CASTINGHOBBY FAQ
(Frequently Asked Questions.)

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Glossary


This is intended to explain a lot of the jargon used in a foundry. Whether it is a backyard affair or a commercial foundry, a cupola or an induction furnace, it helps if we all call things by their right names. 


  • Alloy
  • A combination of metals melted together.

  • Blast gate
  • A device used as a valve for air. It works similar to a gate valve.

  • Burner, blown
  • A device for mixing fuel with air to form a burnable mixture with the aid of a fan or blower.

  • Burner, naturally aspirated
  • A device for mixing fuel (usually propane) with air to form a burnable mixture without the aid of a fan or blower.

  • Charge
  • A quantity of metal, usually about to be melted.

  • Cheek
  • Part of a flask used when a deeper flask is needed. The cheek is an additional section of flask and goes between the cope and drag.

  • CNC
  • Computer Numeric Control. The term used for the motion control interface used to drive machine tools with a personal computer (used mostly in hobby tools) or a dedicated electronic controller (used mostly in commercial machines). CNC milling can be used for pattern making. There are also CNC controlled hot wire cutters for foam.

  • Cold shot
  • Casting defect where two or more streams of molten metal meet in a mold, but fail to weld together. Caused by pouring too slow, or too cold. May also be improperly designed gates that won't allow the mold to fill fast enough.

  • Cope
  • The upper part of the flask when it is in pouring position. (Cope and Drag)

  • Coping down
  • The act of digging away sand in the cope after ramming to expose the parting line of the pattern.

  • Core
  • A device (made in the foundry or bought from a foundry supply) for leaving voids in a casting that would otherwise be impossible to mold. For example, a cylindrical shaped core to leave a hole for a shaft.

  • Crucible
  • A device of refractory material shaped to hold metal as it is melted and poured.

  • Degassing
  • The act of removing absorbed gasses from the melt, such as adding a degassing agent.

  • Die casting
  • Casting using a permanent mold (a die) and forcing the molten metal into the mold under pressure.

  • Draft
  • The taper of a pattern to allow it to be removed from the sand mold.

  • Drag
  • The lower part of the flask when it is pouring position. (Cope and Drag)

  • Drawing
  • 1. The act of removing a pattern from the sand mold.
    2. A sketch or print that gives the dimensions of a part.

  • Dross
  • Impurities on the melt that must be removed by skimming before the pour. Slag.

  • English flask
  • See Flask, English.

  • Facing sand
  • New or very good bank sand that is riddled (sifted) onto the pattern before bank run sand is packed in the flask.

  • Fire brick
  • High temperature bricks with a fusion point not less than 2876 degrees F or 1580 degrees C. (note 1)

  • Fire clay
  • Clay with a fusion point not less than 2868 degrees F. (note 1)

  • Flask
  • A device usually shaped like a box without top or bottom and separated into two (or more) halves, a cope and a drag. It is used to hold the molding sand around the pattern as it is rammed.

  • Flask, English
  • A flask that is designed to be stood on end and poured.

  • Flask, Snap
  • A flask that has hinges on one corner and latches opposite that allow the flask to open after the mold is rammed. The same snap flask can then be used for the next mold allowing you to make many molds at a time with just one flask.

  • Furnaces
  • Devices for concentrating heat to achieve melting temperatures.

  • Gate
  • A tunnel in the sand mold connecting the sprue and the mold cavity.

  • Green sand
  • A mixture of fine sand, bentonite clay and water.

  • Hot wire foam cutter
  • A device used to cut foam for pattern making. Usually made with electrically heated resistance wire. (Ni-Chrome, Kanthanal, Guitar string)

  • Inclusion
  • Casting defect where foreign material is included into the casting, such as a sand inclusion.

  • Inserts
  • Parts formed of a second material placed in the mold before pouring, such as a steel pin that is required to be bonded to an aluminum casting. (note 1)

  • Jacket
  • A jacket is a wood or metal frame which is placed around a mold made in a snap flask during pouring to support the mold and prevent a run out between the cope and drag. The common practice is to have as many jackets (for each size snap flask) as can be poured at a time. ….. The jackets must be kept in good shape and fit like a glove. (note 1)

  • K-bond
  • An oil bonded sand similar to petrobond, but mixed by the user from individual ingredients instead of purchased readymade.

  • Machining allowance
  • The practice of adding depth to a pattern in areas where the casting will be machined.

  • Match plate
  • A device that fits between a cope and drag and mounts a pattern. The pattern is split at the parting line and half mounted above and half below the match plate. It is also common to have the gating system on the match plate. The purpose is to allow faster ramming of molds for a repetitive pattern.

