Cold-heading (or forming as it is often called) is the process of forging metals at near room temperatures. In cold-heading, metal is formed at high speed and forced at high pressure into hardened dies. The cold working of the metal increases the hardness and overall strength. The cold-heading process specifically refers to the upsetting of a volume of metal into a head like on a nail, screw or into some other type of shape.
The cold-heading process is highly flexible in regards to the types of parts that can be made. Parts can be hit once or multiple times while staying in one die (one die, one or multiple blows) or transferred from die to die to progressively form various geometries (multi-die, multi-blow forming). Please refer to animation above showing a single die, two blow cold-heading operation.
Unlike machining, where there is a tremendous amount of scrap, in cold-heading, material is used at almost 100% efficiency, having very little scrap. Because of the high efficiency of material use and the speed of manufacture, cold headed parts have significant cost and strength advantages. Cost savings are mentioned above; high speed production and very minimal scrap. Strength is superior to a machined part in that the process of cold heading (unlike machining) actually causes the material to “work harden” giving the finished part greater strength than the initial material the part was made from. However, cold-heading requires the use of more “project specific”
tools than does machining.
The range of possible shapes is extensive, including heads, shoulders, steps, knurls, chamfers, grooves, undercuts, and tapers. Some features that cannot be directly made in the cold-heading process can be added in secondary operations, such as threading, pointing, finishing, grinding or rolling. Typical parts made using cold-heading processes include standard mechanical fasteners (screws, nuts, bolts, rivets, washers) electrical contacts, and tools. In addition to these high volume standard parts, there are literally thousands of custom configurations made in the cold-heading process.
When considering the manufacturing of a new component, if it can be cold-headed instead of machining, cold-heading is the preferred choice for manufacturing speed, cost savings and improved strength.