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Last week I got the following question:

Many companies face the challenges relevant to the cooperation and joint ventures and need to integrate in a smart way the portfolio’s to offer integrated solutions. In the world of sharing and collaboration, this may be a good argument to dig into. Is PLM software ready for this challenge with best practice solutions or this is a matter that is under specific development case by case? Any guidelines?

Some history

When PLM solutions were developed their core focus was on bringing hardware products to the market in a traditional manner as shown in the figure below. clip_image001

Products were pushed to the market based on marketing research and closed innovation. Closed innovation meant companies were dependent on their internal R&D to provide innovative products. And this is the way most PLM systems are implemented: supporting internal development. Thanks to global connectivity, the internal development teams can collaborate together connected to a single PLM backbone/infrastructure.

Third Party Products (TPP) at that time were sometimes embedded in the EBOM, and during the development phase, there would be an exchange of information between the OEM and the TPP provider. Third Party Products were treated in a similar manner as purchase items. And as the manufacturing of the product was often defined in the ERP system, there the contractual and financial interactions with the TTP provider were handled, creating a discontinuity between what has been defined for the product and what has been shipped. The disconnect between the engineering intent and actual delivery to the customer often managed in Excel spreadsheets or proprietary databases developed to soften the pain

What is happening now?

In the past 10 – 15 years there is the growing importance of first electronic components and their embedded software now followed by new go-to-market approaches, where the customer proposition changes from just a product, towards a combined offering of hardware, software, and services. Let´s have a look how this could be done in a PLM environment.

From Products to Solutions

The first step is to manage the customer proposition in a logical manner instead of managing all in a BOM definition. In traditional businesses, most companies still work around multiple Bill of Materials. For example, read this LinkedIn post: The BOM is King. This approach works when your company only delivers hardware.

Not every PLM system supports Out-Of-The-Box a logical structure. I have seen implementations where this logical structure was stored in an external database (not preferred) or as a customized structure in the PLM system. Even in SmarTeam, this methodology was used to support Asset Lifecycle Management. I wrote about this concept early 2014 in the context of Service Lifecycle Management(SLM) two posts: PLM and/or SLM ? and PLM and/or SLM (continued). It is no coincidence that concepts used for connecting SLM to PLM are similar to defining customer propositions.

PropositionIn the figure to the left, you can see the basic structure to manage a customer proposition and how it would connect to the aspects of hardware, software, and services. In an advanced manner, the same structure could be used with configuration rules to define and create a portfolio of propositions. More about this topic potential in a future blog post.

For hardware, most PLM systems have their best practices based on the BOM as discussed before. When combining the hardware with embedded software, we enter the world of systems. The proposition is no longer a product it becomes a system or even an experience.

For managing systems, I see two main additions to the classical PLM approach:

  1. The need for connected systems engineering. As the behavior of the system is much more complicated than just a hardware product, companies discover the need to spend more time on understanding all the requirements for the system and its potential use cases in operation – the only way to define the full experience. Systems Engineering practices coming from Automotive & Aerospace are now coming into the world of high-tech, industrial equipment, and even consumer goods.
  2. The need to connect software deliverables. Software introduces a new challenge for companies, no matter if the software is developed internally or embedded through TTP. In both situations, there is the need to manage change in a fast and iterative manner. Classical ECR /ECO processes do not work here anymore. Working agile and managing a backlog becomes the mode. Application Lifecycle Management connected to PLM becomes a need.

In both domains, systems engineering, and ALM, PLM vendors have their offerings, and on the marketing side, they might all look the same to you. However, there is a fundamental need that is not always visible on the marketing slides, the need for complete openness.


opennessTo manage a portfolio based on systems a company can no longer afford to manually check in multiple management systems all the dependencies between the product and its components combined with the software deliverables and TTPs. Automation, traceability on changes and notifications are needed in a modern, digital environment, which you might call a product innovation platform. My high-speed blog buddy Oleg Shilovitsky just dedicated a post to “The Best PLM for Product Innovation Platform” sharing several quotes from CIMdata´s talk about characteristics of a Product Innovation Platform and stressing the need for openness.

It is true if you can only manage your hardware (mechanics & electronics) and software in dedicated systems, your infrastructure will be limited and rigid as the outside world is in constant and fast changes. No ultimate solution or product does it all and will do it all in the future. Therefore openness is crucial.


In several companies, original in the Engineering, Procurement & Construction industry, I have seen the need to manage services in the context of the customer delivery too. Highly customized systems and/or disconnected systems were used here. I believe the domain of managing a proposition, a combination of hardware, software, AND services in a connected environment is still in its early days. Therefore the question marks in the diagram.


How Third Party Products management are supported by PLM depends very much on the openness of the PLM system. How it connects to ALM and how the PLM system is able to manage a proposition. If your PLM system has been implemented as a supporting infrastructure for Engineering only, you are probably not ready for the modern digital enterprise.

Other thoughts ???

In my series describing the best practices related to a (PLM) data model, I described the general principles, the need for products and parts, the relation between CAD documents and the EBOM, the topic of classification and now the sensitive relation between EBOM and MBOM.

First some statements to set the scene:

  • The EBOM represents the engineering (design) view of a product, structured in a way that it represents the multidisciplinary view of the functional definition of the product. The EBOM combined with its related specification documents, models, drawings, annotations should give a 100 % clear definition of the product.
  • The MBOM represents the manufacturing view of a product, structured in a way that represents the way the product is manufactured. This structure is most of the time not the same as the EBOM, due to the manufacturing process and purchasing of parts.


A (very) simplified picture illustrating the difference between an EBOM and a MBOM. If the Car was a diesel there would be also embedded software in both BOMs (currently hidden)

For many years, the ERP systems have claimed ownership of the MBOM for two reasons

  1. Historically the MBOM was the starting point for production. Where the engineering department often worked with a set of tools, the ERP system was the system where data was connected and used to have a manufacturing plan and real-time execution
  2. To accommodate a more advanced integration with PDM systems, ERP vendors began to offer an EBOM capability also in their system as PDM systems often worked around the EBOM.

These two approaches made it hard to implement “real” PLM where (BOM) data is flowing through an organization instead of stored in a single system.

By claiming ownership of the BOM by ERP, some problems came up:

  • A disconnect between the iterative engineering domain and the execution driven ERP domain. The EBOM is under continuous change (unless you have a simple or the ultimate product) and these changes are all related to upstream information, specifications, requirements, engineering changes and design changes. An ERP system is not intended for handling iterative processes, therefore forcing the user to work in a complex environment or trying to fix the issue through heavy customization on the ERP side.
  • Global manufacturing and outsourced manufacturing introduced a new challenge for ERP-centric implementations. This would require all manufacturing sites also the outsourced manufacturers the same capabilities to transfer an EBOM into a local MBOM. And how do you capitalize the IP from your products when information is handled in a dispersed environment?

