What are the manual modeling methods of sand casting

There are three types as follows.

1. Clay green sand.

Clay and an appropriate amount of water are used as the main binders of molding sand, and after the sand mold is made, it is directly combined and poured in the wet state. Wet casting has a long history and is widely used. The strength of green sand depends on the clay slurry that is formed by mixing clay and water in a certain ratio.

Once the molding sand is mixed, it has a certain strength, and after it is made into a sand mold, it can meet the requirements of fitting and pouring. Therefore, the amount of clay and moisture in the molding sand is a very important process factor.

It is a casting method in which molding sand and core sand are used as molding materials to make molds, and liquid metal is filled with molds under gravity to produce castings. Steel, iron, and most non-ferrous alloy castings can be obtained using the sand casting method. Because the molding materials used in sand casting are cheap and easy to obtain, the casting manufacturing is simple, and it can adapt to the single production, batch production and mass production of castings, and has been the basic process in casting production for a long time.

2. Clay dry sand.

The wet moisture of the molding sand used to make this sand mold is slightly higher than that of the molding sand used for wet molding. After the sand mold is made, the surface of the cavity should be coated with refractory paint, and then placed in the oven to dry, and then it can be combined and poured after it cools. It takes a long time to dry the clay sand mold, which consumes a lot of fuel, and the sand mold is easy to deform during the drying process, which affects the accuracy of the casting.

3. Chemically hardened sand mold.

The molding sand used in this sand mold is called chemically hardened sand. Its binder is generally a substance that can be polymerized under the action of a hardener and then becomes a three-dimensional structure, and various synthetic resins and sodium silicate are commonly used.

1 Ordinary sand casting.

Method: The use of sand as casting mold material, also known as sand casting, sand turning, including green sand mold, dry sand mold and chemical hardening sand mold 3 types, but not all sand can be used for casting. The advantage is that the cost is lower because the sand used in the casting mold is reusable; The disadvantage is that the casting mold is time-consuming, and the casting mold itself cannot be reused, and it must be destroyed before the finished product can be obtained.

2. Sand casting methods: green sand machine molding method, self-hardening resin sand molding core, sodium silicate sand molding core, dry and surface dry molding, solid casting, negative pressure molding, manual molding.

3. Sand core manufacturing method: It is selected according to the size, shape, production batch and specific production conditions of the sand core, and in production, it can be divided into manual core making and machine core making in general.

4. Metal mold casting method: use metal with a higher melting point than raw materials to make casting molds. Among them, it is subdivided into gravity casting method, low-pressure casting method and high-pressure casting method. Due to the melting point of the casting mold, there are also restrictions on the metals that can be cast.

5. Lost-wax casting method: this method can be outer film casting method and solid casting method. The object to be cast is reproduced with wax, then immersed in a pool containing ceramics and allowed to dry, so that the wax replica is covered with a ceramic outer film, and the process is repeated until the outer film is sufficient to support the casting process (about 1 4 inches to 1 8 inches), then the wax in the mold is melted and the casting mold is extracted.

There are six types of whole mold molding, parting mold molding, three-box molding, loose block molding, sand digging molding, and scraper molding.

There are seven kinds of whole mold modeling, parting mold modeling, three-box molding, loose block modeling, sand digging modeling, scraper modeling, and false box modeling.

It seems that there are sandboxes, scrapers, clays, just remember these few.

1. Cartography. The traditional method is to obtain casting drawings and send them to the foundry. This process can be done in **. Nowadays, more and more customers and foundries are using computer-aided design instead.

2. a mold. In sand casting, molds are made of wood or other metal materials. In this process, we ask our engineers to make the mold size slightly larger than the finished product, and the difference is called the shrinkage allowance.

The purpose is to act on the molten metal to ensure that the molten metal solidifies and shrinks, thus preventing voids during the casting process.

3. Core making. The core is made by placing resin sand grains in a mold to form a casting on the inner surface. Therefore, the gap between the core and the mold is ultimately casting.

4. Molding. In the melting and molding process, a set of molds needs to be prepared. Molding usually involves the supporting frame of the mold, pulling the mold out so that it separates during the casting process, melting the previously placed core in the mold and then closing the mold opening.

5. Cleaning. The purpose of cleaning is to remove excess metal from sand, grinding and castings. Welding, sand removal can improve the surface appearance of castings.

The sand and scale that was burned were removed to improve the surface appearance of the casting. Excess metal and other risers are cleared. One step closer, welding, grinding and other steps. Finally, the defects and overall quality are checked.

6. Finishing. Before shipping, reprocessing. According to different customers' requirements, we can do heat treatment, surface treatment, additional inspection, etc.

Chemically hardened sand molds have much higher strength than clay sand molds, and after being made into a sand mold, they are defilmed after hardening to a fairly high strength, and do not need to be modified. Therefore, the casting mold can accurately reflect the size and contour shape of the pattern, and it is not easy to deform in the subsequent process. The dimensional accuracy of the castings is high.

Because the viscosity of the binder and hardener used is not high, it is easy to mix with the sand particles, and the sand mixing equipment has a light structure, low power and high productivity, and the sand treatment work can be simplified.

The mixed molding sand has good fluidity before hardening, and the molding sand is easy to compact during molding, so there is no need for a large and complex molding machine.

When molding with chemically hardened sand, pattern materials such as wood, plastic and metal can be selected according to production requirements.

The binder content in chemically hardened sand is much lower than that of clay sand, and there is no powdered excipients in it, and the gap between the sand particles is much larger than that of clay sand. In order to avoid the metal seeping between the sand particles during casting, the surface of the sand mold or core should be coated with a good quality coating.

The cost of chemically hardened sand with water glass as a binder is low, and the working environment is odorless in use. However, the molding sand is not easy to collapse after pouring the metal in this casting mold; The used old sand cannot be used directly, it must be recycled, and the regeneration of sodium silicate sand is more difficult.

The cost of chemically hardened sand with resin as a binder is higher, but the casting is easy to separate from the molding sand after pouring, the workload of casting cleaning is reduced, and most of the used sand can be reused.