EBOM & MBOM – What they are and how you can use them together & more intelligently

I’d like to start off my first blog post by defining EBOM & MBOMs. Most companies developing products have both EBOM and MBOMs.

  • Engineering Bill of Materials — as designed
  • Manufacturing Bill of Materials — as shipped

You may not agree, many don’t see it this clearly. Industry does, and therefore, some software tools have more ability than you may know. But, I guarantee, if you overlay these two elements onto what you are doing for BOMs, whether in Engineering, or in Manufacturing or Production, you’ll see the clarity of these two simple elements rise to the surface.


EBOMs are created in engineering, are typically driven from the CAD tool and are usually centric to the final assemblies list of parts or components that make up the as designed or EBOM.

MBOMs will contain, or be ‘driven’ by the EBOM. MBOMs make up the ‘end item’, or product as shipped. Of course, the EBOM, or ‘parts list’…the MBOM requires additional things like shipping containers, crates, peanuts, or packing foam, plastic bags for accessories, power cords, or items necessary to complete the product that are not defined on the EBOM.

Evolution of this ability & pain points:

In the drawing board days, we often communicated this detail as a table on the final assembly drawing. Sometimes as many sheets attached or referred to on the final assembly drawing…Hopefully, you’ve evolved beyond that! If not, that’s okay, there is hope. Unfortunately, many still use this legacy approach, and are still creating (painfully) this table on their CAD assembly drawings. Others may be manually forming them in spread sheet software.

The next step, and pain point, you must re-enter or get the data into your ERP/MRP tool. Either manually, or via an importation, it is error prone. What if changes occur? (But, that never happens, right? 🙂 )

How much time does your organization spend on these tasks? How about on errors because of changes? Do you have the role of Configuration Manger defined?

This task, creating the MBOM from the EBOM usually has many manual and painful disjointed steps. Often involving exporting out of one tool, into another, but only if you are evolved enough — as I stated earlier, many are not this evolved, but have a vision to do so…maybe you’ve already made a connection from your data management tool, to your ERP/MRP system?

Here’s my shameless plug for EAC and Windchill – EAC can help you form this vision, and guide you to a better way of understanding this topic in context of your organization. We strongly believe there is a better way to develop products and managing EBOMs and MBOMs is just one part of doing it better. Windchill can drive the EBOM into the MBOM or vice versa. It has out of the box ability to be the tool for your Configuration Manager roles in your organizations. Options and variants are another use case you’ll see in a future blog topic.