How to determine the preheating temperature and time of die-casting molds during use?
Publish Time: 2024-10-14
It is very important to properly preheat die-casting molds before use, which can not only increase the service life of the mold, but also improve the quality of the casting. However, determining the appropriate preheating temperature and time is not easy, and multiple factors need to be considered comprehensively.
First, the mold material is one of the key factors in determining the preheating temperature and time. Different mold materials have different thermal expansion coefficients and thermal conductivity. For example, hot working die steel usually has good heat resistance, but the optimal preheating temperature of different types of hot working die steel will also vary. Generally speaking, the larger the thermal expansion coefficient of the mold material, the lower the preheating temperature should be to avoid deformation or cracking of the mold due to excessive thermal expansion during heating. At the same time, materials with lower thermal conductivity require longer preheating time to ensure that the mold as a whole reaches a uniform temperature.
Secondly, the material and shape of the casting will also affect the preheating temperature and time. For some alloy castings with higher melting points, such as aluminum alloys and magnesium alloys, die-casting molds need to reach a higher preheating temperature to prevent the molten metal from solidifying rapidly when injected into the mold due to the low mold temperature, resulting in defects such as cold shut and insufficient pouring in the casting. In addition, castings with complex shapes may require different temperature distributions in different parts of the mold, which requires more precise control of temperature and time during the preheating process.
In addition, the working parameters and production rhythm of the die-casting machine also need to be taken into account. If the die-casting machine has a faster injection speed and higher pressure, the mold will be subjected to greater thermal shock during operation, so a higher preheating temperature and an appropriate extension of the preheating time are required to enhance the mold's resistance to thermal fatigue. At the same time, when the production rhythm is faster, the cooling and heating cycles of the mold are more frequent, which also requires a good thermal balance state to be established for the mold during the preheating stage.
In actual production, the preheating temperature and time of die-casting molds can usually be determined by the following methods. First, refer to the technical information and suggestions provided by the mold material supplier, which usually give the approximate preheating range of the material in different application scenarios. The second is to conduct process tests, by performing die-casting production under different preheating temperature and time conditions, observing the quality of the castings and the wear of the molds, so as to determine the best preheating parameters. Advanced temperature monitoring equipment, such as thermocouples or infrared thermometers, can also be used to monitor the temperature changes of the molds during the preheating process in real time, so as to more accurately grasp the preheating effect.
In short, determining the preheating temperature and time of die-casting molds during use requires comprehensive consideration of multiple factors such as mold materials, casting materials and shapes, and die-casting machine working parameters. Only by finding the most suitable preheating conditions through scientific methods and the accumulation of practical experience can the performance of die-casting molds be fully utilized and production efficiency and product quality be improved.
