Qingdao Rinborn Machinery Co., Ltd.
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| Comparison of Different Casting Processes | |||||
| Items | Sand Casting | Permanent Mold Casting | Die Casting | Investment Casting | Shell Mold Casting |
| Typical dimensional tolerances, inches | ± .010" | ± .010" | ± .001" | ± .010" | ± .005" |
| ± .030" | ± .050" | ± .015" | ± .020" | ± .015" | |
| Relative cost in quantity | Low | Low | Lowest | Highest | Medium high |
| Relative cost for small number | Lowest | High | Highest | Medium | Medium High |
| Permissible weight of casting | Umlimited | 100 lbs. | 75 lbs. | Ounces to 100 lbs. | Shell ozs. To 250 lbs. no-bake 1/2 lb. - tons |
| Thinnest section castable, inches | 1/10" | 1/8" | 1/32" | 1/16" | 1/10" |
| Relative surface finish | Fair to good | Good | Best | Very Good | Shell good |
| Relative ease of casting complex design | Fair to good | Fair | Good | Best | Good |
| Relative ease of changing design in production | Best | Poor | Poorest | Fair | Fair |
| Range of alloys tht can be cast | unlimited | Aluminium and copper base preferable | Aluminum base prepferable | Unlimted | Unlimited |
Metal casting are manufacturing processes in which a liquid molten metal and their alloys are usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting or casting part, which is ejected or broken out of the mold to complete the process. Casting materials are usually metals or various cold setting materials that cure after mixing two or more chemical components together. Casting is most often used for producing metal alloyed products of complex shapes those would be difficult or uneconomical to make by forging and other manufacturing processes.
Casting processes have been known for thousands of years. At modern mechanical industrial areas, thanks to the advance technology and equipment, the casting has been developed more advantages. The casting manufacturing process is still a fundamental industry and play an important role in automotive, transportation, arospaces, construction machinery, farm machinery, hydraulic, pumps and valves...almost every mechanical fields nowadays.
According to the methods how to make the mold and patterns, the casting process could divided into many categories. The most widely used casting processes are sand casting and special casting process. Some foundries also put the lost foam casting, vacuum casting as sub-categories of sand casting, because these two casting processes use the dry sand to make the mold before cast pouring. The special casting processes mainly cover lost wax investment casting, permanent mold casting, high pressure die casting, low pressure casting and gravity casting.
The castings could be also divided into different categories by the metals and alloys the foundries use as materials. At our foundry, we can produce gray iron castings, ductile iron castings, malleable cast iron castings, carbon steel casting, alloy steel castings, stainless steel casting, aluminium alloy castings, nickel based alloy castings, cobalt based alloy castings, brass and bronze castings. These metal and alloys could be cast by one or more casting processes, depending their casting performance and the required mechanical properties, dimensional tolerances and other special performances.
Casting and Machining Parts by Different Metals and Alloys
Gray iron is a type of cast iron that has a graphite microstructure. It is named after the gray color of the fracture it forms. The gray cast iron is usually used for components whose stiffness is more important than its tensile strength.
Ductile cast iron, which is also named nodular cast iron, spheroidal graphite cast iron or SG cast iron, is usually used to produce castings with high tensile strength. Ductile iron obtains nodular graphite through spheroidization and inoculation treatment.
Stainless steel castings are usually made by lost wax casting process due to that the better surface and higher accuracy. However, at RMC casting foundry, for some large-scaled castings, we also cast and pour the stainless steel by sand casting, shell mold casting and other casting processes.
The chemical composition of the alloy steel for castings can be customized for each element based on hundreds of different grades. Cast steel should be used when the strength of the castings is relatively high and the cast iron cannot meet the requirements.
High-chromium alloys are composed of chromium as a base element and the addition of other elements. Compared to nickel, metallic chromium has a higher melting point and exhibits excellent oxidation resistance, high-temperature resistance, and corrosion resistance.
Manganese alloys are ferroalloys composed of manganese, silicon, iron, and small amounts of carbon. Ferromanganese is further classified into high-carbon, medium-carbon, and low-carbon types based on its carbon content.
Aluminium and its alloys could be cast and poured by high pressure die casting, low pressure die casting, gravity casting, sand casting, investment casting and lost foam casting. Usually, the aluminum alloy castings have less weight but complex structural and better surface.
Brass castings and bronze castings both are copper-based alloy castings which could be cast by sand casting, investment casting and shell mold processes. Brass composed of copper and zinc is called ordinary brass. Diverse grades of brass and bronze can be casted at RMC foundry.
Nickel Base and Cobalt Base Alloys
The Nickel base alloy is more popular than that of Cobalt. But both of them are used for high-end machinery or industries due ot their high costs. Cobalt-based alloy is a hard alloy that can withstand various types of wear, corrosion and high temperature oxidation.
