Appendix Glossary of Terms
Baked Core: A core which has been A heated for a sufficient time and temperature Abrasion: The displacement and/or to produce the desired physical properties. detachment of metallic particles from a Baked Strength: Compressive, shear, surface as a consequence of being exposed to tensile or transverse strength of a molded flowing solids, fluids or gases. sand mixture when baked at a temperature Aging: A change in properties of metals above 230 oF (110 oC) and then cooled to and alloys that occurs slowly at room room temperature. temperature and will proceed rapidly at Base Plate: A plate to which the pattern higher temperatures. The change in properties assemblies are attached and to which a flask is often, but not always, due to a phase is subsequently attached to form the mold change (precipitation), but never involves a container. change in chemical composition of the metal Blow Holes: 1) Holes in the head plate or or alloy. blow plate of a core-blowing machine Alloy: A substance having metallic through which sand is blown from the properties and composed of two or more reservoir into the core box. 2) Irregular chemical elements of which at least one is shaped cavities with smooth walls produced metal. Usually possesses qualities different in a casting when gas is entrapped during from those of the components. mold filling. The gas sources may be air, Angle Testing (UT): A method of binder decomposition products or gases ultrasonic testing using shear waves dissolved in the molten steel. introduced from the surface of the material at Blow Plate: The plate containing the core approximately 45 degrees. sand entrance holes or blow holes used in Apparent Contraction: The net open-face core boxes. contraction of a casting dimension due to true Blower, Core or Mold: A device using air metal contraction, mold wall movement, and pressure to fill a core box or flask with sand. restraint during solidification and cooling. Boss: A projection of circular cross- As Cast: Referring to metal which has not section on a casting. Usually intended for received finishing (beyond gate removal or drilling and tapping for attaching parts. sandblasting), or treatment of any kind Bracket: Strengthening strip, rib, or including heat treatment after casting. (See projection on a casting. Usually used to Finishing). prevent hot tearing. Breakoff Notch: A thinner section of a B gate or riser to facilitate clean breaking-off Backing Board (backing plate): A second during the cleaning process. bottom board on which molds are opened.
143 144 Rapid Tooling Guidelines For Sand Casting
Brinell Hardness: The value of hardness Casting Layout: A check of dimensions of a metal on an arbitrary scale representing against applicable drawings and kg/mm2, determined by measuring the specifications. diameter of the impression made by a ball of Chaplet: Metal support that holds a core given diameter applied under a known load. in place within a mold; molten metal Values are expressed in Brinell Hardness solidifies around the chaplet and fuses it into Numbers, BHN the finished casting. Buckle: 1) Bulging of a large flat face of Cheek: The intermediate section of a a casting; in investment casting, caused by flask that is used between the cope and the dip coat peeling from the pattern. 2) An drag when molding a shape requires more indentation in a casting, resulting from than one parting plane. expansion of the sand, may be termed the Chill (External): Metal, graphite, or start of an expansion defect. carbon blocks that are incorporated into the Burnishing: Developing a smooth finish mold or core to locally increase the rate of on a metal by tumbling or rubbing with a heat removal during solidification and reduce polishing tool. shrinkage defects. Chill (Internal): A metallic device/insert C in molds or cores at the surface of a casting or CAD: Computer Aided Design. within the mold to increase the rate of heat CAE: Computer Aided Engineering. removal, induce directional solidification and CAM: Computer Aided Manufacturing. reduce shrinkage defects. The internal chill CNC: Computer numerical control. may then become a part of the casting. Carbide: A compound of carbon with one Cleaning: The removal of gates, runners, or more metallic elements. and risers from the rough casting, This term Carbon: Element occurring as diamond also involves any hand finishing such as and as graphite. Carbon reduces many metals grinding or blasting. from their oxides when heated with the latter, CMM: Coordinate Measuring Machine. and small amounts of carbon greatly affect CNC Machine Tools: Computer the properties of iron. Numerical Controlled Machine Tools. Carbon Dioxide Process (Silicate Cold-Box Process: 1) Any core binder Process, Schmidt-Philipp Process): A process process that uses a gas or vaporized catalyst for hardening molds or cores in which carbon to cure a coated sand while it is in contact dioxide gas is blown through dry clay-free with the core box at room temperature. silica sand to precipitate silica in the form of Collapsibility: The requirement that a a gel from the sodium silicate binder. sand mixture break down under the pressures Carburizing: A form of case hardening and temperatures developed during casting, in that produces a carbon gradient inward from order to avoid hot tears or facilitate the the surface, enabling the surface layer to be separation of the sand and the casting. hardened by either quenching directly from Compressive Strength (Yield): The the carburizing temperature or by cooling to maximum stress in compression that can be room temperature, then reaustenitizing and withstood without plastic deformation or quenching. failure. Casting: The metal shape, exclusive of Conductivity (Thermal): The quantity of gates and risers, that is obtained as a result of heat that flows through a material measured pouring metal into a mold. in heat units per unit time per unit of cross- Appendix Glossary of Terms 145 sectioned area per unit of length, (electrical) Core Float: A casting