The ceramic slurry of Dalian precision casting is composed of ethyl silicate hydrolysate and fine refractory sand with relatively pure texture and high thermal stability, such as fused quartz, zircon and corundum. In order to make the ceramic slurry cemented in a short time, calcium hydroxide or magnesium oxide are often added as catalysts. Because the composition and appearance of refractories used are similar to those of ceramics, they are called ceramics. Ceramic mould casting is a new technology developed on the basis of common sand casting. It is widely used in production. The surface roughness of ceramic castings can reach Ra10-1.25 micron, and the dimension accuracy can reach 3-5 grade, which can achieve the goal of less or no cutting.

The production cycle of ceramic mould casting is short and the utilization rate of metal is high. The castings can reach more than ten tons. They are mainly used to cast large-scale thick-wall precision castings and small batches of die, forging die, plastic die, metal die, glass die and other moulds. Crankshafts and other castings are produced by clay green sand technology. When the wet moulds can not meet the requirements, then consider using clay sand surface dry sand moulds, dry sand moulds or other sand moulds.

The casting weight of clay green sand casting can range from several kilograms to tens of kilograms, while that of clay dry casting can reach tens of tons. Solid moulding production efficiency is high, and occupies less space. For middleware, various high-pressure moulding machine production lines with boxes and air impact moulding lines can be selected to meet the requirements of fast and high-precision moulding production lines.

Core-making methods can be selected: cold core box, hot core box, shell core and other efficient core-making methods. For heavy castings produced by single gear measuring instrument, the pit moulding method has low cost and fast commissioning. It is more suitable to adopt multi-box and split-box moulding methods in batch or long-term production of shaped products. Although moulds and sand boxes start to invest heavily, they can be compensated for saving moulding time and improving product quality.

Different enterprises have different production conditions (including equipment, venues, staff quality, etc.), production habits and accumulated experience. We should consider what products are suitable for and what products are not suitable (or not) according to these conditions. At this time, hemihydrate gypsum produces water and reaction, the viscosity of slurry rises, loses fluidity, coagulates and hardens, forming dihydrate gypsum, heating with crystallization growth, causing condensation expansion, which lasts tens of hours to end expansion.