The main heat treatment processes for flat thread rolling dies are tempering heat treatment and carburizing heat treatment.

  • Purpose: To achieve higher hardness and strength for screws after cold forming.
  • Function: Achieve self-locking attachment of metal, improve mechanical properties of metal components such as torsion resistance, tensile strength, and wear resistance.
  • Tempering Heat Treatment (does not add elements to the metal, changes the internal structure of the metal by temperature variation to obtain better mechanical properties): Products with a strength level of 8.8 or higher are all products of tempering heat treatment. The characteristic of this heat treatment is that the hardness is relatively uniform inside and outside.
  • When heat treating the same material, the higher the hardness, the worse the toughness. Therefore, there needs to be a safe match to ensure that toughness is guaranteed while meeting the hardness requirements.
  • Carburizing heat treatment: adding carbon elements to the metal component to increase its surface hardness, targeting metals with low carbon content. Self-tapping screws basically all require this treatment, which is characterized by a very hard surface and a relatively soft core because it needs to be screwed into a hard iron plate.