accelerated life test:
a method designed to approximate in a short time the deteriorating
effects obtained under normal service conditions,
strength of bond between cured rubber surfaces or a cured rubber
surface and a non-rubber surface.
air checks: the
surface markings or depressions which occur due to air trapped
between the material being cured and the mold or press surface.
air oven aging: a
means of accelerating a change in the physical properties of rubber
compounds by exposing them to the action of air at an elevated
temperature at atmospheric pressure. ANSI: the abbreviation for the
American National Standards Institute.
abbreviation for The American Society of Mechanical Engineers.
abbreviation for the American Society for Testing and Materials.
small fissures in the surface of rubber articles caused by exposure
to atmospheric conditions.
backing: a layer or
liner of material on the underside of a sheeted product to provide
bare back: the
textile face of an article which is free of any treatment or
exudation. See also bloom.
blemish: a mark,
deformity, or damage which impairs the. appearance.
blister: a raised
area on the surface or a separation between layers usually creating
a void or air- or gas-filled space in a vulcanized article. See
discoloration or change in appearance of the surface of a rubber
product caused by the migration of a liquid or solid to the surface.
Examples: sulfur bloom, wax bloom. Not to be confused with dust on
the surface from external sources.
blow: a soft area
caused by porosity below the surface.
buffing: grinding a
surface to obtain dimensional conformance or surface uniformity.
calendar: a machine
equipped with three or more heavy, internally heated or cooled rolls
revolving in opposite directions, which is used for continuously
sheeting or plying up rubber compound, or frictioning or coating
fabric with rubber compound.
calender stop: a
mark left on the surface of rubber sheet or sheeting due to
interruption of calender roll motion.
abbreviation for cloth both sides, used to describe a sheet
consisting of a ply of fabric on each surface with a layer of rubber
formation of a powdery surface condition due to disintegration of
surface binder or elastomer by weathering or other destructive
checking: the short,
shallow cracks on the surface of a rubber product resulting from
damaging action of environmental conditions.
Cl: the abbreviation
for cloth-inserted. indicating a sheet of rubber containing one or
more plies of fabric covered with rubber. cloth -both-sides sheet:
cloth impression: see
fabric impression. cloth-inserted sheet: see CI.
cloth-one-side sheet: see
cold flow: continued
deformation under stress. See creep.
a degree of smoothness of an article which acceptable in accordance
with industry practice.
compressed asbestos sheet:
a sheet prepared from a rubber cc pound containing a high percentage
of asbestos fiber and vola solvent by the use of a special calender
(sheeter) in such a man that the solvent is volatilized and the
compound is caused to build as an oriented sheet on one roll of the
property of exhibiting compression under stress In the case of sheet
material, the percent of loss of thickness when subjected to a given
load applied by a disc of a given diameter for a specified short
time and at a specified temperature as defined ASTM F-36.
compression set: the
deformation which remains in rubber after has been subjected to and
released from a specific compress stress for a definite period of
time at a prescribed temperature. Cc Compression set measurements
are used to evaluate the creep and stress relaxation properties of
the ability to conduct or transmit heat electricity. In rubber
products, it generally relates to the capability conducting static
sheet made from cork granules treated with a binder.
abbreviation for cloth one side, similar to CI sheet except that one
fabric ply is exposed at the surface. Generally not friction on the
count: in fabric,
the number of warp ends, the number of filling picks. or both in a
square inch of fabric.
crack: a sharp break
or fissure in a surface. Usually caused by strain and/or
crazing: a surface
effect on rubber articles characterized multitudinous, minute
deformation, in either cured or uncured rubber under stress, which
occurs with lapse of time after the immediate deform ation See cold
creep relaxation: in
a flange gasket. loss of stress accompanied constantly decreasing
compressed thickness. This type of relaxation is encountered in
bolted flange joints. cure: the act of vulcanization. See
cure time: the time
required to produce vulcanization at a given tem perature.
damping: (1) the
progressive reduction of amplitude in a freely vibrating system; (2)
any kind of friction in a freely vibrating system causing the motion
to decrease gradually to the vanishing point.
date code: any
combination of numbers, letters, symbols, or other methods used by a
manufacturer to identify the time of manufacture of a product.
diaphragm: a packing
attached between rigid members in relative motion which absorbs the
motion through its own deformation.
sheet. generally of fabric reinforced rubber, fro which flat
diaphragms may be cut. die cut: shaped by punching from a sheet of
rubber with a die.
the measure of a product's ability to resist passage of a disruptive
discharge produced by an electric stress.
diffusion: a flow or
loss of a gas under pressure through a rubber layer.
drift: a change in a
given hardness value after a specified period of time.
