Core making process of cladding sand

　　 Coated sand core making process, in recent years the application of coated sand research is becoming more and more widely used, can be used in almost all of the enterprise casting technology methods, process analysis methods are also different, but whether it is a core or a modelling, the basic design requirements of the production process we are (except for the wet manual class): heating temperature 200 ~ 300 ℃; curing reaction time 30 ~ 150S; shooting pressure 0.15 ~ 0.6MPA specific parameters should be adjusted according to the type of equipment, type, quality and complexity of the sand core, such as the type of sand cladding principle is: sand core shape is simple, good fluidity (or coarse particle size) can choose to sandblast pressure is low pre-coated sand, for the thin core, you can choose a lower heating temperature, low-temperature heating can be appropriately prolonged curing time, and vice versa.

　　 Theoretically speaking, coated sand can be almost all data types of castings for the enterprise, especially high-precision castings for the production of life solid core. When using wet sand, hot box equipment and tools can be used directly for core making, without any changes to the original equipment and tools. When using dry sand, because of its fluidity, special treatment should be carried out in terms of exhaust, nozzle and core box sealing. Using the principle of angle of repose (the angle of repose of the coated sand is about 30O), it can solve the problem that the coated sand enters the ejection chamber when it is discharged after the gun is fired, and the coated sand falls down automatically when it is not hit. At present, there are many manufacturers use dry sand hot core box core technology.

　　 With coated sand shell type, commonly used in China casting camshafts and other shaft parts or brake pads and other disc parts and some of the problems of surface quality requirements have a high valve class for parts. The relevant parameters are: sand-iron ratio of 1: (1.5) ~ 4; drawing mould inclination angle of 0.5 ° ~ 1 °; shell wall thickness of 8 ~ 12MM. uniform shell wall thickness we can reduce the amount of sand packages, to obtain a more uniform casting structure. Moulds with plastic-coated sand shells can be made with either fixed corer or tumbling corer, the former can be made with either dry-coated sand or wet-coated sand, the latter can only be made with dry-coated sand.

　　 To make shell core, rolling shell core machine (such as K85, K87, K89, etc.) is usually used to make shell core with sand coating. The core making process consists of sand injection, crusting, sand removal, curing and stripping. In order to be able to ensure the quality of the shell core, in addition to ensuring the quality of the coated sand, but also according to the specific actual situation of each of our sand core to choose a reasonable core making process.

　　 Core box temperature core box temperature is one of the main factors affecting the thickness of the shell layer, generally controlled at 230-300 ℃, according to the following principles: the resin in the laminated sand softening and curing heat required; to ensure that the formation of the required thickness of the shell layer, the shell core surface is not coking; try to shorten the hardening time, improve productivity.