Defects of Liquid Mold Forging Parts and Prevention
Introduction
Liquid mold forging process is a kind of forging process that is widely used in manufacturing industry. It has the advantages of high production efficiency, simple production process and low energy consumption, etc. However, because of its high-temperature, high-pressure and high-speed operating environment, it is often accompanied by serious casting defects such as surface foaming, pores and cracks. These defects not only affect the dimensional accuracy and surface quality of forgings, but also reduce the mechanical properties, even leading to failure in use. Therefore, it is necessary to pay attention to the prevention and control of casting defects in the application of liquid mold forging process.
Process Characteristics and Causes of Defects
Liquid mold forging process is mainly a pressure forging process. Compared with the traditional forging process, it has the advantages of high performance, high production efficiency and low energy consumption. However, due to the high pressure (up to 1000MPa), high temperature (usually 900-1100℃) and high speed working environment in the liquid mold forging process, defects in the process are prone to occur.
The emergence of surface foam defects is mainly caused by two aspects:
1. The humidity, temperature and furnace pressure of the furnace are not well controlled, making the liquid state bubbles form large holes or hairs.
2. After the material enters the die cavity, the material can not be completely filled with the die cavity under the action of pressure, resulting in surface foaming.
In order to prevent the surface from foaming and improve the product qualified rate, it is necessary to master the following technological processes:
1. Process Design
The process design should optimize the molten metal temperature, pouring speed, pouring temperature and pourability to produce the most effective result.
2. Material Design
The right alloy should be selected to ensure proper filling and adequate strength.
3. Mold Design
The die should be designed in such a way as to ensure the rapid solidification of liquid metal and reduce the defects caused by residual gas.
4. Furnace Control
The furnace should be kept at an optimal temperature and pressure to reduce the possibility of formation of degassing pores.
5. Forming Stress Control
During the forming of the mold parts, measures such as eliminating the non-uniform force field, controlling the temperature and rate of metal forming, and reducing the air entrapment should be taken to reduce the surface foam.
Conclusion
Above all, the liquid metal forging process has various advantages and is widely used in the manufacture of various parts that require both strength and accuracy. Improper control of the forging process, mold design and other factors may cause casting defects in the final product, such as surface foam, pores and cracks. Therefore, the following preventive measures should be taken when dealing with liquid metal forging process: optimizing process design, selecting right material and alloy, mold design, furnace operation control and stress control. Taking these preventive measures can effectively reduce the occurrence of defects in liquid metal forging process and ensure the quality of the product.
