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To form cavities for castings of various shapes. Special ones are set up due to process requirements (such as sanding, core setting and mold parting convenience, etc.).

Water glass casting may be a casting process in precision casting. The difference between it and sand casting lies in the difference between the shells. The former is a water glass shell, and the latter is a sand-turned cavity. The latter can be directly poured without baking. . The former is mass production, and the latter is mostly used for single-piece production.

  • Gray cast iron (small and medium castings) 1%
  • medium and large: 0.9%
  • High-strength cast iron 1~1.5%,
  • Nodular cast iron 1%,
  • Tin bronze 1.4%,
  • Wuxi bronze 2~2.2%
  • Aluminum silicon alloy 1~1.2%

The above are all linear shrinkage rates (free shrinkage)

Shrinkage rate of sand casting of various metal materials: This problem is too big. For cast steel, there are: 1) Alloy: carbon steel, stainless steel, alloy steel; 2) Carbon content: low carbon steel, medium carbon steel, High-carbon steel; three) molding sand: green sand, surface dry sand, dry sand, sodium silicate sand, resin sand; four) shrinkage: body shrinkage, linear shrinkage; five) casting shape: large simple parts, Large complex parts, medium simple parts, medium complex parts, small simple parts, small complex parts. The same goes for cast aluminum, cast iron, and cast copper.

It acts as a barrier between the casting and the mold to achieve the purpose of anti-sticking sand. It can also effectively prevent the oxidation of high-temperature liquid metal, so that there is no chemical reaction during the contact between the mold and the high-temperature liquid metal, and it can absorb and digest nitrogen, Gases such as sulfur and carbon.

The forming method of smelting metal, making a mold, and pouring the molten metal into the mold, and obtaining a casting with a certain shape and performance after solidification is called casting. When molding (core making) with molding sand, it is called sand casting.
Special casting sand casting has low dimensional accuracy, rough surface, low productivity, unstable quality, and high labor intensity.
All casting methods that are different from traditional ordinary sand casting are collectively referred to as special casting.

The main processes of sand casting are:

  1. Mold production part: make molds according to the requirements of the drawings. Generally, wood molds can be used for single-piece production, plastic molds and metal molds can be made for mass production, and templates can be made for mass castings.
  2. Sand mixing stage: According to the requirements of sand mold manufacturing and the different types of castings, prepare qualified sand for modeling.
  3. Modeling (core-making) stage: including modeling (forming the cavity of the casting with molding sand), core-making (forming the inner shape of the casting), and mold matching (putting the core into the cavity, and closing the upper and lower flasks) ). Modeling is a key link in casting.
  4. Melting stage: match the chemical composition according to the required metal composition, select the appropriate melting furnace to melt the alloy material, and form a qualified liquid metal liquid (including qualified composition and qualified temperature)
  5. Pouring phase: melt the qualified metal Pour into the sand box equipped with the mold. The pouring stage is more dangerous, so special attention should be paid.
  6. Cleaning stage: After pouring, after the molten metal is solidified, the molding sand is removed, and the gate and other attachments are knocked out to form the required casting.

Features of sand casting:

  1. Suitable for making blanks with complex shapes, especially with complex cavities;
  2. Wide adaptability and low cost;
  3. For some materials with poor plasticity, such as cast iron, sand casting is used to make parts or, The only forming process of the blank.

Sand casting is the most traditional casting method, in which sand is used to make a cavity for pouring to obtain castings

However, the pressure of the molten metal in sand casting is often insufficient, resulting in defects such as dissatisfaction and cold isolation;

As a result, a new casting method was produced: pressure casting, which is die casting.

Artificially provide pressure to enhance the fluidity and filling capacity of molten metal to obtain better quality castings

It is a casting method in which molten alloy liquid is poured into a press chamber, the cavity of a steel mold is filled at high speed, and the alloy liquid is solidified under pressure to form a casting. The main characteristics of die casting that distinguish it from other casting methods are high pressure and high speed.

