“Cad does not know raw part geometry, only knows finished part geometry. To machine a finished part from a raw casting or forging or even a simple round steel material involves multiple cuts and tool motions, which CAD has no knowledge of.
The auto companies probably farm out most part production.
I assume the parts makers would have the special software. The engineer would send off the CAD drawing of the part to qualified part makers.
There are 2 distinct classes of manufacture.
1. Mass production in large quantity
2. Production in very small quantities
Category 1 is highly suitable for automation.
Category 2 is highly UNsuitable for automation and will require human work.