Glossary

Plastics Glossary - C

CAE (Computer Aided Engineering). The use of a computer to simulate the function or processing of a part. Plastics flow simulation software and structural analysis software are two examples of CAE tools.

Calcium carbonate Also referred to as ground limestone, marble dust, chalk, whiting, and calcite filler extender. Each shares the common mineral form, calcite (CaCO₃). Used as a filler and extender.

Calendering Subjecting a material to pressure between two or more counter-rotating rollers.

CAM (Computer-Aided Manufacturing) The use of computers and computer technology to control, manage, operate, and monitor manufacturing processes.

Cannon - Fenske Viscometer Modifies Ostwald-type viscometer used to determine the kinemataic viscosity of transparent Newtonian liquids (0.4-16,000 cS).

Capillary Action Phenomenon observed on the surface of liquids due to unbalanced molecular attraction at the liquid boundary.

Capillary Tube Viscometer Instrument for the measurement of viscosity as a function of the time required for a certain amount of fluid to flow through a small-box tube of known diameter and length under a known constant pressure difference. Assuming laminar flow, the viscosity is calculated from the Hagen-Poiseuille law.

Capillary Value of Adsorbent Difference between saturation and retentivity value. Amount of solvent held loosely in pores.

Carbon black A multi-functional pigment used in plastics as a conductor of electricity, a pigment, a filler-extender, and a stabilizer.

Carbon fiber Fibers produced by pyrolysis of an organic precursor fiber in an inert atmosphere at temperatures higher than 1800ºF. Reinforcement for light weight, high strength, and high stiffness structures. The high stiffness and the high strength of fibers depend on the degree of preferred orientation.

Carriage The moveable unit that incorporates the whole barrel and drive assembly on the injection end of the machine.

Cartridge Filling Dispensing a given volume of material into a customer-selected package.

Cartridge heater Cylindrical-bodied, electrical heater for providing heat for injection, compression, and transfer molds; injection nozzles; runnerless mold system; hot stamping dies; sealing, etc.

Cast film A film made by depositing a continuous layer of resin, either molten, in solution, or in a dispersion, onto a chilled surface. Resin solidifies and is removed as a film.

Cast To form an object by pouring a fluid monomer-polymer solution into an open mold where it finished polymerization. Also, forming film and sheet by pouring liquid resin onto a moving belt or roll.

Catalyst Activity Measure of the relative performance of a catalyst in promoting the reaction of a material to give a desired performance.

Catalyst An agent that initiates a chemical reaction but usually does not become part of the final product. A chemical substance added in minor quantities that markedly speeds up polymerization.

Cataphoresis Particle migration in a colloidal solution between electrodes exhibiting a potential difference.

Cation Positively charged ion such as Na+, K+, NH4+.

Cationic Surfactants Ionic surface-active agents in which the portion that associates with the internal phase is the cation. Cationic surfactants have positively charged hydrophobes. They include simple amine salts, quaternary ammonium salts, amino imides and imidazolines. Cationic surfactants often have germicidal anticorrosive, and antistatic properties.

Cavity Blocks Round or rectangular blocks of steel in which the mold cavity is machined.

Cavity Pressure Sensor A sensor or transducer that is usually used behind an ejector pin to measure the melt pressure in the cavity.

Cavity Retainer Plate See A-plate.

Cavity A depression, or a set of matching depressions, in a plastics forming mold which forms the outer surfaces of the molded parts.

Cellulosic resin Family of three resins: cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. Amorphous material.

Center gate In injection and transfer molding, the opening (gate) located in the center of the part through which the plastic is injected.

Centipoise ( cP ) Unit of viscosity equal to 1/100 dyne/sec2/cm2.

Chain fall Lifting device that uses a block and tackle to hoist the mold into the air. It may be hand held or have motors to drive it.

Channeling Physical parting or separating of the body of a lubricant.

Charge The amount of material used to load a mold at one time or during one cycle.

