Casting is a mass production process which involves molten materials (such as metals, plastics or resins) being poured into a mold, allowed to solidify and then extracted for use. Casting can be thought of as a method for reproducing something - whether a mere part or a single unit by itself.
Casting is a process that can be used to manufacture complex parts which would prove too expensive or time-consuming to produce using other methods such as cutting or shaping these from solid materials.
Non-expendable Casting Techniques
This involves the use of more or less permanent or long-lasting molds which do not need to be broken in order to remove the cast material once it has set or cooled. Die casting is probably the most well-known non-expendable casting process known, in which molten metal or other material is forced, under high pressure, into the cavities of steel molds called dies.
The die casting method is straightforward. The die or mold is fabricated (containing the impressions of the piece to be cast). A lubricant is sprayed on the inside of the die both to cool it off as well as assist in making removal of the cast piece easy. Once the whole thing is set up, molten material is 'injected' into the die under high speed and high pressure, this helps a lot in making a casting as smooth and as precise as the original mold. Once the cavity is filled with the desired material, pressure is maintained until the material has cooled (which is helped along by using water to cool the mold). Once the material has cooled and hardened, the die is opened and the material ejected to pave the way for the next casting.
The major advantage of die casting is the ability to use the mold or die repeatedly and continuously - although even the die will deteriorate due to the high-pressure and high-speed injection of molten material (usually nonferrous metals like zinc or aluminum or plastics). At the same time, the mold can be used to replicate intricate and complex patterns ranging from small to large pieces which make it the process of choice for the manufacturing of certain items.
Expendable Mold Technique
As its name implies, expendable mold casting makes use of expendable molds for the casting process. This does not imply the use of inexpensive materials, however; the process refers more to molds that have to be broken to remove the materials cast rather than 'throwaway,' single-use molds.
Among the most common (and oldest) examples of the expendable mold technique is sand casting. Sand casting makes use of a "molding box" - actually a container filled with sand (usually 'green' sand) in which the patterns of the piece to be cast are set.
Expendable casting uses a variety of materials for the mold - plaster, concrete, resins, even wax (in the so-called 'lost-wax' or investment casting technique). Recently, polystyrene foam has been used in expendable casting for complicated and complex parts such as automobile engines and the like.
2007年9月6日星期四
casting Process
Investment casting also can be called "precise casting" or " lost wax casting" or "dewaxing casting". the casting materials can widely used, and no limitation for product shape as well as complex structure. The most important characteristic is the close tolerances control, reduced machining allowances, and fine surface finish. Its application scope can be wider after using the new equipment and advanced technology. In heat processing industry, investment casting can be used for those products which difficult to choice the materials, or materials not easy to form a shape, as well as some forging pieces with higher cost; while in the casting industry, the investment casting can be used instead of other casting methods, so as to reduce machining allowances and the cost, improve the dimensional precision and surface finish as well as the mechanical properties, so as to meet the requirements of a higher level product.
Further information, please don't hesitate to contact with us, we will give you the most satisfied reply.
We undertake the processing cooperation for drawings and samples at home, even all over the world, if you need to inquire about price, please submit the related information, we will offer you a most favorable price as soon as possible. die casting,casting,aluminium die casting,aluminum casting,sand casting,iron sand casting,investment casting,pressure die casting ,gear housing,Quick Coupling Series
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Mature technological process, rich experience, professional large scale production, effective cost management made us possess the strong comprehensive competitive capability better than other manufactory in this vocation, all these not only show in our high quality, the most attractive price also is our treasure book.
If you come from America or Europe, please trust us, because of the lowest productive cost in China, so, purchasing casting in China is your best choice. Don't hesitate, our offer will make you a big surprise.
Further information, please don't hesitate to contact with us, we will give you the most satisfied reply.
