A
Abrasion - Surface loss of a material due to frictional forces.
Abrasion resistance - The resist- ance of a material to loss of surface
particles due to friction.
Accelerated aging - A method in which an attempt is made to produce
and measure the effects of natural aging in a shorter period.
Acid Resistant - Withstands the action of acids.
Adhesion - The state in which two surfaces are held together by interfacial
forces which may consist of molecular forces or interlocking action, or both.
Adhesion Failure - The separation of two materials at the surface interface
rather than within one of the materials itself.
Aging - (1) The irreversible change of material properties after environ-
mental exposure for an interval of time; (2) Exposing materials to an environment
for an interval of time.
Air Checks - See Airtrap
Air trap - Surface markings or depressions due to trapping air voids
in body or part due to entrapped gas between the materials being cured and
the mold or press surface.
Air Curing - The vulcanization of a rubber product in air as distinguished
from vulcanizing in a press or steam vulcanizer.
Apportionment - Referred to here as a part of Reliability Engineering.
Synonymous with the term Reliability Apportionment, which is the assign- ment
of reliability goals from system to subsystem in such a way that the whole
system will have the required reliability.
Autoclave - A pressure vessel into which materials or articles can
be placed and exposed to steam under pressure. It is commonly used for vulcanization.
B
Benchmark Data - The results of an investigation to determine how
competitors and/or best-in-class companies achieve their level of performance.
Backrinding - Defect in which the rubber adjacent to the mold parting
line shrinks below the level of the molded product, often leaving the parting
line ragged and torn.
Batch - The product of the one mixing operation in an intermittent
process.
Bias Angle - (1) Acute angle between the direction of the cut and the
diameter of the wrap in the production of wrapping for hose; (2) Acute angle
between the direction of the cut and the direction of the cords in the production
of fabric plies.
Bill of Material - Total list of all components/materials required
to manufacture the product.
Blister - A cavity or sac that deforms the surface of a material.
Bloom - A liquid or solid material that has migrated to the surface
of a rubber, thereby changing appearance. Sometimes confused with surface
dust.
Bond - The union of materials by use of adhesives, usually used in
related parts vulcanized after attaching.
Brittleness - Tendency to crack when subjected to deformation.
Buna N - A general term for the copolymers of butadiene and acrylonitrile.
Typical commercial polymers are Hycar and Paracril.
Buna S - A general term for the copolymers of butadiene and styrene.
Butt Joint - Joining two ends of material whereby the junction is perpendicular
to the ID of an O-ring.
Butyl - A synthetic rubber of the polybutene type exhibiting very low
permeability to gases.
C
Carbon black - Elemental carbon in finely divided form used to reinforce
elastomeric compounds.
Catalyst - A chemical in small quantities which accelerates a chemical
reaction without itself necessarily becoming part of the final product.
Cellular Rubber - Rubber products which contain cells or small hollow
receptacles. The cells may either be open or interconnecting or closed and
not interconnecting.
Characteristics Matrix - An analytical technique for displaying the
relationship between process para- meters and manufacturing stations.
Checking - The short, shallow cracks on the surface of a rubber product,
resulting from damaging action by environmental conditions.
C.I. - The abbreviation for cloth- inserted, indicating a sheet of
rubber containing one or more plies of fabric covered with rubber.
Cold Flow - Continued deformation under stress.
Compound - A term applied to either vulcanized or unvulcanized mixtures
of elastomers and other ingredients necessary to make a useful rubber-like
material.
Compression set - The residual deformation of a material after removal
of the compressive stress.
Conductive - To conduct or transmit heat or electricity.
Contact stain - Discoloration of a product by another material or by
a rubber article in the area directly touching it.
Copolymer - A polymer consisting of two different monomers chemically
combined.
Crazing - A surface effect on rubber articles characterized by many
minute cracks.
Creep - The deformation, in either cured or uncured rubber under stress,
which occurs with lapse of time after the immediate deformation.
Cross Section - An O-ring as viewed if cut at right angles to the axis
showing internal structure.
Cure - The act of vulcanization. See Vulcanization.
Cut - The distance between cuts or parallel faces of articles produced
by repetitive slicing or cutting of long preshaped rods or tubes such as lathe
cut washers.
D
Design Failure Mode and Effects Analysis (DFMEA) - An analytical technique
used by a design responsible engineer/team as a means to assure, to the extent
possible, that potential failure modes and their associated causes/mechanisms
have been considered and addressed.
Design for Manufacturability and Assembly - A simultaneous engineering
process designed to optimize the relationship between design function, manufacturability;
and ease of assembly.
Design Information Checklist - A mistake proofing checklist designed
to assure that all important items are considered in establishing design requirements.