instrument for measuring the hardness of vulcanized rubber and
an arbitrary numerical value which measures the resistance to
indentation of the blunt Indentor point of a durometer. Value may be
taken immediately or after a very short specified time.
macromolecular material which, in the vulcanized state, at room
temperature can be stretched repeatedly to at least twice its
original length and which, upon release of the stress, will
immediately return to approximately its original length.
increase in length expressed numerically as a fraction or percentage
of the initial length.
fabric impression: a
pattern in a rubber surface formed by contact with fabric during
flange gasket: a
gasket employed in a flange joint.
flex life: the
relative ability of a rubber or plastic product to withstand
cyclical bending stresses.
flex test: a
laboratory method used to evaluate the resistance of a rubber
product to repeated bending.
flow crack: a
surface imperfection caused by improper flow and failure of stock to
knit or blend with itself during the molding operation.
flow mark: a surface
imperfection similar to flow crack, but the depression of which is
not quite as deep.
friction: a rubber
adhesive compound applied to and impregnating a fabric.
friction coating: a
rubber covering applied to the weave of a fabric simultaneously with
the exposed portion of a rubber product formed by a layer of
rubber-impregnated fabric as distinguished from a product having the
fabric completely covered with a layer of rubber.
full-face gasket: a
gasket covering the entire flange surface and drilled with bolt
a deformable material clamped between essentially stationary faces
to prevent the passage of matter through an opening or joint.
ground finish: a
surface produced by grinding or buffing. See buffing.
hydraulic packing: a
slab packing composed of superimposed fine textile frictioned plies.
Used mainly for piston rings.
low temperature flexibility:
the ability of a rubber product to be flexed, bent, or bowed at low
temperatures without loss of serviceability.
an empirical design constant of a flange gasket used in the ASME
Code for Unfired Pressure Vessels. The code equation defines this
term as the ratio of residual gasket load to fluid pressure at leak.
modulus: in the physical testing of rubber, the load necessary to
produce a stated percentage of elongation, compression. or shear.
Modulus: in the
physical testing of rubber, the load necessary to produce a stated
percentage of elongation. Compression, or shear.
having the ability to withstand deteriorating effects of oil
(generally petroleum) on the physical properties.
oxygen bomb: a
chamber capable of holding oxygen at an elevated pressure which can
be heated to an elevated temperature. Used for an accelerated aging
ozone cracking: the
surface cracks, checks, or crazing caused by exposure to an
atmosphere containing ozone.
deformable material used to prevent or control the passage of matter
between surfaces which move in relation to each other.
paper finish: that
finish resulting from curing in contact with paper or film.
permanent set: the
amount by which an elastic material fails to return to its original
form after deformation.
quality or condition of allowing passage of liquids or gases through
plate finish (sheet):
a commercially smooth surface, the usual result of vulcanization
between press plates or platens.
pock marks: uneven
blister-like elevations, depressions. or pimpled appearance. See air
checks and blister.
condition of containing numerous small holes or voids.
press lap: the mark
of the area of overlap of one press cure length on the next.
press length: the
length of a product which can be vulcanized at one time in a press,
limited to the length of the press.
press mark: an
irregularity in the surface of a vulcanized product caused by the
press ends or by corresponding irregularities in the press surface.
abbreviation for The Rubber Association of Canada.
abbreviation for The Rubber Manufacturers Association, Inc.
abbreviation for the Society of Automotive Engineers.
seal: any material
or device which prevents or controls the passage of matter across
the separable members of a mechanical assembly.
sensitivity: in a
diaphragm, the absence of resistance to displacement by light fluid
a diaphragm between two fluids at substantially the same pressure
and, hence, under little or no stress.
set: the amount of
strain remaining after complete release of a load producing a
shape factor: the
ratio of the area of one load face to the combined area of those
surfaces free to expand laterally when a rubber is under
shear modulus: the
ratio of the shear stress to the resulting shear strain (the latter
expressed as a fraction of the original thickness of the rubber
measured at right angles to the force.) Shear modulus may be either
static or dynamic.
shelf storage life:
the period of time prior to use during which a product retains its
intended performance capability.
skim coat: a layer
of rubber material laid on a fabric but not forced into the weave.
Normally laid on a frictioned fabric. Sometimes called skim.
slab: a thick sheet.
spread fabric: a
fabric coated with a rubber cement by a spreading process and then
dried to remove the solvent.
square woven: a
cloth or duck having practically the same count or tensile strength
in both the warp and filling.
the maximum tensile stress applied while stretching a specimen to
rupture. trapped air: air which is enclosed in a product or between
a product and a mold surface during cure. (Usually causes a loose
ply or cover or a surface mark, depression, or void.)
void: the absence of
material or an area devoid of materials where not intended. See