What is thread rolling?
Thread rolling is a metal forging process that forms threads into the mirror image of a roller die. The process is different from metal cutting, grinding, and chasing because it does not remove any metal from the work-piece. Instead, thread rolling uses hardened steel dies to displace and mold ductile metals. The high-pressure process physically changes the properties of rolled metal parts to make the base part and the threads harder and stronger.
The tooth form of the hardened steel dies protrudes into the outside diameter of plain cylindrical blanks to reform the surface. Each tooth exudes extreme pressure against the work-piece's surface, pushing the blank material outward toward the crests in the thread roll profiles, thus producing a part with a thread mirroring that of the die. That displaced metal in the crests forms the threads.
Thread rolling has several advantages that traditional thread cutting processes lack. One key advantage is the strengthening force of the pressure—instead of cutting through the grain of the part’s micro-structure, and intrinsically weakening the work-piece, thread rolling realigns the grain lines while leaving them largely intact. It also hardens the entire affected material. Manufacturers that use thread rolling processes produce parts that are smoother, stronger, long-lasting, and more resistant to handling damage.