Hot core box coated sand for high smoothness. Low-cost green sand (recommended Nanjing red sand), resin sand with high dimensional accuracy (divided into water-washed sand and scrubbed sand)

Coated sand. The surface of the sand particles is covered with a layer of solid resin film molding sand or core sand before molding. There are two coating processes: cold method and hot method: the cold method uses ethanol to dissolve the resin, and urotropine is added during the sand mixing process, so that the two are coated on the surface of the sand grains, and the ethanol volatilizes to obtain the coated sand; Method: Preheat the sand to a certain temperature, add resin to melt, stir to coat the surface of the sand, add urotropine aqueous solution and lubricant, cool, crush and sieving to obtain coated sand.
The hot core box coated sand process is to inject the sand material mixed with foundry sand, thermosetting resin and catalyst into a core box with a heating device, and heat it to 180-250°C to heat the sand material close to the surface of the core box. Under the action of temperature, the binder can be polycondensed and hardened in a short time to form a core without entering the oven for drying.

Using coated sand hot core box core shooting machine, the dimensional accuracy of coated sand castings is CT7~CT8, and the surface roughness Ra value is in the range of 6.3 to 12.5m. The forming quality of the coated sand process can reach the level of the water glass investment casting process, which is an ideal process method.

Green sand is also called green sand. In the foundry production, the sand mixture is made of bentonite as a binder and then mixed with water and other additives, which can be used for molding cores. The sand mold (core) can be poured directly without drying. This kind of sand is called green sand in the foundry industry. At present, green sand is one of the most important casting production processes.
Resin sand Crystrip plastic pellets are pellets made of thermoplastic acrylic or polymerized thermosetting amines. The angular pellet design provides an effective treatment method for most dry strip surface coatings. Crystrip plastic is chemically inert. Through proper use and recycling, this dry strip method can reduce the generation of hazardous waste and reduce environmental pollution.

The raw resin sand is divided into ordinary resin sand, water-washed resin sand, scrub resin sand, etc. Since the mud content in scrub sand is already small, it can greatly reduce the waste of resin sand and should be selected first. Secondly, choose water-washed resin sand, but never use untreated raw sand. The price of scrubbing sand itself is not high, generally ranging from 50 yuan/t to 70 yuan/t, but the freight is relatively high.

Casting is to melt cast iron or steel and pour it into a pre-prepared mold shell. After cooling, the shell is removed and it becomes a rough part. This process reduces the amount of processing, especially for parts with more surface surfaces that are difficult to process. Casting can solve the problem. In order to avoid processing difficulties and improve production efficiency, sand casting is to use quartz sand as a sand mold and then it can be poured after drying. It is characterized by simple and low cost, and parts with rougher shapes and low precision requirements can be used. Investment casting is made of plastic foam. Roll the coating on the surface of the molded tire, dry it and put it in the flask to vacuum the flask before casting. The hot molten iron burns the foam into gas and cools it into a part. This casting is also called vacuum casting, which has a higher cost. The burning gas has a great impact on the environment. Precision casting is also wax mold casting. The mold is made of paraffin, then rolled with paint and quartz sand, and then dewaxed to become a mold shell. The molten iron is poured in to cool the mold shell. It becomes a part when it is knocked out. The parts produced by this process have good surface finish and precise dimensions, so it is called precision casting.

Coated sand is a kind of high-quality selected natural sand as the sand base, resin coating system with special performance and the most ideal process technology. According to the technical requirements of different users, it strives to perform at room temperature, high temperature performance, collapsibility, and flowability. The most perfect combination of performance, surface roughness of castings, etc., is widely used in automobile engines, diesel engines, hydraulic parts and other industries.

Water glass casting may be a casting process in precision casting. The difference between it and sand casting lies in the difference between the shells. The former is a water glass shell, and the latter is a sand-turned cavity. The latter can be directly poured without baking. . The former is mass production, and the latter is mostly used for single-piece production.

