Since way back it has been customary to use the same identity for the Part as for the Drawing, i.e. the drawing is the document that defines the Part is the practical Part Proxy in the Engineering world.
To-day we have Geometric Models of the Parts. Since we live in a world of changes, we also have several versions of the Geometric Model of each Part. It has become impractical to have just a Part Number as the identity of the Part and the documentation of the Part. In order remedy this we have introduced Part Version and we have separated the documentation from the representation of the Part.
We can then relate several documents and several editions or versions of these to the Part Version.
Documents that define and/or describe a specific Part Version may be
- Geometric Model
- Requirements Specification
- Technical Specification with all properties
- Manufacturing Tool drawing
- NC program
This is obviously not a tool for Product Engineers only. Manufacturing Engineers may use the technique as well to achieve a better relation to what they actually are planning for manufacturing etc.
There is of course nothing that prevents the usage of Part Number for documents describing the Parts and the Part Versions. However, it is necessary to carefully differentiate between the Part and the Part Versions and the Documents defining and describing the same.
Some of these documents are defining the Part Version. These are denominated "Primary Documents". Examples could be the Drawing and the Geometric Model.
All other documents are denominated as "Secondary Documents".
Part Version Documents should have a Document ID (possibly a Part Number) and an Issue Number. Normally it should also contain information about Valid from Date, Issued by and Approved by etc. It should also have a Classification Attribute that distinguish the Document as "Primary" or Secondary" and the type of information it carries.