Design Reviews - A proactive process to prevent problems and misunderstandings.
Design Validation - Testing to ensure that product conforms to defined
user needs and/or requi- rements. Design validation follows successful design
verification and is normally performed on the final product under defined
operating conditions. Multiple validations may be performed if there are different
intended uses.
Design Verification - Testing to ensure that all design outputs meet
design input requirements. Design verification may include activities such
as:
- Design Review
- Performing Alternate Calculations
- Understanding Tests and Demonstrations
- Review of Design Stage Documents Before Release
Dielectric strength - The measure of a product's ability to resist
passage of a disruptive discharge produced by an electric stress; the voltage
that an insulating material can withstand before breakdown occurs,
Duck - A compact, firm, heavy, plain weave fabric made from cotton
or synthetic fibers, or a combination of both. Duck is also known as canvas,
army duck, belt duck harvester duck, hose duck and shoe duck.
Durability - The probability that an item will continue to function
at customer expectation levels, at the useful life without requiring overhaul
or rebuild due to wearout.
Durometer - An instrument for measuring the hardness of vulcanized
rubber and plastic. See Shore
E
Elasticity - The property of an article which tends to return to its
original shape after deformation.
Elongation - Extension produced by a tensile stress.
Expanded Rubber - Cellular rubber having closed cells made from a solid
rubber compound.
Extrusion - 1) Distortion, under pressure, of portion of seal into
clearance between mating metal parts. 2) Material, under pressure, which is
forced through the opening of a die in order to obtain a desired cross sectional
shape.
F
Failure Modes Analysis (FMA) - A formal, structured procedure used
to analyze failure mode data from both current and prior processes to prevent
occurrence of those failure modes in the future.
Feasibility - A determination that a process, design, procedure, or
plan can be successfully accom- plished in the required time frame.
Finish, Mold - The quality or appearance of the machined surface of
a mold.
Finish, Product - The quality or appearance of the surface of a rubber
product.
Finite Element Analysis - A technique for modeling a complex structure.
When the mathematical model is subjected to known loads, the displacement
of the structure may be determined.
Flash - Excess rubber on a molded product resulting from cavity overflow
at the parting lines where the mold sections are separated.
Flex cracking - A cracking condition of the surface of rubber articles
such as tires and footwear, resulting from constantly repeated bending or
flexing in service.
Flow Marks - Surface imper- fections due to improper flow and failure
of stock to knit or blend with itself during the molding operation.
Friction - Resistance to motion due to the contact of surfaces.
G
Gate - (rubber injection or transfer mold) - The orifice used to control
the flow of rubber, and through which a shaped cavity in a mold is filled
with rubber.
Glass transition point - Temp- erature at which a material loses its
glass-like properties and becomes a semi-liquid.
Grain - The unidirectional orientation of rubber or filler particles
occurring during pro- cessing (extrusion, milling, calen- dering) resulting
in anisotropy of a rubber vulcanizate.
Green strength - (1) The resistance to deformation of a rubber stock
in the uncured state. (2) Uncured adhesion between plied or spliced surfaces.
H
Heat history - The accumulated amount of heat a rubber stock has been
subjected to during process- ing operations, usually after incorporation of
the vulcanizing agents. Incipient cure or scorch can take place if heat history
has been excessive.
Hydrolysis - Chemical decom- position of a substance involving the
addition of water.
Hysteresis - The heat generated by rapid deformation of a vulcanized
rubber part. It is the difference between the energy of the deforming stress
and the energy of the recovery cycle.
I
Insert - A part, usually metal, which is placed in a mold and appears
as an integral part of the molded product.
IRHD (International Rubber Hardness) - For complete definition see
ASTM D 1415-68 Standard Method of Test for International Hardness of Vulcanized
Natural And Synthetic Rubbers.
K
Kaizen - Taken from the Japanese words kai and zen where kai means
change and zen means good. The popular meaning is continual improvement of
all areas of a company not just quality.
Knit mark - Where raw stock did not unite into a homogeneous mass during
the vulcanization. This is also called poor knitting. See Flow marks
L
Low temperature flexibility - The ability of a rubber product to
be flexed, bent, or bowed at specified low temperature without loss of serviceability.
M
Maintainability - The probability that a failed system can be made
operable in a specified interval or downtime.
Mandrel - A bar, serving as a core, around which rubber is extruded,
forming a center hole.
Masterbatch - A preliminary mixture of rubber and one or more compound
ingredients for such purposes as more thorough dispersion or better processing,
and which will later become part of the final compound in a subsequent mixing
operation.
Mill - A machine with two horizontal rolls revolving in opposite directions
used for the mastication or mixing of rubber.