  • Gray cast iron (small and medium castings) 1%
  • medium and large: 0.9%
  • High-strength cast iron 1~1.5%,
  • Nodular cast iron 1%,
  • Tin bronze 1.4%,
  • Wuxi bronze 2~2.2%
  • Aluminum silicon alloy 1~1.2%

The above are all linear shrinkage rates (free shrinkage)

Shrinkage rate of sand casting of various metal materials: This problem is too big. For cast steel, there are: 1) Alloy: carbon steel, stainless steel, alloy steel; 2) Carbon content: low carbon steel, medium carbon steel, High-carbon steel; three) molding sand: green sand, surface dry sand, dry sand, sodium silicate sand, resin sand; four) shrinkage: body shrinkage, linear shrinkage; five) casting shape: large simple parts, Large complex parts, medium simple parts, medium complex parts, small simple parts, small complex parts. The same goes for cast aluminum, cast iron, and cast copper.

In sand casting, the sharp side is used first because it can still be used.https://themeforest.net/page/customer_refund_policy

Green sand, clay sand, water glass, coated sand, resin sand
They are all sand casting in casting, but they are the difference between different binders.
Green sand, clay sand, and green sand are the same. The binder is all ordinary clay or bentonite. Since water is added during the sand mixing process, it is called green sand.
The binder of water glass sand is sodium water glass, which is generally hardened by blowing carbon dioxide or hardening by adding a hardener.
The binder of coated sand is generally phenolic resin, which is slightly toxic, and is generally used for sand cores.
The binder of the resin sand is furan resin, and the resin sand molding has a relatively large amount of gas after pouring. At present, the quality of castings molded with resin sand is the best in sand casting.

Since the castings cool and solidify faster in the metal mold than in the sand mold, and the metal mold has no tolerance, the casting stress generated in the casting is larger than that in the sand casting. The cracking tendency is also greater, and it is easy to produce pouring. Insufficiency, cold barrier, white mouth (for castings) and other defects. Therefore, when buying sand casting products, you must find large-scale casting manufacturers to ensure the quality.

The forming method of smelting metal, making a mold, and pouring the molten metal into the mold, and obtaining a casting with a certain shape and performance after solidification is called casting. When molding (core making) with molding sand, it is called sand casting.
Special casting sand casting has low dimensional accuracy, rough surface, low productivity, unstable quality, and high labor intensity.
All casting methods that are different from traditional ordinary sand casting are collectively referred to as special casting.

Sand casting is the most traditional casting method, in which sand is used to make a cavity for pouring to obtain castings

However, the pressure of the molten metal in sand casting is often insufficient, resulting in defects such as dissatisfaction and cold isolation;

As a result, a new casting method was produced: pressure casting, which is die casting.

Artificially provide pressure to enhance the fluidity and filling capacity of molten metal to obtain better quality castings

It is a casting method in which molten alloy liquid is poured into a press chamber, the cavity of a steel mold is filled at high speed, and the alloy liquid is solidified under pressure to form a casting. The main characteristics of die casting that distinguish it from other casting methods are high pressure and high speed.

Hot core box coated sand for high smoothness. Low-cost green sand (recommended Nanjing red sand), resin sand with high dimensional accuracy (divided into water-washed sand and scrubbed sand)

Coated sand. The surface of the sand particles is covered with a layer of solid resin film molding sand or core sand before molding. There are two coating processes: cold method and hot method: the cold method uses ethanol to dissolve the resin, and urotropine is added during the sand mixing process, so that the two are coated on the surface of the sand grains, and the ethanol volatilizes to obtain the coated sand; Method: Preheat the sand to a certain temperature, add resin to melt, stir to coat the surface of the sand, add urotropine aqueous solution and lubricant, cool, crush and sieving to obtain coated sand.
The hot core box coated sand process is to inject the sand material mixed with foundry sand, thermosetting resin and catalyst into a core box with a heating device, and heat it to 180-250°C to heat the sand material close to the surface of the core box. Under the action of temperature, the binder can be polycondensed and hardened in a short time to form a core without entering the oven for drying.

Using coated sand hot core box core shooting machine, the dimensional accuracy of coated sand castings is CT7~CT8, and the surface roughness Ra value is in the range of 6.3 to 12.5m. The forming quality of the coated sand process can reach the level of the water glass investment casting process, which is an ideal process method.

