Air Hole- Hole in a casting caused by air or gas trapped in the metal during solidification.

Alloy- Any composite metal produced by the mixing of two or more metals.

Aluminum- A light, white metal obtained from clays.

Atmospheric Pressure- The pressure of air at sea level, approximately 14.7 pounds per square inch.

Back Draft- An undesirable application of draft on a surface of a pattern. The draft slopes in the wrong direction, preventing the proper withdrawal of the pattern from the mold.

Balanced Core- One with the seated portion of the core so proportioned that it will overbalance any tipping of that part of the core extending into the mold cavity.

Basin- A cavity on top of the cope into which metal is poured before it enters the sprue.

Bedding A Core- Resting an irregular shaped core upon a bed of sand for drying.

Bench Molding- The process of making small molds on a bench.

Binders- Materials used to hold molding sand together.

Blind Riser- An internal riser which does not reach to the exterior of the mold.

Blow Hole- A hole in a casting caused by trapped air or gases.

Boot Jack Core- A type of core used in forming comparatively small openings occurring above or below the parting. The seat portion is so shaped that the core is easily dropped into place.

Boss- A projection on a casting of circular cross section.

Bottom Board- A rough board similar to a molding board upon which the finished mold rests.

Bottom Pour Mold- Mold with the gate so positioned as to allow the molten metal to enter the mold cavity at the lowest possible point.

Brass- An alloy composed chiefly of copper and zinc.

Breaker Core- Cores designed for the purpose of easy removal of risers from castings. Breaker cores are set in position over the contact area of the neck on an open riser, creating a small necking effect.

Bronze- An alloy composed chiefly of copper and tin.

Cap Core- A core superimposed upon a pattern to complete a portion of the mold cavity not given shape by the pattern.
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Patternmaking Index