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GLOSSARY OF TERMS
A
B C D E
F G H I
J K L M
N O P Q
R S T U
V W X Y
Z
Select the first letter of
the word from the list above to jump to appropriate section of the glossary.
-
A -
- ABS (Acrylonitrile-Butadiene-Styrene)
-
- A polymer produced from acrylonitrile and styrene liquids, and butadiene
gas, which are polymerized together in a variety of ratios to produce the
family of ABS resins.
-
- Abrasion Resistance -
- The ability of a material to withstand mechanical action (friction) such
as rubbing, scraping, etc.
-
- Absolute Pressure -
- A quantity of pressure with respect to total vacuum; equal to the sum of a
pressure gauge reading and atmospheric pressure (14.69 psia at sea level).
-
- Absolute Zero -
- The minimum point in the thermodynamic temperature scale (-273.16ºC or
-459.69ºF).
-
- Absorption -
- The penetration into the mass of one substance by another.
-
- Accumulator -
- A container which stores fluid under pressure. Used as an energy source or to
absorb hydraulic shock. Common types are piston, bladder and diaphragm.
-
- Acetal -
- A rigid thermoplastic with properties similar to zinc, aluminum, and other
metals. The molecular structure of the polymer is of a linear acetal
consisting of unbranched polyoxymethylene chains.
-
- Acid Resistant -
- The ability of a material to withstand the corrosive action of acids.
-
- Additive -
- A substance compounded into a resin to enhance certain characteristics such
as plasticizers (for flexibility), light stabilizers, flame retardants, etc.
-
- Aging -
- The chemical and/or physical changes which occur in a material after
exposure to environmental conditions over a period of time.
-
- Alloy (polyblend) -
- A composite material made by blending polymers or copolymers with other
polymers or elastomers.
-
- Annealing -
- A process of heating a material to a temperature just below its melting
point and then gradually cooling it. This will relax stress caused during the
molding process without distortion of the shape.
-
- Antioxidant -
- Substances which prevent or slow down oxidation of a polymeric material
exposed to air.
-
- Antistatic Agent -
- Additives put in a resin or substance or applied to the surface of the
finished part for the purpose of eliminating or lessening static electricity;
acts to permit the surface to be slightly conductive, preventing the
formulation of static charges.
-
- ASTM -
- American Society of Testing Materials
-
- Autoclave -
- A closed vessel for conducting chemical reactions under high pressure and
temperature.
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B -
- Bleed -
- To give up color when in contact with water or a solvent; undesirable
movement of certain materials in a plastic (ex: plasticizers in vinyl) to
the surface of the finished article or into an adjacent material.
-
- Bleeder -
- A device for removal of pressurized fluid. Used to bleed air from system.
-
- Bloom -
- A cloudy, greasy film on the surface of a plastic part or film usually
caused by the extraction of an additive, such as a lubricant, stabilizer,
etc.
-
- Brittle Temperature -
- The threshold temperature at which the material will fracture due to cold
induced loss of flexibility.
-
- Burning Rate -
- A term describing the tendency of plastics to burn at a given temperature.
Certain plastics will burn readily at comparatively low temperatures. Others
will melt or disintegrate without actually burning, or will burn only if
exposed to a direct flame. The latter are referred to as self-extinguishing.
-
- Burst Pressure -
- The pressure point at which the tube/hose will suddenly and violently
rupture.
-
- Butt Fusion (welding)
-
- A process of joining the ends of thermoplastic parts by heating the
surfaces to be joined to their molten state and then pressing them together
to form a homogenous bond.
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C -
- Carbon Black -
- A multi-functional additive produced by the incomplete burning of natural
gas or oil and used in plastics as a conductor of electricity, a pigment, a
filler-extender, and a stabilizer.
-
- Catalyst -
- A substance which speeds up the polymerization or cure of a compound when
added in minor quantity as compared to the primary reactants.
-
- Cavitation -
- A gaseous condition within a liquid stream caused when pressure is reduced
to the vapor pressure. To be avoided due to destructive effects on pumps and
motors.
-
- Cellulose -
- A naturally occurring polysaccharide consisting solely of glucose units
and found in most plants. It is the main constituent of dried woods, jute,
flax, hemp, etc.