The solution to this problem is to extend your PDM implementation towards a “real” PLM implementation providing the support for EBOM, MBOM, and potential plant specific MBOM. All in a single system / user-experience designed to manage change and to allow all users to work in a global collaborative way around the product. MBOM information then will then be pushed when needed to the (local) ERP system, managing the execution.

Note 1: Pushing the MBOM to ERP does not mean a one-time big bang. When manufacturing parts are defined and sourced, there will already be a part definition in the ERP system too, as logistical information must come from ERP. The final push to ERP is, therefore, more a release to ERP combined with execution information (when / related to which order).

In this scenario, the MBOM will be already in ERP containing engineering data complemented with manufacturing data. Therefore from the PLM side we talk more about sharing BOM information instead of owning. Certain disciplines have the responsibility for particular properties of the BOM, but no single ownership.

Note 2: The whole concept of EBOM and MBOM makes only sense if you have to deliver repetitive products. For a one-off product, more a project, the engineering process will have the manufacturing already in mind. No need for a transition between EBOM and MBOM, it would only slow down the delivery.

Now let´s look at some EBOM-MBOM specifics

EBOM phantom assemblies

PhantomWhen extracting an EBOM directly from a 3D CAD structure, there might be subassemblies in the EBOM due to a logical grouping of certain items. You do not want to see these phantom assemblies in the MBOM as they only complicate the structuring of the MBOM or lead to phantom activities. In an EBOM-MBOM transition these phantom assemblies should disappear and the underlying end items should be linked to the higher level.

EBOM materials

In the EBOM, there might be materials like a rubber tube with a certain length, a strip with a certain length, etc. These materials cannot be purchased in these exact dimensions. Part of the EBOM to MBOM transition is to translate these EBOM items (specifying the exact material) into purchasable MBOM items combined with a fitting operation.

EBOM end-items (make)

For make end-items, there are usually approved manufacturers defined and it is desirable to have multiple manufacturers (certified through the AML) for make end-items, depending on cost, capacity and where the product needs to be manufactured. Therefore, a make end-item in the EBOM will not appear in a resolved MBOM.

EBOM end-items (buy)

For buy end-items, there is usually a combination of approved manufacturers (AML) combined with approved vendors (AVL). The approved manufacturers are defined by engineering, based on part specifications. Approved vendors are defined by manufacturing combined with purchasing based on the approved manufacturers and logistical or commercial conditions

Are EBOM items and MBOM items different?

MBOM-MOBMThere is a debate if EBOM items should/could appear in an MBOM or that EBOM items are only in the EBOM and connected to resolved items in the MBOM. Based on the previous descriptions of the various EBOM items, you can conclude that a resolved MBOM does not contain EBOM items anymore in case of multiple sourcing. Only when you have a single manufacturer for an EBOM item, the EBOM item could appear in the MBOM. Perhaps this is current in your company, but will this stay the same in the future?

It is up to your business process and type of product which direction you choose. Coming back to one-off products, here is does not make sense to have multiple manufacturers. In that case, you will see that the EBOM item behaves at the same time as an MBOM item.

What about part numbering?

clip_image011Luckily I reached the 1000 words so let´s be short on this debate. In case you want an automated flow of information between PLM and ERP, it is important that shared data is connected through a unique identifier.

Automation does no need intelligent numbering. Therefore giving parts in the PLM system and the ERP system a unique, meaningless number you ensure guaranteed digital connectivity.

If you want to have additional attributes on the PLM or ERP side that describe the part with a number relevant for human identification on the engineering side or later at the manufacturing side (labeling), this all can be solved.

An interesting result of this approach is that a revision of a part is no longer visible on the ERP side (unless you insist). Each version of the MBOM parts is pointing to a unique version of an MBOM part in ERP, providing an error free sharing of data.


Life can be simple if you generalize and if there was no past, no legacy and no ownership of data thinking. The transition of EBOM to MBOM is the crucial point where the real PLM vision is applied. If there is no data sharing on MBOM level, there are two silos, the characteristic of the old linear past.

(See also: From a linear world to a circular and fast)

What do you think? Is more complexity needed?



I will be soon discussing these topics at the PDT2015 in Stockholm on October 13-14. Will you be there ?

And for Dutch/Belgium readers – October 8th in Bunnik:


Op 8 oktober ben ik op het BIM Open 2015 Congres in Bunnik waar ik de overeenkomsten tussen PLM en BIM zal bespreken en wat de constructie industrie kan leren van PLM

classificationIn my previous post describing the various facets of the EBOM, I mentioned several times classification as an important topic related to the PLM data model. Classification is crucial to support people to reuse information and, in addition, there are business processes that are only relevant for a particular class of information, so it is not only related to search/reuse support.

In 2008, I wrote a post about classification, you can read it here. Meanwhile, the world has moved on, and I believe more modern classification methods exist.

Why classification ?

searchFirst of all classification is used to structure information and to support retrieval of the information at a later moment, either for reuse or for reference later in the product lifecycle. Related to reuse, companies can save significant money when parts are reused. It is not only the design time or sourcing time that is reduced. Additional benefits are lower risks for errors (fewer discoveries), reduced process and approval time (human overhead), reduced stock (if applicable), and more volume discount (if applicable) and reduced End-Of-Life handling.

An interesting discussion about reuse started by Joe Barkai can also be found on LinkedIn here, including interesting comments

Classification can also be used to control access to certain information (mainly document classification), or classification can be used to make sure certain processes are followed, e.g. export control, hazardous materials, budget approvals, etc. Although I will speak mainly about part classification in this post, classification can be used for any type of information in the PLM data model.

Classification standards

din4000Depending on the industry you are working in, there are various classification standards for parts. When I worked in the German-speaking countries (the DACH-länder) the most discussed classification at that time was DIN4000 (Sachmerkmal-liste), a must have standard for many of the small and medium sized manufacturing companies. The DIN 4000 standard had a predefined part hierarchy and did not describe the necessary properties per class. I haven’t met a similar standard in other countries at that time.

Another very generic classification I have seen are the UNSPC standard, again a hierarchical classification supporting everything in the universe but no definition of attributes.

15926Other classification standards like ISO13399, RosettaNET, ISO15926 and IFC exist to support collaboration and/or the supply chain. When you want to exchange data with other disciplines or partners. The advantage of a standard definition (with attributes) is that you can exchange data with less human processing (saving labor costs and time – the benefit of a digital enterprise).

I will not go deeper into the various standards here as I am not the expert for all the standards. Every industry has its own classification standards, a hierarchical standard, and if more advanced the hierarchy is also supported by attributes related to each class. But let´s go into the data model part.

