What are the advantages of clad sand casting

What are the advantages of clad sand casting
The composition of overcoated sand is usually composed of quartz sand thermoplastic phenolic resin and calcium stearate, without relevant additives. The amount of resin added is usually relatively high under the requirements, does not have low expansion, low outgassing and other characteristics, suitable for some of the requirements are not high, the structure of the production of simple cast iron parts. Coated sand casting is in the process of moulding and core making, in the hard mould surface covered with a solid resin film of sand. The core sand is called coated sand. This moulding process has the following advantages:

    1, less pollution: the site environment has been significantly improved. As a large amount of coal dust (combustion-aiding substances) is added to the sand, it is mainly used to improve the appearance and permeability of the charged parts. The coal dust added to the sand cannot be reused, resulting in a waste of resources. The residual ash content after combustion has a great impact on our working environment. At the same time, the reduction of reducing gases and PM2.5 produced during the combustion process can seriously pollute the atmosphere. However, based on the combustion of the laminated sand method, although there is a certain impact on the environment, but after all, the amount of sand is small, the use of the waste sand can be recycled all the time, to keep the workplace clean and dust-free pollution.

    2, thin sand layer, less consumption: low production costs, less waste, used sand can be recycled and reuse. As the sand layer is thin, the sand layer is usually designed according to the wall thickness of the charged parts as 5-10mm. the amount of clay sand moulding sand cover can be up to 30-50cm, and the amount of sand used is 10-20mm times. Although the clay can be recycled for secondary use, but high-capacity coal dust, bentonite and other additional raw materials are basically consumed, the quality of sand greatly reduced.

   Laminating sand using laminating sand method for high temperature roasting, laminating sand expansion is greatly reduced, reducing the secondary use in the pickling process. At the same time greatly reduce the amount of solid resin and curing agent added to reduce production costs.

   3, you can change the amount of blanks, reduce the cutting allowance, improve the process yield, stable. Due to the low hardness of clay sand type, the amount of setback, the casting of live parts expansion box, expansion sand, sand leakage, air holes, shrinkage holes and other defects are serious, not only cause defective products, but also lead to bad, internal defects more. Seriously affect the life and increase the scrap rate.

     Coated sand castings of the aggregate after acid washing or high temperature baking, can reduce the expansion of the sand combustion, solidification of the sand high strength, small air volume. The advantages of production are: dimensional accuracy of the inherent defects are far superior to production.

     In the production process, the temperature of the cast steel cladding sand is higher, so the fire resistance requirement of the original sand is also higher. In general, the SiO content of the raw sand should be greater than 98%, and special attention should be paid to the particle size and distribution of the raw sand. Selection of special man-made sand with fire resistance up to 1900-2000℃ is not only good in grain shape, but also with small angular coefficient and moderate grain size, which can make the sand more round. The same amount of fat film is conducive to improving the strength of the sand core.