Reasons for the Formation of Shrinkage Holes in Precision Casting

Precision casting is a common metal manufacturing technique that involves pouring liquid metal into fine molds to produce metal parts with specific shapes and sizes. However, during the precision casting process, there may be problems with shrinkage holes, which may result in the manufactured metal parts not meeting the expected specifications and quality. Therefore, understanding the causes of shrinkage holes in precision casting is of great significance for improving manufacturing quality and production efficiency.
The main reasons for the formation of shrinkage holes in precision casting are as follows:
Unreasonable mold design
The mold is the core of precision casting, and the quality and accuracy of the metal parts manufactured are directly affected by the design of the mold. If the mold design is unreasonable, such as improper parameters such as the shape, size, and gate position of the mold, it can cause obstruction when the metal liquid flows into the mold, resulting in local high temperatures and uneven pressure, and ultimately forming shrinkage holes.
Unreasonable casting process
The casting process is a key factor in the precision casting process, which includes parameters such as gate speed, gate temperature, and mold temperature. If the casting process is unreasonable, such as too fast gate speed, too high gate temperature, or too low mold temperature, it can lead to the inability of liquid metal to quickly fill the mold cavity and form shrinkage holes when entering the mold.
Excessive shrinkage rate of metal materials
The shrinkage rate of metal materials is an important parameter in precision casting. If the shrinkage rate of the selected material is too large, shrinkage holes will be generated during the casting process due to cooling shrinkage. In addition, factors such as the composition and heat treatment state of the material can also affect its shrinkage rate, so selecting appropriate metal materials is crucial to prevent the formation of shrinkage pores.
Insufficient cleanliness of the mold
In the process of precision casting, the cleanliness of the mold is an important factor affecting manufacturing quality and production efficiency. If the cleanliness of the mold is insufficient, such as impurities, oxides, oil stains, etc. on the surface of the mold, it will hinder the flow of liquid metal into the mold and prevent it from evenly filling the mold cavity, resulting in the formation of shrinkage holes.
To solve the problem of shrinkage holes in precision casting, the following measures can be taken:
Optimize mold design
When designing precision casting molds, full consideration should be given to the shape, size, gate position, and other parameters of the molds. For example, the gate design should be as small and narrow as possible to reduce the metal flow rate at the gate; The mold cavity should be as flat as possible to reduce the resistance during liquid metal filling; The gate position should be chosen as low as possible in the mold cavity to facilitate the smooth flow of metal liquid into the cavity. In addition, sufficient preliminary preparation and trial work should be carried out on the mold to verify the rationality and applicability of the mold design.
Adjusting the casting process
The problem of shrinkage holes caused by unreasonable casting processes can be solved by adjusting parameters such as gate speed, gate temperature, and mold temperature. For example, appropriately reducing the gate speed and gate temperature, increasing the mold temperature, can reduce the impact force and resistance of metal liquid when filling the mold cavity, which is beneficial for improving the filling effect. In addition, the gate should be regularly cleaned and maintained to ensure its smoothness and stability.
Choose the appropriate metal material
When selecting metal materials, comprehensive consideration should be given to manufacturing needs and material performance requirements. For materials with excessive shrinkage, measures such as adding an appropriate amount of alloy elements or conducting heat treatment can be taken to adjust the shrinkage rate of the material. In addition, attention should also be paid to the quality and stability of materials, and material suppliers with good reputation and reputation should be selected.
Improve mold cleanliness
To improve the cleanliness of the mold, it can be thoroughly cleaned before manufacturing to remove impurities, oxides, oil stains, etc. from the surface. During the production process, the mold should be regularly maintained and maintained, and the gate material should be replaced regularly to maintain the smoothness and stability of the gate. In addition, the production environment should be controlled to reduce the impact of dust, impurities, etc. on molds and parts.
In summary, the main reasons for the formation of shrinkage holes in precision casting include unreasonable mold design, unreasonable casting process, excessive shrinkage of metal materials, and insufficient mold cleanliness. To address these issues, measures such as optimizing mold design, adjusting casting processes, selecting suitable metal materials, and improving mold cleanliness can be taken. By implementing these measures, the quality and production efficiency of precision casting can be improved, thereby meeting manufacturing needs and enhancing enterprise competitiveness.