Classification and data model

clip_image002The first lesson I learned when implementing PLM was that you should not build your classification hard-coded into the PLM, data model. When working with SmarTeam is was very easy to define part classes and attributes to inherit. Some customers had more than 300 classes represented in their data model just for parts. You can imagine that it looks nice in a demo. However when it comes to reality, a hard-coded classification becomes a pain in the model. (left image, one of the bad examples from the past)

1 – First of all, classification should be dynamic, easy to extend.

2 – The second problem however with a hard-coded classification was that once a part is defined for the first time the information object has a fixed class. Later changes need a lot of work (relinking of information / approval processes for the new information).

3 – Finally, the third point against a hard-coded classification is that it is likely that parts will be classified according to different classifications at the same time. The image bellow shows such a multiple classification.


So the best approach is to have a generic part definition in your data model and perhaps a few subtypes. Companies tend to differentiate still between hardware (mechanical / electrical) parts and software parts.

Next a part should be assigned at least to one class, and the assignment to this class would bring more attributes to the part. Most of the PLM systems that support classification have the ability to navigate through a class hierarchy and find similar parts.

When parts are relevant for ERP they might belong to a manufacturing parts class, which add particular attributes required for a smooth PLM – ERP link. Manufacturing part types can be used as templates for ERP to be completed.

This concept is also shared by Ed Lopategui as commented to my earlier post about EBOM Part types. Ed states:

Think part of the challenge moving forward is we’ve always handled these as parts under different methodologies, which requires specific data structures for each, etc. The next gen take on all this needs to be more malleable perhaps. So there are just parts. Be they service or make/buy or some combination – say a long lead functional standard part and they would acquire the properties, synchronizations, and behaviors accordingly. People have trouble picking the right bucket, and sometimes the buckets change. Let the infrastructure do the work. That would help the burden of multiple transitions, where CAD BOM to EBOM to MBOM to SBOM eventually ends up in a chain of confusion.

I fully agree with his statement and consider this as the future trend of modern PLM: Shared data that will be enriched by different usage through the lifecycle.

Why don’t we classify all data in PLM?

There are two challenges for classification in general.

  • The first one is that the value of classification only becomes visible in the long-term, and I have seen several young companies that were only focusing on engineering. No metadata in the file properties, no part-centric data management structure and several years later they face the lack of visibility what has been done in the past. Only if one of the engineers remembers a similar situation, there is a chance of reuse.
  • The second challenge is that through a merger or acquisition suddenly the company has to manage two classifications. If the data model was clean (no hard-coded subclasses) there is hope to merge the information together. Otherwise, it might become a painful activity to discover similarities.


Modern search based applications

There are ways to improve classification and reuse by using search-based application which can index archives and try to find similarity in properties / attributes. Again if the engineers never filled the properties in the CAD model, there is little to nothing to recover as I experienced in a customer situation. My PLM US peer, Dick Bourke, wrote several articles about search-based applications and classification for, which are interesting to read if you want to learn more: Useful Search Applications for Finding Engineering Data

So much to discuss on this topic, however I reached my 1000 words again Sad smile


Classification brings benefits for reuse and discovery of information although benefits are long-term. Think long-term too when you define classifications. Keep the data model simple and add attributes groups to parts based on functional classifications. This enables a data-driven PLM implementation where the power is in the attributes not longer in the part number. In the future, search-based applications will offer a quick start to classify and structure data.




In my earlier posts, I described generic PLM data model and practices related to Products, BOMs en recently EBOM and (CAD) Documents. This time I want to elaborate a little bit more on the various EBOM characteristics.


The EBOM is the place where engineering teams collaborate and define the product. A released EBOM is supposed to give the full engineering specification how a product should behave including material quality and tolerances. This makes it different from the MBOM, which contains the specification of how this product should be manufactured based on exact components and materials.

Depending on the type of product there are several EBOM best practices which I will discuss here (briefly) in alphabetical order:

EBOM & Buy Part

PDM_ERP_AML_AVLUsually, an EBOM consists of Make and Buy parts –an attribute on the EBOM part indicates the preferred approach. Make parts are typically sourced towards qualified suppliers, where Buy parts can be more generic and based on qualified vendors. Engineering specifies who are the approved Manufacturers for the part (AML) and purchasing decides who are the approved Vendors for this part (AVL). In general Buy parts do not need an engineering efforts every time the part is used in a product.

EBOM & CAD related

My previous post already discussed some of the points related to EBOM and CAD Documents. Here I want to extend a little more addressing the close relation between MCAD parts and EBOM parts. In particular in the Engineering To Order industry, there is, most of the time, no standard product to relate to. In that case, Mechanical CAD can be the driver for the EBOM definition and usually EBOM Make parts are designed uniquely. The challenge is to understand similar parts that might exist and reuse them. Classification (and old post here) and geometric search capabilities support the modern engineer. I will come back to classification in a later post

EBOM – Configuration Item

cmiiIn case a product is designed for mass production throughout a longer lifetime, it becomes necessary to manage the product configuration over time. How is the product is defined today and avoid the need to have for each product variant a complete EBOM to manage. The EBOM can be structured with Options and Variants. In that case, having Configuration Items in the EBOM is crucial. The Configuration Item is the top part that is versioned and controlled. Parts below the configuration item, mostly standard parts do not impact the version of the Configuration Item as long as the Form-Fit-Function from the Configuration Item does not change. Configuration Management is a topic on its own and some people believe PLM systems were invented to support Configuration Management.

EBOM – Company Standard Part

Standard Parts are often designed parts that should be used across various products or product lines. The advantage of company standard parts is that it reduces costs throughout the whole product lifecycle. Less design time, less manufacturing setup time and material sourcing effort and potential lower material cost thanks to higher volumes. Any EBOM part could become at a certain moment a Company Standard part and it is recommended to use a classification related to these parts. Otherwise they will not be found again. As mentioned before I will come back to classification.

EBOM – Functional group

Sometimes during the design of a product, several parts are logically grouped together from the design point of view, either because they are modular or because they always appear as a group of parts.

The EBOM, in that case, can contain phantom parts, which do not represent an end item. These phantom parts assist the company in understanding changing one of the individual parts in this functional group.

