O.K. Till today I have not had to do this. This morning my purchasing department asked me what to do in this case. The deal is we had a Rev. A drawing, it was decided that we wanted to add additional bolt holes to this drawing so it was rev'd to B. It has since been decided that oh we dont want the extra holes we want to manufacturing this piece to Rev. A (Which has now been marked obsolete per procedure). Has anyone had to deal with this type of thing in the past. I'm quessing we could run into this again, like if a customer comes back to us and says I need P/N X that fits our system that was built in 1990 say, will that drawing may be Rev. B and we now may be on Rev. D. What happens if the change is enough to affect fit, form, or function and we need to go back to that Rev. B drawing. Any Suggestons would be greatly appreciated.
It sounds like your change review and approval process might be a bit out of control.
A change review process must include evaluation for impact on cost, schedule and interchangeability.
A change may seem like a good idea but when cost an schedule impact are factored in the change may not be worth it.
The rules of interchangeability must be adhered to:
1. the revision is fully interchangeable - revision A or revision B can be used in all applications (think of a blind man in a bin, doesn't matter which revision part is pulled)
2. the revision is backward interchangeable - revision B replaces revision A and
all previous revisions in all applications. But revision A cannot be used in place of revision B. Old revisions would be purged from stock.
3 the revision is not interchangeable - revision B will not replace revision A or previous revisions in
all applications and revision A cannot be used in place of revision B. This will require a new part number.
Revisions only progress forward. If you need to change the part to the configuration of a previous revision the revision goes up to the next revision even though the two configuration are the same.
