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Plastic Terms Glossary
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Ablative |
|
Heat absorption
through a
decomposition
process called
pyrolysis or near
the exposed
surface. |
|
Accelerator |
|
A chemical
additive that
hastens cure or
chemical
reaction. |
| Adhesive |
|
A substance
applied to mating
surfaces to bond
them by surface
attachment. |
| Adhesive
Film |
|
A thin plastic
film onto which
premixed adhesives
are cast. |
| Aliphatic |
|
Designates a
large class of
organic compounds
having open-chain
structures,
isopropyl alcohol
being one
example. |
|
Anisotropic |
|
Fiber
directionality in
which different
properties are
exhibited when
tested along axes
of different
directions. |
| Aramid |
|
A
high-Strength,
high-stiffness
aromatic polyamide
fiber. |
| Areal
Weight |
|
Weight of a
fiber reinforcement
per unit area
(width times
length) of tape or
fabric. |
| Aspect
Ratio |
|
Ratio of length
to diameter of a
fiber. |
| Autoclave
Molding |
|
A molding
technique in which
an entire assembly
(layup) is placed
into an autoclave
(or closed vessel
with pressure/heat
capability) at 50
to 100 psi pressure
to consolidate the
part laminate by
removing entrapped
air and
volatiles. |
| Automated Tape
Laying |
|
A fabrication
process in which an
automated machine
system lays prepreg
tape in a
preprogrammed
pattern to lay up
the ply schedule on
an open mold. |
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| Bag
Molding |
|
A molding
technique in which
the composite
material is placed
in rigid mold and
covered with a
flexible bag, with
pressure applied by
vacuum, autoclave,
press or by
inflating the
bag. |
| Balanced
Design |
|
In filament
winding, a winding
pattern designed so
that the stressed
in all filaments
are equal. |
| Balanced
Laminate |
|
A laminate in
which all laminae
except those at 0
degrees / 90
degrees are placed
in plus / minus
pairs (not
necessarily
adjacent)
symmetrically
around the lay up
centerline. |
| Barcol
Hardness |
|
A surface
hardness value
obtained by
measuring the
penetration
resistance of a
given material to a
sharp steel point
under a spring
load. The Barcol
Impressor is an
instrument that
measures hardness
on a 0-100
scale. |
| Basket
Weave |
|
Woven
reinforcement
wherein two or more
warp threads go
over and under two
or more filling
threads in a repeat
pattern.This weave
is less stable than
the plain weave but
produces a flatter,
stronger more
pliable
fabric. |
| Batch (or
lot) |
|
Material made
with the same
process at the same
time having
identical
characteristics
throughout. |
| Bias
Fabric |
|
A fabric in
which warp and fill
fibers are at an
angle to the
length. |
| Biaxial
Winding |
|
Filament
winding wherein
helical bands are
laid in sequence,
side by side, with
no haps or overlap
between the
fibers. |
| Bidirectional
Laminate |
|
A laminate with
fibers oriented in
more than one
direction on the
same plane. |
| Binder |
|
The agent
applied to glass
mat or preforms to
bond the fibers
prior to laminating
or molding. |
| Bleeder
Cloth |
|
A layer of
woven or woven
material, not a
part of the
composite, that
allows excess has
and resin to escape
during cure. |
| Bleedout |
|
Excess liquid
resin appearing at
the surface,
primarily occurring
during filament
winding. |
| Bond Ply |
|
A ply or fabric
patch that comes in
contact with a
honeycomb
core. |
| Bond
Strength |
|
The degree of
adhesion between
bonded surfaces.
The stress required
to separate a layer
of material from
the base to which
it is bonded, as
measured by
load/bond
area. |
| Boron
Filament |
|
A strong,
lightweight fiber,
with a high
strength-to-weight
ratio used as a
reinforcement. |
| Boron
Fiber |
|
A fiber usually
of a
tungsten-filament
core with elemental
boron vapor
deposited onto it
to impart strength
and stiffness. |
| Braid |
|
A woven tubular
shape used instead
of a flat fabric
for
reinforcement. |
| Breakout |
|
Separation or
breakage of fibers
when the edges of a
composite part are
drilled or
cut. |
| Breather |
|
A loosely woven
material that does
not come in contact
with the resin but
serves as a
continuous vacuum
path over a part in
production. |
| Bridging |
|
Fabric plies
over a curved edge
that do not come in
full contact with
the core material.