EBOM – Long Lead

In typical Engineering to Order or Build To Order deliveries there are components on the critical path of the product delivery. Components with a long lead time should be identified and ordered as early as possible during the delivery process. Often the EBOM is not complete or mature enough to pass through all the information to ERP. Therefore Long Lead items require a fast track towards ERP and a special status in the EBOM reflecting its ordering status. Long Lead items are the example where a company can benefit from a precise interaction between PLM and ERP with various status handshakes and approvals during the delivery process

EBOM – Make parts

Make Parts in an EBOM are usually specified by their related model and drawings. Therefore Make Parts usually have revisions but be aware that they do not follow the same versioning of the related model or drawing. A Make Part is in an In Work status as long as the EBOM is not released. Once the model is approved, the EBOM part can be approved or released. Often companies do not want to release the data as long as manufacturing is not completed. This to make sure that the first revision comes out at the first delivery of the product.

EBOM – Materials

In many mechanical assemblies, the designer specifies materials with a particular length. For example a rubber strip, tubing / piping. When extracting the information from the 3D CAD assembly, this material instance will get a unique identifier. Here it is important that the Material Part has an attribute that describes the material specification. In the ideal data model, this is a reference to a Materials library. Next when manufacturing engineering is defining the MBOM, they can decide on material quantities to purchase for the EBOM Material.

EBOM – Part Number

QRThis could be a post on its own. Do we need intelligent part numbers or can we use random generated unique numbers? I have a black and white opinion about that. If you want to achieve a digital enterprise you should aim for random generated unique numbers. This because in a digital enterprise data is connected without human transfer. The PLM and ERP link is unambiguous. Part recognition at the shop floor can be done with labels and scanning at the workstation. There is no need for a person to remember or transfer information from one system or location by understanding the part number. The uniquely generated number make sure every person will have a look at the digital metadata online available. Therefore immediately seeing a potential status change or upcoming engineering change. Supporting the intelligent numbering approach allows people to work disconnected again, therefore not guaranteeing that an error-free activity takes place. People make mistakes, machines usually not.

EBOM – Service Parts

It is important to identify already in the EBOM which parts need to be serviced in operation and engineering should relate the service information already to the EBOM part. This could be the same single part with a different packaging or it could be a service kit plus instructions linked to the part. In a PLM environment, it is important that this activity is done upfront by engineering to avoid later retrieval of the data and work again on service information. A sensitive point here is that engineers currently in the classical approach are not measured on the benefits they deliver downstream when the products are in the field. Too many companies work here in silos.

EBOM – Standard Parts

3dFinally, as I reach already the 1000 words, a short statement about EBOM standard parts. These standard parts, based on international or commercial standards do not need a revision and often they have a specification sheet, not necessary a 3D model for visualization. Classification is crucial for Standard Part and here I will write a separate post about dealing with Standard Parts, both mechanical and electrical.

Concluding: this post we can see that the EBOM is having many facets and based on the type of EBOM part different behavior is expected. It made me realize PLM is not that simple as I thought. In general when defining an EBOM data model you would try to minimize the specific classes for the EBOM part. Where possible, solve it with attributes (Make/Buy – Long Lead – Service – etc.). Use classification to store specific attributes per part type related to the part. Classification will be my next topic as it appears

Feel free to jump on any of the EBOM characteristics for an extended discussion

note: images borrowed from the internet contain links to the original location where I found them. The context there is not always relevant for this post.

In my series of blog posts related to the (PLM) data model, I talked about Product, BOMs and Parts. This time I want to focus on the EBOM and (CAD) Documents relation. This topic became relevant with the introduction of 3D CAD.

Before companies were using 3D CAD systems, there was no discussion about EBOM or MBOM (to my knowledge). Engineering was producing drawings for manufacturing and not every company was using the mono-system (for each individual part a specifying drawing). Drawings were mainly made to assist production and making a drawing for an individual part was a waste of engineering time. Parametric drawings were used to specify similar parts. But now we are in the world of 3D!

imageWith the introduction of 3D CAD systems for the mainstream in the nineties (SolidWorks, Solid Edge, Inventor) there came a need for PDM systems managing the individual files from a CAD assembly. The PDM system was necessary to manage all the file versions. Companies that were designing simple products sometimes remained working file-based, introducing the complexity of how to name a file and how to deal with revisions. Ten years ago I was investigating data management for the lower tiers of the automotive supply chain. At that time still 60 % of the suppliers were using CATIA were working file-based. Data management was considered as an extra complexity still file version control was a big pain.

This has changed for several reasons:

  • More and more OEMs were pushing for more quality control of the design data (read PDM)
  • Products became more modular, which means assemblies can be used as subassemblies in other products, pushing the need for where used control
  • Products are becoming more complex and managing only mechanical CAD files is not enough anymore – Electronics & Software – mechatronics – became part of the product

Most PDM systems at that time (I worked with SmarTeam) were saving the 3D CAD structure as a quantity-based document structure, resembling a lot a structure called the EBOM.

CAD DOC structure


This is one of the most common mistakes made in PLM implementations.

The CAD structure does not represent the EBOM !!!

Implementers started to build all kind of customizations to create automatically from the CAD structure a Part structure, the EBOM. Usually these customizations ended up as a mission impossible, in particular when customers started to ask for bidirectional synchronization. They expected that when a Part is removed in the EBOM, it would be deleted in the CAD assembly too.

And then there was the issue that companies believed the CAD Part ID should be equal to the Part ID. This might be possible for a particular type of design parts, but does not function anymore with flexible parts, such as a tube or a spring. When this Part is modeled in a different position, it created a different CAD Document, breaking the one-to-one relation.

Finally another common mistake that I have seen in many PDM implementations is the addition of glue, paint and other manufacturing type of parts to the CAD model, to be able to generate a BOM directly from the CAD.

imageFrom the data model perspective it is more important to understand that Parts and CAD documents are different type of objects. In particular if you want to build a PLM implementation where data is shared across all disciplines. For a PDM implementation I care less about the data model as the implementation is often not targeting enterprise continuity of data but only engineering needs.

A CAD Document (Assembly / Part / Drawing / …) behaves like a Document. It can be checked-in and checked out any time a change is made inside the file. A check-in operation would create a new version of the CAD Document (in case you want to trace the history of changes).

Meanwhile the Part specified by the CAD Document does not change in version when the CAD Document is changed. Parts usually do not have versions; they remain in the same revision as long as the specifying CAD Document matures.

Moving from PDM to PLM

For a PLM implementation it is important to think “Part-driven” which means from an initial EBOM, representing the engineering specification of the Product, maturing the EBOM with more and more design specification data. Design specification data can be mechanical assemblies and parts, but also electrical parts. The EBOM from a PCB might come from the Electrical Design Application as in the mechanical model you will not create every component in 3D.

And once the Electrical components are part of the EBOM, also the part definition of embedded software can be added to the BOM. For example if software is needed uploaded in flash memory chips. By adding electrical and software components to the EBOM, the company gets a full overview of the design maturity of ALL disciplines involved.

