Frequently asked question

The material mixing ratio of green sand casting (wet mold sand) molding sand

From： ZOOMZU Clicks：205 Addtime：2024-07-12

Green sand casting medium-sized sand is reusable and recyclable; It is mainly composed of old sand, and new sand (quartz sand, silica sand), bentonite, coal powder, water and other auxiliary materials are added during the mixing process. After stirring evenly, casting sand that meets the forming and pouring conditions is obtained;

At normal temperature and humidity, the casting sand mixing ratio suitable for automated molding lines is: mixing ratio (weight ratio) casting old sand 95%, new sand 3%, bentonite 0.8-1.0%, coal powder 0.4-0.5%, water accounts for 3% of the total weight of all materials (not exceeding 3%);

The selection of different brands of bentonite varies in price, as well as in strength and viscosity. The above ratio is calculated based on relatively high-quality and stable bentonite. In actual production, samples of molding sand can be obtained in a timely manner through the sampling port of the sand mixer. Testing instruments or automatic molding sand detection equipment can be used to perform real-time online testing of the strength, compactness, and other properties of the already mixed molding sand. Based on the data, appropriate adjustments can be made to the mixing and ratio of the molding sand in a timely manner;



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matters needing attention:

1. The compaction rate of green sand casting molding sand is between 32-40%; It should be noted that the temperature of the old sand during sand mixing should be controlled within 44 ℃, and cooling measures should be taken if it exceeds this temperature;

2. During the mixing process, add water to the old sand and mix for 15 seconds, then add other molding sand materials and mix for 120-150 seconds to prevent the occurrence of sand lumps, granular sand particles, and sand temperature rise;

3. Bentonite and coal powder have a mesh size of 200-300;

4. For green sand castings with lighter weight and smaller volume, 100-150 mesh new sand (quartz sand, silica sand) can be used. For castings with larger volume and weight above 15KG, 70-140 mesh new sand can be used;