We undertake the processing cooperation for drawings and samples at home, even all over the world, if you need to inquire about price, please submit the related information, we will offer you a most favorable price as soon as possible. die casting,casting,aluminium die casting,aluminum casting,sand casting,iron sand casting,investment casting,pressure die casting ,gear housing,Quick Coupling Series
,Precision CNC Machining Components ,Valve Balls and Valve Industry,Pressure Die Casting,aluminum die casting,Investment Casting,Sand casting,Iron casting,CNC machining,alloy die casting,zinc die casting,low pressure die casting,aluminum pressure die casting,die casting machine,lost wax casting,Pressure Die Casting,aluminum die casting,Investment Casting,Sand casting,Iron casting,CNC machining,alloy die casting,zinc die casting,low pressure die casting,aluminum pressure die casting,die casting machine,lost wax casting,high pressure die casting,permanent mold casting,stainless steel casting,aluminum casting foundry,green sand casting,aluminum investment casting,iron casting,aluminum lost wax casting,die casting for lighting industry,die casting Motorcycle Parts
Mature technological process, rich experience, professional large scale production, effective cost management made us possess the strong comprehensive competitive capability better than other manufactory in this vocation, all these not only show in our high quality, the most attractive price also is our treasure book.
If you come from America or Europe, please trust us, because of the lowest productive cost in China, so, purchasing casting in China is your best choice. Don't hesitate, our offer will make you a big surprise.
2007年9月4日星期二
Cast iron
Iron (Fe) accounts for more than 95% of the alloy material, while the main alloying elements are carbon (C) and silicon (Si). The amount of carbon in cast irons is 2.1 - 4%, while ferrous alloys with less carbon are denoted as carbon steel by definition. Cast irons contain appreciable amounts of silicon, normally 1 - 3%, and consequently these alloys should be considered ternary Fe-C-Si alloys.
Despite this, the principles of cast iron solidification are understood from the binary iron-carbon phase diagram, where the eutectic point lies at 1154 °C and 4.3 wt% carbon. Since cast iron has nearly this composition, its melting temperature of 1150 to 1200 °C is about 300 degrees lower than the melting point of pure iron. Cast iron tends to be brittle, unless the name of the particular alloy suggests otherwise. The color of a fracture surface can be used to identify an alloy: carbide impurities allow cracks to pass straight through, resulting in a smooth, "white" surface, while graphite flakes deflect a passing crack and initiate countless new cracks as the material breaks, resulting in a rough surface that appears grey.
With its low melting point, good fluidity, castability, excellent machinability and wear resistance, cast irons have become an engineering material with a wide range of applications, including pipes, machine and car parts.
Despite this, the principles of cast iron solidification are understood from the binary iron-carbon phase diagram, where the eutectic point lies at 1154 °C and 4.3 wt% carbon. Since cast iron has nearly this composition, its melting temperature of 1150 to 1200 °C is about 300 degrees lower than the melting point of pure iron. Cast iron tends to be brittle, unless the name of the particular alloy suggests otherwise. The color of a fracture surface can be used to identify an alloy: carbide impurities allow cracks to pass straight through, resulting in a smooth, "white" surface, while graphite flakes deflect a passing crack and initiate countless new cracks as the material breaks, resulting in a rough surface that appears grey.
With its low melting point, good fluidity, castability, excellent machinability and wear resistance, cast irons have become an engineering material with a wide range of applications, including pipes, machine and car parts.
Coffee Pot
Zhongjiang Company is a professional manufacturer specialized in producing Stainless Steel Daily-use products; the company not only has technical talents, but also an experienced administration and management team; it possesses the advanced production equipments and the technical team of high efficiency production; it adopts and enjoys the outstanding manufacturing technology and process; it gives an accurate control on every manufacturing process and carry out the production in line with the international standards; the Main Products include:
1. Stainless Steel Coffee Utensils: Coffeepot, Coffee Spoon£»
2. Hotel Utensils: Order Holder, Chopsticks Holder, Measuring Cup, Stainless Soap.
3. Kitchen Utensils: Pot, Soup Spoon, Frying Shovel, Special Spoon, Strainer spoon, Strainer Basket;
The products are in a complete range of specifications, a fashionable design and reliable quality; Zhongjiang Products are mainly exported to some regions and countries like Asia, USA and Europe.
Zhongjiang Company, adhering to Quality Foremost, Credit Fundamental and Customer First, will provide and offer its first class products and service to worldwide customers.
Coffee pot
Material:18/8 304 from Korea
Thinkness:0.8mm
MIRROR-POLISHING TREATMENT
Size:1.9L
Qty/Ctn:12pcs
Carton meas:48*44*34.5cm
G.W/N.W(kgs):10/7
from:http://coffeeware.blogspot.com/
1. Stainless Steel Coffee Utensils: Coffeepot, Coffee Spoon£»
2. Hotel Utensils: Order Holder, Chopsticks Holder, Measuring Cup, Stainless Soap.
3. Kitchen Utensils: Pot, Soup Spoon, Frying Shovel, Special Spoon, Strainer spoon, Strainer Basket;
The products are in a complete range of specifications, a fashionable design and reliable quality; Zhongjiang Products are mainly exported to some regions and countries like Asia, USA and Europe.