defect caused by the quantity of electricity that is transferred core movement towards the cope surface of through a material of known cross-section the mold, as a result of core buoyancy in and length. liquid steel, resulting in a deviation from the Contraction: The volume change intended wall thickness. occurring in metals and alloys on Core Prints: Portions of a pattern that solidification and cooling to room locate and anchor the core in the proper temperature. position in the mold. Convection: The motion in a fluid Core Rod: A wire or rod of steel used to resulting from the differences in density. In reinforce and stiffen the core. heat transmission, this meaning has been Core Setting Jig/Gage: A device used to extended to include both forced and natural help position a core in the mold. motion or circulation. Core Shooter: A device using low air Cooling Curve: A curve showing the pressure to fluidize the sand mix which is relationship between time and temperature released quickly in such a way as to force it during the solidification and cooling of a into a core box. metal sample. Since most phase changes Core Vents: 1) Holes made in the core for involve evolution or absorption of heat, there the escape of gas. 2) A metal screen or slotted may be abrupt changes in the slope of the piece used to form the vent passage in the curve. core box employed in a core-blowing Conduction: The transmission of heat, machine. 3) A wax product, round or oval in sound, etc., by the transferring of energy from form, used to form the vent passage in a core. one particle to another. Corrosion: 1) Gradual chemical or Cope: Upper or topmost section of a electrochemical attack on a metal by flask, mold, or pattern. atmosphere, moisture, or other agents. 2) Coping Out: The extension of sand of the Chemical attack of furnace linings by gases, cope downward into the drag, where it takes slags, ashes, or other fluxes occurring in an impression of a pattern. various melting practices. Core: A separate part of the mold, made Cover Core: A core set in place during of sand and cured, which is used to create the ramming of a mold to cover and complete openings and various shaped cavities in the a cavity partly formed by the withdrawal of a casting. loose part of the pattern. Also used to form Core Assembly: Putting together a core part or all of the cope surface of the mold made of a number of sections. cavity. A core placed over another core to Core Arbor: An iron framework create a flat parting fine. embedded in a large core to stiffen it and for Cracking Strip: A fin of metal molded on convenience in handling. the surface of a casting to prevent hot tearing. Core Extruder: A special shell-core- Critical Cooling Rate: minimum rate of making machine that produces a continuous continuous cooling just enough to prevent length of cores, usually of cylindrical cross- undesired transformations. section. Crystallization: The formation of crystals Core Filler: Material used in place of by the atoms assuming definite positions in sand in the interiors of large cores--coke, the crystal lattice, e.g. when a metal cinder, sawdust, etc., usually added to aid solidifies. collapsibility. 146 Rapid Tooling Guidelines For Sand Casting
D ways: bilateral tolerance, unilateral tolerance Datum Plane: In layout and machining and limit dimensions. operations, the reference plane from which Direct AIM™ (ACES Injection dimensions are measured in the perpendicular Molding): This is a new "soft/bridge tooling" direction. process which quickly and inexpensively Datum Points: In layout and machining builds prototype parts using a variety of operations, the reference points that define engineering thermoplastics in a very short the datum plane from which dimensions are time without the need for production tooling. measured. The Direct AIM™ process utilizes core and Decarburization: Loss of carbon from the cavity mold halves produced using the SLA surface of a ferrous alloy as a result of process. heating in a medium, usually oxygen, that Direct Shell Production Casting (DSPC): reacts with carbon. DSPC produces the actual ceramic molds for Defect: A discontinuity in the product metal castings directly from 3-D CAD whose severity is judged unacceptable in designs using the Three Dimensional Printing accordance with the applicable product (3DP) technology. No tooling or patterns are specification. required. Deformation Test: An AFS test using an Disruptive Strength: Maximum strength instrument such as the Dietert Universal of a metal when subjected to three principal Sand-Strength Testing machine (with tensile stresses at right angles to one another deformation accessory) to determine the and of equal magnitude. amount, in inches, that the sand specimen is Dowel: A wooden or metal pin used in the compressed before it ruptures. parting surface of patterns and core boxes to Deoxidation: Removal of oxygen from locate and hold them in position. molten metal, usually accomplished by Downsprue (Sprue, Downgate): The first adding materials with a high affinity for channel, usually vertical, which the molten oxygen, the oxides of which are either metal enters. gaseous or readily form slags. Draft: Slight taper given to pattern to Die Casting: A rapid, watercooled allow drawing from sand. permanent mold casting process limited to Drag: Lower or bottom section of a mold non-ferrous metals. or pattern Dilatometer: An instrument for Drawback: A part of the mold, made of measuring the length of a metal sample green sand, which may be drawn back to during heating and cooling. clear overhanging portions of the pattern. Dimension: A dimension is a numerical Drawing: Removing the pattern from the value associated with an appropriate unit of sand. measurement. It defines the size, shape and Draw Plate: A plate attached to a pattern location of features. to facilitate drawing of a pattern from the Dimensional Tolerance: A tolerance is mold. the permissible variation in size of a feature Dry and Baked Compression Test: A placed on the specified