Different types of steel are used as plastic molds, and […]
Different types of steel are used as plastic molds, and their chemical compositions and mechanical properties are different, so the manufacturing process is different; the same, the heat treatment process used for different types of plastic mold steel is also different. This section mainly introduces the manufacturing process of plastic mold and the characteristics of heat treatment process.
Concept: Heat treatment to heat the steel to the proper temperature, adhere to a certain moment, and then slowly cool it (generally with the furnace). Intent: to reduce the hardness of the steel and improve the plasticity (to facilitate cutting); to refine the grains and to evenly arrange and composition of the steel; to eliminate the residual internal stress in the steel and to avoid deformation and cracking.
Classification: thorough annealing; spheroidizing annealing; stress relief annealing, normalizing. Concept: The method of heating the steel to 30 ~ 500C above Ac3 or ACcm, at the right moment of heat preservation, and cooling in the air. Intent: It is basically the same as the annealing intention, but the normalizing cooling speed is slightly faster than the annealing, so the pearlite arrangement obtained after normalizing is relatively fine, and the strength and hardness are higher than the annealed steel.
Normalizing has a shorter production cycle than annealing, and has low cost and convenient operation. Therefore, normalizing is preferred under possible conditions, but annealing should be used for messy parts. Concept: Heat the steel to a certain temperature above Ac3 or Ac1, keep the heat for a certain time, and then cool at an appropriate rate to obtain a heat treatment process arranged by martensite or bainite.