Also, excess resin
that has formed on
edges during the
curing
process. |
| Broadgoods |
|
Fiber woven or
stitched into
fabrics that may or
may not be
impregnated with
resin: usually
furnished in
rolls. |
| Bromine |
|
A fire
retardant (halogen)
used to reduce or
eliminate a resin's
tendency to
burn. |
| Buckling |
|
A failure mode
usually
characterized by
fiber deflection
rather than
breakage due to
compressive
action. |
| Bulk Molding
Compound (BMC) |
|
A premixed
blend of
thermosetting
resin,
reinforcements,
catalysts and
fillers for use in
compression-,
transfer- or
injection-molding
processes. |
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CAD/CAM |
|
Computer-aided
design /
Computer-aided
manufacturing. |
| Carbon
Fiber |
|
Reinforcing
fiber known for its
lightweight, high
strength and high
stiffness. Fibers
are produced by
high temperature
treatment of an
organic precursor
fiber based on PAN
(polyacrylonitrile),
rayon or pitch in
an inert atmosphere
at temperatures
above 1,800 degrees
F. Fibers can be
pyrolized by
removing still more
non-carbon atoms
via heat-treating
above 3,000 degrees
F. |
| Carbon /
Carbon |
|
A composite of
carbon fiber in a
carbon matrix. |
| Cast
Polymer |
|
A nonreinforced
composite (resin
used without
reinforcing fibers)
that combines
polymers, fillers
and additives as
composites to meet
specific
application
requirements. |
| Catalyst |
|
A substance
that promotes or
controls curing of
a compound without
being consumed in
the reaction. |
| Catalyzed
Resin |
|
A resin mixture
possibly still in
the workable
states, after it
has been mixed with
the catalyst or
hardener. |
| Catenary |
|
Uniformity of
strand length in a
specified length of
roving stretched
under tension. Poor
catenary means some
strands in the
roving length are
longer than
others. |
| Caul Sheet |
|
A plate or
sheet the same size
and shape used in
contact with a
composite layup to
transmit normal
pressure and
temperature during
cure. |
| Centipoise
(cps) |
|
A unit of
measure used to
designate a fluid's
viscosity (At 70
degrees F. water is
1 cps; peanut
butter is 250,000
cps). |
| Centrifugal
Casting |
|
A processing
technique for
fabricating
cylindrical
structures, in
which the composite
material is
positioned inside
hollow mandrel
designed to be
heated and rotated
as resin is
cured. |
| Charge
Pattern |
|
The ply
schedule used in
parts made from
sheet molding
compound (SMC); a
pre-weighed number
of SMC plies cut
from an SMC sheet
and oriented to
fill the mold
cavity when placed
in the mold and
compressed. |
| Chopped
Strand |
|
Continuous
roving that is
chopped into short
lengths for use in
mats, spray up or
molding
compounds. |
| Circumferential
Winding |
|
The process of
winding filaments
perpendicular to
the axis during
filament
winding. |
| Co-Cured |
|
Cured and
simultaneously
bonded to another
prepared
surface. |
| Coefficient of
Expansion |
|
A measure of
the change in
length or volume of
an object. |
| Coefficient of
Friction |
|
The resistance
of a material to
sliding forces
where, the higher
the number, the
higher the
friction. |
| Coefficient of
Linear Thermal
Expansion |
|
A measure of
growth of a
material in length
or volume as
temperature
changes. |
| Cohesion |
|
Adherence of a
single substance to
itself. Also, the
property holding a
single substance
together. |
| Composite |
|
A material that
combines fiber and
a binding matrix to
maximize specific
performance
properties. Neither
element merges
completely with the
other. |
| Compression
Molding |
|
A technique for
molding thermoset
plastics in which a
part is shaped by
placing the fiber
and resin into an
open-mold cavity,
closing the mold,
and applying heat
and pressure until
the material has
cured or achieved
its final
form. |
| Compressive
Modulus Of
Elasticity |
|
The ratio of
force to
deformation as a
material is being
squeezed. |
| Compressive
Strength |
|
The capacity to
resist a crushing
or buckling force;
the maximum
compressive load a
specimen sustains
divided by its
original
cross-sectional
area. |
| Condensation
Polymerization |
|
A
polymerization
reaction in which
simple byproducts
(e.g.,water) are
formed. |
|
Consolidation |
|
A processing
step that
compresses fiber
and matrix to
remove excess
resin, reduce voids
and achieve a
particular
density. |
| Contact
Molding |
|
A process for
molding reinforced
plastics in which
reinforcement
materials such as
mat and woven
roving saturated
with resin, are
applied and to a
mold. The cure
occurs either at
room temperature
using a
catalyst-promoter
system or by
heating in an oven
with no additional
pressure. |
|
Contaminant |
|
An impurity or
foreign substance
that affects one or
more properties of
composite material,
particularly
adhesion. |
| Continuous
Filament |
|
An individual,
small-diameter
reinforcement that
is flexible and
indefinite in
length. |
| Continuous
Roving |
|
Single or
multiple strands of
parallel filaments
coated with sizing
and wound into a
cylindrical
package. It may be
used to provide
continuous
reinforcement in
woven roving,
filament winding,
pultrusion,
prepregs, or
high-strength
molding compounds.
It may also be
chopped. (See
Chopped
Strand.) |
| Core |
|
In sandwich
construction, the
central component
to which inner and
outer skins are
attached. Foam,
honeycomb, paper
and wood are all
commonly used as
core material. |
| Core Crush |
|
Compression
damage of the
core. |
| Core
Depression |
|
A gouge or
indentation in the
core material. |
| Core
Orientation |
|
The standard
used on a honeycomb
core to line up the
ribbon direction,
thickness of the
cell depth, cell
size and transverse
direction. |
| Core
Separation |
|
A breaking of
honeycomb core
cells. |
| Core
Splicing |
|
Joining two
core segments by
bonding them
together. |
| Co-woven Or
Hybrid Fabric |
|
A reinforcement
fabric woven with
two different types
of fibers in
individual yarns,
e.g., thermoplastic
fibers woven side
by side with carbon
fibers. |
| Crazing |
|
A region of
ultrafine cracks
that may develop on
or under a resin
surface. |
| Creel |
|
A device for
holding the
required number of
roving spools or
other supply
packages of
reinforcement in