-
- Cellulosics -
- A family of resins derived from cellulose. The three most common types
are: cellulose-acetate (CA), cellulose-acetate-butyrate (CAB), and
cellulose-acetate-propionate (CAP).
-
- Circuit; Pilot -
- Used to control a main circuit or component.
-
- Circuit; Regenerative -
- Used to increase cylinder speed by directing rod end discharge to the
piston side of the cylinder. Can be incorporated into directional control
valve as fourth position.
-
- Coefficient of
Friction -
- Resistance to sliding or rolling of surfaces of solid bodies in contact
with each other; stated as k=F/W in which F is the force required to move
one surface over another and W is the weight pressing the surfaces together.
-
- Co-Extrusion -
- The technique of extruding two or more materials through a single die
being fed by separate extruders.
-
- Compounding -
- The process of mixing the polymer with all the materials necessary for the
finished resin to be used by the processor.
-
- Compressed Gas -
- Any material or mixture having in the container either an absolute
pressure exceeding 40 psia at 70ºF or an absolute pressure exceeding 104
psia at 130ºF.
-
- Compressive Strength -
- Maximum load at which compression failure occurs in a specimen divided by
the original area of the specimen.
-
- Conductivity -
- The property of transmitting electricity, heat, etc.
-
- Copolymer -
- A compound resulting from the chemical reaction of two chemically
different monomers with each other.
-
- Core -
- The inner-most layer of a multi-layered product.
-
- Corona Resistance -
- The time that a material will withstand a specified level of
field-intensified ionization that does not result in the immediate complete
breakdown of the material.
-
- Corrosive -
- Any substance which chemically attacks materials with which it comes in
contact, such as metals or human tissue.
-
- Crazing -
- Minute cracks near the surface of plastic materials.
-
- Creep (cold flow) -
- The dimensional change with time of a material under physical load. Creep
at room temperature is called “cold flow.”
-
- Cross-Linking -
- The establishing of chemical links between the molecular chains in
polymers. Cross-linking can be accomplished by chemical reaction,
vulcanization, and/or irradiation.
-
- Crystallinity -
- A state of molecular structure in some resins denoting uniformity and
compactness of the molecular chains. This characteristic is attributable to
the existence of solid crystals with definite geometric form.
-
- Cuff -
- A smooth end on an irregularly surfaced tube or hose enabling the secure
and leak-free fitment of the tube or hose to its termination point.
-
- Cure -
- The changing of the physical properties of a material by chemical
reaction; usually by the action of heat and catalysts, alone or in
combination, with or without pressure.
-
- Cylinder -
- A device which converts hydraulic energy into linear mechanical
motion and force.
-
- Cylinder; Double Acting -
- A cylinder which can apply force and motion in either direction.
-
- Cylinder; Single Acting -
- A cylinder which can apply force in one direction only.
-
- Cylinder; Depth Control -
- A mechanical or hydraulic device, adjustable, for limiting cylinder stroke.
-
- Cylinder; Rephasing -
- A cylinder design which permits the use of two or more cylinders in
series, automatically synchronizing cylinder position at the end of each
stroke.
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D -
- Decay Rate -
- The speed in which a material will drain a static electrical charge.
-
- Deflection Temperature
-
- The temperature at which a standard test bar deflects 0.010” under a
load of 66 or 264 psi.
-
- Deformation -
- The result when an object does not return to its original form or shape
after pressure or stress is removed.
-
- Degradation -
- Deleterious change in the chemical structure of a plastic reflected in the
appearance or physical properties.
-
- Delamination -
- The separation of layers in a laminate through failure of the resin binder
or adhesive.
-
- Density -
- The mass per unit volume of a substance expressed in pounds per cubic
foot, grams per cubic centimeter, etc.
-
- Denier -
- a unit of weight for measuring the fitness of threads of silk, rayon,
nylon, etc., equal to .05 gram per 450 meters.
-
- Detent -
- A spring device which maintains the spool of a directional control valve
in position.
-
- Detent Release -
- A mechanical, hydraulic or electrical device for releasing the detent.
-
- Die, Extrusion -
- Placed at the exit of an extruder barrel through which the resin emerges
and is formed into film, rods, pipe, profiles, sheet, tubing, etc.