dimension. It is sand test to determine the maximum usually assigned to a dimension based on compressive stress that a baked sand mixture limitations inherent in production processes is capable of developing. and equipment. It can be expressed in three Dry Permeability: The property of a molded mass of sand bonded or unbonded, Appendix Glossary of Terms 147 dried at 220-230 oF (105~110 oC and cooled to room temperature that allows passage of F gases resulting during pouring of molten Fabrication: The joining, usually by metal into a mold. welding, of two or more parts to produce a finished assembly The components of the E assembly may be a combination of cast and Elastic Limit: Maximum stress that a wrought materials. material will withstand without permanent Fast Freeform Fabrication (FFFF): see deformation. (See Yield Strength). Rapid prototyping. Elasticity: The property of recovering Feature: A feature is any physical portion original shape and dimensions upon removal of an object, such as a hole, surface, or of a stress. groove. It is a general term that is used to Elongation: Amount of permanent denote or refer to any part of an object. extension in the vicinity of the fractures in the Feeding: The process of supplying tensile test; usually expressed as a percentage molten metal to compensate for volume of original gage length. shrinkage while a casting is solidifying. Embrittlement: Loss of ductility of a Fillet: A concave comer piece used on metal due to a chemical or physical change. foundry patterns, a radiused joint replacing EPC (Expendable Pattern Casting): See sharp inside comers. Lost Foam Process. Fin: A thin projection on a casting due to Erosion: Abrasion of metal or other an imperfect joint in the mold. material by liquid or gas. Finish Allowance: The amount of stock Etchant: A solution for the chemical left on the surface of a casting for machining. etching of the polished surface of a metal Finish Mark: A symbol (f, f1, f2, etc.) specimen to reveal macro- or microstructures. appearing on the line of a drawing that Evaporative Pattern Casting/Expendable represents the edge of the surface of the Pattern Casting/EPC: See Lost Foam casting to be machined or otherwise finished. Process. Finite Element Analysis (FEA): A Epoxy: Containing oxygen attached to computerized numerical analysis technique two different atoms already connected to a used for solving mechanical engineering ring. A word often used by itself for epoxy problems relating to stress analysis, heat resin. transfer, and so forth. Epoxy Resin: A plastic resin and hardener Flash: A thin section of metal formed at that sets or hardens itself as room temperature the mold, core or die joint, or parting in a to form a new chemical, used as an adhesive casting due to the cope and drag not or workable material. contacting completely, or where core and Expended Polystyrene: A foamy plastic core print do not contact completely. composed of bonded beads, density between Flask: A metal frame used for making or 1 to 1.2 lb./per ft., compressive strength holding a sand mold. The upper part is the 13~15 psi. cope and the bottom half is the drag. Expended Polyurethane: A lightweight Flask Bar: A reinforcing member expanded plastic polymer whose foamed attached within either half of a flask to assist texture results from the trappings of CO2 in holding the rammed sand in position. evolved during production. In resin from it is Flask Clamp: A device for holding used for coating and adhesive. together the cope, drag and cheek of a flask. 148 Rapid Tooling Guidelines For Sand Casting
Flask Pins: Pins to fit corresponding Geometry Driver: The critical features sockets on the joint of a flask to permit which may affect or determine the tooling separation. path selection. Flask Pin Guides: Guides used to Grain Fineness Number: A system accurately align the match plate pattern in the developed by AFS for expressing the average flask and flask to flask location. grain size of a given sand, It approximates the Flat Back: A pattern with a flat surface at number of meshes per inch of that sieve that the joint of the mold. It ties wholly within the would just pass the sample if its grains were drag, and the cope is a plane surface. of uniform size. Floor Molding: Used where the pattern Green Sand: A naturally bonded sand or size prohibits the use of molding machines. a compounded molding sand mixture which The pattern is bolted to the floor and the has been tempered with water for use while assembled mold is moved by crane. still in the damp or wet condition. Fluidity: The ability of molten metal to Green Sand Core: One that is made of flow. Common devices used to measure green sand but not baked. fluidity are spiral casting and the Chinese Green Strength: The strength of a Puzzle. tempered sand mixture at room temperature. Foam Plastics: Resinoids in spongy form, as polystyrene. The sponge maybe flexible or H rigid, the cells closed or interconnected, with Hardness: Resistance of a material to a density from that of the parent resin to, in a indentation as measured by such methods as few cases, 2 lb/ft3. Brinell, Rockwell, and Vickers. The term Follow Board: A board shaped to the hardness also refers to the ability of the metal parting line of the mold. to resist scratching, abrasion, or cutting. It is Foundry Returns: Metal in the form of related to yield strength and ultimate tensile sprues, gates, runners, risers, and scrapped strength. castings, with known chemical composition High Pressure Mold: A strong high- that are returned to the furnace for remelting. density mold. Sometimes referred to as "revert". Hot Tear: A crack or fracture formed prior to completion of metal solidification as G a result of hindered contraction. A hot tear is Gage Length: The original length of that frequently open to the surface of the casting portion of the specimen over which strain or and is commonly associated with design change of length is determined. limitations. Gage Marks: Reference marks; in tensile Hot Strength (Sand): (compressive, shear testing, the marks which indicate the gage or transverse) Strength of a sand mixture length, used in determination of tensile determined at any temperature above room elongation. temperature. Gate: A channel through which the molten metal enters the casting cavity. I Gating System: The gating system is a Impact Strength: The resistance to channel, or network of channels, through impact loads; usually expressed as the foot which the molten metal flows into the cavity. pounds of energy absorbed in breaking a It is typically composed of a pouring cup, standard specimen. sprue, and runner. Appendix Glossary of Terms 149
