Hello,
Could you let us know what version of Aras Innovator you are using? Aras has added additional options for access control in recent releases. We have a few blog posts I'd recommend checking out including a general overview of these new options and the individual blog posts for MAC Policies and DAC Policies. There's a particular feature that was added to MAC Policies in 12.0 SP6 that I think could handle this use case quite well.
In addition to actually limiting access at a server level, it would also be beneficial to implement client-side changes to reflect this new access. Engineers should be able to see the default form for CAD, sales staff should see a more limited version of the CAD form that removes the native_file field entirely, and other users should see an even more limited view that removes both the native_file and viewable_file fields.
Chris
Christopher Gillis
Aras Labs Software Engineer