-
- Dielectric -
- 1) any insulating medium which intervenes between two conductors; 2) a
material having the property that energy required to establish an electric
field is recoverable in whole or in part, as electric energy.
-
- Dielectric Strength -
- The electric voltage gradient at which an insulating material is broken
down or “arced through,” usually expressed in volts per mil of
thickness.
-
- Dimensional Stability
-
- The ability of a part to retain its shape when exposed to external forces.
-
- D.O.P. (Dioctyl
Phthalate) -
- An ester plasticizer derived from natural fats and oils; can be modified
to meet specific end use requirements.
-
- Ductility -
- Amount of plastic strain a material can withstand before it fractures.
-
- Durometer -
- A trade name of the Shore Instrument Company for an instrument that
measures the hardness of a material. A lower Shore scale number indicates a
softer, more flexible material.
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E -
- Elastic Deformation -
- The portion of deformation of an object under load which can be recovered
after the load is removed.
-
- Elasticity -
- The property of a material of which it tends to recover its original size
and shape after deformation.
-
- Elongation -
- The fractional increase in length of a material stressed in tension.
-
- Embossing -
- Technique using pressure with or without heat to make a permanent marking
in a material's surface.
-
- Encapsulating -
- Encasing an article in a closed envelope of plastic by immersing the
object in a casting resin and allowing the resin to polymerize, or, if hot,
to cool.
-
- End Thrust -
- The total force generated at the far end of a conduit by the sudden
release of a fluid under pressure (spike pressure) into that conduit;
measured in psi and calculated: (¹ x radius [in.]) x spike pressure [psi].
-
- EPDM -
- Ethylene Propylene Diene terpolymer
-
- Ester -
- The reaction product of an alcohol and an acid.
-
- Ethylene Vinyl Acetate
(EVA) -
- A copolymer member of the polyolefin family derived from random
copolymerization of vinyl acetate and ethylene resulting in a resin with
similar properties to that of polyethylene but with greater flexibility and
resistance to impact and elongation.
-
- EVA -
- Ethylene vinyl acetate
-
- Extender -
- A substance added to a plastic compound to reduce the amount of resin
required per unit volume.
-
- Extrusion -
- The process of compacting and melting a plastic material and forcing it
through an orifice (die) in a continuous fashion.
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F -
- FDA -
- Food and Drug Administration
-
- FEP -
- Fluorinated ethylene propylene
-
- FRP -
- Fiberglass reinforced plastic.
-
- Filament -
- Fiber of extreme length used in yarns and other compositions with little
or no twist and usually without the spinning operations required for fibers.
-
- Filler -
- A very inexpensive material which is typically added to a plastic to make
it less costly. They can be inert or can alter various properties of the
plastic, particularly hardness, stiffness, and impact strength.
-
- Filter -
- A device incorporated into a hydraulic system to remove contaminants from the oil.
-
- Fish Eye (Gels) -
- A small globular mass in a transparent or translucent plastic material
caused by the incomplete blending of the mass into the surrounding material.
-
- Fitting -
- A device for connecting hose or pipe to hydraulic components.
-
- Flame Retardant Resin
-
- The result of reactive compounds that become an integral part of the
polymer structure and/or additive chemicals that are physically dispersed in
a polymer to retard or eliminate the polymer's tendency to burn.
-
- Flammability -
- The measure of the extent to which a material will support combustion.
-
- Flaring -
- The enlargement of a tube/hose diameter by mechanical pressure from the
inside.
-
- Flash -
- Excess plastic around the area of the parting line on a molded part.
-
- Flexural Modulus -
- Ratio of applied stress to strain in outer fibers of plastic specimen
during flexure.
-
- Flexural Strength -
- The resistance of a plastic material to cracking or breaking during
bending expressed as the tensile strength of the outermost fibers at the
moment of failure.
-
- Float Spool (Position) -
- A spool valve design which connects all ports to the tank (return) port,
usually in a detented fourth position, allowing a cylinder or motor to "float".
-
- Flow Rate -
- The volume of fluid passing through the system or component in gal. Per min. (or 11m)
-
- Fluid Power System -
- The transmission and control of power through the use of fluid pressure.