Induction Furnace: An AC melting Keyhole Specimen: A type of notched furnace which utilizes the heat of electrical impact test specimen, which has a hole-and- induction. slot notch, shaped like a keyhole. Induction Hardening: A surface Kissing (Touching): Gating with hardening process involving the localized use minimum metal left at casting breakoff point, of pulsating magnetic currents to achieve having a gate just "kiss" the surface. heating above the austenite transformation Knockout Pins (Ejector Pins): Small temperature, AC3, followed by quenching. diameter pins affixed to a pattern back-up Induction Heating: Process of heating by plate for removing the cured mold in the electrical resistance and hysteresis losses shell-molding process. induced by subjecting a metal to the varying magnetic field surrounding a coil carrying an L alternating current. Layered Manufacturing (LM): see Rapid Ingates: See Gate. prototyping. Insert: A part usually formed from metal, Layout: A full size drawing of pattern which is placed in a mold and may become an showing its arrangement and structural integral part of the casting. features. Internal Shrinkage: A void or network of Loam Mold: A mold built up of brick, voids within a casting caused by inadequate covered with a loam bud, and then baked feeding of that section during solidification. before being poured. Internal Stresses (or Thermal Stresses): Loose Molding: The molding process Generally stresses which occur during the utilizing unmounted pattern. Gates and cooling of a part. runners are usually cut by hand. Investment Casting: Casting produced in Loose Piece: Part of a pattern that a mold obtained by investing an expendable remains in the mold and is taken out after the pattern with a refractory to produce a shell. body of the pattern is removed. It can be The expendable pattern may consist of wax, indicated as 1) Core box: part of the core box plastic, or other material, and is removed which remains embedded in the core and is prior to filling the mold with metal. removed after lifting off the core box. 2) Isocyanate Resin: A basic chemical Pattern: laterally projecting pan of a pattern component of the urethanes. so attached that it remains in the mold until the body of the pattern is drawn. Back-draft is J avoided by this means. 3) Permanent mold: Jarring Machine: A molding machine part which remains on the casting and is that packs the sand by jarring. removed after the casting is ejected from the Jig: A device arranged to expedite a hand mold. or machine operation. Lost Foam Process: Casting process in Jolting Machine: See Jarring Machine. which a foam pattern is removed from the Jolt-Squeezer Machine: A combination cavity by the molten metal being poured. machine that employs a jolt action followed by a squeezing action to compact the sand M around the pattern. Machine Allowance: Stock added to the part to permit machining to final dimensions. K Machine Finish: Allowance of stock on the surface of the pattern in order to permit 150 Rapid Tooling Guidelines For Sand Casting machining of the casting to the required compressed air; allows for faster production dimensions. than gravity rollover dump. Master Pattern: An original pattern made Mold Board (Follow Board): The board to produce metal castings that are then used upon which the pattern is placed to make the for production. mold. Matchplate: A plate on which patterns Mold Cavity: The space in a mold which and gating systems, split along the parting is filled with liquid metal to form the casting fine, are mounted. Matchplates are mounted upon solidification. back to back to form an integral piece. Mold Clamps: Devices used to hold or Mechanical Properties: Properties of a lock cope and drag flask parts together. material that reveal its strength and elastic Mold Coating (Mold Facing, Dressing): behavior. Coating to prevent surface defects on Metallurgy: The science and technology permanent mold castings and die castings. 2) of metals. A broad field that includes but is Coating on sand molds to prevent metal not limited to the study of internal structures penetration and improve metal finish. and properties of metals and the effects on Mold Jacket: A wooden or metal form them of various processing methods. slipped over a mold to support the sides Microporosity: See Microshrinkage. during pouring. Microshrinkage: Very finely divided Mold Shift: A casting discontinuity porosity resulting from interdendritic resulting from misalignment of the cope and shrinkage resolved only by use of the drag halves. microscope; may be visible on radiographic Molding, Floor: Making sand molds from films as mottling. Etching shows they occur loose patterns of such size that they cannot be at intersections of convergent dendritic satisfactorily handled on a bench or molding directions. machine, the equipment being located on the Misrun: Denotes an irregularity of the floor during the entire operation of making casting surface caused by incomplete filling the mold. of the mold. Molding, Pit: Molding method in which Mock-up: A full-size model built die mold is made in a pit or hole in the floor. accurately for study, testing or display. Molding Sand: A sand which binds Model: A representative of an object; strongly without losing its permeability to air miniature or full size. or gases. Modulus of Elasticity (E): In tension, it is Mulling and Tempering: The thorough the ratio of stress to the corresponding strain mixing of sand with a binder, either natural or within the limit of elasticity (Yield Point) of a added, with lubricant of other fluid, as water, material. For carbon and low alloy steels of any composition and treatment, the value is N approximately 30,000,000 psi. Non-destructive Testing (NDT): Testing Mold: A body of molding sand or other or inspection that does not destroy the object heat-resisting material containing a cavity being tested or inspected. which forms a casting when filled with Nucleation: 1) (Homogeneous). The molten metal. initiation of solid crystals from the liquid Mold Blower: Molding equipment for stage, or a new phase within a solid without blowing a sand mixture onto the pattern with outside interference-rarely occurs. 