If you want a professional solution, something like this might come into question:
http://killdisk.com/killdesk.h...
At just under $2,000, however, it is not exactly cheap, but it does offer the possibility of creating deletion certificates and labels, among other things.
This might also be an option:
https://www.amazon.com/Standalone...
However, only for one hard disk at a time, but it has the advantage of not requiring a computer for the wipe process.
(However, I don't know if the part is any good).
We used an old pizza tray for such actions (any older HP server with as many disk slots as possible) and then booted Darik's Boot and Nuke (DBAN) via Live CD on it.
It worked, but some of the discs did not survive the wipe process or gave up the ghost in the middle.
These were then physically destroyed (several holes were drilled in them with a table drill).