Modulus - The ratio of stress to strain. In the physical testing of
rubber, the load necessary to produce stated percentage of elongation, compression
or shear.
Mold Register - Means used to align the parts of a mold.
Mooney scorch - A measure of the incipient curing characteristics of
a rubber compound using the Mooney viscometer.
Mooney viscosity - A measure of the viscosity of a rubber or rubber
com- pound determined in a Mooney shearing disc viscometer.
N
Nerve - The elastic resistance of unvulcanized rubber or rubber compounds
to permanent defor- mation during processing.
Non-Blooming - The absence of a bloom.
O
Oil Resistant - Ability of a vulcan- ized rubber to resist the swelling
and deteriorating effects of various type of oils.
Open Cell - A cell not totally enclosed by its walls and hence interconnecting
with other cells.
Optimum Cure - State of vulcan- ization at which maximum desired property
is attained.
Ozone cracking - The surface cracks, checks, or crazing caused by exposure
to an atmosphere contain- ing ozone.
P
Packaging - A unit that provides protection and containment of items
plus ease of handling by manual or mechanical means.
Permanent set - The amount by which an elastic material fails to return
to its original form after deformation.
Permeability - To permit passage of gas through the molecular structure
of a given material.
Plasticity - (1) A measure of the resistance to shear of an unvulcanized
elastomer; (2) A tendency of a material to remain deformed after reduction
of the deforming stress to or below its yield stress.
Pock marks - Uneven blister-like elevations, depressions, or pimpled
appearance.
Polymer - A material formed by the joining together of many (poly)
individual units (mar) of a monomer.
Porosity - The presence of numer- ous small holes or voids.
Post cure - Heat or radiation treatment, or both, to which a cured
or partially cured thermosetting plastic or rubber composition is subjected
to enhanced the level of one or more properties.
Preliminary Bill of Material - An initial Bill of Material completed
prior to design and print release.
Preliminary Process Flow Chart - An early depiction of the anticipated
manufacturing process for a product.
Process Failure Mode and Effects Analysis (PFMEA) - An analytical technique
used by a manufacturing responsible engineer/ team as a means to assure that,
to the extent possible, potential failure modes and their associated causes/mechanisms
have been considered and addressed.
Product Assurance Plan - A part of the Product Quality Plan. It is
a prevention-oriented management tool that addresses product design, process
design, and when applicable software design.
Production Trial Run - Product made using all production tools, processes,
equipment, environment, facility; and cycle time.
Q
Quality Planning Sign-Off - A review and commitment by the Product
Quality Planning Team that all planned controls and processes are being followed.
R
Rebound - Rebound is a measure of the resilience, usually as the
percent- age of vertical return of a body which has fallen and bounced.
Rebound test - Method of deter- mining the resilient properties of
vulcanized rubber, by measuring rebound of a steel ball or pendulum falling
from a definite height onto a rubber sample.
Register - The accurate matching of the plates of a mold.
Reliability - The probability that an item will continue to function
at customer expectation levels at a measurement point, under specified environmental
and duty cycle conditions.
Reliability Apportionment - See Apportionment.
Reproducibility - The variation in the average of measurements made
by different operators using the same gage when measuring identical characteristics
of the same parts.
Resilience - The property of a material that enables it to return to
its original size and shape after removal of the stress which causes the deformation.
Reversion - (1) A deterioration of physical properties that may occur
upon excessive vulcanization of some elastomers, evidenced by a decrease in
hardness and tensile strength, and an increase in elonga- tion; (2) A similar
change in proper- ties after air aging at elevated temperatures. Natural rubber,
butyl, polysulfides and epichlorobydrin polymers exhibit this effect (extreme
reversion may result in tackiness). Most other polymers will harden and suffer
loss of elongation on hot air aging.
Rheometer (Monsanto) - An oscillating disk cure meter used for determining
vulcanization charac- teristics of a rubber compound.
RMS - Root Mean Square - The measure of surface roughness, obtained
as the square root of the sum of the squares of micro-inch deviation from
true flat.
Rotocure - Rotory press.
Rubber - A material that exhibits elastic properties that allow recovery
from large deformations quickly and forcibly. A tough, waterproof substance
obtained through polyme- ric synthesis or in natural form from the sap of
various species of plants or trees.
Rubber Latex - Colloidal aqueous emulsion of an elastomer.
S
Scorch - Premature vulcanization of a rubber compound, generally due
to excessive heat history. Also see Mooney Scorch;
Shore A Hardness - An indentation method of rating the hardness of
rubber using a Shore Durometer with the A scale from 0 to 100.
Shrinkage - Contraction of molded rubber upon cooling.
Skin - A relatively dense layer at the surface of a cellular material.