2) (Heterogeneous). Foreign particles altering Appendix Glossary of Terms 151 the liquid-solid interface energy during phase Pattern Draft: The taper on vertical changes usually occurs. elements in a pattern which allows easy separation of pattern from compacted sand O mixture. Oil Sands: Sands bonded with such oils Pattern Layout: Full-sized drawing of a as linseed and the synthetics. pattern showing its arrangement and structure One-Piece Pattern: Solid pattern, not features. necessarily made from one piece of material. Permanent Mold: A metal mold of two or May have one or more loose pieces. more parts; not an ingot mold. It is used Overheated: A term applied when, after repeatedly for the production of many exposure to an excessively high temperature, castings of the same form. a metal develops an undesirable coarse grain Pilot Casting: Casting produced prior to structure, but is not necessarily damaged the production run to verify correctness of permanently. Unlike burned structure, the procedures, materials, and process to be used structure produced by overhearing can be in production. corrected by suitable heat treatment, by Polymer: A compound of high molecular mechanical work, or by a combination of the weight, in which the molecules are packed two. closely, with water, alcohol and the like Oxidation: Any reaction of an element eliminated. with oxygen. In a narrow sense, oxidation Polymerization: The hardening or setting means the taking on of oxygen by an element of plastic materials, as epoxy, urethane, when or compound, and on the basis of the electron the resin and hardener are mixed together. theory, it is a process in which an element Polystyrene: A polymer of styrene used in loses electrons. making molding products. In particular, used Overhang: The extension on the vertical in the lost foam process. surface of a core print in order to provide Polyurethane: Synthetic resin polymer clearance for closing the mold over the core, used for pattern material, ranging from dense also known as “shingle”. elastomer to expanded, spongy, lightweight. Porosity: Unsoundness in cast metals due P to blow holes, shrinkage cavities and voids. Parted Pattern: A pattern made in two or Post-processing: The processing of a more parts. prototype to remove extra material, finish the Parting: Joint where mold separates to surface, and apply proper protection. permit removal of pattern. Pouring: Filling the mold with molten Parting Line: A line on a pattern or metal. casting corresponding to the separation Pouring Cup: The flared section of the between the cope and drag portions of a sand top of the downsprue. mold. Process Capability: The amount of Parting Sand: A bondless sand dusted on variation in the product of a controlled the parting surface to prevent the parts of the manufacturing process, the range defined by molds from adhering to each other. plus or minus three standard deviations. Pattern: A form of wood, plastic, foam, Pyrometry: A method of measuring metal, or other material around which temperature with any type of temperature- molding material is placed to make a mold. indicating instruments.
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Q part is required and computer numerical Quickcast: A rapid tooling process control technology is used to produce the developed by 3D Ssytems Inc. The Quickcast master pattern or mold. process utilizes a stereolithography (SLA) Rapping: Knocking or jarring the pattern model with a solid outer skin and a hollow, to loosen it from the sand in the mold before honeycombed interior. The model is dipped withdrawing the pattern. in a ceramic slurry, which is allowed to Rapping Plate: A metal plate attached to harden. When the ceramic shell is heated, the a pattern to prevent injury to the pattern and thin-walled SLA model disintegrates allowing assist in loosening it from the sand. a metal of the customer's choice to be poured Rechucking: Reversing a pattern upon a into the empty mold. After solidification, the face plate in order to permit turning the ceramic is broken away to reveal the metal opposite face to the required shape. casting which is then finish machined (adding Recrystallization: A process whereby the threads and removing burrs) as necessary. distorted grain structure of cold-worked Quenching: Rapid cooling for hardening; metals is replaced by a new, strain-free grain normally achieved by immersion of the object structure during annealing above a specific to be hardened in water, oil, or solutions of minimum temperature. salt or organic compounds in water. Resinoid: Solid materials produced by the union (polymerization) of a large number of R molecules of one or more relatively simple Ramming: Packing sand in a mold by compounds. Resinoids are classed as raising and dropping the sand, pattern, and thermosetting or thermoplastic. flask on a table. Jolt squeezers, jarring Rigging: Gates, risers, loose pieces, etc., machines, and jolt rammers are machines needed on the pattern to deliver the metal to using this principle. the mold cavity and produce a sound casting. Rapid Prototyping (RP): The physical Riser: Reservoir of molten metal from modeling of component or tooling geometry which casting feeds as it shrinks during using layered