With the rapid development of the manufacturing industry, plastic molds are indispensable tools in plastic molding processing, and the proportion of total mold production has increased year by year. With the development and continuous production of high-performance plastics, the types of plastic products are increasing. The use continues to expand, and the products are becoming more sophisticated, larger, and more complex. The molding production is developing at a high speed, and the working conditions of the mold are becoming more complicated.
(1) Plastic deformation failure
The surface of the plastic model cavity is pressed and heated to cause plastic deformation failure, especially when the small mold is working on large tonnage equipment, it is more likely to cause overload plastic deformation.The material strength and toughness of the plastic mold are insufficient, and the deformation resistance is low. Another reason for the plastic deformation failure is that the hardened layer on the surface of the mold cavity is too thin, the deformation resistance is insufficient, or the working temperature is higher than the tempering temperature, and the phase change softening occurs. And the mold failed early.
The main cause of the fracture is structural stress, thermal stress or insufficient temper due to structural and temperature differences. At the temperature of use, the retained austenite is transformed into martensite, causing local volume expansion, resulting from tissue stress generated inside the mold.