No matter any object has a certain service life, inject […]
No matter any object has a certain service life, injection molds are no exception. When used to a certain extent, the injection mold will fail. It is necessary to open the mold to produce a new mold. The service life of the injection mold is affected by many factors. Only an injection mold factory that fully understands these factors can prescribe the right medicine to produce a mold with a longer life.
The first factor that affects the life of an injection mold is corrosion failure. The injection molding alloys commonly used in injection mold factories are zinc alloy, aluminum alloy, magnesium alloy and copper alloy, and there are also pure aluminum injection molding. Zn, Al, Mg are more active metal elements, and they have a good affinity with mold materials, especially Al is easy to bite. When the mold hardness is higher, the corrosion resistance is better, and if there are soft spots on the molding surface, the corrosion resistance is unfavorable.
The second reason that affects the life of injection molds is thermal fatigue, cracking, damage and failure. During injection molding, the mold is repeatedly subjected to chilling and heating, and the molding surface and its interior are deformed, which are mutually involved, resulting in repeated cycles of thermal stress, resulting in organizational structure Second, damage and loss of toughness trigger the appearance of micro-cracks and continue to grow. Once the crack expands, molten metal squeezes in, and repeated mechanical stresses accelerate the crack growth. For this reason, on the one hand, the mold must be fully preheated at the beginning of injection. In addition, the mold must be kept in a certain working temperature range during the injection molding production process to avoid early cracking failure. At the same time, it is necessary to ensure that there are no problems with the internal factors before the mold is put into production and during manufacturing. In actual production, most mold failures are thermal fatigue cracking failures.
The third reason that affects the life of injection molds is chipping failure. Under the action of the injection force, the mold will initiate cracks at the weakest part, especially if the scribe marks or electrical processing marks on the molding surface of the mold are not polished, or The formed clear corners will be the first to appear micro cracks, when there are brittle phases or coarse grains in the grain boundaries, it is easy to break. However, the crack propagation is very fast during brittle fracture, which is a very dangerous factor for the fracture and failure of the mold. For this reason, on the one hand, all the scratches and electrical processing marks on the mold surface must be polished, even if it is in the pouring system, it must be polished. In addition, the mold material used is required to have high strength, good plasticity, good impact toughness and fracture toughness.