Good pouring practice contributes to quality castings.Good Pouring Practice Contributes to Quality Castings Because the soundness of a casting, in large part, depends upon how the metal enters the mold and solidifies, the pouring and handling of molten metal is critical to the success of the metalcasting process. This installment of The Metalcasting Process focuses on the importance of proper pouring practices and molten metal handling. Development of mechanical and automatic metal transfer and pouring systems are described as well. Metal Pouring The metal pouring operation in the foundry can be described simply as the transfer of molten metal in some fashion from the melting or holding furnace to the molding line and then placing the metal into a mold in a way that will result in a sound, saleable sale·a·ble adj. Variant of salable. saleable or US salable Adjective fit for selling or capable of being sold saleability or US casting. While this description may seem overly simplistic sim·plism n. The tendency to oversimplify an issue or a problem by ignoring complexities or complications. [French simplisme, from simple, simple, from Old French; see simple , good molten metal handling and mold filling techniques are crucial in producing sound castings and should not be downplayed. Poor pouring and handling practices lead to a wide variety of casting defects and, almost always, render the part unusable. For example, badly designed or poorly implemented transfer methods can lead to excessive temperature loss, which can result in cold shuts and a variety of other casting defects. If the metal is superheated su·per·heat tr.v. su·per·heat·ed, su·per·heat·ing, su·per·heats 1. To heat excessively; overheat. 2. to overcome a poor transfer system, the waste comes in the areas of energy use and refractory wear, as well as damage to the alloy. In the case of nonferrous metals that are susceptible to gas pickup, conveying, handling and pouring techniques that create excessive turbulence of the molten metal can result in gas porosity Abstract Determining the true porosity of a gas filled formation has always been a problem. While gas is a hydrocarbon, similar to oil, the physical properties of the fluids are very different, making it very hard to correctly quantify the total amount of gas in a formation. problems in the final casting. Other examples of poor pouring practice include not keeping the mold sprue sprue, chronic disorder of the small intestine caused by impaired absorption of fat and other nutrients. Two forms of the disease exist. Tropical sprue occurs in central and northern South America, Asia, Africa, and other specific locations. full during mold filling. This can lead to entrapped air in the metal, causing a myriad of gas and air problems, along with slag and dross inclusions, in the casting. Another is not providing enough metal to the mold, or breaking the molten metal stream and then restarting the pour, which can lead to pour shorts or cold shuts. On the other hand, overpouring the mold also creates significant problems. These may include wasted metal, safety hazards and additional work in subsequent operations like shakeout and sand re-use operations. These are just a few examples of the price a foundry pays for poor molten metal handling and pouring practices. In short, lack of good technique and control of the pouring operation can undo all of the good work performed in the foundry that leads up to mold filling, as well as creating problems further down the line. The actual pouring operation can be done manually, mechanically or automatically. In a manual operation, the pourer (or pourers) carries the ladle of molten metal to and directs the stream of molten metal into the mold. Since ladles have to be physically carried, the amount of metal in each ladle is dependent upon the strength of the pourers. This limits the number of molds and the size of casting that can be poured from each mold. Hand pouring, shown in Fig. 1, is usually reserved for lower volume runs and smaller castings. Mechanical pouring of molten metal is accomplished by carrying the ladle to the pouring station by means of an overhead monorail monorail, railway system that uses cars that run on a single rail. Typically the rail is run overhead and the cars are either suspended from it or run above it. system, as shown in Fig. 2. By turning a handwheel (Fig. 3), a series of gears tilt the ladle and allow the metal to be directed into the gating system. Another type of mechanical pouring ladle is tilted by using a lever. The lever replaces the handwheel and gear box. In many modern high production foundries, molten metal is poured into the molds automatically by pouring machines which use a variety of measuring and/or weighing apparatus and other controls. In most automatic pouring operations, the molds are transported to the pouring machines, rather than the metal being moved to the molding line, which is the usual case in manual and mechanical operations. Generally, the ideal molten metal handling and pouring system would be one that moves the correct amount of metal the shortest possible distance. Upon arrival at the mold line, the metal would be the correct temperature and slag or dross free. It