Zhongjiang Company, adhering to Quality Foremost, Credit Fundamental and Customer First, will provide and offer its first class products and service to worldwide customers.
Coffee pot
Material:18/8 304 from Korea
Thinkness:0.8mm
MIRROR-POLISHING TREATMENT
Size:1.9L
Qty/Ctn:12pcs
Carton meas:48*44*34.5cm
G.W/N.W(kgs):10/7
from:http://coffeeware.blogspot.com/
2007年9月2日星期日
stainless steel casting
consisting mostly of iron, with a carbon content between 0.02% and 1.7 or 2.04% by weight (C:1000–10,8.67Fe), depending on grade. Carbon is the most cost-effective alloying material for iron, but various other alloying elements are used such as manganese and tungsten.[1] Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another. Varying the amount of alloying elements and form of their presence in the steel (solute elements, precipitated phase) controls qualities such as the hardness, ductility, and tensile strength of the resulting steel. Steel with increased carbon content can be made harder and stronger than iron, but is also more brittle. The maximum solubility of carbon in iron (in austenite region) is 2.14% by weight, occurring at 1149 °C; higher concentrations of carbon or lower temperatures will produce cementite. Alloys with higher carbon content than this are known as cast iron because of their lower melting point.[1] Steel is also to be distinguished from wrought iron containing only a very small amount of other elements, but containing 1–3% by weight of slag in the form of particles elongated in one direction, giving the iron a characteristic grain. It is more rust-resistant than steel and welds more easily. But at present time this term is rarely used in steel industry. It is common today to talk about 'the iron and steel industry' as if it were a single entity, but historically they were separate products.
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permanent mold casting
Permanent mold castings, while not as flexible as sand castings in allowing the use of different patterns (different part designs), lower the cost of producing a part. At a production run of 1000 or more parts, permanent mold castings produce a lower piece cost part. Of course, the break-even point depends on the complexity of the part. More complex parts being favored by the use of permanent molds.
The usual considerations of minimum wall thicknesses (such as 3mm for lengths under 75 mm), radius (inside radius = nominal wall thickness, outside radius = 3 x nominal wall thickness), draft angles (1 to 3?on outside surfaces, 2 to 5on inside surfaces) etc all apply. Typical tolerances are 2 % of linear dimensions. .
Typical part sizes range from 50 g to 70 kg (1.5 ounces to 150 lb). Typical materials used are small and medium sized parts made from aluminum, magnesium and brass and their alloys. Typical parts include gears, splines, wheels, gear housings, pipefittings, fuel injection housings, and automotive engine pistons.
Other Permanent Mold Castings
Slush Casting: Slush Casting is a special type of permanent mold casting, where the molten metal is not allowed to completely solidify. After the desired wall thickness is obtained, the not yet solidified molten metal is poured out. This is useful for making hollow ornamental objects such as candlesticks, lamps, statues etc.
Corthias Casting: Corthias Casting is another variation of the permanent mold casting, where a plunger is used to pack down the molten metal form the sprue hole. This allows for thinner walls and greater details to be produced.
Low Pressure Permanent Mold Casting: Low Pressure Permanent Mold Casting is yet another variation of the permanent mold casting. Here, instead of using gravity to assist in the metal pour and flow in the mold, a low pressure of upto 1 atmosphere gas is applied to the molten metal. This maintenance of pressure on the melt causes complete fill of the mold and compensates for any shrinkage on cooling. Thin wall castings can be made. Mechanical properties are about 5 % superior to permanent mold casting. Since no riser is used (unlike a regular casting), the yield is generally higher since the metal in the pressurized feed tube is still molten and the mold is ready for the next shot right away.
Vacuum Permanent Mold Casting
Vacuum Permanent Mold Casting is yet another variation of the permanent mold casting. This is similar to the low-pressure permanent mold casting, where a vacuum is used instead of a pressure. Thin wall castings can be made as in the low-pressure permanent mold casting. In addition, the yields are high since no risers are used. Since vacuum is used instead, the purity of the metal is maintained. The mechanical properties of the casting are 10 to 15 % superior to the traditional permanent mold casting. Castings range in size from 200 g to 4.5 kg (6 oz to 10 lb).