-
- Fluorescent Pigments -
- Colorants which absorb radiation of a given frequency and then emit
radiation of a different frequency, creating a glowing effect.
-
- Fluoroplastics -
- Polyolefin polymers in which fluorine, fluorinated alkyl groups, or other
halogens replace hydrogen atoms in the carbon chain resulting in a material
with outstanding electrical properties, excellent resistance to chemical
attack, low coefficient of friction, excellent fire resistance,
exceptionally good performance at high and low temperatures, low moisture
absorption, and outstanding weatherability.
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G -
- Gamma Radiation -
- An electromagnetic radiation of great penetrating power emitted by the
nucleus of a radioactive substance.
-
- Gauge -
- Thickness of plastic film measured in decimal inches or mils.
-
- GMP -
- Good Manufacturing Process
-
- Gummy -
- Having the nature of gum; viscid; sticky.
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H -
- Haze -
- Cloudiness in a plastic material.
-
- HDPE -
- High density polyethylene
-
- Heat Distortion Point
-
- See: “Deflection Temperature.”
-
- Heat Gun -
- An electrically controlled gun for softening, curing, drying, preheating,
and welding plastics, as well as shrinking of thermally reducible tubing.
-
- Heat Resistance -
- The ability to withstand the effects of exposure to high temperature.
-
- Heat Sealing -
- A method of joining plastic films by simultaneously applying heat and
pressure to areas in contact.
-
- Homopolymer -
- A polymer consisting of only one monomeric species.
-
- Hydrolysis -
- The chemical decomposition of a substance by reaction with water.
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I -
- Impact Strength -
- The ability to withstand shock loading.
-
- Impregnation -
- The process of thoroughly soaking a material such as wood, paper, or
fabric with a synthetic resin.
-
- Impulse Sealing -
- A sealing process in which intense thermal energy is instantaneously
applied to the sealing area, immediately followed by rapid cooling.
-
- Inert -
- Substances which do not react with other materials under normal
temperature and pressure.
-
- Inhibitor -
- Substances that slow or halt a chemical reaction; sometimes used in
certain types of monomers and resins to prolong product life.
-
- Injection Molding -
- A process in which melted plastic is forced into a relatively cool mold
cavity which forms the plastic into the desired shape.
-
- IR -
- Isoprene rubber
-
- Irradiation -
- Subjecting plastics or other compounds to radiant energy to cure or
produce a change in the material.
-
- Izod Impact Test -
- A test for shock loading wherein a notched sample bar is held at one end
and broken by striking.
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J -
- Jerk -
- The sharp, quick motion used to remove tubing or hose from a bulkhead or
other connection point. Also see Yank.
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K -
- K factor -
- The coefficient of thermal conductivity; the amount of heat that passes
through a unit cube of material in a given time when difference in
temperature of 2 faces is 1º.
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L -
- LDPE -
- Low density polyethylene
-
- Light-Resistance -
- The resistance of a plastic to change color or other characteristics
during exposure to sun or ultraviolet light.
-
- LLDPE -
- Linear low density polyethylene
-
- Luminescent Pigments -
- Special colorants added to a compound to produce eye-catching effects in
the dark. Basically there are two types: one is activated by U.V. radiation
producing very strong luminescence, and the other is a phosphorescent which
does not require a separate source of radiation.
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M -
- Mandrel -
- A core around which material is wound as in filament winding, which when
removed, forms a hollow center in a tube.
-
- Manifold -
- Configuration of piping in a block of metal or plastic that takes a single
channel flow and divides it into various flow channels to feed more than one
outlet.
-
- MDPE -
- Medium density polyethylene
-
- Melt Index -
- The amount, in grams, of a thermoplastic resin which can be forced through
an 0.0825 “ orifice when subjected to 2160 gms force in 10 minutes at 190ºC.
-
- Memory -
- The tendency of a thermoplastic material which has been stretched while
hot to return to its unstretched shape upon being reheated.
-
- Mer -
- The repeating structural unit of any high polymer.
-
- Migration -
- The extraction of an ingredient from a material by another material, such
as the migration of a plasticizer from one material to an adjacent material
with a lower plasticizer content.