would be poured from the proper height to achieve the required ferrostatic pressure necessary for proper mold filling. Ideally, this would result in sound, gas-, slag- and dross-free castings, accomplished in a safe and productive manner. While this ideal operation is not always possible, the metalcaster should nonetheless aim to provide as efficient a metal transfer and pouring operation as possible. Ladles Ladles are the vehicles most often used in all types of foundries for conveying and pouring molten metal. Generally, a ladle is a steel shelled vessel with refractory lining in which molten metal can be conveyed, or from which molten metal can be poured into other ladles, molds or ingots. A distributing ladle receives its metal either directly from the cupola cupola /cu·po·la/ (koo´pah-lah) cupula. cu·po·la n. A cup-shaped or domelike structure. cupola cupula. spout, melting furnace, forehearth or duplexing furnace. From there, the metal is conveyed to and deposited in smaller ladles for pouring. In other cases, the ladle that receives the tapped metal from the primary melter or holding furnace is also used as the pouring vessel. While a wide variety of ladles are used in foundries, they are most often characterized by their external shape and spout design. The most common external shapes include straight-sided, tapered ta·per n. 1. A small or very slender candle. 2. A long wax-coated wick used to light candles or gas lamps. 3. A source of feeble light. 4. a. and cylindrical. Common spout designs are top lip, teapot spout and bottom nozzle. These spout designs are illustrated in Fig. 4. The teapot ladle receives its name from the fact that it has a deep, internal well adjacent to the lip. Since the opening to this well is near the bottom of the ladle, as in a teapot, metal enters the pouring spout from beneath the metal surface, thereby retaining in the ladle any particles of floating slag or dross. As is shown throughout this article, there are ladles available to meet the needs of nearly any casting operation. For example, many small nonferrous foundries use crucible crucible, vessel in which a substance is heated to a high temperature, as for fusing or calcining. The necessary properties of a crucible are that it maintain its mechanical strength and rigidity at high temperatures and that it not react in an undesirable way with pouring, in which metal is poured from the same crucible in which it is melted. Melting is done in crucible furnaces of different types. The crucible is removed from the furnace by means of tongs tongs long-handled, about 3 feet, shaped like pincers with knobs on the ends of the grasping blades. Applied by standing behind the subject in a confined space and closing the jaws to grasp the animal's head just below the ears. . For pouring, the crucible is transferred to a pouring shank shank (shangk) 1. leg (1). 2. crus ( 2). shank n. The part of the human leg between the knee and ankle. , a device which holds the crucible and permits manual tilting. Many steel foundries, on the other hand, may use very large bottom-pour ladles. In any case, the ladle or ladles should be designed and sized according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the individual foundry's needs. And, the important factor in ladle selection is heat loss. For example, a 300 lb ladle of iron tapped at 2800F (1537C) and held at room temperature will normally lose heat more rapidly than a 2000 lb ladle of iron tapped and held at the same temperature. Also, a tall, small diameter ladle will lose less heat in a given amount of time than a shorter, larger diameter ladle lined with the same refractory and holding the same amount of molten metal. This is because there is less surface area of metal exposed to the air in the tall, smaller diameter ladle. All ladles should be preheated, thoroughly dried and kept close to service temperature by good scheduling of metal delivery. Lining life will be extended when ladles are kept at a high temperature to reduce damage caused by the thermal shock Thermal shock in mechanical models Thermal shock is the name given to cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high of cooling and reheating Reheating The addition of heat to steam of reduced pressure after the steam has given up some of its energy by expansion through the high-pressure stages of a turbine. . Gas and oil torches and electric ladle heating covers are commonly used for ladle preheating. However, ladles should be allowed to cool as often as practical for cleaning. Dross and slag should be chipped away periodically to avoid recontamination of the melt. When necessary, refractory patches can be rammed- or gunned-in to fill areas where the refractory has eroded. Also, lips and spouts should be kept free of accumulated slag or dross. All ladle refractory patching should be dried completely before the ladle is returned to use. An uncured lining can create steam during filling and cause a serious explosion. Another safety measure is to provide vent holes in the steel ladle shell. These should be kept open to permit steam to escape. Uncovered hot ladles cool rapidly if there is a delay between fills. Insulated covers help reduce heat loss from an empty ladle as