Sand casting: Sand casting commonly used in the valve industry can also be divided into various types of sand such as wet sand, dry sand, water glass sand and furan resin no-bake sand according to the different binders.
(1) Green sand is a molding process method in which bentonite is used as the binder in the work. Its characteristics are: the finished sand mold does not need to be dried or undergoes special hardening treatment, the sand mold has a certain wet strength, and the sand core and shell have better concessions, which is convenient for casting cleaning and falling sand. The molding production efficiency is high, the production cycle is short, and the material cost is also low, which is convenient for organizing assembly line production. Its disadvantages are: castings are prone to defects such as pores, sand inclusions, and sticky sand, and the quality of castings, especially the internal quality, is far from enough.
(2) Dry sand is a modeling process using clay as a binder, and a little bentonite can improve its wet strength. Its characteristics are: the sand mold needs to be dried, has good air permeability and air dispersion, is not easy to produce defects such as sand washing, sand sticking, and pores, and the internal quality of the casting is also relatively good. Its disadvantages are: sand drying equipment is required, and the production cycle is relatively long.
(3) Sodium silicate sand is a molding process method using water glass as a binder. Its characteristics are: water glass has the function of being able to harden automatically after encountering CO2, and can have various advantages and advantages of gas hardening modeling and core making. However, there are disadvantages such as poor shell collapsibility, difficulty in sand cleaning for castings, and low recycling rate of used sand.
(4) Furan resin no-bake sand molding is a casting process method with furan resin as a binder. At room temperature, the molding sand is cured due to the chemical reaction of the binder under the action of the curing agent. Its characteristics are: the sand mold does not need to be dried, which greatly shortens the production cycle and saves energy. Resin molding sand is relatively easy to compact and has good collapsibility, and the molding sand of castings can also be easily cleaned, the dimensional accuracy of castings is high, and the surface finish is good, which can greatly improve the quality of castings. Its disadvantages are: the quality requirements for raw sand are also high, the production site has a slightly irritating odor, and the cost of resin is also high. Mixing process of furan resin self-hardening sand: Resin self-hardening sand is preferably made by continuous sand mixer, adding raw sand, resin, curing agent, etc. in turn, and mixing them quickly. Mix and use at any time. The order of adding various raw materials when mixing resin sand is as follows: original sand + curing agent (p-toluenesulfonic acid aqueous solution) – (120-180S) – resin + silane – (60-90S) – sand (5) Typical sand type Casting production process: precision casting.
Post time: Aug-17-2022