Die casting temperature
Die casting temperature is a critical process parameter in the die casting process. This includes both molten metal temperature and mold temperature. These two temperature parameters interact and work together to determine the die casting quality, production efficiency, and mold life. Molten metal temperature refers to the temperature of the molten metal in the injection chamber before injection, while mold temperature refers to the temperature of the mold cavity surface. Proper control of these two temperature parameters is key to ensuring a smooth die casting process and achieving high-quality die castings.
The determination of molten metal temperature primarily depends on the type of die-casting alloy and the structural characteristics of the die-casting part. Different die-casting alloys have different melting points and optimal die-casting temperature ranges. Zinc alloys have a relatively low melting point, approximately 380-420°C, and their die-casting temperature is typically controlled between 410-450°C. Aluminum alloys have a relatively high melting point, approximately 580-660°C, and their die-casting temperature is generally 620-680°C. Magnesium alloys have a melting point between zinc and aluminum alloys, approximately 600-650°C, and their die-casting temperature is typically 650-700°C. For thin-walled, complex die-casting parts, the molten metal temperature can be increased by 5-10°C to increase fluidity and ensure full cavity filling. For thick-walled, simple die-casting parts, the molten metal temperature can be lowered to reduce the heat load on the mold and shrinkage of the die-casting part. For example, when producing thin-walled complex aluminum alloy die castings, the molten metal temperature can be controlled at 660-680°C, while when producing thick-walled simple aluminum alloy die castings, the temperature can be controlled at 620-640°C.
Mold temperature significantly impacts the quality of die-cast parts and requires proper control based on the type of die-cast alloy, part structure, and production batch. For zinc alloy die-casting, the mold temperature is typically controlled between 150-200°C; for aluminum alloy die-casting, the mold temperature is generally between 200-280°C; and for magnesium alloy die-casting, the mold temperature is typically between 200-300°C. Properly increasing the mold temperature can reduce the cooling rate of the molten metal and increase its fluidity, facilitating cavity filling and minimizing defects such as cold shuts and under-casting. It can also reduce internal stress within the die-casting, minimizing deformation and cracking. However, excessively high mold temperatures can prolong the solidification time of die-castings, reducing production efficiency, increasing thermal fatigue damage to the mold, and shortening its service life. Excessively low mold temperatures can rapidly cool the molten metal, reducing fluidity, leading to poor filling, poor surface quality of die-castings, and the development of internal defects such as pores and shrinkage.
There is a close relationship between the molten metal temperature and the mold temperature, and they need to be coordinated with each other. When the molten metal temperature is high, the mold tends to absorb more heat, causing the mold temperature to rise. At this time, the mold preheating temperature can be appropriately lowered or the cooling intensity can be increased to control the mold temperature within a reasonable range. Conversely, when the molten metal temperature is low, the mold absorbs less heat. In order to ensure the fluidity of the molten metal, the mold temperature needs to be appropriately increased. For example, when the temperature of the aluminum alloy molten metal increases from 640℃ to 660℃, the mold temperature may rise by 20-30℃. At this time, the flow rate of the cooling water channel needs to be increased to enhance the cooling effect and keep the mold temperature within the range of 200-280℃. In actual production, it is necessary to monitor the molten metal temperature and mold temperature in real time through temperature sensors, and adjust the heating or cooling system in time according to the monitoring results to ensure a coordinated balance between the two.
The precision of die-casting temperature control is crucial to the quality stability of die-cast parts. The control accuracy of the molten metal temperature should be controlled within ±5°C, and the control accuracy of the mold temperature should be controlled within ±10°C. To achieve these precision requirements, advanced temperature control equipment and systems are required. The molten metal temperature can be monitored in real time using temperature sensors such as thermocouples, and the temperature of the molten metal can be controlled by adjusting the heating power of the furnace. Controlling the mold temperature is more complex, typically using devices such as heating rods and cooling water channels. A temperature controller adjusts the heating power and cooling water volume to achieve precise control of the mold temperature. For example, multiple temperature sensors are installed in different parts of the mold to monitor the temperature of key areas such as the cavity and core. Based on the temperature conditions of different areas, the corresponding heating or cooling devices are adjusted to ensure uniform temperature across the mold.
During the die-casting production process, the die-casting temperature parameters need to be adjusted promptly based on the quality of the die-casting parts. If the die-casting parts exhibit defects such as cold shuts or insufficient pouring, this may be caused by the molten metal temperature being too low or the mold temperature being too low. The molten metal temperature or mold temperature can be appropriately increased. If the die-casting parts exhibit defects such as shrinkage or pores, this may be caused by the molten metal temperature being too high or the mold temperature being too high. The molten metal temperature or mold temperature needs to be appropriately lowered. At the same time, attention must be paid to the stability of the die-casting temperature to avoid excessive temperature fluctuations, otherwise the quality of the die-casting parts will be unstable. For example, when the molten metal temperature fluctuates by more than ±10°C, the dimensional accuracy and mechanical properties of the die-casting parts will vary significantly, affecting the consistency of the product. Therefore, during the production process, it is necessary to regularly check the working status of the temperature control equipment, and promptly maintain and calibrate it to ensure stable control of the die-casting temperature.
