Supplier Part Numbers: Hidden Surprises

Somewhere lurking in your Bill of Material (BOM), there just might be a hidden surprise, and not the good kind of surprise with cake and balloons.

We're talking about the type of surprise that you probably hate; one that costs you time and money (not to mention a little aggravation). The puzzling truth is that surprise can hide in plain sight, in something you might think as rather ordinary: the supplier part number. But what impact could something as simple as a part number really have, after all?

You'll find most good configuration management practice is careful to differentiate between Internal Part Numbers (IPN) and Manufacturer Part Numbers (MPN) aka supplier part numbers. Internal part numbers are uniquely defined and controlled by your company. Supplier part numbers are not.  Whether or not you have control over a part number is rather important, which is why the prevailing recommendation is to keep supplier part numbers out of your BOM. There are some exceptions of course, including parts defined by a recognized industry or international standard such as the National Aerospace Standards (NAS) or the former military standards. Supplier part numbers can be added as metadata, included in auxiliary reference columns, or digitally associated to the supplier numbers within your BOM Management or Enterprise Resource Planning (ERP) tool. But why? The underlying strategy is to isolate the engineering design from supply chain requirements. You don't want to be constantly updating the former to keep up with the latter.


With that in mind, below are some of the hidden surprises you might discover:

  • Supplier Part Number Changes:  Each supplier, like your own company, maintains their own internally developed part numbering system. At any time, that system can change in whole or in part, for reasons that will not at all be transparent to you. Due to mergers and acquisitions or internal process change, it's not all that uncommon for supplier part numbers to change or be re-characterized entirely. If you're carrying such supplier part numbers directly in your BOM, you'll have a really bad day chasing down changes that have nothing to do with your design.
  • Fighting Internal Process:  It's important to maintain consistency in your company numbering methodology.  While we'll leave the quasi-religious debate over using intelligent or generic numbering systems for some future blog post or three, the point is you probably have tools to help support your company's numbering system. Accommodating a wide variety of foreign part numbers is not worth the hassle, it's better to abstract that information as part of your supply chain management.
  • Supplier / Source Changes:  Depending on your specific requirements, many parts can be sourced by multiple suppliers.. Alternates and substitutes may be available and their relative supply will ebb and flow over time. Trying to keep up with this in a BOM is not a constructive use of your time. The sourcing and substitution information can be associated to your internal number. Additionally, as your requirements change you can leverage your internal number into a full source control or even a selected item designation for more tightly controlling eligible parts from a design context, if the application demands.    
  • Numbering Collisions: In all of their seemingly infinite variety, supplier part numbers might seem like snowflakes. But part numbers in fact are not snowflakes. As many companies have adopted generic numbering methodologies, the chances of collisions in some circles have actually increased. The last thing you need to deal with is pulling apart the overlap of two completely different parts, one of which has nothing to do with your design.

So next time you think about straight up popping a supplier part number into your BOM and think nothing of it, keep the above in mind. You just might be in for a surprise.

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