How to manage Parts? It sounds like a trivial and simple question. Every manufacturing companies and engineering organization is facing this problem. However, it is not as simple as you might think so. The information about Parts (aka Items) is often scattered between CAD drawings, multiple Excel files, PDM and ERP systems. One of the biggest problem is to how to manage revisions and changes for Parts. I captured this problem in some of my previous writings. Future CAD-PLM and Assembly Version Management; Why versioning is complicated in PDM?; PLM, ERP and Managing of Effectivity; Revisions in CAD/PLM/ERP: Old Problems or New Challenges?
Recent GrabCAD blog – Part Revisions: Deal or No Deal made me think again about why is so complex to manage parts in every PDM environment. The following passage explains what means Part has no revision:
Documentation can be revised, but the part itself should not. If a part changes, the revised part is issued a new part number. In the case of PMI, where the “documentation” portion is integral to the part, revisions are more esoteric. Allowable PMI revisions in that case depend on whether the documentation portion is being updated or the part model is being physically changed.
The following passage explains one of my 5 Don’ts in BOM management – Don’t use the same ID for Part Numbers and Drawing Numbers:
In many cases, the documentation is a fully dimensioned engineering drawing, though these days it might also be Product Manufacturing Information (PMI), if you’re riding the technology wave. In the case of a drawing, the documentation also carries an identifying number. While it may be tempting to make the part and drawing numbers the same, such an approach aims to misbehave. For example, a drawing is often changed for very different reasons than the part it describes, often in a fashion that has no impact on design. In addition, drawings may describe multiple parts. In other words, drawing and part life cycles are unique, so the identification number for each must also be unique.
Now, let me go back to the original question. Why is so complex to manage parts in PDM? Here are two main reasons:
1- Complexity of two lifecycles – CAD and Items
CAD documents and Part lifecycle is fundamentally different. PDM system manage CAD files revisions and dependencies between files. Parts (Items) requires Part Numbers and Effectivity to control FFF (Form, Fit and Function) also known as interchangeability rules. Revision can be applied, but it won’t be used to identify a part.
2- Disagreement about where is “master” of part information and cross system integration
Part information is scattered between PDM, ERP and supply chain management systems. Organizations are having hard time to agree WHO is controlling Part creation process. When changes happens or new parts is created, information must be synchronized between multiple systems. It raises the complexity of overall integration and data management.
What is my conclusion? Complexity of two lifecycle management is a key problem in part management in PDM. It is hard to combine part lifecycle including interchangeability rules and effectivity with proper management of CAD documents. The user workflows are getting complex and engineers are having hard time to use the system. While the reality of manufacturing is that both documents and parts need to managed in an appropriate way, PDM vendors facing real challenges to get efficient Part Management processes in place. Just my thoughts…
Best, Oleg