manufacturing. RP technologies solidification. make it possible to quickly generate polymer, Riser, Blind: A riser that does not break wax, metal, or paper-based prototype parts through the top of the cope and is entirely from three-dimensional solid model surrounded by sand; opened to the computer-aided design (CAD) atmosphere by means of a firecracker core. representations. Parts are typically generated Riser-Gating: Practice of running metal by building up one layer at a time, with the from the casting through the riser to help in thickness of each layer determining the directional solidification. accuracy of the part and the time required to Riser Neck: The connecting passage make it. between the riser and casting. Usually only Rapid Tooling (RT): The use of RP or the height and width or diameter of the riser CNC machining technology to quickly neck are reported, although the shape can be fabricate tooling for near net shape processes. equally important. Depending on the process and production Riser, Open: Conventional form of riser volume involved, the mold or die can be usually located at the heaviest section of the made directly or a master pattern may be casting and extending through the entire produced that is then used to make the mold height of the cope. or die. In all cases, a CAD solid model of the Appendix Glossary of Terms 153
Riser Pad (Riser Contact): An Shakeout: 1) The operation of removing enlargement of the riser neck where it joins castings from the mold. 2) A mechanical unit the casting. The purpose of the pad is to for separating the molding materials from the prevent the riser from breaking into the solidified metal casting. casting when it is struck or cut from the Shaw (Osborn-Shaw) Process: A casting. precision casting technique in ceramic molds, Rollover Board: A wood or metal plate which does not require wax or plastic on which the pattern is laid top face investment. downward for ramming the drag half mold, Shear Modulus (G): In a torsion test, the the plate and half mold being turned over ratio of the unit shear stress to the together before the joint is made. displacement caused by it per unit length in RTV: Room Temperature Vulcanizing, a the elastic range. Units are Pa or psi. term describing ability of silicone rubber to Shear Strength: Maximum shear stress a set at ambient temperatures, as in flexible, material is capable of withstanding without synthetic rubber molds. There are two failure. families, the RTV-11, 60 and 88 and a newer Shell Molding: A process for forming a high-strength RTV-662. mold from resin-bonded sand mixtures Runner: The channel through which the brought in contact with preheated (300-500 molten metal is carried from the sprue to the oF) metal patterns, resulting in a firm shell gate. with a cavity corresponding to the outline of Runner Extension: In a mold, that part of the pattern. a runner which extends beyond the farthest Shift: A casting defect caused by ingate as a blind end. mismatch of cope and drag, or of cores and Runout: A casting defect caused by mold. incomplete filling of the mold due to molten Shrinkage: The decrease in volume when metal draining or leaking out of some part of molten metal solidifies. the mold cavity during pouring; escape of Shrinkage Hole: A cavity in a casting molten metal from a furnace, mold, or due to the insufficient feed metal. melting crucible. Silica: Silicon dioxide, the prime ingredient of sand and acid refractories. S Slicing: Cutting 3D geometry into thin Sand Mulling: A method of evenly slice using a planar plane vertical to building distributing the bond around the sand grain by direction is called slicing. a rubbing action. Silicon: An abundant element, chemically Sand Reclamation: Processing of used classed as a nonmetal, metallurgically a foundry sand grains by thermal, attraction, or metal, used extensively in ferrous and hydraulic methods so that it may be used in nonferrous alloys; melting point 2593.4 oF place of new sand without substantially (1423 oC). changing current foundry sand practice. Simultaneous Engineering: Refers to the Scale Measurement: Measurements taken process where user/designer and producer from a scale drawing or a model to ascertain interact to reduce lead time and improve the the true dimensions. manufacturing efficiency of a part design. Segment: A section of a circle , the ends This process is faster and more efficient than of which are radial lines. the traditional sequential process of design and manufacture. 154 Rapid Tooling Guidelines For Sand Casting
Sintering: The bonding of adjacent Enables the data representation of a CAD surfaces of particles of a mass of powder or a solid model to be directly converted into a compact by heating to a suitable temperature photo cured plastic model of a part or tool. and cooling. STL format: A data format widely used Skeleton Pattern: A framework in rapid prototyping industry. STL is an representing both the exterior and interior of abbreviation for Stereolithography and was the casting. first proposed by 3D Systems Inc. The .STL Skewed Tolerances: Tolerances which are file is now a de-facto standard interface nonsymmetrically distributed about the between CAD packages and rapid design intent. prototyping. Skim Core (Skimmer): A flat core or tile Stock Core: Core of standard diameter placed in a mold to skim a flowing stream of usually made on a core machine and kept on metal. Commonly used in pouring basins. hand, cut to required length. Skin-Drying: Drying the surface of the Stress, Residual: Those stresses set up in mold by direct application of heat. a metal as a result of nonuniform plastic SLA: See Stereolithography Apparatus. deformation or the unequal cooling of a Slurry: A term loosely applied to any casting. clay-like dispersion. It may be used to wash Striping Plate: A plate, formed to the ladles or other refractory linings to impart a contour of the pattern, which holds the sand smoother surface. in place while the pattern is drawn through Snap Flask: One that has hinges and the