Definitions /Dictionary/Glossary - nptel

includes all areas under pressure during complete closing of the mold. Unit pressure is calculated
by dividing the total force applied by the projected area, expressed in pounds per square inch.
Mold Protection Guard: Prevents over pressurization of the RTM mold during the injection
process.
Mold-Release Agent: Lubricant, liquid or powder (often silicone oils and waxes) that prevents
molded articles from sticking in the cavity.
Mold Shrinkage: Immediate shrinkage that occurs when a part is removed from a mold and
cooled to room temperature; the difference in dimensions, expressed in inches between a
molding and the mold cavity in which it was molded (at normal temperature measurement); the
incremental difference between the dimensions of the molding and the mold from which it was
made, expressed as a percentage of the dimensions of the mold.
Monomer: A simple molecule capable of reacting with like or unlike molecules to form a
polymer; the smallest repeating structure of a polymer; for addition polymers, this represents the
original unpolymerized compound.
Multiple-Cavity Mold: A mold with two or more mold impressions; that is, a mold producing
more than one molding per molding cycle.
Multiple Insert Tooling: Low-risk, high-output composite tooling breakthrough. MIT tooling
technology offers the composite molder quick-change multiple mold surfaces without multiple
tooling costs. Each surface is an exact clone of its counterpart, guaranteeing mold cavity
accuracy and replication of molded parts.
Nesting: In reinforced plastics, placing of plies of fabric so that the yarns of one ply lie in the
valleys between the yarns of the adjacent ply (nested cloth).
NOL Ring: Parallel filament wound test specimen used in whole or in part to measure a
material’s mechanical strength properties.
Non-Air-Inhibited Resin: Resin in which the surface cure will not be inhibited or stopped by
the presence of air.
Non-Woven Fabric: A textile structure produced by bonding or interlocking fibers, or both,
accomplished by mechanical, chemical, thermal and/or solvent means.
Notch Sensitivity: The extent to which a material’s sensitivity to fracture is increased by a
surface in homogeneity such as a notch, a sudden change in section, a crack or a scratch. Low
notch sensitivity is usually associated with ductile materials and high notch sensitivity with
brittle materials.
Orange Peel: Gel coated or painted finish that is not smooth and is patterned similar to an
orange's skin.