well as from a full ladle. Ladle covers reduce temperature loss from the metal surface and also retain heat during a delay in pouring schedules. They also serve to protect pourers from the intense heat. Economics also dictates that heat losses be minimized and that the proper size ladle be used for each production run. It is uneconomical to continually pig that portion of the metal which is too cold to pour. Holding the cooled portion, or heel, until a new hot batch is received is not a good alternative, because it will chill the next ladle of hot metal. Figure 5 demonstrates one method for calculating ladle capacities. Pouring Nonferrous Alloys Handling and pouring some nonferrous alloys present some unique problems, so it is important to identify some characteristics of nonferrous alloys which will affect their pouring. Nonferrous alloys may be distinguished on the basis of their oxidation behavior during melting and pouring. Several families of alloys, including aluminum alloys and some bronze, brass and zinc alloys form insoluble films of oxide or dross on the surface of the melt. These alloys are very susceptible to defects caused by the entrapment entrapment, in law, the instigation of a crime in the attempt to obtain cause for a criminal prosecution. Situations in which a government operative merely provides the occasion for the commission of a criminal act (e.g. of these films as inclusions in the casting. To avoid these conditions, stirring of the molten metal should be avoided in order to prevent oxide films from being pushed under the surface. After the ladle is filled, or the crucible has been removed from the furnace, the metal should be carefully skimmed skim v. skimmed, skim·ming, skims v.tr. 1. a. To remove floating matter from (a liquid). b. To remove (floating matter) from a liquid. c. just before pouring. If the metal must be transferred to a pouring ladle, an effort should be made to minimize the height of fall of the metal during transfer. Likewise, pouring should be done smoothly and evenly to avoid splashing and interrupting the metal stream. With careful pouring of these skin-forming alloys, it is possible to form and maintain and oxide "sleeve" around the metal stream, thus protecting the molten metal from undue exposure to the surrounding air. Pumps have been used to transfer nonferrous metals for over 30 years, but improved design, closer component tolerances and new materials have resulted in improved reliability and increased acceptance. Pumps are used in a number of nonferrous applications including: transport between melting and holding furnaces; direct filling of molds, tundishes or casting units; and supplying refining vessels. The two most common types of pumps are electromagnetic induction electromagnetic induction: see induction. electromagnetic induction Induction of an electromotive force in a circuit by varying the magnetic flux linked with the circuit. and centrifugal centrifugal /cen·trif·u·gal/ (sen-trif´ah-gal) efferent (1). cen·trif·u·gal adj. 1. Moving or directed away from a center or axis. 2. . Most are made either of graphite or stainless steel stainless steel: see steel. stainless steel Any of a family of alloy steels usually containing 10–30% chromium. The presence of chromium, together with low carbon content, gives remarkable resistance to corrosion and heat. . In a centrifugal pump centrifugal pump Machine for moving liquids and gases. Its two major parts are the impeller (a wheel with vanes) and the circular pump casing around it. In the most common type, called the volute centrifugal pump, fluid enters the pump at high speed near the centre of the , either air or electricity is used to turn an impeller. Electrically driven centrifugal pumps are capable of a discharge velocity as high as 1100 ft/min. Operation of electromagnetic pumps may best be described using the analogy of an electric motor in that the metal itself is electrically charged and acts like the rotor, while the pump acts as the stator stator: see generator; motor, electric. . Metal is transferred by continuously reversing the flow of the metal many times each second. The flow rate is controlled by changing the level and frequency of the current in the stator. Automatic Pouring Due to the very nature of the molten metal pouring operation, it can be one of the most uncomfortable jobs in the foundry. And because it is so critical in producing quality castings, many foundries have automated the process where practical. Automatic pouring devices can offer the advantages of increased productivity and metal yield, improved quality and process control, labor savings and reduced scrap. Productivity improvement is due to the consistency of pours from one mold to then next. Increase in yield owes to increased accuracy, resulting in the elimination of overpours, spills and pigging of ladle heels. Labor savings, of course, come from reducing the number of people needed in the pouring operation. The elimination of interrupted pours and irregular pour rates bring about major reductions in scrapped and defective castings. Some automatic pouring units also improve melt temperature control and permit a reduction in pouring temperatures, resulting in better process control and savings in energy and refractory consumption. Also, isolation of the operator from the effects of molten metal spatter spatter, n droplets of airborne particulate matter larger than 50 μm that fall to the ground. , gases, heat and smoke provide health and safety benefits. There are two basic methods of automatic pouring: mechanized mech·a·nize tr.v. mech·a·nized, mech·a·niz·ing, mech·a·niz·es 1. To equip with machinery: mechanize a factory. 