Charpy Impact Test A destructive test of impact resistance, consisting of placing the specimen in a horizontal position between two supports, then applying a blow of known magnitude. If the specimen does not break, a new specimen is put in position and the magnitude is increased until the specimen breaks. (ASTM D-256, Method B)

Chase The box or frame that holds the liquid casting material as it is poured over the master pattern.

Check ring The sliding ring of the non-return valve on the front of the screw that, together with the seat, allows the flow of melted plastic to move forward in front of the screw during plasticating and provides flow back over the flights during injection. A high-wear item that often leaks during injection.

Chemical Change Change in which new substances with new properties are obtained from a chemical composition or decomposition of a substance.

Chemisorption Adsorption process in which a polar group is bound to certain groups in a surface by chemical linkages.

Chiller Cooler for separating wax from petroleum fractions.

Chiller A self-contained system comprised of a refrigeration unit and a coolant circulation mechanism consisting of a reservoir and a pump. Chillers maintain the optimum heat balance in thermoplastic processing by constantly recirculating chilled cooling fluids to injection molds.

Chlorinated PVC Produced by the post chlorination of polyvinyl chloride resins. Used extensively in pipe, fittings, and valves in water piping systems.

Chopped Strand A type of fiber reinforcement consisting of strands of individual glass fibers which have been chopped into short pieces.

Clamping Area The largest rated molding area an injection press can hold closed under full molding pressure.

Clamping Force In injection molding, the pressure which is applied to the mold to keep it closed, in opposition to the fluid pressure of the compressed molding material within the mold cavity and the runner system.

Clamping plate A mold plate fitted to the mold and used to fasten the mold to the machine.

Clamping Pressure In injection molding, the pressure applied to the mold to keep it closed during the molding cycle.

Clamping system Part of the injection molding machine that provides the capability to open and close the mold, to hold the mold closed during injection, and to eject the part.

Clamping tonnage Rated clamping capacity of an injection molding machine.

Clay Treatment Adsorption process used in oil refining.

Clear spots Transparent imperfections in the part.

Closed loop control A mode of control where information is sent back to the controller to be modified if it does not confirm to the original setting.

Closure cylinder The hydraulic cylinder responsible for moving linkages and opening and closing the machine.

Cloud Point Temperature at which solutions become cloudy on cooling or heating.

Coagulation Process in which the small particles in an emulsion are combined in agglomerates but still retain their character as individual particles.

Coalescence Process by which small particles (droplets) in an emulsion combine to form larger particles (drops).

Coarse Emulsion Emulsion that contains large droplets of the internal phase.

Coefficient of friction Resistance to sliding or rolling of surfaces of solid bodies in contact with each other is stated as k = F/W in which F is the force required to move on surface over another and W is the weight pressing the surfaces together.

Coefficient of thermal expansion (CTE) Measures how much a material expands and contracts with thermal changes.

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.

Cohesion Force of attraction of like molecules for one another within a substance.

Co-injection The technique of injecting two materials into a single mold from two plasticating cylinders, either simultaneously or in sequence.

Cold Pressing Separation of a solid petroleum product from a liquid petroleum medium by means of a filter press.

Cold runner mold Developed to provide for injection of thermoset material either directly into the cavity or through a small sub-runner and gate into the cavity. It may be compared to the hot runner molds with the exception that the manifold section is cooled rather than heated to maintain softened but uncured material. The cavity and core plates are electrically heated to normal molding temperature and insulated from the cooler manifold section.

Cold slug well An extension of the runner that traps the cold flow front of the plastic, allowing the hotter plastic to flow into the rest of the runner system.

Cold-runner mold Developed to provide for injection of thermoset material either directly into the cavity or through a small sub-runner and gate into the cavity. It may be compared to the hot-runner molds with the exception that the manifold section is cooled rather than heated to maintain softened but uncured material. The cavity and core plates are electrically heated to normal molding temperature and insulated from the cooler manifold section.

Collapsible core A mold component that usually contains threads or undercuts that collapses in on itself during mold opening to release the undercuts for ejection.

