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Factors Affecting The Service Life Of Injection Molds
- Sep 19, 2018 -

No matter what kind of object has a certain service life, the injection mold is no exception. When the mold is used to a certain extent, the injection mold will be invalid. 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 The injection mold factory that fully understands these factors can produce the mold with longer life expectancy.

The first factor affecting the life of an injection mold is the dissolution failure. The injection molding alloys commonly used in injection mold factories are zinc alloys, aluminum alloys, magnesium alloys and copper alloys, as well as pure aluminum injection molding. Zn, Al and Mg are more active metal elements, and they have better affinity with mold materials, especially Al is easy to bite. When the hardness of the mold is high, the corrosion resistance is good, and if the molding surface has a soft point, the corrosion resistance is disadvantageous.

 

The second factor affecting the life of injection molds is the failure of thermal fatigue cracking. During injection molding, the mold is repeatedly subjected to the action of stimulating heat and chilling. The forming surface and its interior are deformed, and each other involves repeated cyclic thermal stress, resulting in the structure. The second damage and loss of toughness, the occurrence of microcracks, and continue to expand, once the crack is enlarged, there is molten metal liquid squeezed in, and repeated mechanical stresses make the crack accelerate and expand. For this purpose, on the one hand, the mould must be sufficiently preheated at the beginning of the injection. In addition, the mold must be kept in a certain operating temperature range during the injection molding process to avoid early crack failure. At the same time, it is necessary to ensure that the internal factors before and during the production of the mold are not problematic. Due to actual production, most mold failures are thermal fatigue crack failure.

 

The third reason that affects the life of the injection mold is the failure of the fracture. Under the action of the injection force, the mold will crack at the weakest point, especially the trace marks or electromachining marks on the molding surface are not polished, or Fine cracks appear first at the clear corners of the molding. When there is a brittle phase or coarse grain in the grain boundary, it is easy to break. The crack propagates rapidly during brittle fracture, which is a dangerous factor for the failure of the mold. For this reason, on the one hand, scratches, electric machining marks, etc. on the mold surface must be polished, even if it is in the casting system, it must be polished. In addition, the mold material used is required to have high strength, good plasticity, impact toughness and fracture toughness.