The diagram below shows how an EBOM and its related Documents could look like:


This data model contains a lot of details:

  • As discussed in my previous post – for the outside world (the customer) there is a product defined without revision
  • Related to the Product there is an EBOM (Part assembly) simplified as a housing (a mechanical assembly), a connector (a mechanical art) and a PCB (a mechanical representation). All these parts behave like Mechanical Parts; they have a revision and status.
  • The PCB has a second representation based on an electrical schema, which has only (for simplification) two electrical parts, a resistor and a memory chip. As you can see these components are standard purchasable parts, they do not have a revision as they are not designed.
  • The Electrical Part Flash Memory has a relation to a Software Part which is defined by Object Code (a zip-file?) which of course is specified by a software specification (not in the diagram). The software object code has a version, as most of the time software is version managed, as it does not follow the classical rules of mechanical design.

Again I reached my 1000 words, a sign to stop explaining this topic. For sure there are a lot of details to explain to this data model part too.

Most important:

  • A CAD structure is not an EBOM (it can be used to generate a part of the EBOM)
  • CAD documents and EBOM parts have a different behavior. CAD documents have versions, Parts do not have versions (most of the time
  • The EBOM is the place where all disciplines synchronize their data, providing during the development phase a single view of the design status.

Let me know if this was to abstract and feel free to ask questions. Important for this series of blog post is to provide a methodology baseline for a real PLM data model.

I am looking forward to your questions or remarks to spark up the discussion.

observation In my previous post, BOM for Dummies related to Configure To Order, I promised to come back on the special relation between the items in the BOM and the CAD data. I noticed from several posts in PLM and PDM groups that also the importance of CAD data is perceived in a different manner, depending on the background of the people or the systems they are experienced with.

So I would like to start with some general statements based on these observations.

planning People who are talking about the importance of CAD data and product structures are usually coming from a background in PDM. In an environment where products are designed, the focus is around data creation, mostly CAD data. The language around parts in the BOM is mostly targeting design parts. So in a PDM environment CAD data is an important topic – therefore PDM people and companies will talk about CAD data and vaults as the center of information.


When you are working in a PLM environment, you need a way to communicate around a product, through its whole lifecycle, not only the design phase but also supporting manufacturing phases, the possible changes of an existing product through engineering changes, the traceability of as-built data and more. In a PLM environment, people have the physical part (often called the ERP part) in mind, when they talk about a part number.

As PLM covers product information across various departments and disciplines, the information carrier for product information cannot be the CAD data. The BOM, usually the mBOM, is the main structure used to represent and produce the product. Most parts in the mBOM have a relation to a CAD document (in many companies still the 2D drawing). Therefore PLM people and companies understanding PLM will talk about items and products and their lifecycle as their center of information.

CAD data in relation to Engineering to Order

The above generalizations have to be combined with the different main business processes. In a strict Engineering To Order environment, where you design and build a solution only once for a specific customer, there is no big benefit of going through an eBOM and mBOM transition.

During the design process the engineer already has manufacturing in mind, which will be reflected in the CAD structure they build – sometime hybrid representing both engineering and manufacturing items. In such an environment CAD data is leading to build a BOM structure.

And in cases where engineering is done in one single 3D CAD system, the company might use the PDM system from this vendor to manage their Bill of Materials. The advantage of this approach is that PDM is smoothly integrated with the design environment. However it restricts in a certain matter the future as we will see in further reading.

pointNot everyone needs the Engineering to Order process !

Moving to an integrated, multi-disciplinary engineering process or changing the main process from Engineering To Order to Built To Order / Configure To Order will cause major challenges in the company.

I have seen in the recent past, several companies that would like to change their way of working from a CAD centric Engineering To Order process towards a more Built to Order or Configure To Order process. The bottle neck of making this switch was every time that engineering people think in CAD structures and all knowledge is embedded in the CAD data. They now want to configure their products in the CAD system.

For Configure to Order you have to look at a different way to your CAD data:

Questions to ask yourself as a company are:

  • When I configure my products around a CAD structure, what should I do with data from other disciplines (Electrical/Tooling/Supplier data) ?
  • When I upgrade my 3D CAD system to a new version, do I need to convert all old CAD data to the newest versions in order to keep my configurations alive?
  • When configuring a new customer solution, do I need to build my whole product in CAD in order to assure it is complete?
  • In Configure to Order the engineering BOM and manufacturing BOM are different. Does this mean that when I go through a new customer order, all CAD data need to be handled, going through eBOM and mBOM transition again?

For me it is obvious that only in an Engineering to Order environment the CAD data are leading for order fulfillment. In all other typical processes, BTO (Built to Order), CTO (Configure to Order) and MTS (Make to Stock),  product configuration and definition is done around items and the CAD data is important associated data for the product definition and manufacturing

In the case of order fulfillment in a Configure to Order process, the CAD structure is not touched as configuration of the product is available based on items. Each item in the mBOM has it relations to CAD data or other specifying information.

In the case of Built To Order, a huge part of the product is already configured, like in Configure To Order. Only new interfaces or functionality will go through a CAD design process. This new design might be released through a process with an eBOM to mBOM transition. In cases where the impact or the amount of data created in engineering is not huge, it is even possible to configure the changes immediately in an mBOM environment.

old_process A second point, which is also under a lot of discussion in the field ( PLM interest groups), is that PDM is easily to introduce as a departmental solution. The engineering BOM is forwarded to manufacturing and there further (disconnected) processed.  The step from PDM to PLM is always a business change.

When PDM vendors talk about ERP integration, they often mean the technical solution of connecting the two systems, not integrating the processes around the BOM (eBOM/mBOM transition) 0r an integrated engineering change (ECR/ECO). See how easy it is according to some PDM vendors:

PLM requires an adaptation of all departments to work different and together around a single product definition. Especially in a mid-market company, this is a big issue, as all product knowledge is stored in the CAD data and the knowledge how to produce the product is stored in the mBOM on the ERP side. These environments are often disconnected.
Conclusion: In the context of PDM the importance of CAD data is clear and for companies following a strict Engineering To Order process the main source of product knowledge. Companies following the Built To Order / Configure To Order process should configure their products around items to keep flexibility towards the future.

Companies with the intention to move to Built To Order or Configure To Order should not invest too much in CAD data configuration as it creates a roadblock for the future.

In my next post I will address the question that comes up from many directions, addressed by Jim Brown and others, as discussed  in one of his recent posts around a PLM standard definition and more ….

sleep This is the third post on Bill of Material handling for different types of companies, this time the focus on Configure To Order (CTO). In the CTO process, products are assembled and configured based on customer requirements. This means there is no more engineering needed when customer requirements are known. CTO examples are, the ordering process of a car with all its options, or ordering a personal computer over the internet.

