The screw heads are made using a cold forging process. The material is squeezed into a die, where it assumes the shape of the die. This process can be highly automated and through using it, parts can be made economically.
(Courtesy of eFunda.com)

Head Styles:

•Indented hexagonal washer head
•Indented hexagonal head
•Hexagonal head
•Square head
•Round head
•Pan head
•Binding head
•Truss head
•Fillister head
•Flat head
•Oval head

The screw thread is made using the “thread cold rolling process”. Threads can be made for metric or imperial specifications.

•Hexagonal head screws / bolts
•Carriage bolts
•Machine screws
•Wood screws
•Furniture screws
•Self tapping screws
•Thread cutting screws
•Self drilling screws
•High strength bolts
•Screws and washers assembled

   Surface Treatments:

    Nickel plated                                     Black oxidized
    Gray phosphate                                Brass plated
    Chrome plated                                  Hot-dip galvanized
    Unichrome (clear) zinc plated            Dichrome (yellow) zinc plated