Simulation - The practice of mimick- ing some or all of the behavior
of one system with a different, dissimilar system.
Simultaneous Engineering - A way of simultaneously designing products,
and the processes for manufacturing those products, through the use of cross
functional teams to assure manufacturability and to reduce cycle time.
Smoke sheets - Plantation natural rubber sheets that, after passing
through a mill that puts the conven- tional ribbing design on them, are washed
and hung on racks in a smoke house where they undergo a combined smoking and
drying process.
Special Characteristics - Product and process characteristics designated
by the customer including govern- mental regulatory and safety; and/or selected
by the supplier through knowledge of the product and process.
Specific gravity - The ratio of the mass of a unit volume of a material
to that of the same volume of water at a specified temperature.
Splice - A joint or junction made by lapping or butting edges, straight
or on a bias, and held together through vulcanization or mechanical means.
Sprue - (1) The primary feed channel that runs from the outer face
of an injection or transfer mold to mold gate in a single cavity mold or to
runners in a multiple cavity mold; (2) The piece of material formed or partially
cured in the primary feed channel.
Sprue mark - A mark, usually elevated, left on the surface of an injection
or transfer molded part, after removal of the sprue.
Squeeze - Cross section diametrical compression of O-ring between bottom
surface of the groove and surface of other mating metal part in the gland
assembly.
State of cure - The cure condition of a vulcanizate relative to that
at which optimum physical properties are obtained.
Stress - Force per unit of original cross sectional area required to
stretch a specimen to a stated elongation.
Stress relaxation - The decrease in stress after a given time of constant
strain.
Substrate - A material upon the surface of which an adhesive promo-
ter is applied for any purpose such as bonding or coating.
Subsystem - A major part of a system which itself has the charac- teristics
of a system, usually consisting of several components.
Swelling - The increase in volume or linear dimensions of a specimen
immersed in a liquid or exposed to a vapor.
System - A combination of several components or pieces of equipment
integrated to perform a specific function.
T
Tack - The ability to adhere to itself; a sticky or adhesive quality.
Team Feasibility Commitment - A commitment by the Product Quality Planning
Team that the design can be manufactured, assembled, tested, packaged, and
shipped in sufficient quantity at an acceptable cost, and on schedule.
Tear Strength - The maximum load required to tear apart a specified
specimen, the load acting substan- tially parallel to the major axis of the
test specimen.
Temperature Range - Lowest temperature at which rubber remains flexible
and highest temperature at which it will function.
Tensile Strength - Force in pounds per square inch required to cause
the rupture of a specimen of a rubber material.
Tensile Stress - The applied force per unit of original cross sectional
area of a specimen.
Tensile Stress at Given Elong- ation - The tensile stress required
to stretch a uniform section of a specimen to a given elongation.
Tension Set - The extension remaining after a specimen has been stretched
and allowed to retract.
Thermoplastic Rubber - Rubber that does not require chemical vulcanization
and will repeatedly soften when heated and stiffen when cooled; and which
will exhibit only slight loss of its original charac- teristics.
Thermosetting Rubber - Chemi- cally vulcanized rubber that cannot be
remelted or remolded without destroying its original characteristics.
Timing Plan - A plan that lists tasks, assignments, events, and timing
required to provide a product that meets customer needs and expec- tations.
Trim - The process Involving removal of mold flash.
U
Ultimate Elongation - The maxi- mum elongation prior to rupture.
Undercure - State of vulcanization less than optimum. It may be evidenced
by tackiness or inferior physical properties.
V
Value Engineering (Value Analy- sis) - A planned, clean sheet approach
to problem solving, focusing on specific product design and process characteristics.
Where value analysis is employed to improve value after production has begun,
value engineering is employed to maximize value prior to expend- itures of
facilities and tooling money.
Viscosity - The resistance of a material to flow under stress.
Voice of the Customer - Customer feedback both positive and negative
including likes, dislikes, problems and suggestions.
Voice of the Process - Statistical data that is feedback to the people
in the process to make decisions about the process stability and/or capability
as a tool for continual improvement.
Voids - The absence of material or an area devoid of materials where
not intended.
Vulcanization - An irreversible process during which a rubber compound
through a change in its chemical structure (for example, cross-linking) becomes
less plastic and more resistant to swelling by organic liquids and elastic
properties are conferred, improved, or extend- ed over a greater range of
temper- ature.
W
Water Absorption - The increase in weight and volume after immersion
in water.
Water resistance - The ability to withstand swelling by water for a
specified time and temperature.
Wetting - Completeness of contact between particles dispersed in a
medium, such as carbon black rubber.
Y
Young's modulus - The ratio of normal stress to corresponding stress
or compressive stresses below the proportional limit of the material.