-
- Modulus of Elasticity
-
- The ratio of stress to strain below the proportional limit of the
material.
-
- Moisture Vapor
Transmission -
- The rate at which water vapor permeates through a plastic at a specified
temperature and relative humidity.
-
- Mold -
- A hollow form or cavity into which molten plastic material is placed to
produce the shape of the required component.
-
- Molecular Weight -
- The sum of the atomic weights of all atoms in a molecule.
-
- Monomer -
- A single molecule which can join with another monomer or molecule to form
a polymer or molecular chain.
-
- Motor -
- A device which converts hydraulic energy into rotary motion, either
fixed or variable.
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N -
- Natural Rubber (NR)-
- An elastic substance produced by coagulating and drying the milky sap
(latex) of various tropical plants, especially a tree (Heva brasiliensis) of
the spurge family.
-
- Neoprene -
- A synthetic rubber produced by the polymerization of chloroprene providing
a high resistance to oil, light, heat, and oxidation.
-
- Nitrile Resin -
- Polymers of which the principal monomer is acrylonitrile. This provides
the functionality of good chemical resistance and gas barrier properties.
-
- Notch Sensitivity -
- Extent to which the sensitivity of a material to fracture is increased by
the presence of a surface inhomogeneity, such as a notch.
-
- NSF -
- National Sanitation Foundation
-
- Nylon -
- The generic name for all synthetic fiber-forming polyamides; characterized
by great strength, toughness, and abrasion resistance, good fatigue
resistance and lubricity, and low coefficient of friction. They can be
formed into a monofilament and yarn. Current types include 6, 6-6, 6-10, 11,
& 12.
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O -
- Oil Resistance -
- Ability to withstand the deteriorating effects of an article by the
absorption of oil; usually causing volumetric swell and/or hardening.
-
- Outgassing -
- The release of a volatile substance from a compound during curing.
-
- Oxidant -
- A gas which supports combustion.
-
- Ozone Resistance -
- Ability to withstand the deteriorating effect of Ozone (which generally
causes cracking).
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P -
- Parting Line -
- The line formed by the mating surfaces of the molded part.
-
- Peristaltic Pump -
- A type of pump in which the forward movement of material inside a tube is
performed in a wave-like fashion caused by the contraction and dilation of
the tube in a longitudinal direction.
-
- Permeability -
- The rate at which a liquid or gas under pressure passes through a solid
material by diffusion and solution.
-
- PFA -
- Perfluoroalkoxy
-
- Plasticize -
- To impart softness and flexibility in a plastic through the addition of a
plasticizer additive or the application of heat.
-
- Plasticizer -
- A chemical agent added to a resin to increase its workability during
processing, and to impart flexibility and other desired properties to the
finished product; usually of an organic ester having a high boiling point.
-
- Polyamides (PA)-
- A polymer in which the structural units are lined by amide groupings. Many
polyamides are fiber-forming.
-
- Polycarbonate (PC)-
- Polymers derived from the direct reaction between aromatic and aliphatic
dihydroxy compounds with phosgene or by the ester exchange reaction with
appropriate phosgene derived precursors. Structural units are linked by
carbonate groups.
-
- Polyester -
- A family of resins produced by reaction of dibasic acids with dihydric
alcohols or by the polymerization of of a hydroxy carboxylic acid.
-
- Polyethylene (PE)-
- A thermoplastic composed by polymers of ethylene; normally a translucent,
tough, waxy solid which is unaffected by water and a large range of
chemicals.
-
- Polymer -
- A high molecular-weight organic compound, natural or synthetic, whose
structure can usually be represented by a repeated small unit, the MER.
Synthetic polymers are formed by addition or condensation polymerization of
monomers. Some polymers are elastomers, some plastics, and some are fibers.
-
- Polymerization -
- The chemical reaction in which the molecules of monomers are linked
together to form polymers.
-
- Polypropylene -
- A tough, lightweight, rigid plastic made by the polymerization of
high-purity propylene gas in the presence of an organometallic catalyst at
relatively low pressures and temperatures.
-
- Polystyrene -
- A water-white thermoplastic produced by the polymerization of styrene
(vinyl benzene) offering outstanding electrical properties; relatively
unaffected by moisture.
