Maintenance methods for die-casting molds

Maintenance methods for die-casting molds

Die casting die belongs to a process method of casting liquid forging and completing it on a dedicated die casting die forging machine. For die casting, the three elements of die casting material, die casting machine, and die are indispensable. In order to improve production efficiency, brand quality, and high economic benefits during the production process, and to extend the service life of die-casting molds, the use and maintenance of die-casting molds are very important.

Correct use and maintenance methods for die-casting molds:

1. Minimize the rapid cooling and heating of the mold as much as possible, and strive for continuous production. 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 has basically been fluctuating back and forth between 160 ° C and 350 ° C. The mold rapidly cools and heats up, causing continuous thermal expansion and contraction, resulting in mold fatigue damage. When starting production in the cold mold state, the mold temperature starts to rise from low temperature, the temperature difference increases, the mold expansion and contraction increase, and the corresponding increase in mold fatigue will accelerate mold damage and shorten mold life. Therefore, in die casting production, continuous production should be carried out as much as possible to minimize the rapid cooling and heating of the mold, thereby extending the life of the mold.

In addition, in the cold mold state, if the mold has not reached the normal production temperature and the gaps between the various parts of the mold are relatively large, it is strictly prohibited to start high-speed injection and pressurization. Otherwise, the gaps in the mold, including the slider, top rod hole, and other parts, are prone to aluminum skin penetration, which can damage the mold and affect its lifespan.

2. Try to reduce the injection speed as much as possible, minimize the specific pressure, and minimize mold impact.

During die-casting production, the speed of injection not only affects the filling speed and internal gate speed of die-casting, but also increases the peak impact when the injection speed is high. Therefore, if the injection speed is high and the injection speed of the inner gate is fast, it will intensify the erosion of the mold, increase the impact peak value, and the impact force borne by the mold will also increase, greatly reducing the life of the mold. Therefore, when adjusting the die-casting process, it is important to minimize the injection speed while ensuring product quality, in order to improve the service life of the mold and enhance the economic benefits of the die-casting enterprise. At present, advanced die-casting machines are equipped with injection brakes, which are very beneficial for reducing the peak impact, reducing the impact force borne by the mold, and improving the life of the mold.

The injection specific pressure in die-casting process is also an important parameter, which is generally between 400-900 kg/square centimeter according to the quality requirements and characteristics of the casting. Exceeding 900 kilograms per square centimeter generally has little effect on the internal quality of castings. However, if the injection pressure ratio is too high, it not only increases the expansion force borne by the mold, but also causes the expansion force to exceed the locking force of the machine tool, resulting in aluminum channeling. Meanwhile, if the mold bears a large expansion force, it will also damage the mold or shorten its lifespan. Therefore, in die casting production, in addition to focusing on injection speed, we should also pay more attention to injection specific pressure, as injection specific pressure is not as easy to observe as injection speed and is often overlooked. In fact, the specific pressure of injection molding is an important parameter in die-casting technology, which not only affects the quality of castings, but also has a huge impact on the lifespan of molds. This should particularly attract the attention of die-casting enterprises.

3. During the use of the mold, if there is any sealing or aluminum skin, it should be cleaned in a timely manner to prevent damage to the mold.

In the use of molds, there are often various reasons for the appearance of sealing and aluminum skin on the mold. At this time, it is necessary to clean it in a timely manner, otherwise continuing production will crush the mold. Especially for the slider part, if the slide enters the aluminum sheet, due to the very large clamping force of the die-casting machine, the slider will collapse and be damaged. Therefore, when encountering such problems, it is necessary to clean the mold in a timely manner and find the cause to repair the mold in a timely manner. Otherwise, repairing the mold only when it is damaged will seriously affect its lifespan.

4. Try to reduce the pouring temperature of aluminum liquid as much as possible to improve the service life of the mold.

The pouring temperature of aluminum liquid during die-casting production not only affects the quality of castings, but also affects the service life of die-casting molds. In general, during die casting, the pouring temperature of aluminum liquid is between 630 ° C and 720 ° C. For different parts, we should choose a lower pouring temperature as much as possible. This not only saves energy, but also extends the service life of the die casting mold. Because the higher the temperature of the aluminum liquid, the greater the erosion on the mold, the larger the range of temperature field changes in the mold, the greater the thermal expansion and contraction, the greater the fatigue of the mold, and the easier it is to be damaged. Therefore, appropriately reducing the pouring temperature of aluminum liquid is beneficial for extending 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 their usage conditions are relatively harsh. During use, the mold may cause damage or potential malfunctions. Therefore, it is very important to strengthen the maintenance of the mold, regularly maintain the mold, replace damaged parts, replace vulnerable parts, clean the slide, top rod holes, etc., to ensure the reliability of the mold during die-casting production and also extend the service life of the mold.

Meanwhile, due to the continuous impact and thermal expansion and contraction of die-casting molds during use, new internal stresses will be generated. If not eliminated in time, the mold is prone to surface 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. In general, after the mold is put into use, the first tempering should be carried out after 3000-5000 cycles. In the future, according to usage, for every 10000 molds produced, it is generally necessary to perform stress relief tempering on the mold cavity, which can greatly extend the service life of the mold.

Precision machining