So what has Configure To Order to do with PLM as there is no engineering?

The main PLM activity takes places when designing the configurable product. Designing a product that is configurable, requires a complete different approach as compared to Engineering to Order or Build to Order. Although we see a similar Configure to Order activity in the R&D departments of companies that follow the Build to Order process. They are also designing products or modules that can be used as-is in customer specific orders as part of the solution.

dashboard The challenge of CTO is to design products that are modular, and where options and variants are designed on a common platform with common interfaces. If you look to the dashboard of a car you will see placeholders for additional options (in case you have the minimal car version) and also you might see that for example the radio display in a basic car version differs from the complete board computer in the luxury version. The common platform is one dashboard, fitting to numerous options.

An engineering department will not focus on designing and defining each of the possible combinations of options as this would be impossible to manage. What can be managed is the common platform (the baseline) and all different options on top of this baseline.

So what happens with the BOM?

The initial design of configurable products goes through similar steps as the BTO process, which means starting from a conceptual BOM, moving to an Engineering BOM (eBOM) and finally produce a BOM for manufacturing (mBOM). The difference is that in the CTO process the mBOM is not developed for just one product, but contains all definitions for all possible products. In this situation we talk about a generic mBOM.

Only when a customer order exists, the generic mBOM is resolved into a specific mBOM for this customer order, which then can be sent to the ERP system for execution.

filter In a generic BOM the relations are managed by filters. These filters define the effectivity of the link, in simple words if the relation between two parts in the BOM is valid (and shown) or not. There are various ways to define effectivity – with again a differentiation in usage

  • revision based effectivity – which means the relation between two items is valid in case the revisions match
  • date effectivity – which means the relation is valid during a certain time interval

Both methods are used most of the time for non-configurable products. The revision and date effectivity are used to be able to track the product history through time and therefore to have full traceability. But this does not work if you want to configure every time a customer specific order.

In that case we use unit or option based filtering.

  • unit effectivity – which means the relation between two items is valid for a unit (or a range of units) produced. For example a batch of products or a unique product with a serial number
  • option effectivity – which means the relation between two items is valid in case a certain condition is valid. Which condition depends on the configuration rules for this option. Example of options are: color, version, country

It is clear that unit and option based filtering of a BOM can lead to a conceptual complex product definition which goes beyond the BOM for Dummies target.  Below an illustration of the various filter concepts (oops the animated gif does not work – i will investigate):


The benefit of this filtering approach is that there is a minimum of redundancy of data to manage. This makes it a common practice in the aerospace and automotive industry. An example describing all the complexity can be found for example here, but I am sure on this level there are enough publications and studies available.

And what about the CAD ?

I will write a separate post on this topic, as all the possible interactions and use cases with CAD are a topic on its own. You can imagine, having the 3D virtual world combined with a configurable BOM brings a lot of benefits

What PLM functions are required to support Configure to Order ?

  • Project management – not so much focus here as the delivery project for a customer does not require much customer interaction. Of course, the product development processes requires advanced capabilities which I will address later in a future post.
  • Document management – same approach as for project management. The product related documentation needs to exist and secured. Customer specific documentation can be generated often automatically.
  • Product Management – managing all released and available components for a solution, related to their Bill of Materials. Often part of product management is the classification of product families and its related modules
  • Item management – The main activities here are in the mBOM area. Capabilities for BOM generation (eBOM/mBOM), baseline and compare using filtering (unit based / option based) in order to support the definition if the manufactured product
  • Workflow processes – As we are dealing with standardized components in the BOM, the Engineering Change Request (ECR) and Engineering Change Order (ECO) processes will be the core for changes. And as we want to manage controlled manufacturing definition, the Manufacturer Change Order process and Standard Item Approval process are often implemented


  • Requirements Management – specially for complex products, tracking of individual requirements and their implementation, can save time and costs during delivery to understand and handle the complex platform
  • Service Management – as an extension of item management. When a customer specific order has been delivered it might be still interesting for the company that delivered the product to keep traceability of the customer configuration for service options – managing the Service and As-Built BOM
  • Product Configurator – the reason I write it as optional, is because the target is order execution, which is not a PLM role anymore. The ERP system should be able to resolve the full mBOM for an order. The PLM product configuration definition is done through Product and Item management. Depending on the customer environment the role of configurator might be found in PLM in case ERP does not have the adequate tools.


It is hard to describe the Configure To Order process in the scope of BOM for Dummies. As various detailed concepts exist per industry there is no generic standard. This is often the area where the PLM system, the PLM users and implementers are challenged the most: to make it workable, understandable and maintainable

Next time some industry specific observations for a change

sleep Continuing the posts on Bill of Material handling for different types of companies, this time the focus on BOM handling in a Build to Order process. When we are talking about Build to Order process, we mean that the company is delivering solutions for its customers, based on existing components or modules. A typical example is the food processing industry. In order to deliver a solution, a range of machinery (ingredient manipulation) and transporting systems are required. The engineering tasks are focused on integrating these existing components. In many cases new or adjusted components are required to complete the solution.

Research and Development in a BTO company

In a typical BTO company you see actually two processes.

  • The main BTO process, fulfilling the needs for the customers based on existing components
  • An R&D department, which explores new technologies and develops new components or modules, which will become available for selling to new customers.

idea This is the innovation engine of the company and often can be found in a complete isolated environment – extra security – no visibility for other departments till release. The task for this R&D department is to develop machinery or modules based on new, competitive technologies, which are rapidly configurable and can be used in various customer solutions. The more these machines or modules are configurable, the better the company can respond to demands from customers, assuming a generic machine and interfaces does not degrade performance, compared to optimal tuned machinery.

I will describe the BOM handling for this department in a future post, as also here you will see particular differences with the ETO and BTO BOM handling.

Back to the core of BTO

I found a nice picture from 2003 published by Dassault Systems describing the BTO process:


We see here the Bidding phase where a conceptual BOM is going to be defined for costing. Different from the ETO process, the bidding company will try to use as much as possible known components or technology. The reason is clear: it reduces the risk and uncertainties, which allow the bidding company to make a more accurate and competitive cost estimate for these parts. When a company becomes mature in this area, a product configurator can be used to quantify the estimated costs.

The result from the bidding phase is a conceptual BOM, where hopefully 60 % or more is already resolved. Now depending on the amount of reuse, the discussion comes up: Should modifications being initiated from the eBOM or from the mBOM?

In case of 60 % reuse, it is likely that engineering will start working around the eBOM and from there complete the mBOM. Depending on the type of solution, the company might decide to handle the remaining 40 % engineering work as project unique and treat it the same way as in an ETO process. This means no big focus on the mBOM as we are going to produce it only once.