-
- Polysulfone -
- An amorphous structure; this engineering thermoplastic has inherent
resistance to heat, hydrolysis, oxidation, and radiation;
self-extinguishing.
-
- Polytetrafluoroethylene
(PTFE) -
- Member of the fluorocarbon family of plastics created by the
polymerization of tetrafluoroethylene and characterized by extreme chemical
inertness, very high thermal stability and low frictional properties.
-
- Polyurethane
(thermoplastic) -
- Polymers which have properties combining the advantages of elastomers and
plastics; formed by the reaction of bifunctional polyols with diisocyanates.
-
- Polyvinyl Chloride
(PVC) -
- Thermoplastic compounds formed by polymerization or copolymerization of
vinyl or vinylidene halides and vinyl esters. They are strong, with good
abrasion resistance and superior aging properties than that of rubber.
-
- Porosity -
- The ratio of the volume of a material's pores (voids) to its total volume;
usually expressed as a percentage.
-
- Post-Cure -
- The operation on a thermoset part in which the part is subjected to
elevated temperatures for a period of time to effect full cure, stress
relaxation, etc., and to enhance property levels.
-
- Postforming -
- The forming, bending, or shaping of fully cured thermoset laminate.
-
- Port -
- The internal or external terminus of a passage. The point where the fitting is attached.
-
- Pressure -
- The force per unit area, expressed in pounds per square inch (psi), bars, or atmospheres.
-
- Pressure; Back -
- The pressure encountered on the downstream or return side of a component.
-
- Pressure; Cracking -
- The pressure at which a pressure operated valve begins to pass fluid.
-
- Pressure Drop -
- The difference in pressure between any two points of a component or
system.
-
- Pressure; Maximum Rated -
- The maximum pressure at which a component should be operated on a continuous basis,
usually the relief valve setting at maximum flow rate.
-
- PSI -
- Pounds per square inch.
-
- PVDF -
- Polyvinylidene fluoride
-
- Pump -
- A device which converts mechanical energy into hydraulic. Energy,
either fixed or variable.
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Q -
- No terms at this time.
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R -
- Radiopaque -
- Not allowing the passage of X-rays, gamma rays, or other forms of radiant
energy.
-
- Random Copolymer -
- A copolymer in which the molecules of each monomer are randomly arranged
in the polymer backbone.
-
- Reinforced Plastics -
- Molded, formed, filament wound, or shaped plastic parts consisting of
resins to which reinforcing fibers, mats, fabrics. etc., have been added
before the forming operation resulting in enhanced strength properties.
-
- Reinforcement -
- A material used to reinforce, strengthen, or give dimensional stability to
another material.
-
- Reservoir -
- A container which stores the liquid in a fluid power system.
-
- Resin -
- An organic substance of natural or synthetic origin characterized by being
polymeric in structure and predominantly amorphous. Most resins, though not
all, are of high molecular weight and consist of long chain or network
molecular structure. Usually resins are more soluble in their lower
molecular weight forms.
-
- Resistivity -
- The ability of a material to resist passage of electrical current either
through its bulk or on a surface. The unit volume resistivity is the ohm-cm,
or surface resistivity, the ohm.
-
- Retractable -
- The ability to draw back to an original form once tension is relieved.
-
- Rockwell Hardness -
- A common method of testing for resistance to indentation in which a
diamond or steel ball, under pressure, is used to to pierce the test
specimen. The load used is expressed in kilograms (kg) and a 10 kg pre-load
is first applied and the degree of penetration noted. The major load (60 to
150 kg) is next applied and a second reading obtained. The hardness is then
calculated from the difference between the two loads and expressed with nine
different prefix letters to denote the type of penetrator used and the
weight of the major load.
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S -
- SAE -
- Society of Automotive Engineers
-
- Santoprene® -
- A thermoplastic rubber with good fluid and flex fatique resistance.
Commonly used in peristaltic pumps for both medical and general industry.
-
- SBR -
- Styrene butadiene rubber
-
- Seal -
- A device which prevents or controls the escape or passage of hydraulic fluid.