  • Mold
  • A device used to form molten metal to a specific shape. For example, the rammed sand inside a flask.

  • Molding board
  • Flat board used under a flask when ramming, thick enough not to spring as the sand is rammed.

  • Molding sand
  • A mixture of fine sand and binder that when packed will hold the shape of a pattern.

  • Mull, Mulling
  • The process of coating sand with clay via a smearing action as well as mixing.

  • Muller
  • A device that mulls foundry molding sand.

  • N. A.
  • Abbreviation for Naturally aspirated.

  • Naturally Aspirated
  • Regarding burners, naturally aspirated generally means there is no blower to force air into the burner. See also Burner...

  • Oil Bonded Sand
  • A mixture of fine sand, bentone clay and oil that will pack very hard. also called Petrobond, K-bond.

  • Parting dust
  • A powder that coats the surface of an object so that the molding sand will not stick to it. This allows a pattern to be drawn from the sand and leave a clean, sharp impression behind. Parting dust also coats the sand in one half of the mold and prevents the sand in the other half from sticking to it. This allows the halves to be separated and the pattern removed. This separation line is called the parting line. (Shamelessly stolen from Budget Casting Supply's on-line catalog). Old books talk about using rafter dust. An old sock makes a good dispenser. Shake it to release the parting dust. Store in an air tight container to keep it dry. People also use talc or baby powder.
     
  • Parting line
  • The widest point of a pattern. The point that will allow a mold to separate easily.

  • Pattern
  • A pattern is a device used to make the hollow cavity of a mold. It can be thought of as the positive or original. Traditionally made of wood, it can be made of anything that will withstand the pressure of being rammed in the sand.

  • Petrobond
  • Commercially available oil bonded sand.

  • Plinth, Plinth block
  • Refractory pedestal for the crucible to sit on.

  • Pouring shank
  • See shank.

  • Pyrometer
  • A device used to measure very hot temperatures. A thermometer with a very high range.

  • Rammer
  • A tool used to pack sand in a flask.

  • Ramming
  • The act of packing molding sand into a flask.

  • Refractory
  • A substance that resists break down by heat.

  • Riddle
  • A screen for sifting molding sand.

  • Riser
  • A riser is similar to a sprue because it is a vertical hole in the sand. A riser is a place for metal to go after the mold is full. Watching the riser will tell you when the mold is full, but it also feeds metal back to the casting as the metal cools and shrinks. Ideally, and shrink voids should be in a riser and not in the casting. Risers should be placed at the thickest parts of the casting.
  • Shake out
  • The act of removing castings from the sand mold.
  • Shank (or pouring shank)
  • A tool for holding a hot crucible and tipping it to pour the hot metal. Often shaped like a ring with shafts extending from it; may have a latch to keep the crucible from toppling out.
  • Short pour
  • A casting defect where the mold doesn't fill completely. Caused by pouring too cold, too slow or interrupted pouring.
  • Shrink, Shrinkage
  • Metals contract when cooling and solidifying. This contraction is called shrink, and is predictable for a particular metal. This is important when making patterns because they must be oversize by the shrink amount for a close tolerance casting.
  • Shrink cavity, shrink depression
  • Casting defect caused by lack of feed metal as the casting solidifies.
  • Shrink Rule
  • A device used by pattern makers. It appears to be a regular ruler, but the graduations are over sized to make up for the shrink in the metal poured. Shrink rules are specific to the metal being cast, due to different metal having different shrink rates.
  • Slush casting
  • A method akin to ceramics where the mold is poured with metal and almost immediately emptied of its molten metal by dumping. This leaves a thin shell of solidified metal in the mold. Used for making hollow castings like small statues or lamp bodies.
  • Snap flask
  • See Flask, snap.
  • Sodium Silicate
  • See Water Glass.
  • Sprue
  • A vertical hole in the sand mold that molten metal is poured into.
  • Thermocouple
  • Thermocouples are two dissimilar metals welded at the end. When you heat dissimilar metals, a voltage is generated proportional to the temperature.
  • Tongs
  • A tool to grasp and lift a hot crucible from a furnace.
  • Upset
  • When you need a taller cope section or drag section, then the flask on hand you use a frame of the required additional depth.(note 1)
  • Water Bonded Sand
  • See Green sand.
  • Water Glass
  • Also known as sodium silicate. It is a honey-like liquid that hardens in the presence of CO2. It is used for cores by mixing with straight (unbonded) sand and packed into a core box (mold) and then CO2 is passed through it to instantly harden it. Alternatively, you can let it air harden, but it takes much longer.

    Note 1...Information sourced from The Metalcaster's Bible by C. W. Ammen