Learning from the past to understand the future – moving to the MBOM - 6
Already five postssince we started looking at the roots of PLM, where every step illustrated that new technical capabilities could create opportunities for better practices. Alternatively, sometimes, these capabilities introduced complexity while maintaining old practices. Where the previous posts were design and engineering-centric, now I want to make the step moving to manufacturing-preparation and the MBOM. In my opinion, if you start to manage your manufacturing BOM in the context of your product design, you are in the scope of PLM.
For the moment, I will put two other related domains aside, i.e., Configuration Management and Configured Products. Note these domains are entirely different from each other.
Some data model principles
In part five, I introduced the need to have a split between a logical product definition and a technical EBOM definition. The logical product definition is more the system or modular structure to be used when configuring solutions for a customer. The technical EBOM definition is, most of the time, a stable engineering specification independent of how and where the product is manufactured. The manufacturing BOM (the MBOM) should represent how the product will be manufactured, which can vary per location and vary over time. Let us look in some of the essential elements of this data model
The logical definition of the product, which can also be a single component if you are a lower tier-supplier, has an understandable number, like 6030-10B. A customer needs to be able to order this product or part without a typo mistake. The product has features or characteristics that are used to sell the product. Usually, products do not have a revision, as it is a logical definition of a set of capabilities. Most of the time, marketing is responsible for product definition. This would be the sales catalog, which can be connected in a digital PLM environment. Like the PDM-ERP relation, there is a similar discussion related to where the catalog resides—more on the product side later in time.
Related to the product or component in the logical definition, there is an actual EBOM, which represents the technical specification of the product. The image above shows the relation represented by the blue “current” link.
Note: not all systems will support such a data model, and often the marketing sides in managed disconnected from the engineering side. Either in Excel or in a specialized Product Line Engineering(PLE) tools.
We discussed in the previous postthat if you want to minimize maintenance, meaning fewer revisions on your EBOM, you should not embed manufacturer-specific parts in your EBOM.
The EBOM typically contains purchase parts and make parts. The purchased parts are sourced based on their specification, and you might have a single source in the beginning. The make parts are entirely under your engineering control, and you define where they are produced and by whom. For the rest, the EBOM might have functional groupings of modules and subassemblies that are defined for reuse by engineering.
Note: An EBOM is the place where multidisciplinary collaboration comes together. This post mainly deals with the mechanical part (as we are looking at the past)
Note: An EBOM can contain multiple valid configurations which you can filter based on a customer or market-specific demand. In this case, we talk about a Configured EBOM or a 150 % EBOM.
The MBOM represents the way the unique product is going to be manufactured. This means the MBOM-structure will represent the manufacturing steps. For each EBOM-purchase-part, the approved manufacturer for that plant needs to be selected. For each make-part in the EBOM, if made in this plant per customer order, the EBOM parts need to be resolved by one or more manufacturing steps combined with purchased materials.
Let us look at some examples:
The flat MBOM
Some companies do not have real machinery anymore in their plants, the product they deliver to the market is only assembled at the best financial location. This means that all MBOM-parts should arrive at the shop floor to be assembled there. As an example, we have plant A below.
Of course, this is a simplified version to illustrate the basics of the MBOM. The flat MBOM only makes sense if the product is straightforward to assemble. Based on the engineering specifications, the assembly drawing(s) people on the shop floor will know what to do.
The engineering definition specifies that the chassis needs to be painted, and fitting the axles requires grease. These quantities are not visible in the EBOM; they will appear in the MBOM. The quantities and the unit of measure are, of course, relevant here.
Note: The exact quantities for paint and grease might be adjusted in the MBOM when a series of Squads have been manufactured.
The MBOM and Bill of Process
Most of the time, a product is manufactured in several process steps. For that reason, the MBOM is closely related to the Bill of Process or the Routing definitions. The image below illustrates the relationship between an MBOM and the operations in a plant.