I have worked with companies, which tried to analyze the 40 % customer specific engineering per order and from there worked towards more generic solutions for future orders. This would mean that a year later the same type of order would now be defined for perhaps 80 %. Many companies try to change themselves from a project centric company towards a product centric company, delivering configured products through projects.

Of course when solutions become 100 % configurable, we do not speak from BTO anymore, but from Configure to Order (CTO). No engineering is needed; all components and interfaces are designed to work together in certain conditions without further engineering. As an example, when you buy a car or you order a PC through the internet – it is done without sales engineering – it is clearly defined which options are available and in which relation.

See below:


However the higher the amount of reuse, the more important it becomes to work towards an mBOM, which we will than push the order to ERP.

And this is the area where most of the discussions are in a PLM implementation.

  • Are we going to work based on the mBOM and handle all required engineering modifications from there?


  • Do we first work on a complete eBOM and once completed, we will complete the mBOM?

The reuse from existing components and modules (hardware) is one of the main characteristics of BTO. Compare this to ETO where the reuse of knowledge is the target no reuse of components.

The animation shows the high level process that I discussed in this post.

What PLM functions are required to support Build to Order ?

  • Project management – the ability to handle data in the context of project. Depending on the type of industry extended with advanced security rules for project access
  • Document management – where possible integrated with the authoring applications to avoid data be managed outside the PLM system and double data entry
  • Product Management – managing all released and available components for a solution, related to their Bill of Materials. Often part of product management is the classification of product families and its related modules
  • Item management – The main activities here are in the mBOM area. As items in a BTO environment are reused, it is important to provide relevant ERP information in the PLM environment. Relevant ERP information is mostly actual costs, usage information (when was it used for the last time) and availability parameters (throughput time / warehouse info).

As historically most of the mBOM handling is done in ERP, companies might not be aware of this need. However they will battle with the connection between the eBOM in PLM and the mBOM (see many of my previous posts).
As part of the BTO process is around engineering, an EBOM environment with connections to specifying documents is needed. This requires that the PLM system has eBOM/mBOM compare capabilities and an easy way to integrate engineering changes in an existing mBOM.

  • Workflow processes – As we are dealing with standardized components in the BOM, the Engineering Change Request (ECR) and Engineering Change Order (ECO) processes will be the core for changes. In addition you will find a Bidding Process, a Release process for the customer order, Manufacturer Change Order process and a Standard Item Approval process.


  • A Sales Configurator allowing the sales engineering people to quickly build the first BOM for costing. Working with a Sales Configurator requires a mature product rationalization.
  • Supplier Exchange data management – as many BTO companies work with partners and suppliers
  • Service Management – as an extension of item management. Often in this industry the company who Builds the solutions provides maintenance services and for that reason requires another Bill of Material, the service BOM, containing all components needed when revising a part of the machine
  • Issues Management – handling issues in the context of PLM gives a much better environment for a learning organization
  • Requirements Management – specially for complex products, tracking of individual requirements and their implementation, can save time and costs during delivery

Conclusion (so far):

When you compare these PLM requirements with the previous post around ETO, you will discover a lot of similarities. The big difference however is HOW you use them. Here consultancy might be required as I do not believe that by having just functionality a company in the mid-market will have time to learn and understand the special tweaks for their business processes.

Next post more on configurable products

sleep This time a few theoretical posts about BOM handling, how the BOM is used in different processes as Engineering To Order (ETO), Make To Order (MTO) and Build To Order (BTO) organizations and finally which PLM functions you would expect to support these best practices.

I noticed from various lectures I gave, from the search hits to my blog and from discussions in forums that there is a need for this theoretical base. I will try to stay away from too many academic terminologies, so let’s call it BOM for Dummies.

Note: All information is highly generalized to keep is simple. I am sure in most of the companies where the described processes take place more complexity exists.

What is a BOM?

A BOM, abbreviation for Bill of Materials, is a structured, often multi-level list of entities and sub-entities used to define a product

I keep the terminology vague as it all depends to who is your audience. In general when you speak with people in a company that does engineering and manufacturing, you have two major groups:

  • The majority will talk about the manufacturing BOM (mBOM), which is a structure that contains the materials needed to manufacture a product in a certain order.
    We will go more in depth into the mBOM later.
  • When you speak with the designers in a company they will talk about the eBOM, which is a structure that contains the components needed to define a product.

Both audiences will talk about ‘the BOM’ and ‘parts’ in the BOM, without specifying the context (engineering or manufacturing). So it is up to you to understand their context.

Beside these two major types of BOMs you will find some other types, like Conceptual BOM, Customer Specific BOM, Service BOM, Purchase BOM, Shipping BOM.

Each BOM is representing the same product only from a different usage point of view

The BOM in an Engineering To Order company

In an Engineering to Order company, a product is going to be developed based on requirements and specifications. These requirements lead to functions and systems to be implemented. For complex products companies are using systems engineering as a discipline, which is a very structured approach that guarantees the system you develop is matching all requirements and these requirements have been validated.

In less complex and less automated environments, you will see that the systems engineering is done in the head of the experienced engineers. Based on the requirements, they recognize solutions that have been done before and they build a first conceptual structure to describe the product. This is a conceptual BOM, often only a few levels deep, and this BOM is mainly used for costing and planning the work to be done.

A conceptual BOM could like this (open the picture in a separate window to see the animation)


Depending of the type of engineering company, they are looking for the reuse of functions or systems. The reuse of functions means that you manage your company’s Intellectual Property (IP) where the reuse of systems can be considered as the reuse of standard building blocks (modules) to build a product. The advantage of system reuse of course is the lower risk, as the system has been designed and built and tested before.

From the conceptual BOM different disciplines start to work and design the systems and their interfaces. This structure could be named the eBOM as it represents the engineering point of view from the product. In Engineering to Order companies there is a big variation on how to follow up after engineering. Some companies only specify how the product should be made, which materials to use and how to assemble them. The real manufacturing of the product is in that case done somewhere else, for example at the customer site. Other companies still do the full process from engineering and manufacturing.

As there is usually no reuse of the designed products, there is also no investment in standardizing items and optimizing the manufacturing of the product. The eBOM is entered in the ERP system and there further processed to manufacture the product. A best practice in this type of environments is the approach that the eBOM is not a 100 % pure the eBOM, also items and steps needed for manufacturing might be added by the engineers as it is their responsibility to specify everything for manufacturing without actually making the product.

