The preparation of molding sand mainly includes three core steps:
raw material processing, batching, and mixing. The specific process is as follows:
Raw Material Processing: New sand needs to be dried to remove moisture and then sieved through a drum screen or vibrating screen to ensure uniform particle size. Damp raw sand easily leads to difficulties in sieving and uncontrolled moisture content in the molding sand.
Clay Processing: Mined clay needs to be dried, crushed, and ground into powder. Some factories will pre-mix bentonite and coal powder into a clay slurry for direct use during sand mixing.
Additives Processing: Additives such as coal powder and wood cellulose need to be crushed and sieved to avoid impurities affecting the molding sand’s performance.
Batching Calculation: Based on the casting type (e.g., cast steel, cast iron) and process requirements (e.g., machine molding or manual molding), the raw sand, clay, and additives are mixed in proportion. For example, silica sand is mostly used for cast steel, while quartz feldspar sand is suitable for cast iron.
Mixing Process: Ingredients are added to a sand mixer (such as a roller type or pendulum type), and mechanical stirring ensures the binder evenly coats the sand particles. The quality of the mixed sand directly affects key properties of the molding sand, such as permeability and strength.
Large castings often use dry molding sand (containing more clay), while medium and small castings mostly use moist molding sand (containing less clay).
Of course, professional foundry companies can properly handle molding sand issues; this is a basic skill for foundries. If you have large-scale custom casting needs, you can choose to cooperate with Mulan Metal. Mulan Metal has 12 years of experience in custom casting production and has helped clients in more than 30 countries complete various custom casting commissions, receiving consistent praise. We look forward to your cooperation inquiries.
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