In the modern manufacturing industry, die casting technology is widely used in automotive, electronics, aerospace and other fields because of its efficient and accurate forming ability. However, improper injection pressure control in the process of die casting often leads to casting defects such as pores, cold insulation and shrinkage holes, which seriously affect product quality. Therefore, mastering and implementing effective pressure control strategies is crucial to improving casting quality. Here we discuss how to prevent these common casting defects by finely adjusting the injection pressure of the die casting machine to ensure the stability of the production process and the high quality of the finished product.

1、 The importance of injection pressure of die casting machine

In the process of die casting, injection pressure is one of the key factors that determine the filling of the mold cavity with liquid metal. The appropriate injection pressure can ensure that the metal liquid fills the cavity smoothly at the appropriate speed, and avoid the gas being wrapped into the metal liquid to form pores due to the too fast speed, or the problems such as insufficient filling and cold isolation caused by the too slow speed. At the same time, reasonable injection pressure can also promote the solidification and shrinkage of liquid metal, reduce the formation of shrinkage holes, and improve the density and mechanical properties of castings.

2、 The basic principles of injection pressure control

Phased adjustment: The control of injection pressure should follow the principle of “slow-fast-slow”. At the beginning, low pressure is used to slowly enter the metal liquid into the cavity to avoid the gas being quickly involved; As the cavity is gradually filled, timely increase the pressure to increase the filling speed to ensure that the cavity is fully filled; In the final stage, the pressure is reduced again, which is conducive to reducing the impact of the metal liquid on the mold and preventing splashing and sticking.

Pressure and speed matching: The injection pressure should be matched with the injection speed, and adjusted flexibly according to the complexity of the casting structure, wall thickness changes and other factors. Thin-walled parts or castings with complex shapes may require a higher injection speed and corresponding pressure to overcome resistance, while thick-walled parts can be appropriately reduced.

Real-time monitoring and feedback: The use of advanced die casting machine control system, real-time monitoring of injection pressure, speed and mold temperature and other parameters, and timely adjustment according to feedback data, to ensure that the entire die casting process in the best state.

3、Specific measures to prevent stomata

Optimize the exhaust system: Design a reasonable mold exhaust groove and channel to ensure that the gas can be discharged smoothly during the injection process and reduce the formation of pores. If necessary, vacuum die casting technology can be used to further reduce the gas content in the cavity.

Control the pouring temperature: The appropriate pouring temperature helps to reduce the gas precipitation in the metal liquid, too high temperature will increase the gas solubility, too low will affect the fluidity. The optimum pouring temperature range should be determined according to the alloy type and casting characteristics.

Use of degassing agents: For some specific alloys, such as aluminum alloys, a degassing agent (such as nitrogen, hexachloroethane) can be added during the melting process to remove the gas in the melt through a chemical reaction and reduce the risk of stomata.

4、 Methods to solve other casting defects

Prevent cold isolation: maintain sufficient injection pressure and speed, especially in the thick or corner of the casting, to ensure the continuous flow of metal liquid and avoid cold isolation caused by rapid temperature drop.

Reduce shrinkage: Reasonable design of the pouring system and riser position, the use of the principle of feeding, through the setting of riser or cold iron and other means to guide the metal liquid solidification, reduce the shrinkage caused by local overheating.

Mold preheating and cooling: Proper mold preheating can improve the contact conditions between liquid metal and mold and reduce the defects caused by chilling; Local rapid cooling helps to control the solidification sequence and prevent defects.

5、Case analysis and practice verification

Through a specific case analysis, such as the stoma problem encountered in the die casting process of an auto part, it shows how to successfully solve the problem by adjusting the injection pressure, optimizing the mold structure, improving the process parameters and other measures to improve the product pass rate. In addition, some of the best practices and technological innovations within the industry can be shared, such as the application of intelligent die casting production lines, how to automatically optimize injection pressure Settings through big data analysis and machine learning algorithms to further improve production efficiency and product quality.

6、conclusion

Pressure control of die casting machine is the core link to ensure the quality of castings, through scientific and reasonable control of injection pressure, combined with mold design optimization, material treatment and process parameter adjustment, can effectively prevent the occurrence of porosity and other casting defects. In the future, with the continuous development of intelligent manufacturing technology, automated and intelligent pressure control systems will become a new trend in the die casting industry, providing strong technical support for the manufacture of higher quality castings.

 

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