The casting process is an important manufacturing method in the field of metal forming. Its core is to pour molten metal into the gravity casting mold and wait for it to cool and solidify to form the required casting. During the casting process, the generation of gas inside the mold has a significant impact on the casting quality, production efficiency and operational safety.

Gas source analysis
During the casting process, the generation of gas mainly comes from the following aspects:
Volatilization of metal liquid: Some metal alloys release gas when melted at high temperature. For example, aluminum alloys may release hydrogen at high temperature, which cannot be ignored.
Decomposition of mold materials: Some mold materials will undergo thermal decomposition at high temperature and release gas. This phenomenon is particularly obvious when using organic coatings or certain polymer materials.
Humidity of the casting environment: After the moisture in the casting environment comes into contact with the molten metal, it may form steam and increase the generation of gas.
Chemical reaction: Chemical reactions between different metals or alloys may also lead to the release of gas, especially when the alloy composition is complex or the reaction is active.

Effect of gas on casting quality
The effect of gas on casting quality during the casting process is mainly reflected in the following aspects:
Porosity and inclusions: If the gas is not discharged in time, pores or inclusions may be formed inside the casting. These defects not only affect the appearance of the casting, but also significantly reduce its mechanical properties, such as strength and toughness, thereby shortening the service life of the product.
Surface defects: The retention of gas may cause defects such as bubbles and cracks on the surface of the casting. These surface defects not only affect the appearance of the casting, but may also cause more serious problems in subsequent processing and use.
Phase change defects: In some cases, the presence of gas will cause uneven phase changes in the casting during solidification, which will in turn affect the microstructure of the casting and lead to performance degradation.

The effect of gas on production efficiency
The generation of gas not only affects the quality of the casting, but also has a significant impact on the efficiency of the casting process:
Extended cooling time: The retention of gas may cause the cooling rate of the metal liquid in the mold to slow down, thereby extending the casting cycle. This not only affects production efficiency, but may also lead to an increase in production costs.
Rework and scrapping: Due to defects caused by gas, castings may need to be reworked or scrapped, which directly increases production costs and reduces production efficiency.
Equipment wear: The generation of gas may also cause increased wear of molds and casting equipment, affecting the service life of the equipment, thereby increasing maintenance and replacement costs.

Impact of gas on safety
During the casting process, the generation of gas may also pose a threat to the safety of operators:
Explosion risk: Some gases (such as hydrogen) have an explosion risk under high temperature conditions, especially in a confined environment. If the gas cannot be effectively discharged, it may cause pressure to accumulate, thus posing an explosion hazard.
Toxic gas release: Some casting materials may release toxic gases at high temperatures, which poses a threat to the health of operators. Therefore, it is particularly important to ensure good ventilation and exhaust design during the casting process.