With the development of industry and technology! Jinan mold development trend is more and more extensive, but do you know what are the factors that affect the model forming, and the three major problems often encountered are some? So today with Jinan Hongjie Mold Co., Ltd. to understand it!
For the life of die-casting die, when the temperature of die-casting die is high, it is also important to do a good job of cooling in time. The cooling methods of die casting die include water cooling, air cooling, heat pipe cooling and direct cooling.
(1) water cooling: a cooling water channel is arranged on the die-casting mould to make the circulating water enter the forming insert or core and bring the heat out of the mould. The cooling efficiency of water-cooling is high, which can effectively reduce the temperature of cavity surface, but increase the disorder degree of die-casting mold structure, which is mainly used for the mold requiring large heat dissipation. In order to avoid condensation on the surface of the cavity, the temperature of the cooling water should be higher than the room temperature.
(2) air cooling: for the parts difficult to be cooled by water in the die casting mold, air cooling can be adopted, and blower or compressed air can be used for air cooling. Air cooling can not only cool the die-casting mold, but also blow the coating evenly, release the volatile gas of the coating, and reduce the porosity of the casting. The cooling temperature of air cooling is much lower than that of water cooling.
(3) heat pipe cooling: it is mainly used for small parts that are difficult to be directly cooled with cooling water. In the small parts to be cooled, the heat pipe is used to export the special heat, and then the cooling water is used to cool the heat pipe.
(4) direct cooling: Alloy with high heat transfer coefficient (ammonium bronze, tungsten base alloy, etc.) can be used for direct cooling at the hot spot of die-casting mould of mould temperature machine. The ammonium bronze pin is screwed into the fixed core, and the end of the copper pin is provided with heat sink to enhance the cooling effect
Three major issues:
I. thermal fatigue, cracking, damage and failure
During die casting production, the mold is repeatedly stimulated by cold and exciting heat, the forming surface and its interior are deformed, and they are involved in each other, resulting in repeated cycle of thermal stress, resulting in damage and loss of tolerance of the second arrangement structure, causing the appearance and continuous growth of microcracks. Once the cracks expand, there is also molten metal squeeze in, and the repeated mechanical stress makes the cracks expand faster. Therefore, on the one hand, it is necessary to fully preheat the die at the beginning of die casting. In addition, in the process of die-casting production, it is necessary to keep the mold in a certain scale of working temperature to avoid early cracking failure. Together, to ensure that the mold before production and production of internal causes do not occur. In practice, most die failures are thermal fatigue cracking failures.
II. Fragmentation failure
Under the action of the injection force, the mold will sprout cracks at the weakest place, especially the marking marks or machining marks on the molding surface of the mold are not polished, or the fine cracks will appear at the clear corner of the mold at the earliest time. When there are brittle phases or coarse grains on the grain boundary, it is a simple crack. However, the crack propagation is very fast when brittle fracture occurs, which is a very dangerous factor for the fracture failure of the die. For this reason, on the one hand, it is necessary to polish the scratches and machining marks on the mold surface, even if they are in the pouring system. Other requirements of the mold material used for high strength, good plasticity, impact resistance and cracking resistance are good.
III. corrosion failure
The commonly used die-casting alloys are zinc alloy, aluminum alloy, magnesium alloy and copper alloy, but also pure aluminum die-casting. Zn, Al, Mg are more vivid metal elements, they have a good affinity with the mold material, especially Al is easy to bite the mold. When the hardness of the mould is high, the corrosion resistance is good, and if there are soft spots on the surface of the mould, the corrosion resistance is bad.
The above is the introduction of Jinan Hongjie Mold Co., Ltd. to the factors that affect the model forming, and the three major problems often encountered! I hope I can help you. To learn more, please click http://www.jnhjgs.cn