What are Bill of Material (BOM) find numbers and why do they exist at all? Find numbers are a feature of the very first BOMs, a simple method to individually distinguish BOM lines in order to explicitly identify or "find" the corresponding callout and depiction on an engineering drawing. In other words, find numbers are a BOM index.
Days of Future Past
Find numbers should not to be confused with sequence numbers, which are often assigned in manufacturing environments to identify fabrication process order. Many believe find numbers are dead. After all, why should they exist with today's modern Computer Aided Design (CAD) and Product Data Management (PDM) technology? Find number critics are not without reason, yet rumors concerning the death of find numbers are greatly exaggerated. Chances are they are lurking somewhere in your BOM.
Find Numbers of Days Long Past
Find numbers made perfect sense in the classical world of drawings past. Back then, modern CAD concepts like product structure and part components simply did not exist. BOMs were often constructed as integral parts lists placed directly on engineering drawings and were either painstakingly drawn out by hand or cobbled together using 2D CAD entities and manually entered text. Find numbers were assigned sequentially starting with the first line in the BOM. They served as the primary (albeit manual) relationship between the detailed part information and the drawing callout. On the field of the drawing, callouts would include the find number circumscribed by a circle, or bubble. Using only the find number in the drawing callout saved time by avoiding the requirement to initially draw and/or update a part number in multiple places. Yes, we used to worry about such things. While times have certainly changed it's still rather common for engineering drawings to emulate this exact format, but with better automation.
Find Numbers Today
Find numbers tend to live inconspicuously these days, perhaps as part of a witness protection program, under a variety of aliases including item number, balloon number, bubble number, BOM ID, or occurrence ID. Find numbers make less sense today, especially now that BOM information can be directly related to CAD product structure through software relationships. Regardless find numbers continue to persist, for several reasons:
- Excel-based BOMs are still abundant. We warned you to cut that out, by the way. An Excel BOM is just a dumb list, and the find number is the only persistent link between the BOM and CAD. Furthermore, the order of BOM lines can be critically important, especially with respect to multi-level BOMs. Ever wonder what happens when an Excel BOM ends up out of order? OK, now try to put it back. Whoops. There's just no logical way to restore the original order without having a find number column to sort on.
- Traditional Use. Most CAD packages now have automation available to create integral BOMs as part of the drawing. These integral BOMs are based on CAD component structure with the capability to append other annotations. Yet most CAD software will include a find number equivalent by default. Even several PDM/PLM packages still carry on the tradition even though their BOM functionality is considerably more advanced. Why is this necessary if the part data already carries a digital relationship with the CAD assembly? The answer: too many use cases involve reading drawings either on paper or PDF outside of the database, where the only method to traverse relationships between BOM and CAD is –you guessed it– the find number.
- Separation between BOM system and CAD system. Sometimes the software a particular firm uses for BOM authoring and maintenance is not directly linked to the CAD software. In such cases, digital relationships aren't leveraged as they could be, and so find numbers live on to continue providing reference to the governing CAD drawing.
Find Numbers To Infinity and Beyond (Not Really)
Find numbers will make little sense in the future, so it's probably best for everyone if you don't get too attached to them. There will come a day where the find number is finally retired, and we can move on to the next chapter of BOM management. How can you get to that future faster, you might ask? That's the easy part: move away from all those outdated BOM authoring tools (like Excel for one), and adopt a modern, integrated BOM editing capability.
A well-structured bill of materials (BOM) will help you keep track of materials, components and quantities - avoiding confusion and costly errors. To help you stay organized, GrabCAD is providing a free BOM Excel template so you don't have to start from scratch