-
- Self-Extinguishing -
- A loosely-used term describing a material's ability to stop burning once
the source of the flame is removed.
-
- Shear Strength -
- The stress at which a material fails in shear or the ability of a material
to withstand shear stress.
-
- Shelf Life -
- The period of time during which a material or product may be stored at
ambient temperature and humidity without measurable degradation of its
physical properties.
-
- Shore Hardness -
- A common method of determining the hardness of a plastic material as
developed by the Shore Instrument Company. The device used, called a
durometer, consists of a small conical hammer fitted with a diamond point
and acting in a glass tube. The hammer is made to strike the material under
test and the degree of rebound is noted on a graduated scale. Generally, the
harder the material, the greater the rebound.
-
- Silicone -
- One of the family of polymeric materials in which the recurring chemical
group contains silicon and oxygen atoms as links in the main chain. These
compounds are derived from silica (sand) and methyl chloride. Silicones are
characterized by their resistance to heat and low thermal expansion.
-
- Sintering -
- The process of holding a fusible pressed-powder article at a temperature
just below its melting point for a period of time to fuse (sinter) the
particles together.
-
- Slitting -
- The process of making a long, straight, lengthwise cut in an article.
-
- Solvent Bonding -
- A process of joining articles made of thermoplastic resins by applying a
solvent to soften the surfaces to be joined, and then the surfaces are
pressed together. Adhesion comes from evaporation of the solvent, absorption
of solvent into the material surfaces, and/or polymerization of the solvent.
-
- Specific Gravity -
- The ratio of the mass of any volume to the mass of an equal volume of
another substance taken as a standard. The standard for solids and liquids
is usually water, and for gases the standard is air.
-
- Specific Heat -
- The amount of heat required to raise a specified mass by one unit of a
specified temperature at constant pressure.
-
- Stabilizer -
- An ingredient included in the compounding of some polymers to assist in
maintaining desirable physical and chemical properties of the compounded
material throughout the life of the material; ex: heat or U.V. stabilizers.
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- Sterilization -
- The process of applying great heat or chemical action to an article in
order to clean it of all living microorganisms.
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- Strain -
- Elastic deformation due to stress; measured as the change in length per
unit of length in a given direction, and expressed in percentage or inches
per inch, etc.
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- Stress -
- The unit force or component of force at a point in a body acting on a
plane through the point; expressed in psi.
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- Stress Crack -
- External or internal cracks in a plastic caused by tensile stresses; often
appear as a network of fine cracks known as crazing.
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- Stress Relaxation -
- Time dependent decreases in stress for a specimen constrained in a
constant strain condition.
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- Synthetic Resin -
- Any complex organic liquid or solid formed from simpler molecules by
polymerization or condensation; any of various chemically modified natural
resins.
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T -
- Tack -
- Stickiness of a material, measurable as the force required to separate an
adherend.
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- Talc -
- An inert refined mineral product (hydrated magnesium silicate) that is a
reinforcing filler extender. Because of its platy configuration, it tends to
add stiffness to the resin, while its low cost categorizes it as an
extender. Talc is also commonly applied to reduce the tackiness of some
plastic materials.
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- Tear Resistance -
- The resistance of a material to a force acting to initiate and then
propagate a failure at the edge of a test specimen.
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- Tensile Strength -
- The maximum tensile stress sustained by the specimen before failure in a
tension (pull) test; usually expressed in pounds per square inch (psi).
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- Thermal Conductivity -
- Ability of a material to conduct heat.
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- Thermoforming -
- Any process in which thermoplastic material is heated to its softened
point and then drawn and/or forced against an open mold. Depending on the
technique, the mold can either be male or female, and the method of forming
either vacuum and/or pressure.
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- Thermoplastic -
- A material which has a linear macromolecular structure that will
repeatedly soften when heated and harden when cooled.
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- Thermoset -
- A material that will undergo or has undergone a chemical reaction by the
action of heat, ultraviolet light, catalysts, etc., leading to a relatively
infusible and cross-linked state.
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- Torsion -
- The stress produced by twisting one end of an object along its
longitudinal axis while the other end is held firm or twisted in the
opposite direction.
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- Toxic -
- Substances which chemically produce injurious or lethal effects to humans;
poisons.
