage BOMs. This approach is problematic as it leads to data silos, making it difficult to maintain synchronization and leverage data for analytics and integration.
BOMs consist of dynamic data that evolve with changes such as material revisions or replacements. This necessitates robust revision management, baselining, and comparison capabilities.
Organizations with design and engineering departments often mistakenly equate CAD application data with their BOM. However, CAD BOMs are specific to design needs and may include unnecessary items. Exporting this data directly for manufacturing or purchasing in ERP systems is not advisable.
Collaboration around BOMs is essential, especially for large, mobile, and multi-site organizations. This collaboration should extend to third-party suppliers involved in product development and manufacturing.
BOM Management Best Practices
A reliable BOM process should include:
- One authoritative product definition: avoid uncontrolled copies across spreadsheets, folders and email.
- Clear revision rules: distinguish working changes from formal released revisions.
- Structured item ownership: define who owns item attributes, BOM structures and downstream updates.
- Baseline important milestones: preserve approved structures for releases, design reviews and manufacturing handoffs.
- Use where-used analysis: understand every product affected before replacing or revising a component.
- Compare BOM versions: identify additions, removals, quantity changes and revision differences.
- Connect BOM changes to change control: do not edit released structures without traceable approval.
- Validate before release: check completeness, revisions, lifecycle state and required relationships.
- Maintain EBOM-MBOM traceability: manufacturing structures should remain connected to engineering intent.
- Integrate after approval: send controlled product data downstream rather than work-in-progress definitions.
Managing a BOM Through an Engineering Change
Suppose an industrial equipment manufacturer needs to replace a motor because the existing component is becoming obsolete. The motor appears in several assemblies and product configurations.
With structured BOM management, the team can:
- Identify every assembly and product where the motor is used.
- Review the current revision, drawings, specifications, and supplier information.
- Evaluate an approved replacement and its impact on related components.
- Create an engineering change linked to the affected BOM records.
- Update the EBOM and evaluate the corresponding MBOM impact.
- Route the change for review and approval.
- Release the updated product structure while preserving the previous revision and complete change history.
- Synchronize approved downstream data with ERP or manufacturing systems.
This is the practical difference between editing a parts list and managing a BOM as controlled product data.
How Nora IPLM Supports Modern BOM Management
Nora IPLM manages BOMs as connected product structures rather than isolated lists. Teams can create and update multi-level BOMs, manage revisions, navigate parent-child relationships, and use reverse or where-used views to understand how components are connected across products.
BOM data can remain connected to CAD information, documents, suppliers, workflows, and engineering changes. Nora IPLM also supports configurable product structures and EBOM/MBOM processes, helping engineering and manufacturing teams maintain traceability as product definitions evolve.
BOM Health Analysis adds another layer by helping teams identify issues and review product structures before downstream release, while controlled change and revision management preserves the history behind BOM updates.
Also Read: Common BOM Management Errors
Frequently Ask Questions (FAQs)
What is the BOM management process?
The BOM management process includes defining the product structure, standardizing item data, connecting related product information, controlling revisions and changes, validating the BOM, releasing the appropriate product structure and synchronizing approved information with downstream systems.
What is a BOM management method?
A BOM management method is the structured approach an organization uses to create, update, validate, release and maintain product structures throughout the product lifecycle. The exact process varies by company, but it normally includes revision control, change management, validation and downstream synchronization.
What is the difference between an EBOM and an MBOM?
An EBOM represents the product as designed by engineering. An MBOM represents how the product will actually be manufactured. The MBOM may reorganize the engineering structure and add manufacturing-specific items, effectivity, alternates or plant-specific information.
How do you keep multiple BOMs synchronized?
Keep BOMs connected through controlled relationships, revision management, baselines and engineering change processes. When an engineering revision changes, teams should identify which downstream BOMs are affected and update only the relevant structures.
What are BOM management best practices?
Use one controlled source of product information, standardize item data, manage revisions, maintain baselines, perform where-used analysis, compare BOM versions, connect changes to formal approval workflows and validate BOM completeness before release.
What software is used for BOM management?
BOMs may be managed in CAD, PDM, PLM and ERP systems depending on lifecycle stage. PLM is commonly used to manage the engineering product definition, revisions, changes and relationships between product structures, while ERP focuses on operational planning and transactions.
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