the desired
position for
unwinding. |
| Creep |
|
The dimensional
change in a
material under
physical load over
time beyond
instantaneous
elastic
deformation. |
| Cross
Lamination |
|
Layers oriented
at various angles
to other layers
with respect to the
laminate grain. A
cross-ply laminate
usually has plies
oriented only at
0°/90°. (See Fiber
Architecture.) |
|
Cross-Linking |
|
Polymerization
reactions that
branch out from the
main molecular
chain to form a
networked pattern
of chemical
links. |
| Cross-Ply
Laminate |
|
A laminate with
plies oriented at
0° and 90°
only. |
|
Crystalline |
|
A molecular
structure in which
the atoms are
arranged in an
orderly,
three-dimensional
pattern. |
| CTE |
|
See coefficient
of thermal
expansion. |
| Cure |
|
To irreversibly
change the
molecular structure
and physical
properties of a
thermosetting resin
by chemical
reaction via heat
and catalysts alone
or in combination,
with or without
pressure. |
| Cure
Temperature |
|
The temperature
at which a material
attains final
cure. |
| Curing Agent or
Hardener |
|
A catalytic or
reactive agent that
brings about
polymerization when
added to a
resin. |
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Damage
Tolerance |
|
A measure of
the ability of
structures to
retain
load-carrying
capability after
exposure to sudden
loads (for example,
ballistic
impact). |
| Damping |
|
Diminishing the
intensity of
vibrations. |
| Debonding |
|
An unplanned
separation of
bonded
surfaces. |
|
Delamination |
|
The separation
of ply layers due
to adhesive failure
or the separation
of layers of fabric
from the core
structure. A
delamination may be
associated with
bridging, drilling
and trimming. |
| Demold |
|
To remove a
part from a tool,
or a tool from an
intermediate
model. |
| Denier |
|
A numbering
system for yarn and
filament in which
yarn number is
equal to weight in
grams of 9,000
meters of
yarn. |
| Design
Allowable |
|
A limiting
value for a
material property
that can be used to
design a structural
or mechanical
system to a
specified level of
success with 95%
statistical
confidence. |
| Dielectric |
|
Nonconductor of
electricity; the
ability of a
material to resist
the flow of an
electrical
current. |
| Dielectric
Constant |
|
The ability of
a material to store
an electrical
charge. |
| Dielectric
Strength |
|
The amount of
volts/mil required
to cause an
electrical
"breakthrough". The
voltage required to
penetrate
insulating
material. Material
with high
dielectric strength
offers excellent
electrical
insulating
properties. |
| Dimensional
Stability: |
|
Change in
height, width, and
shape when exposed
to changes in
temperature. |
| Dissipation
Factor |
|
The ability of
a material to
dissipate an
electrical
charge. |
| Doubler |
|
An extra layer
of reinforcement
for added stiffness
or strength where
fasteners or other
abrupt load
transfers
occur. |
| Draft
Angle |
|
A mandrel's
taper or angle for
ease of part
removal. |
| Draft |
|
The degree of
taper allowed on
the sides of a mold
so the part can be
removed. |
| Drape |
|
The ability of
fabric (or prepreg)
to conform to the
shape of a
contoured
surface. |
| Dry
Winding |
|
A filament
winding operation
in which resin is
not used. |
| Durometer
Hardness |
|
The ability of
a non-metallic
material to resist
indentation using a
Shore tester. |
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|
E-Glass(Electrical
Glass) |
|
Borosilicate
glass fibers most
often used in
conventional
polymer matrix
composites. |
| Elastic
Limit |
|
The greatest
stress a material
is capable of
sustaining without
permanent strain
remaining after
complete release of
the stress. |
| Elasticity |
|
The property by
which materials
tend to recover
their original size
and shape after
deformation. |
| Elastomer |
|
A material that
substantially
recovers its
original shape and
size at room
temperature after
removal of a
deforming
force. |
| Elongation |
|
The fractional
increase in length
of a material
stressed in
tension. When
expressed as a
percentage of the
original length, it
is called
percentage of
elongation. |
| End |
|
A strand of
roving consisting
of a given number
of filaments
gathered together.
The strand is
considered an end
or strand before
twisting. |
| End Count |
|
An exact number
of strands
contained in a
roving. |
| Engineering
Plastics |
|
A general term
covering all
plastics, with or
without fillers or
reinforcements,
that have
mechanical,
chemical and
thermal properties
suited for use as
construction
materials, machine
components and
chemical processing
equipment
components. |
| Epoxy
Plastics |
|
Thermoset
resins made by the
reaction of
epoxides or
oxiranes with other
materials such as
amines and
alcohols; used as a
matrix resin in
reinforced
composites and
structural
adhesives. |
| Epoxy
Resin |
|
A common
thermoset material
used as a bonding
matrix to hold
fibers together.
When mixed with a
catalyst, epoxy
resins are
resistant to
chemicals and water
and are unaffected
by heat or
cold. |
| Exotherm |
|
Heat released
during a chemical
reaction (e.g.,
curing). |
| Exothermic |
|
Characterized
by a chemical
reaction to
heat. |
| Extenders |
|
Low-cost
materials used to
dilute or extend
high-cost resins
without extensive
lessening of
properties. |
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Fabric,
Nonwoven |
|
A material
formed from fibers
or yarns without
interlacing (e.g.,
stitched nonwoven
broadgoods). |
| Fabric,
Woven |
|
A material
constructed of
interlaced yarns,
fibers or
filaments. |
|
Fabrication |
|
The process of
making a composite
part or tool. |
| Fatigue |
|
The failure of
a material's
mechanical
properties caused
by repeated stress
over time. |
| Fatigue
Strength |
|
The maximum
cyclical stress a
material can
withstand for a
given number of
cycles before it
fails. |
| Fiber |
|
Filamentary
material. |
| Fiber
Architecture |
|
The design of a
fibrous part in
which the fibers
are arranged in a
particular way to
achieve the desired
result. This may
include braided,
stitched or woven
fabrics, mats,
rovings or carbon
tows. |
| Fiber
Bridging |
|
Reinforcing
fiber material
bridging an inside
radius of a
pultruded product.
