BOM 101: How Many Levels Do You Need in BOM?

January 30, 2013

I’m continue my BOM 101 series of posts. When working on bill of materials, you can often hear about the ability of BOM management software to support so-called "multi-level" BOM. You can search for the definition of multi-level BOM using Google and find many results. I found the following definition of multi-level BOM on Arena website quite balanced. Here is the passage from the Mult-level BOM article:

A multi-level BOM, also referred to as an indented BOM, depicts parent-child relationships and shows the hierarchical structure of assemblies and their related parts and components. A multi-level BOM is essentially a nested list whose parts or items are listed in two or more levels of detail to illustrate multiple assemblies within a product’s BOM. In contrast, a single-level BOM depicts one level of children in an assembly and only the components needed to make that assembly are listed.

In the past, when BOM was managed using paper and spreadsheets, to create multi-level BOM wasn’t a simple task. Computer systems create an opportunity to manage and manipulate easily with multiple levels of BOM. However, the question people are asking usually – how many levels of BOM do we need? This simple question is actually leads to many interesting discussions. From my practice it related to many factors. The most typical are – type of BOM (engineering, manufacturing, support), type of the product, maturity of product development and many others.

I found an interesting writeup about BOM levels in the Frank Watts’ book – Configuration Management Metrics. Navigate to the following link – I was able to access this book fragment using Google Books. Here is an interesting passage:

The tendencies of the companies to create multi-level assembly structures seems to be overwhelming. This analyst has witnessed 11 levels at a couple of companies and had a seminar attendee tell about 16 levels. Many departments wish to add structure for their apparent need and many needs are not in best interest of the company as a whole. Because agreement cannot be reached on one structure, often an "Engineering BOM" and a "Manufacturing BOM" are created. Often a material folks create "Planning BOM". Many times various department can reach agreement only by adding additional layers to the BOM.

The following diagram shows the number of levels in BOM correlated to maturity of product development. The analyst believes a better communication can be achieved by creating a BOM with minimum levels of structure.

What is my conclusion? The fact you can create multiple levels of BOM doesn’t mean you need to utilize it at full capacity. Multi-level BOMs are complicated and adding an additional work in the process of changes. How to maintain the right number of BOM levels? I’m interested to learn more about your experience. How many BOM levels do you have in your company ERP/MRP/PDM/PLM system? Speak your mind.

Best, Oleg

PLM, Multiple BOMs and Cross Functional Teams

April 26, 2012

The ability to develop virtual conversation accorss continents and timezones is one of the most exciting parts of my blogging hobby. Earlier last week, I had a very interesting discussion about multiple Bill of Materials. It started from the discussion about BOM management and PLM 360 with John Evans here. Furthermore, it ended in almost one-hour conversation with additional twitter conversation.

The conversation about multiple bill of materials and different ways to implement it drove me to get back to one of my favorite books – Engineering Documentation Control Handbook by Frank Watts. This book is a bible. It is "a must-read book" for every CM in manufacturing company, and every product manager involved into software development for PDM/PLM. Here is the link from Amazon.

Cross-Functional Teams

The organization of cross-functional teams is one of the most important things in a modern product-development process organization. Things can go very easy if you are sort of "garage level company". Everybody speaks to everybody in this company and there is no problem in coordination and collaboration. However, as soon as a company is growing, it faces the problem of collaboration, communication and terminology. Things can go in a quite disconnected way when people from design and manufacturing are collaborating with manufacturing or production people. The following picture below (picture credit to EDC Handbook) presents the idea of cross-functional teams very nicely.


Multiple Bill of Materials

BOM plays a fundamental role to establish communication and collaboration between teams. I see Bill of Material as a universal media in cross-functional teams. Different people contribute to this Bill of Material with a diverse set of information. You can see a picture that can illustrate this process (picture credit to EDC Handbook). The ability of software involved into product development (PDM, PLM, ERP, SCM, etc.) is to provide this level of media to collaboration across the teams.


What becomes clear to me that notion of a single BOM, constantly shrinking and growing is the one I envision as the one of the most efficient ways to maintain Bill of Material in manufacturing organization. Few years ago, I had a chance to share the idea of a single BOM in my post – Seven Rules Towards Single Bill of Material.

What is my conclusion? To manage Bill of Material is one of the most complicated tasks in product development. For the last 10 years, multiple ideas and strategies were introduced in the field of BOM management. Synchronization of multiple BOM views and representations is a painful and complicated task. If future PLM software will be able to eliminate the need of synchronization of BOM across multiple systems and teams, it will be a huge pain relief to product development. To think about cross-functional teams in that context is probably a good starting point. Just my thoughts…

Best, Oleg

PS. I will continue with my "single BOM investigation" in future posts. Stay tuned…


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