Classification of foundry sands
According to the basic composition of raw sand, the casting raw sand can be divided into silica sand and non-silica sand. Crystalline silica in nature can be divided into three different crystal forms: quartz, squamose and cristobalite. The three crystal forms have homomorphic and heteromorphic transformation, which can be divided into two types: transverse transformation and longitudinal transformation.
The particle composition of raw sand includes particle size, particle size distribution, particle shape and surface properties.
At present, the processing methods of raw sand mainly include water washing, scrubbing and flotation. Magnesia is obtained from magnesite calcined at high temperature and then crushed and sorted. The main component is magnesium oxide. Chromite sand is sand particles obtained by crushing chromite. The main minerals are chromite, magnesite chromite and alumino magnesite chromite. Therefore, its main chemical composition is Cr2O3. Generally speaking, olivine sand is the intermediate of forsterite and iron olivine homogeneous system, but forsterite should be the main component of olivine sand for casting.
Fused ceramic sand, also known as ceramic sand, is a new type of casting material made of bauxite melted at high temperature, blown by compressed air, and screened. With the advantages of spherical particle shape, high refractoriness, neutral property, low crushing rate and so on, it is a casting sand with comprehensive properties at present.
Production process of fused ceramic sand
Select high-quality bauxite - simple crushing - arc melting - Air spraying into ball-shape particles - pelletizing - Screening - mixing - Fused ceramic sand finished products.
In order to ensure the excellent quality of fused ceramic sand products in production, the following work should be done well.
(1) Strictly control the quality of raw materials
The quality of raw materials used directly affects the performance of Fused ceramic sand. The selection of each raw material should meet the required indicators. Raw materials should be strictly tested and recorded when entering the factory.
(2) Control of production process
This production includes several links: quality control plan, production operation instructions, supervision of ingredients, on-site sampling and testing, process records, sample preservation, emergency plan and equipment management.
(3) Inspection of finished products
After the production of Fused ceramic sand, strict inspection shall be carried out, and various chemical products and particle size indexes shall be tested one by one, so as to better control the quality and avoid the ex factory sale of unqualified products.