The condition is
caused by shrinkage
stresses around
such a radius
during cure. |
| Fiber
Content |
|
The amount of
fiber in a
composite expressed
as a ratio to the
matrix. (The most
desirable fiber
content is a 60:40
ratio, or 60
percent fiber and
40 percent matrix
resin.) |
| Fiber
Reinforced Plastics
(FRP) |
|
A composite
material or part
that consists of a
resin matrix
containing
reinforcing fibers
such as glass or
carbon having
greater strength or
stiffness than the
resin. The term FRP
is most often used
to denote glass
fiber-reinforced
plastics; the term
"advanced
composite" usually
denotes
high-performance
aramid or carbon
fiber-reinforced
plastics. |
| Fiber Wash |
|
Processing
distortion wherein
resin flow may
unevenly bunch or
spread fibers in an
area of the
part. |
| Fiberglass |
|
Reinforcing
fiber made by
drawing molten
glass through
bushings. The
predominant
reinforcement for
polymer matrix
composites, it is
known for its good
strength,
processability and
low cost. |
| Filament
Winding |
|
An automated
process for
fabricating
composites in which
continuous roving,
either
preimpregnated with
resin or drawn
through a resin
bath, is wound
around a rotating
mandrel. |
| Filaments |
|
Individual
fibers of
indefinite length
used in tows, yarns
or roving. |
| Fill Threads
(Or Weft or
Woof) |
|
The crosswise
fibers woven at 90°
to the warp
fibers. |
| Filler |
|
Material added
to the mixed resin
to increase
viscosity, improve
appearance and/or
lower density and
cost. |
| Filler Ply |
|
An additional
patch used to fill
in a depression in
repair or to build
up an edge. |
| Film |
|
Sheeting having
a nominal thickness
not greater than
0.25 mm (0.010
inches). |
| Film
Adhesive |
|
An adhesive in
the form of a thin,
dry resin film with
or without a
carrier. Commonly
used for adhesion
between laminate
layers. |
| Finish |
|
Material
applied to fibers
(after sizing is
removed) to improve
bonding between
resin and
fiber. |
| Finite Element
Analysis (FEA) |
|
A process of
selecting the
optimum combination
of materials in a
composite based on
software
analysis. |
| Flammability
Rating |
|
The ability of
a material to
harbor a
flame. |
| Flexural
Modulus Of
Elasticity |
|
The ratio of
force to
deformation when a
material is being
flexed or bent. The
ratio, within the
elastic limit, of
the applied stress
on a test sample in
flexure to the
corresponding
strain in the
outermost fibers of
the sample. |
| Flexural
Strength |
|
The resistance
of a material to
being bent or
flexed. The
strength of a
material in bending
expressed usually
in terms of force
per unit area, as
the stress of a
bent test sample at
the instant of
failure. |
| Fracture |
|
A rupture of
the surface of a
laminate, due to
external or
internal forces;
may or may not
result in complete
separation. |
|
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| Gel
Coat |
|
A pigmented
coating resin
applied to a mold
or part to produce
a smooth, more
impervious finish
on the part. |
| Gel Time |
|
The period of
time from initial
mixing of liquid
reactants to the
point when gelation
occurs, as defined
by a specific test
method. |
| Glass
Fiber |
|
See
Fiberglass. |
| Glass
Transition |
|
The reversible
change in an
amorphous polymer
between a viscous,
rubbery condition
and a hard,
relatively brittle
one. |
| Glass
Transition
Temperature
(Tg) |
|
The temperature
at which
crystalline
materials change
from solid to a
rubbery state. (Or)
The approximate
temperature above
which increased
molecular mobility
causes a material
to become rubbery,
rather than
brittle. The
measured value of
Tg can vary,
depending on the
test method. |
|
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| |
|
Halogenated
Resin |
|
A resin
combined with
chlorine or bromine
to increase fire
retardancy. |
| Hand Layup |
|
A fabrication
method in which
reinforcement
layers are placed
in a Mold by hand,
saturated with
resin, then cured
to the formed
shape. |
| HAPs |
|
Hazardous Air
Pollutants, as
determined by the
Environmental
Protection Agency
(EPA). |
| Hardener |
|
A substance
that reacts with
resin to promote or
control (Or Curing
Agent) curing
action. |
| Heat |
|
A term used
colloquially to
indicate any
temperature above
ambient (Room)
temperature to
which a part or
material is or will
be subjected. |
| Heat Deflection
Temperature |
|
The temperature
at which a material
will bend a given
distance when a
given load is
applied. |
|
Heat-Distortion |
|
The temperature
at which a test bar
deflects a certain
amount under
specified
temperature and
stated load. |
| Helical |
|
Describing ply
laid onto a mandrel
at an angle, often
a 45° angle. |
| Helix
Angle |
|
The angle at
which continuous
filaments are wound
in relation to the
longitudinal
mandrel axis in the
filament-winding
process. |
| Honeycomb |
|
A lightweight
cellular structure
made from either
metallic sheet
materials or
nonmetallic
materials (e.g.,
resin-impregnated
paper or woven
fabric) and formed
into hexagonal
nested cells. |
| Hoop |
|
Ply laid onto a
mandrel at a 90°
angle. |
| Hoop
Stress |
|
Circumferential
stress in a
cylindrically
shaped part as a
result of internal
or external
pressure. |
| Hybrid
Composite |
|
A composite
made with two or
more types of
reinforcing
fibers. |
| Hygroscopy |
|
A material’s
readiness to absorb
or retain
moisture. |
|
|
|
|
|
| |
| Izod
Impact |
|
The ability of
a material to
resist fracture at
a machined “V”
notch when hit with
a swinging
weight. |
| Impact
Strength |
|
A material’s
ability to
withstand shock
loading as measured
by fracturing a
specimen. |
| Impregnate |
|
To saturate the
voids and
interstices of a
reinforcement with
a resin. |
| Impregnated
Fabric |
|
See
Prepreg. |
| In Situ |
|
(in the
original position)
— In filament
winding, designates
a mandrel that
remains in place
after winding, as
opposed to a
mandrel that is
removed after
winding. |
| Inhibitor |
|
A chemical
additive that slows
or delays cure
cycle. |
| Injection
Molding |
|
A method of
forming a plastic
to the desired
shape by forcibly
injecting the
polymer into a
mold. |
| Integral
Heating |
|
A system in
which heating
elements are built
into a tool,
forming part of the
tool and usually
eliminating the
need for an oven or
autoclave as a heat
source. |
| Interface |
|
The surface
between two
materials (in glass
fibers, for
instance, the area
at which the glass
and sizing meet; in
a laminate, the
area at which the
reinforcement and
laminating resin
meet.) |
| Interior
Components |
|
Finished
internal aircraft
components usually
made of glass fiber
composites,
including overhead
stowbins,
sidewalls, floor
panels, ceiling
panels,
laboratories and
galleys. |
|
Interlaminar |
|
Existing or
occurring between
two or more
adjacent
laminae. |
| Interlaminar
Shear |
|
A shearing
force that produces
displacement
between two laminae
along the plane of
their
interface. |
| Isocyanate |
|
A highly
reactive monomer
used in reaction
injection molding
(RIM). |
| Isotropic |
|
Fiber
directionality with
uniform properties
in all directions,
independent of the
direction of
applied load. |
| Isotropic
Laminate |
|
A laminate in
which the strength
properties are
equal in all
directions, such as
contact-molded
laminates or
metals. |
|
|
|
|
|
| |
|
Kevlar |
|
A strong,
lightweight aramid
fiber trademarked
by DuPont and used
as a reinforcement
fiber. |
|
|
|
|
|
| |
|
Laminate |
|
To unite layers
with a bonding
material, usually
via pressure and
heat. |
| Laminate
Ply |
|
A fabric/resin
or fiber/resin
layer that is
bonded to adjacent
layers in the
curing
process. |
| Lap Joint |
|
A joint made by
overlapping two
parts and bonding
them together. |
| Layup |
|
Placement of
layers of
reinforcement in a
mold. |
| Liner |
|
The continuous,
usually flexible,
reinforced resin
barrier on the
inside surface of a
plastic or
thermoset laminate
used to protect the
laminate from
chemical attack or
to prevent leakage
under stress. |
| Low
Profile |
|
Resin compounds
formulated for low
or zero shrinkage
during
molding. |
|
|
|
|
|
| |
|
Melting Point |
|
The temperature
at which a
materials change
from a solid to a
liquid. |
| MACT |
|
Maximum
achievable control
technology. A
technology-based
air pollution
control standard
developed by the
Environmental
Protection Agency
(EPA) aimed at
reducing emissions
of HAPs during
manufacturing
processes. |
| Mandrel |
|
An elongated
mold around which
resin-impregnated
fiber, tape or
filaments are wound
to form structural
shapes or
tubes. |
| Mat |
|
A fibrous
reinforcing
material composed
of chopped
filaments (for
chopped-strand mat)
or swirled
filaments (for
continuous-strand
mat) with a binder
applied to maintain
form; available in
blankets of various
widths, weights,
thicknesses and
lengths. |
| Matched Metal
Molding |
|
See Compression
Molding. |
| Matrix |
|
The material in
which the fiber
reinforcements of a
composite system
are imbedded.
