yvonne@nydcasting.com 
During casting, the curing agent (or hardener) promotes bonding and curing of molding sand, ensuring the sand mold has sufficient strength, stability, and heat resistance for molten metal pouring.
1. Forming a solid sand mold
The curing agent can react chemically with the binder in the molding sand to form a solid sand mold. This reaction quickly solidifies the sand mold, providing strength and stability against molten metal. Mold stability and strength are key to ensuring casting quality and precision.
2. Improve the quality of castings
The use of an appropriate amount of curing agent can significantly improve the quality of castings. By enhancing the strength and stability of the sand mold, the curing agent helps to reduce defects that may occur in the casting process, such as cracks, pores, etc. The reduction of these defects helps to improve the overall quality and performance of the casting.
3. Control the reaction speed and degree
Adjusting the curing agent type and amount controls the reaction speed and degree. This enables flexibility and precision in casting. It ensures sand mold strength and stability meet varying requirements.
Control process time: The type and amount of curing agent can adjust the initial setting time and final setting time of the sand, adapting to different production rhythms and environmental conditions.
High temperature environment: It is necessary to reduce the amount of curing agent or select a slow-setting one to prevent the sand mold from hardening prematurely.
Low temperature environment: It is necessary to increase the amount of curing agent or select a fast-setting one to speed up the reaction.
4. Improve thermal stability
High temperature resistance: The cured bonding system resists decomposition under high-temperature molten metal, reducing sand mold expansion or collapse and ensuring casting dimensional accuracy.
For example: The thermosetting plastic network formed after the resin sand is cured can still maintain a certain strength at high temperatures.
5. Optimize the collapsibility
Balance strength and collapsibility: Some curing agents (e.g., organic esters in water glass sand) can adjust sand mold collapsibility, making it easier to clean the mold after casting and reducing sand removal difficulty.
Notes
1. Selection of curing agent: When selecting a curing agent, factors such as its compatibility with the molding sand and binder, reaction speed, and strength after curing need to be considered.
2. Dosage control: The dosage of curing agent needs to be strictly controlled to ensure the quality of the sand mold. Excessive curing agent will cause the sand mold to become brittle or crack, while too little curing agent will result in insufficient strength. .
3. Mixing uniformity: When mixing the curing agent with the molding sand, it is necessary to ensure uniform mixing to avoid problems such as poor local curing or over-curing.
4. Environmental adaptability: The type and dosage of curing agent need to be adjusted according to temperature and humidity.
In summary, curing agents are key to forming solid sand molds and improving casting quality. They control reaction speed and degree in molding sand. Proper selection and use of curing agents ensure casting quality.