i will have to check back w/this thread as i work with a few manufactoring co and have come in contact with others thru my line of work...not sure bout how BIG them be in comparison as whole in the charlotte area but to name a few off the top of my head
dixon quick coupling/perfecting coupling
arjobex america
curtis screw
roberts polypro
i do know
nsesc.com lists out major employers in our area, not sure what u would find for manf on that list though