We have
provided below a glossary of terms commonly encountered in the
plastics world.
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A - C | D -
E | F - H |
I - O | P -
Q | R - S |
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Additives
Additives are materials that are added to a
polymer to produce a desired change in material properties or
characteristics. A wide variety of additives are currently
used in thermoplastics, to expand or extend material
properties, enhance processability, modify aesthetics, or
increase environmental resistance. Additives enhance
properties like flame retardancy and UV light stability.
Back Pressure
The applied hydraulic
pressure used to restrict the shot size formation. Applied to
the back of a melt accumulator or reciprocating screw. Used to
control screw drift, mixing, and shot size adjustments. In
molding, back pressure increases the temperature of the melt,
and contributes to better mixing of colors and homogeneity of
the material.
Barrel
Cylinder that contains the screw and
the heaters. Built to withstand pressure of 7,500-20,000 psi.
Barrel Heaters
Heaters that raise the barrel temperature in
order to transform the thermoplastic material into a melt.
Blow Needles, Extrusion Blow Molding
Device
used to pierce and inflate the parison, usually actuated by an
air cylinder.
Blow Pressure, Extrusion Blow Molding
Dimension of bottle
divided by the parison diameter. Bottles usually have many
ratios. However, only the maximum ratio usually needs to be
considered.
Coextrusion
The process of extruding two or
more materials through a single die with two or more orifices
arranged so that the extrudates merge and weld together into a
laminar structure before chilling.
Compound
A mixture of resin and the
ingredients necessary to modify the resin to a form suitable
for processing into finished articles.
Compounding
The process of selection of additives and their
incorporation into a polymer. Compounding is done to obtain
desirable properties for particular uses. Modification of the
polymer properties is done by ingredients such as polymeric
resins, plasticizers, fillers, reinforcing agents, various
stabilizers, lubricants, coloring agents, flame retardants,
etc.
Compression Molding
A method of molding in which the molding
material, generally preheated, is placed in an open heated
mold cavity, the mold is closed with a top force, pressure is
applied to force the material into contact with all mold
areas, and heat and pressure are maintained until the molding
material has cured. This process is most often used with
thermoses.
Cooling Time
The elapsed time required for
the melt to reach its Vicat softening temperature.
Copolymer
This term usually, but not
always, denotes a polymer of two chemically distinct monomers.
Cycle
Complete, repeating sequence of
operations for injection molding a part.
Cycle Time
In a molding operation, cycle time is the time
elapsing between a particular point in one cycle and the same
point in the next cycle.
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