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Riser (casting)
A riser, also known as a feeder, is a reservoir built into a metal casting mold to prevent cavities due to shrinkage. Most metals are less dense as a liquid than as a solid so castings shrink upon cooling, which can leave a void at the last point to solidify. Risers prevent this by providing molten metal to the casting as it solidifies, so that the cavity forms in the riser and not the casting.. Risers are not effective on materials that have a large freezing range, because directional solidification is not possible. They are also not needed for casting processes that utilized pressure to fill the mold cavity. Theory Risers are only effective if three conditions are met: the riser cools after the casting, the riser has enough material to compensate for the casting shrinkage, and the casting directionally solidifies towards the riser. For the riser to cool after the casting, the riser must cool more slowly than the casting. Chvorinov's rule briefly states that the slowest cool ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reservoir
A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of water, interrupting a watercourse to form an Bay, embayment within it, excavating, or building any number of retaining walls or levees to enclose any area to store water. Types Dammed valleys Dammed reservoirs are artificial lakes created and controlled by a dam constructed across a valley and rely on the natural topography to provide most of the basin of the reservoir. These reservoirs can either be ''on-stream reservoirs'', which are located on the original streambed of the downstream river and are filled by stream, creeks, rivers or rainwater that surface runoff, runs off the surrounding forested catchments, or ''off-stream reservoirs'', which receive water diversion, diverted water from a nearby stream or aqueduct (water supply), aq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Casting
In metalworking and jewelry making, casting is a process in which a liquid metal is delivered into a mold (usually by a crucible) that contains a negative impression (i.e., a three-dimensional negative image) of the intended shape. The metal is poured into the mold through a hollow channel called a sprue. The metal and mold are then cooled, and the metal part (the ''casting'') is extracted. Casting is most often used for making complex shapes that would be difficult or uneconomical to make by other methods. Casting processes have been known for thousands of years, and have been widely used for sculpture (especially in bronze), jewelry in precious metals, and weapons and tools. Highly engineered castings are found in 90 percent of durable goods, including cars, trucks, aerospace, trains, mining and construction equipment, oil wells, appliances, pipes, hydrants, wind turbines, nuclear plants, medical devices, defense products, toys, and more. Traditional techniques include los ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molding (process)
Molding (American English) or moulding ( British and Commonwealth English; see spelling differences) is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have been made using a pattern or model of the final object. A mold or mould is a hollowed-out block that is filled with a liquid or pliable material such as plastic, glass, metal, or ceramic raw material. The liquid hardens or sets inside the mold, adopting its shape. A mold is a counterpart to a cast. The very common bi-valve molding process uses two molds, one for each half of the object. Articulated molds have multiple pieces that come together to form the complete mold, and then disassemble to release the finished casting; they are expensive, but necessary when the casting shape has complex overhangs. Piece-molding uses a number of different molds, each creating a section of a complicated object. This is generally only used for larg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cavities
Cavity may refer to: Biology and healthcare *Body cavity, a fluid-filled space in many animals where organs typically develop ** Gastrovascular cavity, the primary organ of digestion and circulation in cnidarians and flatworms * Dental cavity or tooth decay, damage to the structure of a tooth * Lung cavity, an air-filled space within the lung *Nasal cavity, a large, air-filled space above and behind the nose in the middle of the face Radio frequency resonance * Microwave cavity or ''RF cavity'', a cavity resonator in the radio frequency range, for example used in particle accelerators * Optical cavity, the cavity resonator of a laser * Resonant cavity, a device designed to select for waves of particular wavelengths Other uses * Cavity (band), a sludge metal band from Miami, Florida * Cavity method, a mathematical method to solve some mean field type of models * Cavity wall, a wall consisting of two skins with a cavity See also * Cavitation Cavitation in fluid mechanics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shrinkage (casting)
In metalworking and jewelry making, casting is a process in which a liquid metal is delivered into a mold (usually by a crucible) that contains a negative impression (i.e., a three-dimensional negative image) of the intended shape. The metal is poured into the mold through a hollow channel called a sprue. The metal and mold are then cooled, and the metal part (the ''casting'') is extracted. Casting is most often used for making complex shapes that would be difficult or uneconomical to make by other methods. Casting processes have been known for thousands of years, and have been widely used for sculpture (especially in bronze), jewelry in precious metals, and weapons and tools. Highly engineered castings are found in 90 percent of durable goods, including cars, trucks, aerospace, trains, mining and construction equipment, oil wells, appliances, pipes, hydrants, wind turbines, nuclear plants, medical devices, defense products, toys, and more. Traditional techniques include los ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directional Solidification