2. ladle pouring and automatic direct pouring. Mechanized Ladles--These are used to transfer measured amounts of metal from a storage vessel or controlled pouring unit to the mold. Automated dip and pour mechanized ladles also are used, primarily in nonferrous operations. Units are programmed to duplicate pouring sequences for a given mold requirement using load cell weighing systems and controlled tilt rates. Carrousel System--One automated mechanized ladle system, which has been in use for over a decade, uses a carrousel to synchronize See synchronization. pouring with a continuously moving molding line. The ladles are filled under a pour box attached to a holding furnace. The pouring ladles rotate from pour to fill and back on a circular carrousel track. A timed, air-activated stopper rod controls the amount (said to be accurate to within 2%) of metal dispensed to the ladle. Direct Pouring--Direct bottom-pour ladles use either slide gates or, more commonly in foundry operations, stopper rods and nozzles to control the flow of metal to the mold. Metal is metered directly into the mold from the pouring vessel. An automatic iron pouring system with ladles and stopper rod control is shown in Fig. 6. With the addition of resistance or induction heating induction heating Method of raising the temperature of an electrically conductive material by subjecting it to an alternating electromagnetic field. Energy in the electric currents induced in the object is dissipated as heat. equipment to the pouring vessel, the metal temperature can be controlled. Also, the vessel will hold the molten metal and replace heat losses during pouring interruptions. Electric Pouring Furnaces--Metal transfer and pouring vessels are eliminated entirely when the molding line is brought to a stationary melting/pouring vessel. Resistance furnaces typically are bottom-pour units with stopper rods and nozzles mounted in the furnace bottom or in an attached pour box. Automatic pouring from a channel furnace, illustrated by Fig. 7, can be accomplished either through a pour spout or a nozzle, with or without a stopper rod. This is because the vessels can be sealed and pressurized pres·sur·ize tr.v. pres·sur·ized, pres·sur·iz·ing, pres·sur·iz·es 1. To maintain normal air pressure in (an enclosure, as an aircraft or submarine). 2. with an inert gas inert gas or noble gas, any of the elements in Group 18 of the periodic table. In order of increasing atomic number they are: helium, neon, argon, krypton, xenon, and radon. . The pressure can be varied to control the rate of pouring or to establish a constant head pressure above the nozzle. Consistent pouring is the result in either case. Pouring Controllers Some pouring controllers control only the volume of metal poured per mold. More sophisticated units control both volume and rate of molten flow, while others control the positioning of the mold and nozzle as well. Some systems use simple timing devices which may be reset depending upon the size of the mold. Most mechanized ladling systems use an automatic scaling device to measure the weight of metal dispensed based on the exact weight of metal required for the mold. Once programmed with this information, programmable controllers Programmable controllers Electronic computers that are used for the control of machines and manufacturing processes through the implementation of specific functions such as logic, sequencing, timing, counting, and arithmetic. permit repeatable, controlled pouring duration. Control of the rate of molten metal flow (pour rate) is necessary to maintain the proper height of metal in the sprue to achieve the required ferrostatic pressure necessary for proper mold filling. To achieve such control in automatic pouring, more sophisticated stopper rod controls are used. If the metal flow rate is consistent through the nozzle, programmed repetition of calculated stopper rod positions provides a controlled, consistent pouring rate. However, slag buildup on the nozzle and/or variations in metal head pressure can cause flow variations. In such cases, a real-time feedback loop can compensate for these variations to maintain a consistent pour rate. Sensing systems that measure the rate of mold fill or level of metal in the pour cup have been developed for this purpose. The level of the molten metal in the mold may be measured either with a video camera or laser measuring probe. These measurements are used to control the position of the stopper rod and thus, the pour rate. Video System--The video system displays an edited and digitized picture that separates the molten metal stream from the rest of the pouring basin, based on the brightness level of the stream. The area of metal fill can be compared to the actual area of the pouring basin, providing a comparative