Definitions /Dictionary/Glossary - nptel

One-Off: A fabrication process in which a single part is fabricated.
One-Part Resin System: A resin system (often used in resin-transfer molding) in which the neat
resin and catalyst are mixed together by the materials supplier as part of the resin production
operation.
One-Sided Tolerance Limit Factor: See Tolerance Limit Factor.
Orange Peel: Backside of the gel coated surface that takes on the rough wavy texture of an
orange peel.
Organic: Matter originating in plant or animal life or composed of chemicals of hydrocarbon
origin, either natural or synthetic.
Orientation: The alignment of the crystalline structure in polymeric materials in order to
produce a highly aligned structure.
Oriented Materials: Composites whose constituents are aligned in a particular way.
Orifice: An opening generally referred to regarding spray tip size.
Original Equipment Manufacturer (OEM): Companies that design and build products bearing
their name, such as Boeing 777 aircraft of Prince tennis racquets.
Ortho: Abbreviation for orthophthalic acid type resins and gel coats.
Orthophthalic Or Ortho Resin: A polyester resin based on orthophthalic acid, also known as a
general-purpose resin (GP).
Orthotropic: Having three mutually perpendicular planes of elastic symmetry.
Outgassing: It is the release of solvents and moisture from composite parts under the hard
vacuum of space.
Out-Time (Out-Life): The period of time a prepreg material remains in a handleable form and
with properties intact outside of the specified storage environment; for example, out of the
freezer in the case of thermoset prepregs.
Oven Dry: The condition of a material that has been heated under prescribed conditions of
temperature and humidity until there is no further significant change in its mass.
Overlay Mat: A tissue of staple fibers lightly bonded with a medium, which insures good
draping and wetting out in contact resins. It is particularly valuable in masking the veining of
strands on the surface of matched metal die moldings.