Directional solidification (DS) and progressive solidification are types of solidification within castings. Directional solidification is solidification that occurs from farthest end of the casting and works its way towards the sprue. Progressive solidification, also known as parallel solidification,. is solidification that starts at the walls of the casting and progresses perpendicularly from that surface.. Theory - Most metals and alloys shrink as the material changes from a liquid state to a solid state. Therefore, if liquid material is not available to compensate for this shrinkage a '' shrinkage defect'' forms. When progressive solidification dominates over directional solidification a shrinkage defect will form. The geometrical shape of the mold cavity has a direct effect on progressive and directional solidification. At the end of tunnel-type geometries, divergent heat flow occurs, which causes that area of the casting to cool faster than surrounding areas; this is cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chvorinov's Rule
Chvorinov's rule is a physical relationship that relates the solidification time for a simple casting to the volume and surface area of the casting. It was first expressed by Czech engineer Nicolas Chvorinov in 1940. Description According to the rule, a casting with a larger surface area and smaller volume will cool more quickly than a casting with a smaller surface area and a larger volume under otherwise comparable conditions. The relationship can be mathematically expressed as: :t = B \left( \frac \right)^n Where is the solidification time, is the volume of the casting, is the surface area of the casting that contacts the mold, is a constant, and is the mold constant. This relationship can be expressed more simply as: :t = BM^n Where the modulus is the ratio of the casting's volume to its surface area: : M = \frac The mold constant depends on the properties of the metal, such as density, heat capacity, heat of fusion and superheat, and the mold, such as initial t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chill (casting)
A chill is an object used to promote solidification in a specific portion of a metal casting mould. Normally the metal in the mould cools at a certain rate relative to thickness of the casting. When the geometry of the moulding cavity prevents directional solidification from occurring naturally, a chill can be strategically placed to help promote it. There are two types of chills: ''internal'' and ''external'' chills.. Types ''Internal'' chills are pieces of metal that are placed inside the moulding cavity. When the cavity is filled, part of the chill will melt and ultimately become part of the casting, thus the chill must be the same material as the casting. Note that internal chills will absorb both heat capacity and heat of fusion energy. ''External'' chills are masses of material that have a high heat capacity and thermal conductivity. They are placed on the edge of the moulding cavity, and effectively become part of the wall of the moulding cavity. This type of chill can be us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Casting Riser Types
Casting is a manufacturing process in which a liquid material is 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, which is ejected or broken out of the mold to complete the process. Casting materials are usually metals or various time setting materials that cure after mixing two or more components together; examples are epoxy, concrete, plaster and clay. Casting is most often used for making complex shapes that would be otherwise difficult or uneconomical to make by other methods. Heavy equipment like machine tool beds, ships' propellers, etc. can be cast easily in the required size, rather than fabricating by joining several small pieces. Casting is a 7,000-year-old process. The oldest surviving casting is a copper frog from 3200 BC. History Throughout history, metal casting has been used to make tools, weapons, and religious objects. Metal casting history and developmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The New Scientist
''New Scientist'' is a popular science magazine covering all aspects of science and technology. Based in London, it publishes weekly English-language editions in the United Kingdom, the United States and Australia. An editorially separate organisation publishes a monthly Dutch-language edition. First published on 22 November 1956, ''New Scientist'' has been available in online form since 1996. Sold in retail outlets (paper edition) and on subscription (paper and/or online), the magazine covers news, features, reviews and commentary on science, technology and their implications. ''New Scientist'' also publishes speculative articles, ranging from the technical to the philosophical. ''New Scientist'' was acquired by Daily Mail and General Trust (DMGT) in March 2021. History Ownership The magazine was founded in 1956 by Tom Margerison, Max Raison and Nicholas Harrison as ''The New Scientist'', with Issue 1 on 22 November 1956, priced at one shilling (). An article in the magazin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pipe (casting)
A casting defect is an undesired irregularity in a metal casting process. Some defects can be tolerated while others can be repaired, otherwise they must be eliminated. They are broken down into five main categories: ''gas porosity'', ''shrinkage defects'', ''mould material defects'', ''pouring metal defects'', and ''metallurgical defects''. Terminology The terms "defect" and "" refer to two specific and separate things in castings. Defects are defined as conditions in a casting that must be corrected or removed, or the casting must be rejected. Discontinuities, also known as "imperfections", are defined as "interruptions in the physical continuity of the casting". Therefore, if the casting is less than perfect, but still useful and in tolerance, the imperfections should be deemed "discontinuities". Types There are many types of defects which result from many different causes. Some of the solutions to certain defects can be the cause for another type of defect. The following de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
