Cold heading is one of the foundational fastener manufacturing operations, producing hundreds of millions of fastener blanks each year around the world. Its origins have been said to have started at Clark Brother Bolt in Southington, Connecticut, when an enterprising person, filled with Yankee ngenuity, fed a length of iron rod into a forge to produce one blank after another. This represented a nice productivity gain over the one-at-a-time rate of a blacksmith and his anvil. An Internet search shows a Civil War era patent for a method of trimming hex bolt heads using the cold forging method. Waterbury headers and Hartford thread rollers, both named for the Connecticut cities near which their factories were located, were bedrock equipment for many successful fastener manufacturers. I believe the Industrial Fastener Institute published a well-respected history on fastener manufacturing.
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