-V-

Vacuum Casting . . . A casting process in which metal is melted and poured under very low atmospheric pressure; a form of permanent mold casting where the mold is inserted into liquid metal, vacuum is applied and metal drawn up into the cavity.

Vacuum Degassing ... The use of vacuum technique to remove dissolved gases from molten alloys.

Vacuum Refining . . . Melting in a vacuum, usually by electrical induction, to remove gaseous contaminants from the metal.

Vanadium ... A white, hard, metallic element, mp 1800 C (3272 F), used as an alloy in iron and steel; a powerful carbide stabilizer and deoxidizer.

Vegetable Oils . . . Oils extracted from plants, used as drying oils in core oil manufacture. Linseed oil is an example.

Veining . A defect on the surface of a casting appearing as fins, veins or wrinkles and associated with excessive thermal movement of the sand, especially core sands.

Venting ... Perforation with a vent wire of the sand over and around a mold cavity to assist in the escape of the gases.

Vibrator . . . A device, operated by compressed air or electricity, for loosening and withdrawing patterns from a mold, or for vibrating a hopper or chute to promote the flow of material from the hopper or chute.

Vickers Diamond Pyramid Hardness Tester . . . Patented indentation hardness machine.

Virgin Metal (Primary Metal) ... Metal extracted directly from the ore; not previously used.

Viscosity . . . The resistance of fluid substance to flowing, quantitatively characteristic for an individual substance at a given temperature and under other definite external conditions.

Void ... A shrinkage cavity produced in castings during solidification.