Sunday, January 19, 2014

Bill of Material Concept

BOM management is most important functionality of PLM system. BOM is most critical component in a product based industry and managing it is still most challenging aspect in PLM system. The complexity increases as BOM lifecycle doesn’t reside just in one system or domain but in multiple Enterprise systems. Also Bill of Material for a given Product or Part means different to different section of people in the company based on their perspective and functionality for the given BOM. In this blog, I will discuss BOM basic, variation and challenge for managing it in any enterprise.

Concept of Bill of Material: BOM is defined as “A comprehensive list of raw materials, components and assemblies required to build or manufacture a product”. Hence it is a detail recipe of product which help to define, build and maintain a product. Since product goes through various lifecycle and interacts with various discipline or domain from Design to Manufacturing to Service to Finance, Bill of material also goes through similar lifecycle and various discipline or domain. Hence for a given product there resides many BOM based on the lifecycle and discipline which required using it. For example Design Engineer mainly deals with Functional aspect of product where as Manufacture Engineer deals with manufacturability aspect of product. Hence the way the Design Engineer look same BOM is different from manufacture engineer. Same is true for Service Engineer, Procurement etc. Each one has his own way of looking of BOM. There is numerous ways for defining the BOM for same product. In technical terms, BOM can mainly classified as follow

a)      Design BOM (EBOM): This deal with functional aspect of product. This is mainly first steps of BOM creation for a product. The design BOM usually originates from CAD model or Functional architecture breakdown. Manufacturing BOM usually derived from Design BOM.\

b)      Manufacturing BOM (MBOM): This BOM deals with manufacturing aspect of Product. Hence it can have detail related to manufacture information along with part detail of product. For example Tools or Fixture can be part of Manufacturing BOM (or it can be reference in the Part). Also some single design part can be consider combination of component ( Ex : Welding two plates ).

c)      Material BOM: This BOM mainly managed in ERP system for inventory and process planning. They deal with actual physical aspect of parts. Design or Manufacturing BOM can have component which might not be real or perishables item. For example MBOM can have component for intermediate manufacturing operation which doesn’t exist as storage or tangible part.

d)      Service BOM: This BOM deals with Serviceability of Product. This BOM has only that information which defines the service aspect of Product. Hence it deals only with list of part which is serviceable. Therefore this BOM doesn’t have detail for subassembly which constitute as a single part from service perspective.

Apart from above BOM type there are some other BOM type like Order BOM, Procurement BOM etc which are derivatives of above BOMs with some variation. Also BOM can also be distinguishing based on configurability of BOM.

Configurable BOM: From single BOM, based on certain rules or condition you can derive various resultants BOM. For example for a given model of a car, you can multiple versions. The Configurable BOM is used to dynamically create "end-items" that a company sells. The rule as basically variant and condition are option for those variant. For example based on engine type, power train can be selected in a given BOM. Configurable BOM provide a means to company to manage single BOM for multiple products variant. This saves considerable time and cost to company. All major PLM tools provide configurable BOM management modules.

Master BOM: Looking at so many BOMs variant for a given product, it is always a night mare for the company to manage all BOM and synchronize all when there is any change in either upstream (Design) or downstream (Service). To overcome this challenge, the concept of Master BOM has come.  Master Bill of Material can be defined as single source of BOM having all aspect of information for various configuration and discipline. Hence Master BOM by definition is single source of truth for all BOM. Industry is still struggling to find the exact solution in term of defining and managing Master BOM. Also it become more complex due to the facts that different BOM types are managed in different systems. PLM vendors including Siemens PLM has come various solution and tools, but still required to show the success and maturity of managing Master BOM as a single source of truth across various BOM lifecycle and discipline.
That’s all from my side on Bill of material. PLM vendors provide various powerful BOM tools for Managing, Collaboration and Visualization. I will discuss some of those in my coming blogs.

See Also :
Bill of Material Lifecycle


  1. Good Explaination and overview of BOM and its type.
    Looking forward to see Best Practises followed to manage these different types of BOM in different systems and How the BOM transformation or derivation takes place from EBOM---MBOM----SBOM.

  2. What I mis a little bit in this Blog is the concept of As-Designed, As-Build and As-Maintained. These BOM's are normally used for CM purposes.


    Menk Slot

  3. I have heard that some Organizations have 110% BOM or 150% BOM what are these ?

  4. @Deepak - Representing the BOM with different variations using options and variants is referred to as 150% BOM.


  5. Good summary of BOM-related topics. What is not clear is how all eBOM, mBOM, sBOM and other BOMs can co-exist. IMHO, this is a place where most of today PLM systems and related application stuck... What is your take?

    1. That is most challenging aspect of BOM management. The solution resides both in process and technology. The problem in present solution provided by various Vendors is that they look totally from technical which results in very complex management. This make it fails on actual implementation (just see the number of BOM modules Tc itself had :) ). Hence from my perpective first you should define overall process on managing various BOM and then try to fit technology to manage those process.

  6. In my opinioy, eBOM, mBOM and sBOM and process plans subsequently coming under PLM umbrella issues of managing and aligning between them should be ironed out. More collaboration and openness(open standards of Data Exchange) is required where Business related BOMs like Material BOM, Purchase BOMs, and other BOMs have to be linked/synced with Product Side BOM (eBOM, mBOM, Bill of Process etc).

  7. As-designed EBOM
    As-manufactured MBOM
    As-planned ??
    As-built P BOM
    As-serviced SBOM
    You have explained all BOMs in this blog excepr As Planned Can you brief how it is represented in PLM.

  8. i have recently started working on PLM this information is very subtly given. I really appreciate it.


  9. Here is a question: is there an industry group or SIG within a group that is focused on a formal definition of these.

    While DJain points out that a data exchange standard is needed, it almost sees that a basic agreement (the likes that Manoj depicts - as an example - with these other-mentioned BOMs included) on definitions could be a good starting point followed by a process breakdown map (like the folks at SCORE did for supply chain). Such definitions and mapping would go a long way in identifying what the interface mapping should be AND provide operational scenarios that all of us could use to for implementation concepts and best practices.

  10. Nice and wonderful article that provides BOM information for beginners.

  11. Here is the question: has any one used cutting tool such as end mills, cutting insert, drills etc in manufacturing BOM and if so can you provide a example and what system was used to develop tooling Bill of material.

  12. Is there a way to manage service bom within PLM? If so how would it be and would it be derived from the mbom?

  13. Can anyone please tell me if the sBoM provides visibility to acceptable/allowable parts substitutions? Also, will it provide 3D exploded views of assemblies?

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