value used to control the position of the stopper rod. Laser System--A laser measurement system makes use of optical triangulation triangulation: see geodesy. The use of two known coordinates to determine the location of a third. Used by ship captains for centuries to navigate on the high seas, triangulation is employed in GPS receivers to pinpoint their current location on earth. between the laser probe source, the top of the mold and a photodetector A device that senses light. It uses the principle of photoconductivity, which is exhibited in certain materials that change their electrical conductivity when exposed to light. See photoelectric, photocell and photodiode. . The laser probe focuses on the top of the mold when positioning the next mold for pouring. Also, it focuses on the level of metal in the sprue cup when controlling the pour rate. The photodetector measures the distance of light reflected back from the mold top or sprue cup. During the positioning phase, the probe monitors the top surface of the mold and detects the leading edge of the pour cup as it moves into place under the pouring nozzle. Because the indexing stroke has been programmed into the controller's memory, the controller can calculate the final pouring position of the incoming sprue cup. The pouring until will be automatically adjusted to the proper position above the sprue cup during mold indexing. During the pour, the system continuously measures the level of the molten metal in the pour cup. This level is continuously compared to a predetermined pre·de·ter·mine v. pre·de·ter·mined, pre·de·ter·min·ing, pre·de·ter·mines v.tr. 1. To determine, decide, or establish in advance: , ideal level. A servo actuator A mechanism that causes a device to be turned on or off, adjusted or moved. The motor and mechanism that moves the head assembly on a disk drive or an arm of a robot is called an actuator. See access arm. throttles the stopper rod, allowing the desired level of metal to be reached quickly. The system then maintains the proper level. Mold Filling Automatic mold filling methods are ideal methods for production of precision castings, meeting requirements for greater casting integrity, as well as thinner wall thicknesses enhanced mechanical properties. They utilize such techniques as pressurized pouring vessels or flasks with vacuum capability to effect metal transfer, or both. CLA/CLAS--Developed in the U.S., these patented counter gravity low pressure processes (CL) for filling of investment ceramic molds with air melt alloys (CLA CLA, n.pr See acid, conjugated linoleic. ) and vacuum melt alloys (CLV (Constant Linear Velocity) Rotating a disk at varying speeds. By changing speed depending on which track is being accessed, the density of bits in each track can be made uniform. ); and for filling of chemically bonded molds with air melt alloys (CLAS CLAS 1. Cholesterol-Lowering Atherosclerosis Study A study using colestipol and niacin in ♂ with previous CABG surgery 2. Circulating lupus anticoagulant syndrome. See Antiphospholipid antibody syndrome, Lupus anticoagulant. ), permit highly consistent mold filling with less turbulence. The basic concept of the CLA process, typically used to cast aluminum alloys, is to place the mold in a special casting chamber that has vacuum capability. The mold, open at the bottom, is submerged into the molten metal vessel. The porosity of the mold permits it to be filled when a vacuum is created in the chamber. Similarly, in the CLAS process, which is most applicable for a variety of iron and steel alloys, castings are gated from the drag half of the mold. The cope is attached to a vacuum chamber and the drag is submerged in the molten bath. Metal is pulled up into the mold cavities by vacuum and decomposition gases are drawn up into the vacuum system vacuum system Urology A mechanical system used to facilitate and maintain an erection; an erection erector. Cf Penile implant. . One important feature of both these processes is a reduction in nonmetallic non·me·tal·lic adj. 1. Not metallic. 2. Chemistry Of, relating to, or being a nonmetal. Adj. 1. inclusions. Floating slag is held at the meltlining area by the meniscus meniscus /me·nis·cus/ (me-nis´kus) pl. menis´ci [L.] something of crescent shape, as the concave or convex surface of a column of liquid in a pipet or buret, or a crescent-shaped cartilage in the knee joint. established by the holding force on the melt and is not carried into the mold. Instead, molten metal is drawn into the mold cavity from the clean portion of the melt, below the slag layer. Cosworth Process--A low pressure sand casting Casting is the process of production of objects by pouring molten material into a cavity called a mold which is the negative, or mirror image of the object, and allowing it to cool and solidify. process to produce high integrity aluminum alloy castings was developed in England in 1978. The mold is filled from below in such a manner that the metal rises with an unbroken surface. Filling head and feeding pressure is provided by an electromagnetic pump which is permanently submerged in the holding furnace. Flow rate can be controlled with extreme precision. Efficient degassing degassing (dēgas´ing), adj related