Sand mold casting is a widely used form of casting. As the name suggests, the mold is made of sand. Sand mold casting requires putting a finished part model or a wooden model (pattern) in the sand, and then filling the pattern with sand. After the pattern is taken out of the box, the sand forms a mold.
In order to take out the model before casting the metal, the casting mold should be made into two or more parts; during the manufacturing process of the casting mold, holes and vent holes for casting the metal into the casting mold must be reserved to synthesize the casting system. After pouring the metal liquid into the mold, keep it for an appropriate time until the metal solidifies. After the parts were taken out, the mold was destroyed, so a new mold must be made for each casting. Sand mold processing plants can cast large parts. Sand molds can be used for iron casting, bronze casting, brass casting and aluminum casting. Wet casting is another sand casting process, which is low in cost and can produce parts of various sizes.
In order to confirm that the mold sand meets the required quality, the following tests need to be carried out on him:
1. Moisture Content Test
Too little or too much moisture in the sand mold will affect the strength and air permeability of the sand mold
Take 50 grams of mold sand and heat it until it is completely dry, and then measure the weight again, calculate the difference between the two, and then obtain the percentage of moisture content.
2. Clay Content Test
The clay content in the mold sand is also related to the strength and air permeability of the mold sand. Take 50 grams of dried mold sand, add 475cc of distilled water and 25cc of caustic soda solution, and stir for 5 minutes with a fast mixer. After adding enough water, let it stand for 10 minutes and then suck out the water. Repeat so many times After the second time, the sand is dried and weighed to obtain the difference between the original weight of 50 grams, which is the weight of the clay, and the percentage can be calculated by this.
3. Strength Test
The bonding strength of sand molds is usually measured with longitudinal compressive strength as the main test item.
The test adopts a spring-loaded manual test, and the pressure strength of the test piece when it is broken can be directly read from the scale.