ISE Magazine August 2018 Volume Number: 50
By Craig Currie
Keeping up with EBOM and MBOM
Engineering teams create their EBOM (engineering bill of materials) to define exactly what is to be built. It is one of the principal sources of data that manufacturing teams use to define how that product is going to be manufactured and assembled. From the EBOM, they create their MBOM (manufacturing bill of materials), manufacturing process plan (MPP) and work instructions (which often contain both text and graphical information).
The problem is there are many discrepancies that can occur in the journey between the EBOM created by the design engineer and the MBOM for the actual product created on the shop floor. The manufacturing engineer takes the EBOM and restructures it to create the MBOM, which is often a manual process that can be prone to errors. The amount and nature of restructuring to create the MBOM depends on the customers and their manufacturing processes. MBOMs tend to have more levels to describe each stage of the assembly process in more detail. While some customers have MBOMs that are exactly the same as the EBOM from a structure perspective, other customers will restructure the MBOM so it looks different structurally than the EBOM. Other than the EBOM parts, the MBOM can also contain “MBOM only parts” like consumables (glue, paint, etc.).
When restructuring the MBOM, one of the manufacturing engineer’s main objectives is to ensure that all the parts in the EBOM are consumed, and accounted for, in the MBOM. This means that the full quantity of a part as specified in the EBOM is consumed by the part in the MBOM. For example, if a chair has four legs in an EBOM, then the MBOM should also contain four legs, not three, not five. When a part in the MBOM may have a quantity different than what is defined in the EBOM, this discrepancy needs to be reconciled.
In addition to different approaches for creating process plans, the fact is that a company may have different manufacturing locations, meaning that there may be distinctly different MBOMs created for each of them. Ultimately, there can be many MBOMs for a single EBOM, creating the potential for significant disconnects between the data in the EBOM and the MBOM(s).
Going digital can pay off
As changes are made, the EBOM and MBOM fall out of sync. But it’s not only the lack of integration between EBOM and MBOM – manufacturing process plans and work instructions also get out of sync. Ultimately, this leads to disconnected silos of data that can cause miscommunication, errors, rework, increased product costs, problems with quality and delays in time to market. Moreover, the gaps created by these information silos make it impossible to create a digital thread – a communication framework that houses the relationship connections between all of a product’s digital assets and their revisions – over the course of the product’s life cycle, allowing your enterprise to access, integrate, analyze and transform data from disparate systems to fully trace the lifecycle of your assets.
In addition to the issue of disconnected data silos, the fact that the MBOM represents the data differently than in the EBOM can further complicate matters. While the EBOM typically has product components structured by function, the MBOM represents its data in terms of how it will be manufactured and assembled. So, if you have an item that is used in four different parts of the manufacturing process, you need to have the manufacturing process knowledge as to the where, when and how each of the four is being used. Again, when you have siloed data and something changes (and rest assured, it will), trying to keep track of everything and ensuring that the MBOM accurately reflects what’s happened in the EBOM can be a complex challenge to say the least.
Many enterprises are working to create a digital twin, an exact virtual representation of your enterprise’s physical assets – it’s as if the physical product or system was looking in a virtual mirror. So, as product complexity continues to evolve at a rapid pace, how does an organization solve the challenge of integrating EBOM, MBOM, manufacturing process planning and work instructions, allowing for digital thread traceability and the ability to create a true digital twin?
Automation will reduce errors
This is one of the many areas where the age of automation can help manufacturing. By automating the process of transforming the EBOM to MBOM, organizations can significantly reduce many of the errors introduced when relying on manual processes. And, of course, fewer errors will have a direct impact on the delays and expense of rework, which should result in improved quality and shorter time to market.
What is needed is a solution that provides process plan authoring capabilities that simultaneously allow creation of the MBOM and process plan from the EBOM – keeping everything connected and in sync. How does this work? The process plan takes all of the EBOM data structures the way they are to be used in the manufacturing process plan and at the same time creates an MBOM from them. You will want to ensure that this MBOM includes all necessary resources such as consumables, tooling, etc. The EBOM, MBOM, process plan, work instructions and graphics are now linked and in sync.
Change is inevitable. Without an automated process for keeping EBOM and MBOM aligned, companies need to try and track multiple changes manually. They may still be resorting to spreadsheets and notes while hoping that all changes are included as they try to reconcile everything to keep EBOM and MBOM synchronized. By using an automated solution, all changes made to the EBOM – regardless of the number or variations – are captured and automatically reflected back in the MBOM and process plans. Furthermore, process plans can be linked to quality documents, inspection and test control plans.
Enabling the creation of a true digital thread is the goal of many leading manufacturers, but it simply can’t be done when product development and manufacturing remain siloed, as “connectedness” is a key requirement. For those who are hoping to advance to the creation of a digital twin, the digital thread is the first, essential step.
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