to degasification, the process by which dissolved gas is removed from water or other liquid solutions. is provided in the furnace. An inert gas blanket minimizes subsequent gas pickup and oxidation. The mold is allowed to solidify under pressure and any further requirement of the mold for additional feed-metal is supplied under pressure by the pump. Zircon zircon Silicate mineral, zirconium silicate, ZrSiO4, the principal source of zirconium. Zircon is widespread as an accessory mineral in acid igneous rocks; it also occurs in metamorphic rocks and, fairly often, in detrital deposits. sand is used as the molding medium because of its low expansion and high heat extraction rate. The high heat capacity, said to approach that of permanent molds, along with pressure solidification, creates very rapid, directional solidification Directional solidification is a series of measures applied to control the feeding of castings. As most metals and alloys solidify, changing from the liquid state to the solid state they will undergo an appreciable volume contraction. of the casting back to the ingate. FM--The font mince (thin iron) or FM process was developed by a French foundry. It is a casting process using a controlled differential pressure to produce complex, very thin walled irons, steels and superalloys. Controlled, very rapid filling of molds is accomplished by combining: * a low pressure exerted on the liquid metal; * a negative pressure on the mold; * evacuation of gases from the mold; * casting in open molds with air gating. The effects of reduced pressure In thermodynamics, the reduced pressure of a fluid is defined as its actual pressure divided by its critical pressure. Vacuum Lift Foam Filled Casting Process--Perhaps the newest counter-gravity casting process is one especially designed to improve the cleanliness of high quality steels produced in the evaporative evaporative pertaining to evaporation. evaporative loss loss of body water by evaporation of water from the body to the air; a heat control mechanism and a factor in water balance studies. pattern casting (EPC (1) (Entertainment PC) See HTPC. (2) (Electronic Product Code) A standard code for RFID tags administered by EPCglobal Inc. (www.epcglobalinc.org). ) process. A vacuum pump Vacuum pump A device that reduces the pressure of a gas (usually air) in a container. When gas in a closed container is lowered from atmospheric pressure, the operation constitutes an increase in vacuum in this container. attached to the top of an EPC flask flask (flask) 1. a laboratory vessel, usually of glass and with a constricted neck. 2. a metal case in which materials used in making artificial dentures are placed for processing. creates a negative pressure throughout the flask due to the permeability of the unbonded sand. The vacuum draws the metal from the pouring vessel up into the flask through a porous media tube. The process reduces turbulence and atmospheric contamination of the molten steel. Castyral--Another new EPC process adds isostatic i·sos·ta·sy n. Equilibrium in the earth's crust such that the forces tending to elevate landmasses balance the forces tending to depress landmasses. pressure to the sand flask in order to improve soundness and mechanical properties in EPC-cast aluminum alloys. The method consists of placing the flask in a pressure vessel Pressure vessel A cylindrical or spherical metal container capable of withstanding pressures exerted by the material enclosed. Pressure vessels are important because many liquids and gases must be stored under high pressure. . Immediately after pouring, the pressure is increased gradually to a value which is held until solidification is complete. PHOTO : Fig. 1. Hand pouring is usually reserved for smaller nonferrous castings. PHOTO : Fig. 2. Mechanical pouring of molten metal by means of an overhead monorail system is PHOTO : shown. PHOTO : Fig. 3. By turning a handwheel, a series of gears tilt this ladle. PHOTO : Fig. 4. Shown are typical foundry ladle a vessel for holding molten metal and conveying it from cupola to the molds. See also: Foundry types--(a) teapot; (b) bottom pour; (c) teapot PHOTO : shank; (d) lip-pour shank. Reprinted from "Metals Handbook, Ninth Edition, vol 15", PHOTO : courtesy of ASM International ASM International, formerly known as the American Society for Metals, is a professional organization for materials scientists and engineers working with metals. ASM provides several information resources, including standards and the ASM Handbooks, a series of reference books . PHOTO : Fig. 5. A practical method for calculating ladle capacities is shown. Reprinted from PHOTO : "Useful Information for Foundrymen," courtesy of the Whiting Corp. PHOTO : Fig. 6. An automatic iron pouring system utilizing intermediate ladles and stopper rod PHOTO : control is shown, courtesy of Asea Brown Boveri Corp. PHOTO : Fig. 7. This automatic pouring furnace utilizes an induction channel loop to maintain PHOTO : temperature, a pressurized vessel to maintain the proper metal head above the pouring PHOTO : nozzle and a laser controlled stopper rod to control the pouring rate. Photo courtesy of PHOTO : Inductotherm Corp. |
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