Metal Castings

Metal castings terminology is a glossary of the various terms encountered when discussing metal casting. The list of castings terms below does not cover casting processes.

Glossary of Metal Castings Terminology

• Acceptable Quality Level or AQL is determined by a process of random selection and inspection of samples.
  
• As-cast Condition – Casting process that doesn’t use subsequent heat treatments
  
• Backing Sand – Referring to the majority of the sand in the flask.
  
• Binder – An additive to the mold that strengthens or plasticizes “green” or dry core sand
  
• Burn-on Sand – The sand that sticks to the surface of the casting and is extremely hard to remove.
  
• Chaplet – A metal spacer or insert that provides core support in molds
  
• Charge – The specified weight of metal put into the furnace
  
• Chill – A metal device inserted into a sand mold to chill locally and equalize the solidification rate in the casting.
  
• Cold Shut – A surface imperfection resulting from an unsatisfactory fusion of metal
  
• Cope – The horizontally-parted mold top half
  
• Core – A metal or sand piece inserted into a mold to form the inside of the casting that cannot be formed by the pattern.
  
• Core Assembly – A number of cores together
  
• Corebox – The tool of plastic, metal or wood used to make cores.
  
• Coreprint – A part of a pattern that creates an impression to support the core in the mold.
  
• Core Wash – A refractory material in a liquid suspension that is applied to cores and when dried improves the surface of the casting.
  
• Crush – The dislocation of sand at the joints in the mold.
  
• Cupola – A straight cylinder shaft furnace used to melt metal that is in direct contact with coke by forcing pressurized air through openings in the base.
  
• Die – A permanent mold made out of metal that is used for die casting for creating a wax pattern used in investment casting
  
• Dowel – Describes the various types of pins used in both halves of a pattern or die to ensure correct alignment.
  
• Draft – The taper on a pattern or corebox that allows the sand mold or core to be removed without destroying the shape of the sand.
  
• Drag – The lower half of a horizontally parted mold.
  
• Ejector pins – The adjustable pins in dies that enable patterns to be removed
  
• Facing Sand – The sand that is closest to the pattern and produces the surface on contact with the molten metal
  
• Feeder – AKA “riser” is part of the system that forms the reservoir of molten metal required to balance the shrinkage losses created as the metal solidifies
  
• Finish Allowance – The surface material deliberately left for machining
  
• Flask – The metal or wooden box or frame that holds the sand in which a mold is created. The flask usually consists of a top “cope” and bottom “drag”.
  
• Foundry Returns – Metal bits and pieces from the gates, sprues, risers and runners and machines metal castings that are remelted in the furnace.
  
• Gas Porosity – A condition created when gas is trapped when the molten metal is poured into the casting.
  
• Gate – The part of the mold where the molten metal is poured into the mold
  
• Green Sand – The moist clay and sand for molding
  
• Heat – A single furnace charge of metal
  
• Heat Treatment – A process of timed and applied heating and cooling of a solid state metal or alloy designed to produce specific properties
  
• Hotbox – Uses coreboxes that are heated and used in a resin-based process to create cores
  
• Hot Tear – An uneven fracture created in a casting as a result of sudden temperature changes in the casting during the solidification process
  
• Inclusions – Bits of slag, metal, deoxidation products or sand trapped in the casting during the pouring and solidification process.
  
• Ladle – A spoon or cup-shaped container used to move the molten metal from the furnace to the mold
  
• Locating Pad – A raised place on a casting the enables the casting to be in proper alignment for machining
  
• Locating Surface – A casting surface that serves as a dimensional basis during secondary machining
  
• Master Pattern – Generally a metal model of the object that will be used to make a die
  
• Mechanical Properties – Those elastic and inelastic material properties that are revealed under force.
  
• Metal Lot – A master heat approved for casting and given a sequential foundry number
  
• Mold – A form made of sand, metal or other material with top and bottom sections that have cavities into which molten metal is poured.
  
• Paring Line – The line that remains when two halves are joined together
  
• Pattern – The plastic, wood, metal or plastic original form that is used to create the impression in the sand what will hold the molten metal.
  
• Pattern Draft – (See “Draft”)
  
• Pattern Layout – Full-sized diagram of a pattern, depicting arrangement and structural features
  
• Patternmaker’s Shrinkage – Each pattern has a shrinkage allowance built into the design to account for shrinkage that occurs during the cooling and solidifying process, so that once the casting has cooled it has the correct dimensions.
  
• Permeability – The ability of a mold’s material that would permit mold or core gases to escape while the molten metal is being poured
  
• Physical Properties – Describes the characteristics of matter such as electrical and thermal conductivity, density, expansion, etc. These are different properties than mechanical properties.
  
• Pig Iron – Chunks of iron of a positive metal chemical analysis that are combined with scrap in melting for ferrous castings.
  
• Pilot Casting – A sample casting made from a pattern production die in order to verify dimensional accuracy and resulting quality of subsequent metal castings.
  
• Porosity – Holes in the solidified casting as a result of trapped gasses, reaction of molten metal and sand moisture, or a less than perfect fusion of chaplets with molten metal.
  
• Recovery Rate – The total number of manufactured parts and the total percentage of those that are actually saleable.
  
• Refractory – Heat-resistant ceramic material
  
• Reject Rate – Percentage rate of those parts that must be scraped compared to the total number of parts produced.
  
• Runner System or Grating – The channels in a mold which connects the downgate to the mold cavity and feeders in which the molten metal is poured into the mold.
  
• Sand Inclusions – Surface imperfections created on a casting when sand washes into the mold cavity.
  
• Scrap – Can be any scrap metal melted to create castings or reject castings, usually melted in conjunction with pig iron or ingots.
  
• Shrinkage – The amount of contraction as the metal solidifies in the mold. It can also describe a casting defect “shrinkage cavity” which comes from insufficient or inadequate metal feed or overall poor design.
  
• Slag – A nonmetallic material that extract specific impurities from the molten metal while protecting it from the air.
  
• Slag Inclusions – Imperfections on the surface of the casting as a result of charge material, fuel ash, or silica and clay eroded from the refractory lining during the melting process. Can also be a result of metal-refractory reactions the take place in the ladle while pouring metal castings.
  
• Slurry – A liquid mixture of refractory particles
  
• Sprue – AKA “downsprue” or “downgate” describes a channel that allows the molten metal to enter the mold.
  
• Test Bar – A sample metal bar that is poured to allow the mechanical properties of the metal to be tested.
  
• Test Lug – A lug that is part of the casting that can be removed for testing
  
• Vent – An opening created in a mold or core that allows gases to escape during the pouring process.
  

Metal Castings Terminology see also Metal Casting Processes.

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