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Strength, accuracy, economy, and fine surface finish are some of the advantages of thread rolling. In contrast to cutting or grinding threads, the rolling process allows for higher rates of production, lower material costs, and no chips or loss of metal. Thread rolling is a cold forming operation in which a blank, having an outside diameter between the major and minor diameters of the finished thread, is rotated between hardened steel dies bearing the reverse thread form. The rolling dies penetrate the blank surface to form the thread roots and displace material radially outward to form the crests. In this process the metal is cold worked rather than removed. The cold working strengthens the material. Static tensile tests have reported increases in the ultimate strength of parts of approximately 30%.

Unlike cut threads, the material’s grain structure is not severed during the threading process. It is instead reformed in continuous unbroken lines following the thread contours. Rolled threads have increased resistance to stripping because such failures are compelled to take place across, rather than with, the grain flow.

Fatigue resistance is realized in several ways. Threads are produced with burnished roots and flanks, free from surface imperfections that might prove to be starting points for fatigue failure. Surface layers of the thread, particularly those in the roots, are stressed in compression. These compressive stresses must be overcome before the tensile stresses that cause fatigue failure can be built up. Fatigue strength is reported to be improved by 50 –75 percent. Test on bolts first heat treated to a hardness of 35-40 Rockwell C and subsequently rolled show increased fatigue strength.