CAD, PDM, BOM, and ERP

CAD, PDM, BOM and ERP – four three letters abbreviations that most of engineers have heard more than enough of.

There are lots of rumors, sales messages, and wishful thinking in the social media and communication channels resulting in a thinking model that has nothing to do with reality and that only  has a purpose to help sell more products without the functionality, that they claim to have.

This article is written to state our opinion on how these things work in real life.
Hopefully this helps readers to avoid following will-o’-the-wisps.

CAD-PDM

The purpose of a CAD tool, and we’re talking mainly of modern 3D systems, is to create geometry. During geometry generation production drawings are also created. Out of those, the part drawings are the most important, because production uses them as base for creating parts. Assembly drawings are mainly used to get a right quantity of parts for the assembly process. Since the assembling process may be tricky it’s smart to create an assembly manual for more complex assemblies as well. That is a document more complex than a simple assembly drawing.

Today’s CAD tools have a lot of integrated modules, however the main purpose is still to create geometry and to make an initial parts list which is commonly referred to as the BOM.

What if in addition to a CAD system, there are PDM-PLM systems additionally used within the company? How does this affect the BOM?
(Un)fortunately, these days, not so much at all. The PDM system BOM (or parts list) is the same as the one used in the CAD system. The main purpose of a document management system is to feed the next system ERP with the right revisions. Therefore it only exists to keep the revision system up and running. All the other features are more like bonuses and work speedups.

What about named BOMs within SOLIDWORKS PDM? In all seriousness, we do not understand the need for it at all and we can’t see a real life application for it. Perfectly prepared demos by VAR and YouTube sales videos and polished PowerPoints don’t often do much to help in real life application.

ERP

Enterprise Resource Planning – behind these words is a huge system that is built to produce everything that comes from the CAD and PDM systems, be it correct geometry, revisions, working hours or something entirely different.

Furthermore, the ERP system also generally keeps the information regarding the suppliers of particular parts, lead times, pricing information, parts color, stock location etc. In short – all the important information for manufacturing.

When the product manufactured is not pretty basic, then there are going to be much more materials used than SOLIDWORKS is built to handle. There may be a discussion over cables, cable ties, various forms of clips, gaskets, manuals, order specific stickers and so on. Of course, with unlimited time, money and motivated labor it’s possible to eventually create anything in SOLIDWORKS, but is it cost-efficient?

Conclusion

Every tool has been created to serve a particular purpose. To use CAD or a PDM system to create production BOM is simply madness and it should be avoided. There are simply better tools for that. And when the company has problems on the ERP side, then it’s usually much smarter to fix the issues instead of messing around with the engineering table.

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