Thermoplastic and
thermoset resin
systems, as well as
metal and ceramic,
can be used. |
|
Microcracking |
|
Cracking in
composites at
points where
thermal stresses
exceed the strength
of the matrix. |
| Mil |
|
The unit used
in measuring the
diameter of glass
fiber strands, wire
and so forth (1 mil
= 0.001 inch). |
| Milled
Fiber |
|
Continuous
glass or carbon
strands
hammer-milled into
very short
fibers. |
| Modulus |
|
The physical
measurement of
stiffness in a
material, equaling
the ratio of
applied load
(stress) to the
resultant
deformation of the
material, such as
elasticity or
shear. (A high
modulus indicates a
stiff
material.) |
| Moisture
Absorption |
|
A material
assimilation of
water vapor from
air, as
distinguished from
water absorption by
immersion, which
results in weight
gain. |
| Mold |
|
The cavity or
matrix into or on
which the
resin/fiber
material is placed
and from which it
takes form. |
| Mold Release
Agent |
|
A lubricant
used to prevent a
part from sticking
to a mold. |
| Molding |
|
The forming of
a resin/fiber
material into a
solid mass of
prescribed shape
and size. |
| Monomer |
|
A single
molecule that can
react with like or
unlike molecules to
form a
polymer. |
|
Multifilament |
|
A yarn
consisting of many
continuous
filaments. |
|
|
|
|
|
| |
|
Naphtha |
|
Solvent naphtha
is a petroleum
distillate commonly
used as a solvent
for natural resins
and rubber. |
| Near-Net
Shape |
|
A part
fabrication with
final dimensions
that require
minimal machining
or cutting. |
| Net Shape |
|
A part
fabrication with
final dimensions
that do not require
machining or
cutting. |
| Nondestructive
Inspection
(NDI) |
|
Determination
of material or part
characteristics
without permanent
alteration of the
test subject.
(Nondestructive
testing (NDT) and
nondestructive
evaluation (NDE)
are generally
considered
synonymous with
NDI.) |
| Nonwoven
Roving |
|
A reinforcement
composed of
continuous fiber
strands loosely
gathered
together. |
| Nylon |
|
The generic
name, by common
usage, for all
synthetic
polyamides. |
|
|
|
|
|
| |
|
One-Off |
|
A single part
that is
individually
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
material supplier
as part of the
resin production
operation. |
| Original
Equipment
Manufacturer(OEM) |
|
A company that
designs and builds
products bearing
its name, such as
Boeing 777. |
| Out-Time |
|
The period of
time in which a
prepreg retains
acceptable handling
and other
properties outside
a specified storage
environment (a
freezer, in the
case of thermoset
prepregs). |
| Outgassing |
|
The release of
solvents and
moisture from
composite parts
under a
vacuum. |
|
|
|
|
|
| |
| PV
or Limiting PV |
|
The ratio of
simultaneous load
and speed in
relation to
wear. |
| PAN |
|
See
Polyacrylonitrile. |
| Part
Consolidation |
|
A process of
composites
fabrication in
which multiple
discrete parts are
designed and
fabricated together
into a single part,
thus reducing the
number of
fabricated parts
and the need to
join those parts
together. |
| Parting
Film |
|
A layer of thin
plastic to prevent
bagging materials
from sticking to a
part It may be
perforated to vent
excess resin. It is
removed after
cure. |
| Peel Ply |
|
Layer of
material applied to
a lay up surface
that is removed
from the cured
laminate prior to
bonding operations,
leaving a clean,
resin-rich surface
ready for
bonding. |
| Peel
Strength |
|
Strength of an
adhesive bond
obtained by stress
that is applied in
a peeling
mode. |
| Phenolic
Resin |
|
Thermosetting
resin produced by
condensation of an
aromatic alcohol
with an aldehyde,
particularly phenol
with
formaldehyde. |
| Pin Holes |
|
Small holes
caused by the mold
used. |
| Pitch |
|
Residual
petroleum product
used in the
manufacture of
certain carbon
fibers. |
| Planar
Winding |
|
Filament
winding in which
the filament path
lies on a plane
that intersects the
winding
surface. |
| Plastic |
|
A high
molecular weight
thermoplastic or
thermosetting
polymer that can be
molded, cast,
extruded or
laminated into
objects. A major
advantage of
plastics is that
they can deform
significantly
without
rupturing. |
| Ply |
|
One of the
layers that makes
up a stack or
laminate. Also, the
number of single
yarns twisted
together to form a
plied yarn. |
| Ply
Schedule |
|
Lay up of
individual plies or
layers to build an
FRP part laminate.