Green sand is also called green sand. In the foundry production, the sand mixture is made of bentonite as a binder and then mixed with water and other additives, which can be used for molding cores. The sand mold (core) can be poured directly without drying. This kind of sand is called green sand in the foundry industry. At present, green sand is one of the most important casting production processes.
Resin sand Crystrip plastic pellets are pellets made of thermoplastic acrylic or polymerized thermosetting amines. The angular pellet design provides an effective treatment method for most dry strip surface coatings. Crystrip plastic is chemically inert. Through proper use and recycling, this dry strip method can reduce the generation of hazardous waste and reduce environmental pollution.

The raw resin sand is divided into ordinary resin sand, water-washed resin sand, scrub resin sand, etc. Since the mud content in scrub sand is already small, it can greatly reduce the waste of resin sand and should be selected first. Secondly, choose water-washed resin sand, but never use untreated raw sand. The price of scrubbing sand itself is not high, generally ranging from 50 yuan/t to 70 yuan/t, but the freight is relatively high.

To form cavities for castings of various shapes. Special ones are set up due to process requirements (such as sanding, core setting and mold parting convenience, etc.).

Green sand, clay sand, water glass, coated sand, resin sand
They are all sand casting in casting, but they are the difference between different binders.
Green sand, clay sand, and green sand are the same. The binder is all ordinary clay or bentonite. Since water is added during the sand mixing process, it is called green sand.
The binder of water glass sand is sodium water glass, which is generally hardened by blowing carbon dioxide or hardening by adding a hardener.
The binder of coated sand is generally phenolic resin, which is slightly toxic, and is generally used for sand cores.
The binder of the resin sand is furan resin, and the resin sand molding has a relatively large amount of gas after pouring. At present, the quality of castings molded with resin sand is the best in sand casting.

Sand casting has properties such as air permeability, strength, fire resistance, plasticity, and retreat.

Since the castings cool and solidify faster in the metal mold than in the sand mold, and the metal mold has no tolerance, the casting stress generated in the casting is larger than that in the sand casting. The cracking tendency is also greater, and it is easy to produce pouring. Insufficiency, cold barrier, white mouth (for castings) and other defects. Therefore, when buying sand casting products, you must find large-scale casting manufacturers to ensure the quality.

In sand casting, the sharp side is used first because it can still be used.https://themeforest.net/page/customer_refund_policy

Casting is to melt cast iron or steel and pour it into a pre-prepared mold shell. After cooling, the shell is removed and it becomes a rough part. This process reduces the amount of processing, especially for parts with more surface surfaces that are difficult to process. Casting can solve the problem. In order to avoid processing difficulties and improve production efficiency, sand casting is to use quartz sand as a sand mold and then it can be poured after drying. It is characterized by simple and low cost, and parts with rougher shapes and low precision requirements can be used. Investment casting is made of plastic foam. Roll the coating on the surface of the molded tire, dry it and put it in the flask to vacuum the flask before casting. The hot molten iron burns the foam into gas and cools it into a part. This casting is also called vacuum casting, which has a higher cost. The burning gas has a great impact on the environment. Precision casting is also wax mold casting. The mold is made of paraffin, then rolled with paint and quartz sand, and then dewaxed to become a mold shell. The molten iron is poured in to cool the mold shell. It becomes a part when it is knocked out. The parts produced by this process have good surface finish and precise dimensions, so it is called precision casting.

Coated sand is a kind of high-quality selected natural sand as the sand base, resin coating system with special performance and the most ideal process technology. According to the technical requirements of different users, it strives to perform at room temperature, high temperature performance, collapsibility, and flowability. The most perfect combination of performance, surface roughness of castings, etc., is widely used in automobile engines, diesel engines, hydraulic parts and other industries.

It acts as a barrier between the casting and the mold to achieve the purpose of anti-sticking sand. It can also effectively prevent the oxidation of high-temperature liquid metal, so that there is no chemical reaction during the contact between the mold and the high-temperature liquid metal, and it can absorb and digest nitrogen, Gases such as sulfur and carbon.

The forming method of smelting metal, making a mold, and pouring the molten metal into the mold, and obtaining a casting with a certain shape and performance after solidification is called casting. When molding (core making) with molding sand, it is called sand casting.
Special casting sand casting has low dimensional accuracy, rough surface, low productivity, unstable quality, and high labor intensity.
All casting methods that are different from traditional ordinary sand casting are collectively referred to as special casting.

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