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- TPE -
- Thermoplastic Elastomer
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- TPR -
- Thermoplastic Rubber
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U -
- UHMWPE -
- Ultra high molecular weight polyethylene
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- U.L. -
- Underwriters' Laboratories
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- Ultrasonic Welding -
- A method of joining plastics using ultrasonic vibrations which are
produced by the mechanical motion of a converter expanding some 20,000 times
per second. The vibratory energy creates frictional heat which is channeled
through a horn and applied to thermoplastic materials to produce a molecular
interaction that welds the materials.
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- USDA -
- United States Department of Agriculture
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- U.S.P. -
- United States Pharmacopoeia
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- U.V. (Ultraviolet
Light) -
- The radiation from sunlight or artificial light having wavelengths shorter
than those of visible light and longer than those of x-rays (250-400
millimicrons).
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V -
- Valve
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- A device which controls fluid flow rate, direction, or pressure.
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- Valve;
Directional Control- A device for
directing or preventing the oil flow in a system.
Open
Center (Tandem) Type - Has the inlet
port connected to the outlet (tank) port in neutral.
Closed
Center Type - Has the inlet port
blocked from the outlet and work ports in neutral.
Two-Way
- A 2 port valve with inlet and outlet
ports.
Three-Way
- A 3 port valve (in, out ~r,d work)
normally used with a single acting cylinder or uni-directional motor.
Four-Way
- A 4 port valve (in, out and 2 work)
used with double acting cylinders, bi-directional motors.
Two,
Three, Four Position - The number of
positions in which a valve can be positioned.
Series
Type - A multiple spool valve in which
the return oil from the first spool is directed to the inlet of the second spool
(and from the second to the third, etc.). This type valve permits simultaneous
operation of two or more functions with the same oil flow. However, the total
pressure requirements of all functions are accumulative.
Parallel
Type - A multiple spool valve in which
the inlet oil is connected to all spools simultaneously. If more than one spool
is actuated, the function requiring the lowest pressure will operate first.
Series-Parallel
Type - A multiple spool valve which
has all spools connected to the open center passage in neutral. However, when
actuated, the upstream valve takes full priority. The return oil is directed to
downstream spools as in a series type valve.
Power
Beyond (High Pressure Carryover) - A
sleeve attachment which permits the oil flow from one valve (when in neutral) to
be used by another valve downstream. Hence, a 3-spool valve cou1d be connected
to a 2-spool valve to create a 5-spool valve, The first valve takes priority and
thrust have a separate outlet port to return oil from an activator back to
the reservoir.
Load Check (Lift Check) - A device which prevents a load from dropping when a valve is shifted,
until ample pressure and flow is available to hold or move the load
- Vicat Softening Point -
- The temperature at which a flat-ended needle of 1 mm2 circular cross
section will penetrate a thermoplastic specimen to a depth of 1 mm under a
specified load using a selected uniform rate of temperature rise.
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- Viscosity -
- The measure of the resistance of a fluid flow (either through a specific
orifice or in a rotational viscometer). The absolute unit of viscosity
measurement is the poise (or centipoise). Kinematic viscosity is expressed
in stokes.
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- Vulcanization -
- The chemical reaction which induces extensive changes in the physical
properties of a rubber or plastic and which is brought about by the reaction
of the material with sulphur and/or other suitable agents. The changes
typically include decreased plastic flow, solubility, and surface tackiness,
along with increased elasticity and much greater tensile strength.
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W -
- Weld Lines -
- The marks visible on a finished part made by the meeting of two flow
fronts of resin during molding.
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- Welding -
- Joining pieces by one of several heat-softening processes.
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- Working Life -
- The period of time during which a material or product retains the physical
properties for which it was created.
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- Working Pressure -
- The maximum recommended pressure at ambient temperature for continuous
operation.
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X -
- X-Ray Specs -
- Used to obtain visual contact with flow.
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Y -
- Yield Strength -
- The lowest stress at which a material undergoes plastic deformation. Below
this stress the plastic is elastic; above it , viscous.
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- Yank -
- The sharp, quick motion used to remove tubing or hose from a bulkhead or
other connection point. Also see Jerk.
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Z -
- No terms at this time.
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