Drawing Revision Best Practice

1. I would say this decision is a case-by-case basis. If you are changing a part that substantially affects the other drawings, I would say you should update the other drawings. If you are making a minor modification to a part that may show visually on the other drawings but doesn't substantially affect form-fit-function, then I would simply wait till the next revision on the affected drawings. Typically, others outside of engineering are not looking directly at your Creo models so they don't see the changes to sub-level parts (or at least that has been my experience).

2. #1 answers #2. If a change is warranted, a revision bump (or whatever your internal change management system requires) is necessary.

I've worked at several companies, large and small, and they all handle the situation as Stephen details above.

This is the age old catch 22 of parametric CAD. The intelligence of the machine is what actually trips it up.

I have seen so many policies come and go with regard to this very question that it is a fruitless task mostly because those that you hold responsible simply cannot maintain the intent. And if this effort cumulates over time, you will find your drawings in a serious state.

I prefer a very strict policy on managing CAD models and drawings with all where-used implementations corrected as changes occur. This includes the check function that is required to make sure it is "transparent" on documents that are affected but not substantially changed (bin compatible).

There are many organizations that are contractually held liable for erroneous changes. Due diligence is the only way to manage this level of detail.

The policy that allows this is to have non-revision update allowances in your policies and procedures. They are noted on ECOs and they are checked by check functions (personnel assigned to check ECO incorporations).

Here is the real case problem that I have run into all too often:

A manufacturing engineer makes a small change by replacing a part in an assembly. The drafter replaces the part in the assembly for an ECO. The engineer is the checker and he sees that the part if indeed replaced on the drawing and signs it off. Little did the engineer know that the assembly had 10 sublevel ECOs affecting the assembly where the drawing did not require updating through their process. Page 2 or even the same page of the drawing is destroyed. Parts or features in the exploded view have re-arranged to all new locations; Parts have appeared from nowhere because they were once hidden and somehow became visible again. Drafting curves are completely out of place because they were not associated to views. And etc...

All the manufacturing engineer cared about was the little corner of his change and the file set gets released. What do you think Boeing is going to think when they receive the drawing revision and they notice it is substantially different from the previous revision? I promise you, you won't have a contract with Boeing very long if this continues.

There is no shortcut to good engineering. If you have important contracts, you must have policies and procedures to deal with this real world possibility. It is all to easy to loose control over one of your organization's most valuable assets... your proprietary heritage.