This animation shows on high level the process that I described (open the link in a separate window to see the animation)


What PLM functions are required to support Engineering To Order

The following core functions apply to this process:

  • Project management – the ability to handle data in the context of project. Depending on the type of industry extended with advanced security rules for project access
  • Document management – where possible integrated with the authoring applications to avoid data be managed outside the PLM system and double data entry
  • Classification of functions and/or systems in order to have an overview of existing IP (what have we done) and to promote reuse of it
  • Item management – to support the eBOM and its related documentation. Also the items go through a lifecycle representing its maturity:
    – The eBOM might be derived from the mechanical 3D CAD structure and further extended from there.
    – For design reviews it would be useful to have the capability to create baselines of the eBOM including its specifying documents and have the option to compare baselines to analyze progress
    – The completed eBOM would be transferred to the ERP system(s). In case of a loose ERP connection a generic XML export would be useful (or export to Excel as most companies do)
  • Workflow processes – to guarantee a repeatable, measurable throughput of information – both approval and change processes


  • Supplier Exchange data management – as many ETO companies work with partners and suppliers
  • Issues Management – handling issues in the context of PLM gives a much better environment for a learning organization
  • Requirements Management – specially for complex products, tracking of individual requirements and their implementation, can save time and costs during delivery
  • A configurator allowing the sales engineering people to quickly build the first conceptual BOM based on know modules combined with engineering estimates. This is the base for a better controlled bidding / costing

Let me know if this kind of posts make sense for you …..

Next time we will look at the BOM in a Build To Order process

sleepAfter two posts on objections for PLM, I want to come back to the basics around connecting PLM and ERP systems. Most of the people are enjoying their holiday at this moment and for that reason I have the time to complete the PLM and ERP story. I guess, for a company in the mid-market, it is hard to decide which approach to follow.

ERP vendors will claim that by managing items and relations to the design documents, they are able to provide an  environment that supports engineering on top of their system. For mid-market companies this might be the ‘cheapest’ option – buy or get your solution from a single vendor. Especially when the ERP vendor provides the PLM module for free. And this is exactly one of the reasons why it will fail. When no PLM knowledge or best practices are provided to the company, but just a set of function and features, how would these companies know how to implement PLM ?
If you give a module for free it obviously also shows you do not understand the value of it.

My two last posts with the common title 5 reasons not to implement PLM are addressing some of these issues.

But now back to the PLM and ERP connection. In my two previous posts, I described how would be shared between a PLM and an ERP system, combined with issues as: intelligent part-numbers and classification. You will find similar discussions on the manufacturing center.

The connection between PLM and ERP has little value in case only items are exchanged. Of course engineering can have the benefit of early visibility of item logistical data, like costs, stock and status. But the real value comes when engineering, through the PLM environment, feeds the ERP system with the definition of how to manufacture a product. The way to manufacture a product is based on the MBOM (Manufacturing Bill of Materials), combined with operations that need to be performed on the items in the BOM.

In my post Where is the MBOM I already discussed the classical challenge many companies are facing. Historically they enter all the data for manufacturing in their ERP system, as this was the first system driving production. The input for the ERP system came from the engineering department, sometimes provided as Excel sheet or in case of more automation with the CAD environment as an EBOM (Engineering Bill of Material)

As the concept of connection CAD through PLM with ERP might be new for many companies, I will describe below some ‘bad practices’ that I found in past implementations and what we can learn from them.

Bad practice 1: A CAD file equals and Item number

As PLM is often introduced starting from the design department, the initial thought to connect CAD files and Items is based on the simple rule: “Every CAD file represents an item number”. In the ‘good old’ 2D world this might have been true, as in the ERP system, related to each item to be manufactured a drawing existed.

However in the 3D world this approach leads to the following problems:

  • Flexible parts like rubber tubes or belts have a different file representations when used in a different position. This means for one item number several CAD files may exist.
  • Some CAD systems like CATIA, SolidWorks allow the designer to store within one file different configurations of a design, as they share a common design but vary on some specific points. Each variation of course is a different item number. This means for one CAD file several item numbers may exists.

The conclusion from the above exceptions is:

  • Handle CAD files and Item numbers as separate entities in your PLM system
  • A CAD file CAN NOT BE equal to an Item Number

Bad practice 2: The CAD structure can be used as the BOM to be send to ERP

As in many companies the EBOM and the MBOM resemble a lot, the temptation exists to push the engineer instead of defining a design in the concept of the EBOM, to work in a mixed environment.

This approach will lead to the following problems:

  • Drawing of non-design items in the 3D CAD assembly as they are needed to represent an item. For example a paint-can symbol, an oil-can, etc. As these materials are needed for manufacturing, the designer has to add them to the product structure as in this way they will appear in the BOM. This approach leads to a dependency on the CAD assembly that is not needed. Imagine another type of paint is needed – this would require the designer to change the CAD assembly files as they represent the manufacturing structure – or you do not update the CAD assembly files and in that case you have no reliable data anymore.
  • The designer might use in the design subassemblies that group two or more items logically together. For example a bolt, a nut and two rivets. As the subassembly does not exist as an item number in the ERP system, the ERP system treats this assembly as a phantom assembly. No operations needed, but an extra intermediate step is defined in the ERP system, as-if for each usage the bolt, the nut and rivets need to be assembled.

The conclusion from the above points is:

  • Handling the MBOM in the CAD system to send it automatically to ERP leads to complexity either in the design environment or in the ERP system
  • There is no need to have this complexity when the concept of EBOM and MBOM is implemented in PLM
  • Handling EBOM/MBOM transformation in the interface leads to costly complexity, see Where is the MBOM ?

Bad practice 3: The Items in CAD structure are tightly linked to the MBOM

This practice often appears in combination with the two bad practices above. As the company focuses on a resemblance of the CAD structure and the MBOM, people start to imagine also the other way around. They expect the PLM system to keep the CAD structure in-sync with the BOM. In case an item is deleted or replaced in the BOM, the CAD system should be updated automatically..

I guess this is one of the things I learned that is an utopia and probably not needed if a clear understanding of CAD structure, EBOM and MBOM exists. Removing or changing items in a BOM does not give enough information about the impact on the CAD structure. For example if one item appears 3 times in an assembly and one instance is replaced by another item, how would the CAD structure know which item should be replaced ?

The conclusion from the above point is:

  • changes in a product assembly can be initiated from the BOM but should be executed in the CAD system
  • Automatic synchronization of CAD structure based on BOM changes is an utopia


In general my conclusion is (after many years of trying to satisfy customers learning from the above points and more) :

In order to create a smooth connection between PLM and ERP you need:

  • Item creation in PLM – completion in ERP
  • ERP provides feedback on costs and availability
  • In case of production issues an ECR/ECO should be launched – going through PLM to assure engineering impact has been analyzed
  • PLM needs to manage the capture of the CAD structure towards the EBOM
  • EBOM/MBOM transformation needs to be done in PLM
  • The connection between PLM and ERP should go through the MBOM
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