For patterned pieces and assembled soft products we most always provide engineering drawings but they vary in detail depending on the client / client's contract manufacturer. If you can query the PM about contacting the plant, or allowing you to do so, that would be the best way to handle dynamic direction project by project.
For formed pieces we sometimes provide simple sketched direction and offer to provide 3D data but most cut and sew shops overseas farm out the formed stuff and don't care to coordinate data - offering and even documenting shaded 3D captures into PDFs is sometimes all you can do.
Often, we will also provide renderings, either static or step-by-step to explain assembly expectations. Those are always valuable and help limit back and forth revisions.
The linked image below shows bits of all of the above from recent to long-ago! Hope that helps. https://dl.dropbox.com/u/6368171/Generator_softsewn_2013.pdf