Joe, My earlier glib answer - 'drawings' - has been niggling in the back of my brain all day. Sorry about it, because you brought up a good point. Drawings convey the CTF dims, but CAD commonly drives the rest. So how do I save that to use in the next decade?
What if I try to open that CAD file in ten years and tool off of it?
With a SWx file, I won't warranty that the 3D data was the same if you open it in ten DAYS if there was a new service pack to SWx. Most of the baseline features will rebuild correctly, but there is plentiful history of other features (lofts & sweeps for sure, and possibly fills and boundaries based on their relatives) not rebuilding the same from service pack to service pack. And certainly, over the last ten years of explosive growth in the product, we can expect 'fillet' and other features to act differently after a rebuild today than they did in 1997.
If you want to retain your CAD data as a snapshot in time to represent the released state of your design, I don't think (and in my experience I know that) you cannot currently rely on history based files.
If you want to build the same tool in 2017 that you built in 2007 you need a copy of the data in a 'dumb' format like IGES or, preferably for SWx, parasolid.
And here I am just being Ed - To be honest, I have no data that those files also won't change as versions change, but I make a point of saving all released parts in both on the assumption that they are locked in time. It's the only option that I know of that I have (love to hear others comments on that)
To predict the next ten years, all I can call on is the last ten years.
Parasolid and iges were there ten years ago, and I have heard nada about them going away, so they seem like a safe bet (except for not KNOWING that the file as opened today is exactly the same as it was in
1997. Anyone tested this?).
The bigger problem in my mind is storage media... For instance, I have hundreds of files on zip disks and I have had to make a point of carrying over my old zip drive to access them How much longer will that old zip drive be supported? Burned CD's turn into coasters in less than half a decade (though there are exceptions in both directions). Hard drives are cheap and seem to hold up for a good long time, but who hasn't had personal or secondary experience with a hard-drive un-recoverably failing? In ten years, will we still be on hard drives or will it all be solid state? No clue.
Then there is turnover in the company (which hopefully a pdm system will mitigate, assuming that your current pdm is still viable in 2007 and that 'Bob' followed the rules) and a lot of other soft factors (when 'Bob' left the company did he tell someone how stuff was saved?).
I don't know what will happen in 2017, but maybe we can extrapolate lessons for the future from what happens today.
When we are asked to reproduce a design from 1997, the CAD data is usually lost on some zip disk or a long lost tape or hard-drive, and everyone involved has moved on to other jobs.
- Give me the drawing so I can understand the CTF dims and tolerances
- We 3D scan an early article of the product (or in the worst case the worn tooling of the prodcut) so we can rebuild it from scratch.
In 2017, It'll always be a bonus round if we have an IGES or Parasolid of the orignal nominal design, but in our back pockets we will always have the fallback of 3D scan of early articles or tooling for lost data files. But for CTF dims and tolerances, nothing in my imagination will ever beat a drawing. And that is the long version of my earlier glib answer.
Hope this has some value to you, Ed