plate. latches so that it may be removed from the Styrene: See Polystyrene. mold prior to the pouring. Styrofoam: A proprietary name for Soldiers: Wooden pegs used to reinforce expanded polystyrene. a body of sand. Synthetic Molding Sand: Any sand Splash Core: A core of tile placed in a compounded from selected individual mold to prevent erosion of the mold at places materials which, when mixed together, where metal impinges with more than normal produce a mixture of the proper physical and force. Splash cores are commonly used at the mechanical properties from which to make bottom of large rammed pouring basins, at the foundry molds. bottom of long downsprues, or at the ingates of large molds. T Spline: A thins strip of wood to reinforce Template: A thin piece of material with butt joints. Also known as “feather” or the edge contour in reverse to the shape to be “tongue”. checked. Split Pattern: A pattern that is parted for Tensile Strength: The maximum stress in convenience of molding. uniaxial tension testing which a material will Sprue: The opening into which the metal withstand prior to fracture. The ultimate is first poured. tensile strength is calculated from the Squeeze Board: A board used on the cope maximum load applied during the test divided half of a green sand mold to permit squeezing by the original cross-sectional area. of the mold. Tessellation: Representation of a smooth Stereolithography Apparatus (SLA): curvilinear CAD solid model surface with Equipment used for computerized building of triangular shaped facets. Most RP processes three-dimensional models and patterns. Appendix Glossary of Terms 155 require tessellated surfaces which is a part of Tooling Points: The fixed positions on the .STL data format. the casting surfaces used for reference during Thermal Conductivity: The property of layout and machining. matter by which heat energy is transmitted through particles in contact. For engineering U purposes, the amount of heat conducted Ultrasonic Testing: A nondestructive through refractories is usually given in Btu method of testing metal for flaws based on per hour for one square foot of area, for a the fact that ultrasonic waves are reflected temperature difference of one degree and refracted at the boundaries of a solid fahrenheit, and for a thickness of one inch, medium. Btu/hr - ft2 - 0F/in. Urea Formaldehyde Resin: A Thermal Shock: Stress developed by thermosetting product of condensation from rapid and uneven heating of a material. urea or thio-urea and formaldehyde, soluble Thermal Spalling: Breaking up of in water, and used as a sand binder in core refractory caused by stresses that arise during and mold compounds. repeated heating and cooling cycles. Urethane Elastomer: A resilient Thermal Stability: Resistance of a rubberlike pattern compound which has material to drastic changes in temperature. excellent abrasion resistance. It is a castable Thermocouple: A device for measuring plastic requiring a hardener to complete poly- temperatures by the use of two dissimilar merization. metals in contact; the junction of these metals Urethane Foam: See Polyurethane. gives rise to a measurable electrical potential which varies with the temperature of the V junction. Thermocouples are used to operate Vacuum Casting: A casting process in temperature indicators or heat controls. which metal is melted and poured under very 3D KeltoolTM: A rapid tooling process low atmospheric pressure; a form of developed by 3D Systems Inc. that integrates permanent mold casting where the mold is the use of SLA master patterns, RTV inserted into liquid metal, vacuum is applied, intermediate molds, 3D KeltoolTM fused and metal drawn up into the cavity. powder metal inserts and standard MUD Veins: A discontinuity on the surface of a (Master Unit Die) frames to produce cores casting appearing as a raised, narrow, linear and cavity inserts. ridge that forms upon cracking of the sand Tight Flask: A type of flask which mold or core due to expansion of the sand remains on mold during pouring. Lugs are during filling of die mold with molten metal. normally provided for clamping cope and Vent: Small opening in mold to facilitate drag together for pouring. escape of air and gases. Tongue: See Spline. Vibrator: A mechanical device used to Tooling Alternative Selection: the loosen pattern from mold. comprehensive mental exercise involved in Viscosity: The resistance of fluid selecting the most efficient way to produce substance to flowing, quantitatively sand casting tooling. It generally includes the characteristic for an individual substance at a choice of tool fabrication method, material given temperature, and under other definite selection, and choice of tooling approach. external conditions.
W 156 Rapid Tooling Guidelines For Sand Casting
Washburn Core: A thin core which Yield: Comparison of casting weight to constricts the riser at the point of attachment total weight of metal poured into mold, to the casting. The thin core heats quickly and expressed as a percentage. promotes feeding of the casting. Riser Yield Strength: The stress at which a removal cost is minimized. material exhibits a specified limiting permanent strain. X Young's Modulus (E): See Modulus of X-Ray: Form of radiant energy with wave Elasticity. length shorter than that of visible light, and with the ability to penetrate materials that Z absorb or reflect ordinary light. X-rays are Zircon: The mineral zircon silicate, usually produced by bombarding a metallic ZrSiO4, a very high melting point acid target with electrons in a high vacuum. In refractory material used as a molding material nuclear reactions, it is customary to refer to in steel foundries. photons originating in the nucleus as gamma Zirconia: ZrO4, an acid refractory up to rays, and to those originating in the 4532 oF (2500 oC) having good thermal shock extranuclear part of the atom as x-rays. resistance and low electrical resistivity. Zirconium: Silvery-white, metallic Y element, mp 3380 oF (1860 oC), a powerful oxidizer and aluminum stabilizer, when added to molten steel.
