CIMdata PLM Industry Summary Online Archive
March 2007
CIMdata News
Ask the Expert: Sorting Through Revisions
Through Managing Automation's Ask the Expert service, Ken Amann, CIMdata Director of Research received the following question:
Each time a design change (ECO) is needed, the same question pops up: Is the modified item a rev-up of the old, or a new item? The most common way to answer that question is to find out whether the old and modified items are still interchangeable. When in the design phase, engineers like to release the current state of their design to ease communications. However, these released documents may still need to be changed. So, when in the design phase, the interchangeability criteria don't seem practical, as most changes are not interchangeable, meaning that a new item number shall be assigned to the modified items most of the time. Do you think it's OK not to use the interchangeability rule while still in design and keep the item numbers unchanged following revision of items? If so, how would you manage prototypes? Would you generate complete product trees for the various prototypes built throughout the design phase?
Ken's answer:
What most people do is have design revisions and then part revisions. In other words, a design undergoes design revisions until it is released (i.e., released outside of the design environment). Then it would undergo part revisions. While in the design revision state, interchangeability rules don't apply. In the released state, interchangeability rules do apply. This also usually means different ECO processes. When a design is in the design state, people often place it in a rather light ECO process. Once in any type of released state, all the information about that part is under a strict ECO process.
As far as dealing with prototypes, most people use different part numbers for prototypes and have them managed in their own revision scheme.
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