The biggest feature of pressure casting that is different from other casting processes is the use of high-speed and high-pressure methods. During the filling process, various mechanics, thermal and fluid mechanics principles are fully utilized. The changes from pressure, injection speed to metal temperature are very Pay attention to. This makes the process of making Lead Die Castings very complicated. The following describes the factors that affect the quality of lead die castings.
1. The influence of mold
The influence of die-casting mold on the quality of die-casting is decisive. The mold is composed of multiple elements such as feed, cavity, gas outlet, and slag discharge. It is required that the alloy liquid enters the cavity in the most suitable flow state, and the gas in the cavity is discharged to the maximum. The inlet direction and distribution of the gate have a significant impact on the exhaust, and the molten metal flow must be filled in an orderly manner along the wall without holding the gas. Opening exhaust grooves and overflow grooves at suitable locations is more conducive to expelling the gas in the cavity and preventing the formation of vortex.
2. The influence of die casting process parameters
In the die-casting process, the setting of die-casting process parameters includes many contents. Among them, the speed and speed of the exhaust stroke are the two aspects that have a greater impact on the probability of the occurrence of pores. They can be used for orderly filling and effective discharge of molten metal. Qi has a greater impact. Exhausting too early may cause insufficient exhaust and generate entrainment; too late exhaust will cause cold barrier and under-casting. The exhaust speed is generally chosen to be a slower speed, so that it is not easy to produce entrainment, and it can also reduce the formation of impact, splash and vortex.
3. The impact of shock waves
When the molten metal flow completes the mold filling, the moment the injection head stops moving, a pressure shock wave will be generated in the cavity, which will have a negative impact on the quality of die castings, mold life, production efficiency, production management, and operational safety. Try to eliminate. The method of prolonging the boosting time can be adopted to gradually increase the boosting pressure to the set value, so as to achieve the purpose of slowly condensing the metal, which can effectively reduce the generation of shock waves. In addition, with the improvement of the chemical stability of mold materials in recent years, and the development of die-casting mold cooling technology, high-energy filling can be used, and shock waves can be reduced by increasing the injection speed.
4. The influence of mold temperature
During the filling process, the mold temperature has a great influence on the temperature, viscosity, fluidity, filling time and filling state of the molten metal flow, and therefore also affects the quality of the die casting. If the mold temperature fluctuates, it will cause early cracks in the mold and affect the surface quality of the die casting; if the mold temperature is uneven or unstable, it will cause inconsistent dimensional changes of the die casting and reduce the dimensional accuracy.
5. The influence of release agent
The release agent is an auxiliary tool for smoothly releasing the die casting from the mold. It needs to be applied to the contact surface of the inner surface of the mold before die casting. A suitable release agent needs to meet the following requirements: it can maintain good lubricity at high temperatures; its thinner should have a low volatilization point, which can be quickly volatilized at 100 to 150 degrees Celsius; stable performance, non-toxic and harmless , Non-corrosive; will not form fouling on the surface of die castings.
6. The influence of die casting machine
The pros and cons of the injection performance of the die casting machine largely determines the quality of the die casting, and is extremely important for improving production efficiency, reducing production costs and ensuring production safety. Die casting machines are divided into two categories: hot chamber die casting machines and cold chamber die casting machines. The hot chamber die casting machine is suitable for die casting metal materials with low melting point, such as zinc, tin, lead, etc.; the cold chamber die casting machine is suitable for die casting metal materials with higher melting point, such as copper, aluminum alloy, etc. In recent years, with the successful development of new high-temperature resistant materials, the application range of hot-chamber die-casting machines has continued to expand. When considering whether to choose a hot-chamber die-casting machine or a cold-chamber die-casting machine, it is necessary to comprehensively analyze the product quantity, size, Factors of structure, casting material and quality requirements.
7. The influence of die casting model
Choosing a properly designed die-casting model helps to obtain high-quality die-casting parts. Computer graphics technology, such as mold CAD/CSM technology, can effectively shorten the model design and manufacturing cycle, which has reached a consensus in the model manufacturing industry.
The above are some factors that affect the quality of lead die castings. For more details, please contact:Lead Die Casting Supplier