The usual considerations of minimum wall thicknesses (such as 3mm for lengths under 75 mm), radius (inside radius = nominal wall thickness, outside radius = 3 x nominal wall thickness), draft angles (1 to 3?on outside surfaces, 2 to 5on inside surfaces) etc all apply. Typical tolerances are 2 % of linear dimensions. .
Typical part sizes range from 50 g to 70 kg (1.5 ounces to 150 lb). Typical materials used are small and medium sized parts made from aluminum, magnesium and brass and their alloys. Typical parts include gears, splines, wheels, gear housings, pipefittings, fuel injection housings, and automotive engine pistons.
Other Permanent Mold Castings
Slush Casting: Slush Casting is a special type of permanent mold casting, where the molten metal is not allowed to completely solidify. After the desired wall thickness is obtained, the not yet solidified molten metal is poured out. This is useful for making hollow ornamental objects such as candlesticks, lamps, statues etc.
Corthias Casting: Corthias Casting is another variation of the permanent mold casting, where a plunger is used to pack down the molten metal form the sprue hole. This allows for thinner walls and greater details to be produced.
Low Pressure Permanent Mold Casting: Low Pressure Permanent Mold Casting is yet another variation of the permanent mold casting. Here, instead of using gravity to assist in the metal pour and flow in the mold, a low pressure of upto 1 atmosphere gas is applied to the molten metal. This maintenance of pressure on the melt causes complete fill of the mold and compensates for any shrinkage on cooling. Thin wall castings can be made. Mechanical properties are about 5 % superior to permanent mold casting. Since no riser is used (unlike a regular casting), the yield is generally higher since the metal in the pressurized feed tube is still molten and the mold is ready for the next shot right away.
Vacuum Permanent Mold Casting
Vacuum Permanent Mold Casting is yet another variation of the permanent mold casting. This is similar to the low-pressure permanent mold casting, where a vacuum is used instead of a pressure. Thin wall castings can be made as in the low-pressure permanent mold casting. In addition, the yields are high since no risers are used. Since vacuum is used instead, the purity of the metal is maintained. The mechanical properties of the casting are 10 to 15 % superior to the traditional permanent mold casting. Castings range in size from 200 g to 4.5 kg (6 oz to 10 lb).
Lost-wax casting
1. Sculpting. An artist creates an original artwork from wax, clay, or another material. Wax and oil-based clay are often preferred because these materials retain their softness.
2. Moldmaking. A mold is made of the original sculpture. Most molds are at least two pieces, and a shim with keys is placed between the two halves during construction so that the mold can be put back together accurately. Most molds of small sculptures are made from plaster, but can also be made of fiberglass or other materials. To preserve the fine details on the original artwork's surface, there is usually an inner mold made of latex, vinyl, or silicone which is supported by the plaster part of the mold. Usually, the original artwork is destroyed during the making and initial deconstruction of the plaster mold. This is because the originals are solid, and do not easily bend as the plaster mold is removed. Often long, thin pieces are cut off of the original and molded separately. Sometimes, especially in the case of large original (such as life-size) sculptures, many molds are needed to recreate the original sculpture.
3. Wax. Once the plaster and latex mold is finished, molten wax is poured into it and swished around until an even coating, usually about 1/8 inches thick, covers the entire inner surface of the mold. This must be done in several layers until desired thickness is reached.
4. Removal of wax. This new, hollow wax copy of the original artwork is removed from the mold. The artist may reuse the mold to make more wax copies, but wear and tear on the mold limit their number. For small bronze artworks, a common number of copies today is around 25.
5. Chasing. Each hollow wax copy is then "chased": a heated metal tool is used to rub out all the marks which show the "parting line" or "flashing" where the pieces of the mold came together. The wax is then "dressed" to hide any imperfections. The way the wax looks at this stage, is what it will look like when it is cast. Wax pieces that were molded separately can be heated and attached; foundries often use "registration marks" to indicate exactly where they go.
6. Spruing. Once the wax copy looks just like the original artwork, it is "sprued" with a treelike structure of wax that will eventually provide paths for molten bronze to flow, while allowing air to escape. The carefully-planned spruing usually begins at the top with a wax "cup," which is attached by wax cylinders to various points on the wax copy.