Plies may be
arranged
(scheduled) in
alternating fiber
orientation to
produce a
multi-directional
strength part. (See
Fiber
Architecture). |
| Poisson’s
Ratio |
|
When a material
is stretched, its
cross sectional
area changes as
well as its length.
Poisson’s ratio is
the constant
relating these
changes in
dimensions, and is
defined as the
ratio of the change
in width per unit
width to the change
in length per unit
length. |
| Polar
Winding |
|
Filament
winding in which
the filament path
passes tangent to
the polar opening
at one end of the
chamber and tangent
to the opposite
side of the polar
opening at the
other end of the
chamber. |
|
Polyacrylonitrile
(PAN) |
|
A polymer,
which is spun into
fiber that is used
as a precursor
material in the
manufacture of
certain carbon
fibers. |
| Polyester |
|
Thermosetting
resins produced by
dissolving
unsaturated,
generally liner,
alkyd resins in a
vinyl-type active
monomer such as
styrene. The resins
are usually
furnished in
solution form, but
powdered solids are
also
available. |
| Polymer Alloy
(or Polymer
Blend) |
|
A blend of
polymers,
copolymers or
elastomers. |
| Polymer |
|
A large
molecule formed by
combining many
smaller molecules
or monomers in a
regular
pattern. |
|
Polymerization |
|
A chemical
reaction that links
monomers to form
polymers. |
| Porosity |
|
The presence of
visible voids
within a solid
material into which
either air or
liquids may
pass. |
| Postcure |
|
Additional
elevated
temperature cure,
usually without
pressure, to
improve final
properties and/or
complete the cure.
In certain resins,
complete cure and
ultimate mechanical
properties are
attained only by
exposure of the
cured resin to
higher temperatures
than those of
curing. |
| Pot Life |
|
The length of
time in which a
catalyzed
thermosetting resin
retains
sufficiently low
viscosity for
processing. |
| Precursor |
|
For carbon
fibers, the rayon,
PAN or pitch fibers
from which carbon
fibers are
made. |
| Preform |
|
A fibrous
reinforcement
pre-shaped on a
mandrel or mock-up
to the approximate
contour and
thickness desired
in the finished
part. |
| Prepreg |
|
Resin-impregnated
fibers, fabric or
mat in flat form
that is
preimpregnated with
resin before being
stored for later
use in molds and in
hand layup. |
| Promoter (or
Accelerator) |
|
A chemical,
which hastens the
reaction between a
catalyst and a
resin. |
| Prototype |
|
The process of
creating a test
article not
intended for
commercial release
that establishes
design, material
and fabrication
parameters for a
new product. May
entail multiple
iterations to
arrive at final/
commercial part
design. |
| Pultrusion |
|
An automated,
continuous process
for manufacturing
composite rods,
tubes and
structural shapes
having a constant
cross-section.
Roving and other
reinforcements are
saturated with
resin and
continuously pulled
through a heated
die, where the part
is formed and
cured. The cured
part is then cut to
length. |
| Puncture |
|
A break in
composite skin in
sandwich structure
that may or may not
go through to the
core material or
completely through
the part. |
| Pyrolysis |
|
The
decomposition or
transformation of a
compound caused by
heat. |
|
|
|
|
|
| |
|
Quasi-isotropic |
|
Approximating
isotropy by
orienting plies in
several
directions. |
|
|
|
|
|
| |
|
Ramping |
|
A gradual
programmed
increase/decrease
in temperature or
pressure to control
cure or cooling of
composite
parts. |
| Reagent |
|
A substance
used in a chemical
reaction to produce
other
substances. |
| Regrind |
|
Scrap
composites (both
thermoset and
thermoplastic)
collected in-plant
or from
post-consumer
sources that are
reground into
pellets or fine
powder for use in
new parts, either
as new base
material or in
combination with
virgin
materials. |
|
Reinforcement |
|
The key element
added to matrix to
provide required
properties
(primarily,
strength and
stiffness); ranges
from short fibers
and continuous
fibers through
complex textile
forms. |
| Release
Agent |
|
A substance
usually sprayed or
painted on mold to
prevent cured
matrix material
from bonding to
tooling. |
| Release
Film |
|
An impermeable
film layer that
does not bond to
the composite
during cure. |
| Resin |
|
A solid or
pseudosolid
material with
indefinite and
often high
molecular weight
and a softening or
melting range that
exhibits a tendency
to flow when
subjected to
stress. (As
composite matrices,
resins bind
together
reinforcement
fibers.) |
| Resin Rich |
|
Localized area
filled with excess
resin, as compared
to consistency of
resin/fiber
ratio. |
| Resin
Starved |
|
Characterizing
a localized area
lacking sufficient
resin for fiber
wetout. |
| Resin
System |
|
A mixture of
resin and
ingredients
required for an
intended processing
method and final
product. |
| Resin Transfer
Molding (RTM) |
|
A molding
process in which
catalyzed resin is
pumped into a
two-sided, matched
mold, which a
fibrous
reinforcement has
been placed. The
mold and/or resin
may or may not be
heated. |
| Resin
Viscosity |
|
The viscous
property of a resin
system, or
solid-to-liquid
transition
resistance to flow,
which can be
altered by
temperature and
pressure to achieve
desired flow
characteristics. |
| Ribbon
Direction |
|
On a honeycomb
core, the way the
honeycomb can be
separated; the
direction of one
continuous
ribbon. |
| Reaction
Injection Molding
(RIM) |
|
A process
involving high
pressure mixing of
two components,
primarily to mold
polyurethane. |
| Reinforced
Reaction
(RRIM) |
|
A molding
process that mixes
two highly reactive
resin Injection
Molding:components
for cure. To one of
the resin
components is added
a reinforcement,
usually consisting
of flake glass or
milled fibers, to
stiffen the part
and reduce thermal
expansion. |
| Rockwell
Hardness |
|
The ability of
a material to
resist indentation
using a Rockwell
Tester. |
| Roving |
|
A collection of
bundles of
continuous glass
fiber filaments,
either as untwisted
strands or as
