BOM 101: 5 “Don’ts” for Bill of Materials Management

BOM 101: 5 “Don’ts” for Bill of Materials Management

BOM is fascinating. After posting 3 Modern BOM Management Challenges a week ago, I keep getting back to Bill of Materials management topic.  If you missed my previous BOM 101 posts, here are links to get up to speed: BOM 101- The four pillars of every BOM management solution, BOM 101- How to optimize Bil of Materials. You can also take a look on this post as well – Single BOM in 6 steps. Today, I’d like to take a bit different angle by stating my 5 top most important “don’ts” you need to follow when designing and implementing bill of materials solution in your company. These topics are not necessarily reflecting PLM system. You can face the same problems when implementing BOM solutions using Excel spreadsheets, homegrown DIY data management and large ERP solution.

1. Don’t use significant numbers for Part Numbers – Use Classification

The discussion about “significant” vs. “non-significant” part numbers is probably endless. If you are new in this discussion (or just came out of computer science college), a significant Part Number looks like this 60-44-FN400587-60-NM-40-DWG-CHI. The information in this number is coded and different groups of this number are representing different meaning. Is there something wrong here? No, it is absolutely fine to have significant part number. Even more, if you are still using Excel spreadsheets or legacy data management system, this is probably the only way you can do it. However, it is complicated and eventually will lead you to mistakes. These days, most of PLM systems will provide you with the easy way to use insignificant part numbers. One of the features of good data management system is advanced classification mechanism. Such type of mechanism will help you to define all meaningful terms and characteristics of your Parts, Assemblies and Materials.

2. Don’t use supplier’s part number – use your own Item Master number 

When working with suppliers, you may decide to use supplier’s part numbering schema. Especially if you are small company, it sounds very reasonable and it can simplify the communication with suppliers. However, this is a wrong thing to do, in my view. Again, PDM / PLM system maintaining item master record with cross-reference mechanism between parts and supplier part numbers can easy solve this problem and simplify your life in the future. What will happen with your system and processes if supplier will decide to change their number schema one day? it will be probably a very complicated day for you. So, use your own item master numbering schema and don’t rely on suppliers.

3. Don’t use the same ID for Part Numbers and Drawing Numbers 

This is another question often asked during implementations. To use the same number for items and for drawings as well as process sheets, specification documents, etc. Initially sounds like something that could be simple enough to support and manage, can potentially lead to significant complexity and limitation in managing of change processes. The same drawing can be used for different part numbers. At the same time, changes of part numbers related to materials, stock, etc. won’t require drawing changes. Keep separate numbers and manage relationships between them is a good data management practice to follow.

4. Don’t be afraid to use extra part numbers 

Identification is a very important mechanism. Sometimes, the assembly process is quite complicated and requires some temporarily pre assembled elements of the equipment to be maintained separately. In addition, you might have materials such as service parts, replacements, process result chemicals, etc. Bottom line – you don’t want materials in your bill to fly without identification. Everything needs to be included into the bill. Today’s data management systems are powerful enough to manage “extra Part Numbers” to identify everything you need in your bill.

5. Don’t put Bill of Materials on the drawings 

Another topic coming from historical usage of paper drawing. In the past, it was the only way to share information. Obvious decision back that days was to put Bill of Materials on the drawing list. In modern digital life, such practice can create a lot of complications and additional procedures (such as updates of drawing when only part list will be changed). The good practice today is to keep cross reference links between drawings and bill of materials. It will allow you to manage your changes process efficiently and optimize your and your company time.

What is my conclusion? Control and efficiency. These are two important words to remember when  you deal with Parts, BOMs and Documents. Many processes in this space were developed in the past and can trail lots of complexity if you not update them to “digital era”. To streamline processes and make change management simple are important goals to following when creating the foundation of your BOM management solutions. Just my thoughts. I’m sure missed some issues and useful tips. Speak your mind and share your experience….

Best, Oleg

Disclaimer: I’m co-founder and CEO of OpenBOM developing cloud-based bill of materials and inventory management tool for manufacturing companies, hardware startups, and supply chain. My opinion can be unintentionally biased.


