1. Minimize the rapid cooling and heating of the mold as much as possible, and try to produce continuously. In the cold mold state, high-speed injection is strictly prohibited.
During the die-casting process, the die-casting mold has been in a reciprocating fatigue state of thermal expansion and contraction. The temperature of the mold cavity part has basically been changing back and forth between 160 degrees and 350 degrees. The mold is rapidly cooled and heated, and the continuous thermal expansion and contraction will cause mold fatigue damage. When production starts in the cold mold state, the mold temperature starts to rise from a low temperature, the temperature difference increases, the mold expands and contracts, and the mold fatigue increases accordingly, which will accelerate mold damage and shorten the mold life. Therefore, continuous production should be tried during die-casting production, and the rapid cooling and heating of the mold should be minimized to extend the mold life.
In addition, in the cold mold state, the mold has not reached the temperature during normal production, and the gaps between the various parts of the mold are relatively large. In this case, it is strictly forbidden to open high-speed injection and pressurization. Otherwise, the gaps between the mold, including the slider, the ejector hole and other parts, are prone to enter the aluminum skin, thereby damaging the mold and affecting the mold life.
2. Try to reduce the injection speed, reduce the specific pressure, and reduce mold impact.
During die casting production, the injection speed not only affects the filling speed and injection gate speed of die casting, but also increases the impact peak when the injection speed is high. Therefore, when the injection speed is high and the injection gate speed is fast, the scouring of the mold will be aggravated, the impact peak will increase, the impact force on the mold will also increase, and the life of the mold will be greatly reduced. Therefore, when we adjust the die casting process, it is very important to reduce the injection speed as much as possible while ensuring the quality of the product to improve the life of the mold and the economic benefits of the die casting enterprise. At present, advanced die casting machines are equipped with injection brake devices, which are very beneficial for reducing the impact peak, reducing the impact force on the mold, and improving the life of the mold.
The injection ratio pressure in the die casting process is also an important parameter. The injection ratio pressure is generally 400-900 kg/cm2 according to the quality requirements and characteristics of the casting. More than 900 kg/cm2 generally has little effect on the internal quality of the casting. If the injection ratio pressure is too high, it will not only increase the expansion force on the mold, but even make the expansion force exceed the clamping force of the machine tool, causing aluminum channeling. At the same time, if the mold is subjected to a large expansion force, it will also damage the mold or shorten the life of the mold. Therefore, in die-casting production, in addition to paying attention to the injection speed, we should pay more attention to the injection ratio pressure. Since the injection ratio pressure is not as easy to observe as the injection speed, it is often ignored. In fact, the injection ratio pressure is an important parameter in the die-casting process. It not only affects the quality of the casting, but also has a huge impact on the life of the mold. This point should especially attract the attention of die-casting companies.
3. If the mold is covered with seals and aluminum skins during use, they should be cleaned in time to prevent the mold from being squeezed.
During the use of the mold, the mold often has seals and aluminum skins due to various reasons. At this time, it must be cleaned in time, otherwise the mold will be squeezed if production continues. Especially in the slider part, if the slide enters the aluminum skin, etc., the slider will be squeezed and squeezed due to the very large clamping force of the die-casting machine. Therefore, when encountering such problems, the mold must be cleaned in time, and the cause must be found and the mold repaired in time. Otherwise, if the mold is damaged before repair, it will seriously affect the life of the mold.
4. Try to reduce the pouring temperature of aluminum liquid to increase the service life of the mold.
The pouring temperature of aluminum liquid during die casting not only affects the quality of castings, but also affects the service life of die casting molds. Generally, during die casting, the pouring temperature of aluminum liquid is between 630 and 720 degrees. For different parts, we should try to choose a lower pouring temperature, which not only saves energy, but also prolongs the service life of die casting molds. Because the higher the temperature of aluminum liquid, the greater the erosion of the mold, the greater the range of change of the mold temperature field, the greater the thermal expansion and contraction, the greater the mold fatigue, and the easier it is to damage. Therefore, appropriately lowering the pouring temperature of aluminum liquid is beneficial to prolong the service life of die casting molds.
5. Strengthen the maintenance of the mold, perform regular maintenance, and regularly temper and stress relieve the mold cavity.
Die casting molds have been continuously produced under high pressure, high speed, and high temperature, and the use conditions are relatively harsh. During use, the mold will have hidden dangers of damage or failure. Therefore, it is very important to strengthen the maintenance of the mold, regularly maintain the mold, replace damaged parts, replace wearing parts, clean the slideway, ejector hole, etc., to ensure the reliability of the mold during die casting production, and also prolong the service life of the mold.
At the same time, because the die-casting mold is constantly impacted and expands and contracts during use, new internal stress will be generated. If it is not eliminated in time, the mold surface is prone to cracking or cracking. Therefore, regular stress relief tempering of the mold cavity to eliminate stress is also an important means to extend the life of the mold. Generally, after the mold is put into use, it should be tempered for the first time after 3000-5000 molds. In the future, according to the usage, the mold cavity needs to be stress relieved and tempered for every 10,000 molds produced, which can greatly extend the service life of the mold.
