Definitions /Dictionary/Glossary - nptel

Flash: Portion of the charge that flows or is extruded from the mold cavity during the molding.
Also refers to extra plastic attached to a molding along the parting line that must be removed
before the part is considered finished.
Flash Point: Lowest temperature at which a substance gives off enough vapors to form a
flammable mixture.
Flexible Molds: Rubber or elastomeric plastic molds used for casting plastics. They can be
stretched to remove cured pieces with undercuts.
Flexural Modulus: A number referring to a material’s stiffness. It is used to calculate how far a
bar will bend when a bending load is applied. Units are normally millions of pounds per square
inch. (106 psi) - Giga Pascals (GPa). In two materials of equal thickness, the one with a higher
number is more resistant to deflection.
Flexural Strength: Also known as bending strength. Describes how much nonmoving load can
be applied to a bar before it yields or breaks. Units are normally thousands of pounds per square
inch. (103 psi) - Mega Pascals (MPa). Higher numbers indicate stronger materials that can
withstand a heavier load.
Flow: The movement of resin under pressure, allowing it to fill all parts of a mold. The gradual
but continuous distortion of a material under continued load, usually at high temperatures; also
called creep.
Flow Line: A mark on a molded piece made by the meeting of two flow fronts during molding.
It is also called striae, weld mark, or weld line.
Flow Marks: Wavy surface appearance of an object molded from thermoplastic resins, cased by
improper flow of resin into the mold.
Fly: Fibers that fly out into the atmosphere during handling and processing.
Foam: Lightweight, cellular plastic material containing glass-filled voids. Typical foams include
urethane, PVC, and polyester.
Force: The male half of the mold that enters the cavity, exerting pressure on the resin and
causing it to flow. It is also called punch.
Forming: It is the process of glass fiber production during which fibers are drawn, attenuated
from molten glass and collected in forming cakes.
Forming Cakes or "Cakes": Package of glass fibers produced during forming. This package is
generally found on a tube placed on a forming carrier and sent through a drying/curing oven.
"Cakes" are subsequently put into a roving creel and collected together into a roving doff.