7. Slurry. A "sprued" wax copy is dipped into a slurry of liquid silica, then into a sand-like "stucco", or dry crystalline silica of a controlled grain size. The slurry and grit combination is called "ceramic shell" mold material, although it is not literally made of ceramic. This shell is allowed to dry, and the process is repeated until a half-inch thick or thicker dries coating covers the entire piece. The bigger the piece, the thicker the shell needs to be. Only the inside of the cup is not coated, and the cup's flat top serves as the base upon which the piece stands during this process.
8. Burnout. The ceramic shell-coated piece is placed cup-down in a kiln, whose heat hardens the silica coatings into a shell, and the wax melts and runs out. The melted wax can be recovered and reused, although often it is simply combusted by the burnout process. Now all that remains of the original artwork is the negative space, formerly occupied by the wax, inside the hardened ceramic shell. The feeder and vent tubes and cup are now hollow, also.
9. Testing. The ceramic shell is allowed to cool, then is tested to see if water will flow through the feeder and vent tubes as necessary. Cracks or leaks can be patched with thick refractory paste. To test the thickness, holes can be drilled into the shell, then patched.
10. Pouring. The shell is reheated in the kiln to harden the patches, then placed cup-upwards into a tub filled with sand. Bronze is melted in a crucible in a furnace, then poured carefully into the shell. If the shell were not hot, the temperature difference would shatter it. The bronze-filled shells are allowed to cool.
11. Release.The shell is hammered or sand-blasted away, releasing the rough bronze. The spruing, which are also faithfully recreated in metal, are cut off, to be reused in another casting.
12. Metal-chasing. Just as the wax copies were "chased," the bronze copies are worked until the telltale signs of casting are removed, and the sculptures again look like the original artwork. Pits left by air bubbles in the molten bronze are filled, and the stubs of spruing filed down and polished.
13. Patinating. The bronze is colored to the artist's preference, using chemicals applied to heated or cooled metal. Using heat is probably the most predicatable method, and allows the artist to have the most control over the process. This coloring is called patina, and is often green, black, white or brownish to simulate the surfaces of ancient bronze sculptures. (Ancient bronzes gained their patinas from oxidisation and other effects of being on Earth for many years.) However, with current artistic trends in the United States, many artists prefer that their bronzes have brighter, more stylized patinas. Patinas can be applied to replicate marble or stone. Depending on how the metal is prepared, either sandblasted or polished, the finish can be either opaque or transparent. After the patina is applied, a coating of wax, which is the most traditional type of sealer, is usually applied to protect the surface. Many artists prefer to use lacquer as a sealer on some of the more unstable patinas. This protects the piece more from ultraviolet rays. Some patinas change color over time because of oxidiation, and the wax layer slows this down somewhat.
On the left is an example of a lost-wax process mold, and on the right is the resulting bronze sculpture.
On the left is an example of a lost-wax process mold, and on the right is the resulting bronze sculpture.
The lost-wax process can also be used with any material that can burn, melt, or evaporate to leave a mold cavity. Some automobile manufacturers use a lost-foam technique to make engine blocks. The model in this case is made of polystyrene foam, which is then placed into a casting flask, consisting of a cope and drag, which is then filled with casting sand. The foam supports the sand, allowing shapes to be made which would not be possible if the process had to rely on the sand alone to hold its shape. The metal is then poured in, and the heat of the metal vaporizes the foam as the metal enters the mold.
2. Moldmaking. A mold is made of the original sculpture. Most molds are at least two pieces, and a shim with keys is placed between the two halves during construction so that the mold can be put back together accurately. Most molds of small sculptures are made from plaster, but can also be made of fiberglass or other materials. To preserve the fine details on the original artwork's surface, there is usually an inner mold made of latex, vinyl, or silicone which is supported by the plaster part of the mold. Usually, the original artwork is destroyed during the making and initial deconstruction of the plaster mold. This is because the originals are solid, and do not easily bend as the plaster mold is removed. Often long, thin pieces are cut off of the original and molded separately. Sometimes, especially in the case of large original (such as life-size) sculptures, many molds are needed to recreate the original sculpture.
3. Wax. Once the plaster and latex mold is finished, molten wax is poured into it and swished around until an even coating, usually about 1/8 inches thick, covers the entire inner surface of the mold. This must be done in several layers until desired thickness is reached.