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  • Jack Brown

    The ultimate goal of any PLM system should be to turn a drawing format into a Box and hopefully into a non-existent relic of the past. For those worried about drawings being on a production floor, there is something called a Staple that integrates non-integrated BOMS to the drawing. Also, CPU and graphics power allow for drawings and 3D interrogation from a laptop or tablet. Preserving bills of materials on a drawing (Or as Norm approiately put it, the “Bill of Errors”) only complicates and stagnates the configuration mangement process. A BOM change should only have to involve the modification of the metadata of the engineering. If the form fit or function has not changed, the drawing would not be impacted and you can save time and money performing the change if it is only a database change.

  • beyondplm

    Jack, agree! We should separate the way we “manage” drawings and BOMs from the way we “present” it to people in the organization (shop floor included). Love your “bill of errors” example :). Thanks!

  • beyondplm

    Norm, (sorry for missing your comment). Agree – information should be integrated from multiple system. The consistency of the information is absolutely must in engineering/manufacturing environment.

  • beyondplm

    Adam, sorry for late answer. The problem is not to “visualize” BOM on the drawing. The problem is to “manage” BOM in the drawing. It can easy cause disconnect between BOM drawing information and rest of the system.

  • beyondplm

    Paul, The question is how BOM is making their way to the drawing. If actual BOM is managed separately and placed on the drawing for visualization / printing, it is okay. However, this mechanism should guarantee the updates in case BOM is changing.

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  • Samrat Chatterjee

    Hi Oleg,

    I am a regular reader of your blogs and a practicing consultant in similar area for BOM boundaries , PLM strategy et al… From my past few experiences i have come across the challenges of representing BOM importance for project based organizations – Where “Product” is not what they think they sell – Yet invariably end up designing , manufacturing and supplying for their project executions –

    In situations such as these – we have often found relevance of a Project / Plant or Site BOM that starts with the As- Conceptuaized state of the requirements and milestones costs (Often the WBS is defined as a Project BOM)- These are then evolved to create EBOM / MBOM / SHipping BOM / As Installed BOM and AS – Serviced BOM’ /Views

    To your understanding and to all the readers reading this – Do you think it is the right way to go – Are there any better suggestions or comments

    Thanks and BR

  • beyondplm

    Samrat, thanks for you comment! This is a great question. In my view, “project” is a different thing. Most of “BoM” related definition won’t work for project. At the same time, BoM is absolutely important in projects such as “Build to Order” or “Engineering to Order”. So, I can see an importance of BoM in project driven environment. Best, Oleg

  • Carl Tinker Anderson

    I have worked with many companies that removed their BOM off the drawings. Actually the true BOM is the ERP system. This is where the financial decisions are made. The logistical aspect of all parts and assemblies. If for example someone updates the ERP but neglects to update the CAD/Drawing BOM you could end up with inventory problems. Lets say shop floor builds to the drawing BOM and not the ERP. Now you have discrepancies with your $$$ inventory which could lead to missed Production Schedules for other products. Product Engineers should always make sure 3D CAD BOMs and the ERP BOMS match. With certain integrations products like TIBCO and Biztalk this could be automated to some degree. Great Article

  • beyondplm

    Carl, thanks for your comment! You’re absolutely right- ERP system should have correct and up to date information about BoM and parts, otherwise production schedule won’t happened as expected. But, at the same time ERP system cannot manage many aspects of engineering BoM. That’s why I can see a reason for single integrated BoM concept that can absorb multiple dimensions of BoM complexity.

    Best, Oleg

  • Ramon

    who is responsible for the integrity of information of the BOM’s?

  • beyondplm

    it is a great question, which doesn’t have a simple answer. If “who” is a person then the answer – it depends on what BOM and lifecycle stage. You will find moments when engineering will be responsible for integrity of engineering BOM and you can be in a situation when MRO will take responsibility. From other standpoint, it depends on how many systems you use and how you integrate data. Even if you buy a fully fledged PLM concept, you can find BOMs in many places and applications inside your organization. I hope it makes sense. Best, Oleg

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