If we continue with our example of the Squad, let us now assume that the wheels and the axle are joined together in a work cell. In addition, the chassis is painted in a separate cell. The MBOM would look like the image below:
In the image, we see that the same Engineering definition now results in a different MBOM. A company can change the MBOM when optimizing the production, without affecting the engineering definition. In this MBOM, the Axle assembly might also be used in other squads manufactured by the company.
The MBOM and purchased parts
In the previous example, all components for the Squad were manufactured by the same company with the option to produce in Plant A or in Plant B. Now imagine the company also has a plant C in a location where they cannot produce the wheels and axle assembly. Therefore plant C has to “purchase” the Wheel-Axle assembly, and lucky for them plant B is selling the Wheel+Axle assembly to the market as a product.
The MBOM for plant C would look like the image below:
For Plant C, they will order the right amount of the Wheel+Axle product, according to its specifications (HF-D240). How the Wheel+Axle product is manufactured is invisible for Plant C, the only point to check is if the Wheel+Axle product complies with the Engineering Definition and if its purchase price is within the target price range.
Why this simple EBOM-MBOM story?
For those always that have been active in the engineering domain, a better understanding of the information flow downstream to manufacturing is crucial. Historically this flow of information has been linear – and in many companies, it is still the fact. The main reason for that lies in the fact that engineering had their own system (PDM or PLM), and manufacturing has their own system (ERP).
Engineers did their best to provide the best engineering specification and release the data to ERP. In the early days, as discussed in Part 4, the engineering specification was most of the time based on a kind of hybrid BOM containing engineering and manufacturing parts already defined.
Next, manufacturing engineering uses the engineering specifications to define the manufacturing BOM in the ERP system. Based on the drawings and parts list, they create a preferred manufacturing process (MBOM and BOP) – most of the time, a manual process. Despite the effort done by engineering, there might be a need to change the product. A different shape or dimension make manufacturing more efficient or done with existing tooling. This means an iteration, which causes delays and higher engineering costs.
The first optimization invented was the PDM-ERP interface to reduce the manual work and introduction of typos/misunderstanding of data. This topic was “hot” between 2000 and 2010, and I visited many SmarTeam customers and implementers to learn and later explain that this is a mission impossible. The picture below says it all.
We have an engineering BOM (with related drawings). Through an interface, this EBOM will be restructured into a manufacturing BOM, thanks to all kinds of “clever” programming based on particular attributes. Discussed in Part 3
The result, however, was that the interface was never covering all situations and became the most expensive part of the implementation.
Good business for the implementing companies, bad for the perception of PDM/PLM.
The lesson learned from all these situations:If you have a PLM-system that can support both the EBOM and MBOM in the same environment, you do not need this complex interface anymore. You can still use some automation to move from an EBOM to an MBOM.
However, three essential benefits come from this approach
Working in a single environment allows manufacturing engineers to work directly in the context of the EBOM, proposing changes to engineering in the same environment and perform manual restructuring on the MBOM as programming logic does not exist. Still, compare tools will ensure all EBOM-parts are resolved in the manufacturing definition.
All product Intellectual Property is now managed in a single environment. There is no scattered product information residing in local ERP-systems. When companies moved towards multiple plants for manufacturing, there was the need for a centralized generic MBOM to be resolved for the local plant (local suppliers / local plant conditions). Having the generic MBOM and Bill of Process in PLM was the solution.
When engineers and manufacturing engineers work in the same environment, manufacturing engineering can start earlier with the manufacturing process definition, providing early feedback to engineering even when the engineering specification has not been released. This approach allows real concurrent engineering, reducing time to market and cost significantly
Again 1600 words this time. We are now at the stage that connecting the EBOM and the MBOM in PLM has become a best practice in most standard PLM-systems. If implemented correctly, the interface to ERP is no longer on the critical path – the technology never has been the limitation – it is all about methodology.
Next time a little bit more on advanced EBOM/MBOM interactions
Author: Jos Voskuil
PLM Coach, Blogger & Lecturer - passionate advocate for a digital future. Connecting the dots.
This content originally appeared on - Virtual Dutchman