Casting is an ancient manufacturing process. It melts metal and pours the metal liquid into the mold, and obtains parts with the required shape and performance after cooling and solidification. According to the different characteristics of the casting process and the materials used, casting can be divided into several categories, mainly including sand casting, metal mold casting, special casting, investment casting, ceramic mold casting, continuous casting, centrifugal casting, vacuum suction casting, etc.
1.Sand casting
A casting method for producing castings in sand molds. Steel, iron and most non-ferrous alloy castings can be obtained by sand casting. It is suitable for making blanks with complex shapes, especially those with complex inner cavities; it has wide adaptability and low cost; for some materials with poor plasticity, such as cast iron, sand casting is the only forming process for making its parts or blanks.
2.Investment casting
It usually refers to making a pattern in fusible material, coating the surface of the pattern with several layers of refractory material to make a mold shell, and then melting the pattern and discharging the mold shell, so as to obtain a casting without a parting surface, and after high-temperature roasting, it can be filled with sand and poured. High dimensional accuracy and geometric accuracy; high surface roughness; can cast castings with complex shapes, and the cast alloys are not restricted.
3.Pressure casting
It is to use high pressure to press the molten metal into a precision metal mold cavity at high speed. The molten metal cools and solidifies under pressure to form a casting. During die casting, the metal liquid is under high pressure and has a fast flow rate; the product quality is good, the size is stable, and the interchangeability is good; the production efficiency is high, and the die casting mold is used many times; it is suitable for large-scale mass production and has good economic benefits.
4.Low-pressure casting
It refers to a method of filling the mold with liquid metal under low pressure (0.02~0.06MPa) and crystallizing under pressure to form a casting. The pressure and speed during pouring can be adjusted, so it can be applied to various casting molds (such as metal molds, sand molds, etc.), casting various alloys and castings of various sizes; the bottom injection filling method is adopted, the metal liquid fills the mold smoothly, there is no splashing phenomenon, it can avoid the entrapment of gas and the scouring of the mold wall and core, and improve the qualified rate of castings; the castings crystallize under pressure, the castings have dense structure, clear contours, smooth surface, high mechanical properties, which is particularly beneficial for the casting of large thin-walled parts; the shrinkage feeder is omitted, and the metal utilization rate is increased to 90-98%; the labor intensity is low, the working conditions are good, the equipment is simple, and it is easy to realize mechanization and automation.
5.Centrifugal casting
It is a casting method in which the molten metal is poured into a rotating mold, and the mold is filled and solidified under the action of centrifugal force. There is almost no metal consumption in the pouring system and the riser system, which improves the process yield; when producing hollow castings, the core can be omitted, so the metal filling capacity can be greatly improved when producing long tubular castings; the casting has high density, few defects such as pores and slag inclusions, and high mechanical properties; it is convenient to manufacture tube and sleeve composite metal castings.
6.Metal mold casting
It refers to a molding method in which liquid metal fills the metal mold under gravity and cools and solidifies in the mold to obtain a casting. The thermal conductivity and heat capacity of the metal mold are large, the cooling speed is fast, the casting structure is dense, and the mechanical properties are about 15% higher than those of sand castings; castings with higher dimensional accuracy and lower surface roughness values can be obtained, and the quality stability is good; because no or very little sand core is used, the environment is improved, dust and harmful gases are reduced, and labor intensity is reduced.
7.Vacuum die casting
It is an advanced die casting process that eliminates or significantly reduces the pores and dissolved gases in the die casting by removing the gas in the die casting mold cavity during the die casting process, thereby improving the mechanical properties and surface quality of the die casting. Eliminate or reduce the pores inside the die casting, improve the mechanical properties and surface quality of the die casting, and improve the plating performance; reduce the back pressure of the cavity, use alloys with lower specific pressure and poor casting performance, and it is possible to die-cast larger castings with a small machine; improve the filling conditions, and die-cast thinner castings.
8.Squeeze casting
It is a method of solidifying and flowing liquid or semi-solid metal under high pressure to directly obtain parts or blanks. Direct squeeze casting: spraying coating, pouring alloy, closing the mold, pressurizing, holding pressure, releasing pressure, parting the mold, demolding the blank, and resetting; indirect squeeze casting: spraying coating, closing the mold, feeding, filling, pressurizing, holding pressure, releasing pressure, parting the mold, demolding the blank, and resetting.
9.Lost foam casting
It is a new casting method that combines paraffin or foam models with similar size and shape to the casting into a model cluster, brushes refractory paint and dries it, buries it in dry quartz sand for vibration molding, pours it under negative pressure, vaporizes the model, and the liquid metal occupies the position of the model. After solidification and cooling, it forms a casting.
10.Continuous casting
It is an advanced casting method. Its principle is to continuously pour molten metal into a special metal mold called a crystallizer. The solidified (crusted) casting is continuously pulled out from the other end of the crystallizer. It can obtain castings of any length or specific length.
Post time: Aug-19-2024