4. Removal of wax. This new, hollow wax copy of the original artwork is removed from the mold. The artist may reuse the mold to make more wax copies, but wear and tear on the mold limit their number. For small bronze artworks, a common number of copies today is around 25.
5. Chasing. Each hollow wax copy is then "chased": a heated metal tool is used to rub out all the marks which show the "parting line" or "flashing" where the pieces of the mold came together. The wax is then "dressed" to hide any imperfections. The way the wax looks at this stage, is what it will look like when it is cast. Wax pieces that were molded separately can be heated and attached; foundries often use "registration marks" to indicate exactly where they go.
6. Spruing. Once the wax copy looks just like the original artwork, it is "sprued" with a treelike structure of wax that will eventually provide paths for molten bronze to flow, while allowing air to escape. The carefully-planned spruing usually begins at the top with a wax "cup," which is attached by wax cylinders to various points on the wax copy.
7. Slurry. A "sprued" wax copy is dipped into a slurry of liquid silica, then into a sand-like "stucco", or dry crystalline silica of a controlled grain size. The slurry and grit combination is called "ceramic shell" mold material, although it is not literally made of ceramic. This shell is allowed to dry, and the process is repeated until a half-inch thick or thicker dries coating covers the entire piece. The bigger the piece, the thicker the shell needs to be. Only the inside of the cup is not coated, and the cup's flat top serves as the base upon which the piece stands during this process.
8. Burnout. The ceramic shell-coated piece is placed cup-down in a kiln, whose heat hardens the silica coatings into a shell, and the wax melts and runs out. The melted wax can be recovered and reused, although often it is simply combusted by the burnout process. Now all that remains of the original artwork is the negative space, formerly occupied by the wax, inside the hardened ceramic shell. The feeder and vent tubes and cup are now hollow, also.
9. Testing. The ceramic shell is allowed to cool, then is tested to see if water will flow through the feeder and vent tubes as necessary. Cracks or leaks can be patched with thick refractory paste. To test the thickness, holes can be drilled into the shell, then patched.
10. Pouring. The shell is reheated in the kiln to harden the patches, then placed cup-upwards into a tub filled with sand. Bronze is melted in a crucible in a furnace, then poured carefully into the shell. If the shell were not hot, the temperature difference would shatter it. The bronze-filled shells are allowed to cool.
11. Release.The shell is hammered or sand-blasted away, releasing the rough bronze. The spruing, which are also faithfully recreated in metal, are cut off, to be reused in another casting.
12. Metal-chasing. Just as the wax copies were "chased," the bronze copies are worked until the telltale signs of casting are removed, and the sculptures again look like the original artwork. Pits left by air bubbles in the molten bronze are filled, and the stubs of spruing filed down and polished.
13. Patinating. The bronze is colored to the artist's preference, using chemicals applied to heated or cooled metal. Using heat is probably the most predicatable method, and allows the artist to have the most control over the process. This coloring is called patina, and is often green, black, white or brownish to simulate the surfaces of ancient bronze sculptures. (Ancient bronzes gained their patinas from oxidisation and other effects of being on Earth for many years.) However, with current artistic trends in the United States, many artists prefer that their bronzes have brighter, more stylized patinas. Patinas can be applied to replicate marble or stone. Depending on how the metal is prepared, either sandblasted or polished, the finish can be either opaque or transparent. After the patina is applied, a coating of wax, which is the most traditional type of sealer, is usually applied to protect the surface. Many artists prefer to use lacquer as a sealer on some of the more unstable patinas. This protects the piece more from ultraviolet rays. Some patinas change color over time because of oxidiation, and the wax layer slows this down somewhat.
On the left is an example of a lost-wax process mold, and on the right is the resulting bronze sculpture.
On the left is an example of a lost-wax process mold, and on the right is the resulting bronze sculpture.
The lost-wax process can also be used with any material that can burn, melt, or evaporate to leave a mold cavity. Some automobile manufacturers use a lost-foam technique to make engine blocks. The model in this case is made of polystyrene foam, which is then placed into a casting flask, consisting of a cope and drag, which is then filled with casting sand. The foam supports the sand, allowing shapes to be made which would not be possible if the process had to rely on the sand alone to hold its shape. The metal is then poured in, and the heat of the metal vaporizes the foam as the metal enters the mold.
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