Plastic Mold Failure Manifestation

- Mar 27, 2018-

          Plastic molds are plastic processing molds made of 45 steel, P20, 718, and other plastic mold steels. Plastic mold failures are: 

1, the wear and corrosion of the cavity surface 

         1) The plastic melt flows in the mold cavity with a certain pressure, and the solidified plastic parts are removed from the mold, causing friction on the molding surface of the mold and causing wear. 

         2) Reinforcing the resin filler in plastic will cause flushing, wear and corrosion on the surface of the mold cavity. 

         3) At the same time, the chlorine, fluorine and other components in the plastic processing are decomposed by the thermal decomposition of HCl and HF. These crossovers can cause damage to the coating or protective layer on the surface of the cavity, resulting in wear and corrosion. 

2, plastic deformation failure 

         1) The surface of the plastic mold cavity under pressure and heat can cause plastic deformation failure. Especially when the small mold is working on large-tonnage equipment, it is more likely to cause excessive plastic deformation.

         2) Materials used for plastic molds have insufficient material strength and toughness, and have low deformation resistance.          3) The hardened layer on the surface of the plastic mold cavity is too thin, the deformation resistance is insufficient or the working temperature is higher than the tempering temperature and the phase change softens. These will cause the mold surface to produce depressions, wrinkles, pits, corners and other damage. 3, plastic mold fracture           1) There are many corners, thin walls and other parts in the complex shape of plastic molds, and local stress concentration in these parts will cause fracture.           2) Due to the structural stress, thermal stress or insufficient tempering due to temperature difference, the retained austenite is transformed into martensite at the use temperature, causing local volume expansion and resulting in structural stress within the mold.           Summarizing the failure modes of plastic molds can better guide the development of mold steels. The material developer of the mold should be considered based on the above aspects to develop better carbon, alloy, and composite plastic mold steel.