twisted yarn. |
|
|
|
|
|
| |
|
S-Glass |
|
Magnesia/alumina/silicate
glass reinforcement
designed to provide
very high tensile
strength. (Commonly
used in
high-performance
parts.) |
| Sandwich
Structure |
|
A composite
composed of
lightweight core
material to which
two relatively
thin, dense,
high-strength,
functional or
decorative laminate
skins are
adhered. |
| Sealant |
|
A paste or
liquid applied to a
joint that hardens
in place to form a
seal. |
| Secondary
Bonding |
|
The joining by
adhesive of two or
more already cured
composite
parts. |
| Separator |
|
A permeable
layer that
separates and also
acts as a release
film (e.g., porous
Teflon-coated
fiberglass). Often
placed between lay
up and bleeder to
facilitate bleeder
systems’ removal
from laminate after
cure. |
| Shear |
|
An action or
stress resulting
from applied forces
that causes or
tends to cause two
contiguous parts of
a body to slide
relative to each
other. |
| Shear
Strength |
|
The maximum
shear stress that a
material is capable
of sustaining. |
| Shear
Strength |
|
The resistance
of a material to
being punched or
sheared. |
| Sheet Molding
Compound (SMC) |
|
A ready-to-mold
glass
fiber-reinforced
polyester material
primarily |
| Shelf Life |
|
The length of
time for which a
material can be
stored and continue
to meet
specification
requirements,
remaining suitable
for its intended
use. |
| Shot |
|
One complete
cycle on an
injection-molding
machine. Shot
weight is the
measured compound
delivered to
completely fill the
mold in injection
or transfer
molding. |
| Sizing |
|
A solution of
chemical additives
used to coat
filaments. The
additives protect
the filaments from
water absorption
and abrasion; they
also lubricate the
filaments and
reduce static
electricity. |
| Skin |
|
A relatively
dense laminate
comprising the
outer surfaces
(layers) of the
core in a sandwich
structure. |
| Soft Tool |
|
A tool made of
composites or a
similar soft
material that is
vulnerable to
damage during use,
storage or
transportation. |
| Solvent |
|
A liquid used
to dissolve and
clean
materials. |
| Spec |
|
Specification
of the properties,
characteristics or
requirements a
particular material
or part must have
to be acceptable to
a potential user of
the material or
part. |
| Specific
Gravity |
|
The density
(mass per unit
volume) of a
material divided by
that of water at a
standard
temperature. |
| Sprayup |
|
A technique in
which continuous
strand roving is
fed into a chopper
gun, which chops
the roving into
predetermined
lengths and sprays
the chopped fiber,
along with a
measured amount of
resin and catalyst,
onto an open
mold. |
| Stiffness |
|
A material’s
ability to resist
bending;
relationship of
load to deformation
for a particular
material. |
| Structural
Reaction Injection
Molding (SRIM) |
|
A process that
uses a fiber
reinforced preform
or mat in clamped
molds to inject
reactive resin that
impregnates fibers
and cures
quickly. |
| Starved
Area |
|
An area in a
plastic part that
has an insufficient
amount of resin to
completely wet out
the
reinforcement. |
| Storage
Life |
|
The amount of
time a material can
be stored and
retain specific
properties. |
| Strain |
|
Elastic
deformation
resulting from
stress. |
| Strand |
|
A collection or
bundle of
continuous glass
filaments. |
| Stress |
|
Internal
resistance to
change in size or
shape, expressed in
force per unit
area. |
| Stress
Concentration |
|
The
magnification of
applied stress in
the region of a
notch, void, hole
or inclusion. |
| Stress
Corrosion |
|
Preferential
attack of areas
under stress in a
corrosive
environment, that
alone would not
have caused
corrosion. |
| Stress
Crack |
|
External or
internal crack in a
composite caused by
tensile stresses;
cracking may be
present internally,
externally or in
combination. |
| Substrate |
|
A material on
which an
adhesive-containing
substance is spread
for any purpose,
such as bonding or
coating. |
| Surfacing
Veil |
|
Accompanying
other reinforcing
mats and fabrics to
enhance the quality
of the surface
finish. Designed to
block out the fiber
patterns of the
underlying
reinforcements, it
often adds
ultraviolet
protection to the
structure. |
| Synthetic
Fiber |
|
Fiber made of
materials other
than glass or
carbon, such as
polyester. |
| Specific
Gravity |
|
The ratio of
the weight of an
object, to the
weight of the same
volume of
water. |
| Surface
Resistivity |
|
The ability of
a material to
impede the flow of
electricity across
its surface. |
|
|
|
|
|
| |
|
Tensile
Elongation |
|
The % a
material will
stretch as it is
pulled in a slow
stretch until it
breaks. |
| Tensile Modulus
Of Elasticity |
|
The ratio of
force to
deformation when a
material is being
slowly pulled
apart. |
| Tensile
Strength |
|
The resistance
of a material to
being slowly pulled
apart. |
| Tack |
|
Stickiness of
an uncured
prepreg. |
| Tape |
|
Thin
unidirectional
prepreg in widths
up to 12
inches. |
| Tape
Laying |
|
An automated
fabrication process
in which
preimpregnated tape
is laid side by
side or overlapped
to form a
structure. |
| Tensile
Strength |
|
The maximum
stress sustained by
a composite
specimen before it
fails in a tension
test. |
| Thermal
Conductivity |
|
The ability to
transfer heat. |
| Thermal Stress
Cracking |
|
Crazing and
cracking of some
thermoplastic
resins from
overexposure to
elevated
temperatures. |
|
Thermocouple |
|
Wire assembly
used with a control
device to sense
temperature. |
|
Thermoplastic |
|
A composite
matrix capable of
being repeatedly
softened by an
increase in
temperature and
hardened by a
decrease in
temperature. |
| Thermoset |
|
Composite
matrix cured by
heat and pressure
or with a catalyst
into an infusible
and insoluble
material. Once
cured, a thermoset
cannot be returned
to the uncured
state. |
|
Thixotropic |
|
A consistency
that is gel-like at
rest, but fluid
when agitated.
Having high static
shear strength and
low dynamic shear
strength
simultaneously.