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Numbers 25mm projectile, 133 D 2D drawing, 48, 74, 100, 102, 104 Data preparation, 48 2D CAD file, 102 Data status, 102, 113 3D Modeling, 48 Datum, 84 3DP, see three dimensional printing datum reference, 85 Datum points, 31, 48, A Decision factors, 101 Accuracy, 69, data status, 101 dimensional accuracy, 69 physical parts, 101 tessellation accuracy, 75 intermediate representation, 101 Actual size, 87 production volume, 103 Allowance, 23-27, 84 prototype, 104 pattern allowance, 23 production, 104 part geometry, 104
B pattern shop capability, 106 Bridge tooling, 58-59 tool cost, 107 Build direction, 55 lead-time, 107 Building, 55 required accuracy, 107 Building procedure, 53 tool durability, 107 Decision process, 113 data status, 113 C geometry independent requirements, CAD, 15, 32, 33, 35 CAD model, 37, 38, 40 114 CAD modeling, 53 geometry analysis, 114 CAD software, 38, 102-103 alternative tooling proposals, 114 Carrier housing 1, 125-126 negotiate the final selection, 115 Carrier housing 2, 135-136 Decision space, 107 Casting, 1 sand casting, 1 Decision structure, 107 Caliper, 96 decision constraints, 110 Ceramic powders, 46 tradeoffs, 110 Cleaning, 1, 4 geometry considerations, 111 CNC based tooling, 54-55 Decision variables, 99 Cold gas dynamic spray, 68 fabrication method, 99-101 Coordinate measuring machine (CMM), 97 Core, 3, 8, 20, 34, 101, 105 tool material, 101 core making, 21, 70 tooling approach, 101 core fabrication, 34, 101 Decubing, 40, 50-51, 73-74 core fabrication process, 34 decubing error, 76-77 Core box, 34-35 Dependent factors, 101 core box fabrication, 34-35 Die casting, 53, 56, 63 Core sand molding, 8 Dimensions, 82
161 162 Rapid Tooling Guidelines For Sand Casting
basic dimension, 82 fillets, 28 reference dimension, 82 undercuts, 29 specified dimension, 82 loose piece, 29 nominal dimension, 82 ribs, 29 Dimensional accuracy, 4, 7, 9, 17, 64, 69 lugs, 29 Dimensional error, 75-77, 89 bosses, 29 Dimensional metrology, 88 Geometric dimensions and tolerances, 81 Dimensional tolerance, 83, 87 Geometric symbols, 85 Dimensional variability, 69 Geometric tolerance, 83 Direct AIM™ , 55, 58 Green sand molding, 4-7 Discretizing, 37 Draft, 27-28 Drawing interpretation, 48 H Dry-sand molding, 7 Hard tooling, see KelToolTM
Hitch housing, 121 E Errors, 69 I conversion error, 74 Ice cleat, 138 decubing error, 76 Independent factors, 101 orientation error, 76 Injection molding, 57, 63 post-finishing error, 77 Inlet boost pump, 127 process parameter error, 76 Investment casting, 57, 59-60, 66 random error, 69, 89 ISO, 87 system error, 69, 89 ISO 8062, 87 tessellation error, 74 ISO/CD 8062-2, 87 time dependent error, 77
Error sources, 69-73 ExpressTool, 68 J
K F TM Fast freeform fabrication, 33, 37-48 KelTool Process, 55, 56, 58
3DP, 45 L FDM, 41 Laminated object manufacturing (LOM ), LOM, 39 39 materials, 39-48 Least material condition (LMC), 86-87 methods, 39-48 Load material, 49 processes, 39-48 LOM based RT, 59 LOMPapersTM, 40 SGC, 44 Lost paper process, 59 SLA, 38 Lower specification limit (LSL), 92 SLS, 42 SP, 46 M FDM based RT, 66 Manifold, 128 Feature control, 84 Master core, 35-36 Fishbone diagrams, 70-74 Master pattern fabrication, 30 Fused deposition modeling (FDM), 41 manual, 31 CNC, 32 G fast freeform fabrication, 33 Gage, 95 Machine parameters, 49 Gage R&R, 95 Machine setup, 49 Geometry considerations, 28, 111 Maximum material condition (MMC), 86 Index 163
Measurement system analysis, 95-98 special patterns and device, 19 Melting, 1, 3 Photo-reactive polymer, 44 Metal prototype, 59-61 Micrometer, 96-97 Photopolymer, 39, 54 Model repair, 51 Plastic, 59 Mold dimensions, 80 Plastic prototypes, 61 Molding, 1, 3 Polysteel, 67-68 Mold making process, 4 Portage machine, 97 core sand molding, 8 Post processing, 37, 48, 50, 100 dry sand molding, 7 Pouring, 1, 3 green sand molding, 4 Precision, 88 shell molding, 8 Muzzle brake, 136 Process capability, 92 ProMetal rapid tooling, 66-67 N ProtoBuild, 47 Nickel-ceramic composite (NCC) tooling, 67 Q QuickCastTM, 58-59 O R Random error, 69 P Rapid prototyping (RP), see fast freeform Paper, 23, 33, 39-41 fabrication Parting line, 1, 28 Rapid tooling (RT), 53, 73 parting line complexity, 106 Repeatability, 88, 95 Parting plane, see parting line Reproducibility, 88 Rigid connecting link, 132 Pattern Allowance, 23 Roller bracket, 139 shrinkage allowance, 23 Room temperature vulcanizing (RTV), 56 distortion allowance, 25 Rubber plaster casting, 61 machining allowance, 26 Rubber tooling, 56 Casting finish allowance, 26 Pattern, 15 S pattern design, 20 Sand casting, 1-10 pattern fabrication, 30 Sand casting process, 1, 70 pattern type, 15 Sanders prototype (SP), 46 Patternmaking, 1, 2 Select materials, 49 Pattern design, 20 Selective laser sintering (SLS), 42-44 Pattern Materials, 20 Sensor box, 117 wood, 20 Set parameters, 49 Sheet vacuum forming, 62 metal, 20 Shell molding, 8 plastic, 21 Shrinkage, 77 styrofoam, 22 Silicone rubber molding, 57, 61 fast freeform fabrication, 22 SLS based RT, 63 Pattern Type, 15 Soft tooling, 54 single pattern, 16 Solid ground curing (SGC), 44 Solidification shrinkage, 78 loose pattern, 16 Spray metal tooling, 62 gated pattern, 17 Stereolithography, 38 match-plate pattern, 17 Stereolithography apparatus (SLA), 38 cope and drag pattern, 19 STL, 38 Stock size, see nominal dimension 164 Rapid Tooling Guidelines For Sand Casting
Surface finish, 51 System error, 69
T Tessellation, 48-49 Tessellation error, 74 Three dimensional printing (3DP), 45 Thin wall, 51 Tolerances, 81 Tool, 11 Tool design, 11 Tool construction see Tool fabrication Tool fabrication, 13 manual, 13 CNC, 14 fast freeform fabrication, 14 Tooling alternatives, 99, 108 Tooling path review form, 119 Tooling path selection process, 115 Two part negative tooling, 60 Turbine blade machining fixture, 129
U Ultrasonic machine, 98 Upper arm, 130 Upper specification limit (USL), 92
V Vacuum molding, 62 Volume contraction, 78
W Weight tolerance, 84
Y Yoke, 123