No, most companies are pretty hush hush and look down of strangers coming in.  They don't want any of their secrets (either stealing product ideas or lack of standard requirements) getting out.  Plus most aren't going to waste their time giving a tour to a group when it's not for business (money rules all).  

Most factories will only give tours to paying clients.  There are some (like pottery factories) that will give public tours, but they pretty much expect you to buy something at the end of the tour.

Even the factory we use won't even let me see some things for fear I will steal the idea and hire some other factory to make it.
It's a cutthroat business here.
Can you imagine Foxconn giving tours?  LMAO!!

Maybe if you had some guanxi with the boss....and then only maybe.  Employee IP theft is already rampant enough, most places aren't going to just let some strangers come in and have a look. Of course, who knows what else is going on behind closed doors they don't want you to see.

I've been on tours of the coca cola and wahaha factories in hangzhou.