Losing viscosity
under stress. |
| Tool |
|
The mold,
either one- or
two-sided and
either open or
closed, in or upon
which composite
material is placed
to make a
part. |
| Toughness |
|
The ability of
a material to
absorb energy. |
| Tow |
|
An untwisted
bundle of
continuous
filaments (usually
carbon), typically
designated by a
number followed by
K, indicating
multiplication by
1,000 (for example,
12K tow has 12,000
filaments). |
| Tracer |
|
A fiber, tow,
or yarn added to a
prepreg to verify
fiber alignment or
to distinguish warp
fibers from fill
fibers. |
| Thermal
Conductivity |
|
The ability of
a material to
insulate changes in
temperature. |
|
|
|
|
|
| |
|
Unidirectional
(UD) |
|
Orientation of
fibers in the same
direction, as in
unidirectional
fabric, tape or
laminate. |
|
|
|
|
|
| |
|
Volume
Resistivity |
|
The ability of
a material to
impede the flow of
electricity through
itself. |
| Vacuum Bag
Molding |
|
A molding
technique wherein
the part is cured
inside a layer of
film from which
entrapped air is
removed by
vacuum. |
| Vacuum-Assisted
Resin Transfer
Molding
(VARTM) |
|
An infusion
process by which a
vacuum draws resin
into a one-sided
mold; a cover,
either rigid or
flexible, is placed
over the top to
form a vacuum-tight
seal. |
| Veil |
|
An ultra-thin
mat often composed
of organic fibers
as well as glass
fibers and used
primarily as a
corrosion
barrier. |
| Vinyl
Esters |
|
A class of
thermosetting
resins containing
ester of acrylic
and/or methacrylic
acids. |
| Viscosity |
|
The tendency of
a material to
resist flow. As
temperature
increases, the
viscosity of most
materials
decreases. |
| VOCs |
|
Volatile
organic compounds.
Chemical
substances, such as
solvents, that
readily evaporate
or volatilize into
the air. Many VOCs
are considered
hazardous air
pollutants (HAPs)
because of
potential health
concerns. |
| Voids |
|
Pockets of
entrapped gases
that have been
cured into a
laminate. (In a
composite that has
been cured
properly, void
content is usually
less than 1
percent.) |
| Volatiles |
|
Materials in a
sizing or resin
that can be
vaporized at room
or slightly
elevated
temperatures. |
| Volatile
Organic Compounds
(VOC) |
|
Carbon-containing
chemical compounds
(e.g., solvents and
styrene) that
evaporates readily
at ambient
temperatures.
Environmental,
safety and health
regulations often
limit exposure to
these compounds; so
low VOC content is
preferable. |
| Volatile
Content |
|
The percent of
volatiles that are
driven off as a
vapor from a
plastic or an
impregnated
reinforcement
during cure. |
|
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|
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| |
| Water
Absorption |
|
The ability of
a material to
absorb
moisture. |
| Warp |
|
Yarns running
lengthwise and
perpendicular to
the narrow edge of
woven fabric. |
| Warpage |
|
Dimensional
distortion in a
composite
part. |
| Water
Absorption |
|
The ratio of
weight of water
absorbed by a
material to weight
of dry
material. |
| Water Jet |
|
High-pressure
water stream used
for cutting polymer
composite
parts. |
| Weave |
|
The pattern by
which a fabric is
formed from
interlacing yarns.
In plain weave,
warp and fill
fibers alternate to
make both fabric
faces identical. In
satin weave, the
pattern produces a
satin appearance
with the warp
roving crossing
over several fill
rovings and under
the following one.
(For example,
eight-harness satin
would have warp
roving over seven
fill rovings and
under the
eighth.) |
| Weeping |
|
A slow passage
of fluid through an
FRP laminate that
can occur when a
leak path is
established by
extensive
cracking. |
| Weft
Threads |
|
See Fill
Threads. |
| Wet Layup |
|
Application of
a resin to a dry
reinforcement in
the mold. |
| Wet
Winding |
|
Filament
winding wherein
fiber strands are
impregnated with
resin immediately
before they contact
the mandrel. |
| Wetout |
|
Saturation with
resin of all voids
between strands and
filaments. |
| Wetting
Agent |
|
A
surface-active
agent that promotes
wetting by
decreasing the
cohesion within a
liquid. |
| Whisker |
|
A short single
crystal fiber or
filament used as a
reinforcement in a
matrix. |
| Wind Angle |
|
The measure in
degrees between the
direction parallel
to filaments and an
established
reference. |
| Winding
Pattern |
|
The regularly
recurring pattern
of the filament
path in a filament
winding after a
certain number of
mandrel
revolutions. |
| Wire Mesh |
|
A fine wire
screen used to
increase electrical
conductivity;
typically used to
dissipate the
electrical charge
from
lightning. |
| Woof
Threads |
|
See Fill
Threads. |
| Woven
Roving |
|
Heavy, coarse
fabric produced by
weaving continuous
roving
bundles. |
| Wrinkle |
|
Imperfection in
the surface of a
laminate that looks
like a crease in
one of the outer
layers. This occurs
in vacuum-bag
molding when the
bag is improperly
placed. |
| Wear or K
Factor |
|
The ability to
resist wear against
steel. |
|
|
|
|
|
| |
| X-,
Y-, Z-Axis |
|
The axis in the
plane of a laminate
used as 0°
reference. The
y-axis is the axis
in the plane of a
laminate
perpendicular to
the x-axis. The
z-axis is the
through-the-plane
thickness. |
|
|
|
|
|
| |
| Yarn |
|
Continuously
twisted fibers or
strands suitable
for weaving into
fabrics. |
| Yield
Point |
|
The first
stress in a
material, less than
the maximum rate
attainable stress,
at which the strain
increases at a
higher rate than
the stress. The
point at which
permanent
deformation of a
stressed specimen
begins to take
place. |
| Young’s
Modulus |
|
The ratio of
normal stress to
the corresponding
strain for tensile
or compressive
stresses less than
the proportional
limit of the
material. |
|
|
|
|
|
| |
| Zero
Bleed |
|
A laminate
fabrication
procedure that
prohibits loss of
resin during
cure. |
|
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|
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|
