Vacuum Casting
A casting 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. See Cavity, Mold, Mold Casting.
Vacuum Degassing
The use of a vacuum technique to remove dissolved gases such as hydrogen, oxygen, and nitrogen from molten alloys.
Vacuum Melting
Melting, usually by induction heating, in a closed container which is subjected to a vacuum.
Vacuum Refining
Melting in a vacuum, usually by electrical induction, to remove gaseous contaminants from the metal.
Value Analysis
In manufacturing, an analysis to determine the most economical method of manufacturing, taking into account the cost and the process capability of alternate manufacturing systems under consideration, their degree of variation, the benefits of the resultant product, and desired quality and production quantity and rate.
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 oil core manufacture. Linseed oil is an example.
Veining
Surface defect on castings appearing as veins or wrinkles, which results from cracks in the sand due to elevated temperature conditions and occurs mostly in cores. See Casting, Cores, Defect.
Veins
A discontinuity on the surface of a casting appearing as a raised, narrow, linear ridge that forms upon cracking of the sand mold or core due to expansion of the sand during filling of the mold with molten metal. See Defect.
Vent
Small opening or passage through which gases can escape during the pouring of a mold. It is alco called a vent hole.
Vent Rod
A piece of wire or bar to form the vents in the sand.
Vent Wax
Wax in rod shape placed in the core during manufacture. In the oven the wax is melted out, leaving a vent or passage.
Venting
Perforation with a vent wire of the sand over and around a mold cavity to assist in the escape of the gases.
Vertical Axis Casting Machine
A centrifugal casting machine in which the axis of rotation of the mold is vertical.
Vibrator
A mechanical device, operated by compressed air or electricity, used to loosen a pattern from a mold by jarring or vibration as it is withdrawn from the sand.
Vickers Diamond
The diamon pyramid used in Vickers Hardness Testing. See Vickers Hardness Test.
Vickers Diamond Pyramid Hardness Tester
Patented indentation hardness machine. See Hardness.
Vickers Hardness Test
A method of determining the hardness of steel using a diamond pyramid that is pressed into the polished surface of the specimen and the diagonals of the impression are measured with a microscope fitted with a micrometer eye piece. The rate of application and duration are automatically controlled and the load can be varied. See Vickers Diamond.
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 casting during solidification. See Casting, Cavity, Shrinkage, Solidification.
V-Process
A casting technique.