Collector Chemical additive controlling the wettability of ores in a flotation process.

Colloid Finely divided substance 0.001-1 µ in diameter. The physical properties of a colloid are controlled by the surface forces.

Colloid Mill Machine used for the preparation of emulsions of fine particle size. The emulsion is forced through the adjustable small annular space between a stator and a rapidly revolving rotor.

Colloidal Metals Colloidal suspension of metals.

Colloidal Suspension Two-phase system having small dispersed particles suspended in a dispersant.

Color Concentrate A plastic compound which contains a high percentage of pigment, to be blended in appropriate amounts with the base resin so that the correct final color is achieved.

Color concentrates Plastic resins which contain a high loading of pigment. Concentrates provide dust-free method of handling colors. Color pellets mixed with plastic pellets to make colored parts.

Colorant Dyes and pigments used to color plastics.

Complex Liquid Liquid in which the rate of shear is not proportional to the shearing stress; a non-Newtonian liquid.

Complex Mixture Mixture of more than three components.

Composite A material containing two or more distinct materials (fillers, reinforcing materials, and compatible plastic resin) designed to develop specific performance properties.

Compound Oils Oils made by mixing mineral oils with other oils, vegetable or animal.

Compound A mixture of resin and the ingredients necessary to modify the resin to a form suitable for processing into finished articles.

Compounding The step of mixing base resins with additives such as stabilizers, fillers, pigments into a form suitable for processing into finished articles.

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.

Compression ratio The relationship between the feed depth and the meter depth of the screw. It indicates the degree to which the core of the screw is tapered and is an important indication of the degree to which the plastic will be compressed as it is conveyed from the feed to the metering section of the screw.

Compressive modulus Ratio of compressive stress to compressive strain below the proportional limit.

Compressive Strength The load sustained by a test specimen in a compressive test divided by the original area of the specimen.

Compressive stress The compressive load per unit area of original cross-section carried by the specimen during the compression test.

Concentration of Emulsifying Agent Amount of surface-active agent in the emulsion. May be based on the volume or weight of the total emulsion or on one phase.

Condensation hot air dryer A type of dryer that condenses moisture out of the air to lower its dew point but the dew point is still limited by the temperature of the condensation coils.

Condensation polymerization A chemical reaction in which two or more molecules combine by the separation of water or some other simple substance. If a polymer is formed, the process is called polycondensation (as opposed to addition polymerization).

Conditioning Subjecting a material to standard environmental and/or stress history prior to testing.

Conductivity Reciprocal of volume resistivity; the conductance of a unit cube of any material. Continuous use temperature. The recommended temperature at which a material should be used so as to retain its good performance over long periods.

Conjugate Layers Coexisting layers in an extraction—the solvent and diluent.

Conradson Test Method for the determination of the percentage by weight of carbonization residue left from burning a petroleum product according to an ASTM standard method.

Consistency Resistance of a fluid to deformation. For simple (Newtonian) fluids the consistency is identical with the viscosity, for complex (non-Newtonian) fluids, identical with apparent viscosity.

Contact Surface Area of a phase interface.

Contamination Visible defects caused by a foreign substance.

Continental Method Procedure for preparing emulsions whereby the oil and surfactant(s) are thoroughly mixed and water is added to the mixture. As progressively more water is added, the emulsion will invert and water will become the continuous phase.

Continuous Phase External phase of an emulsion.

Continuous use temperature The recommended temperature at which a material should be used so as to retain its good performance over long periods of time.

Control panel The controls next to the safety gate that the technician uses to control the machine manually.

Convection Natural or forced motion in a fluid induced by heat or the action of gravity.

Conversion process The process of converting thermoplastic pellets into parts.

Cooling channels Channels located within the body of a mold through which a cooling medium, usually water, is circulated to control the mold surface temperature.

Cooling circuit Grooves or channels, cut into the core plates, cavity plates, and inserts, that are designed to transfer heat away from the mold, keeping it cool.

Cooling fixture (shrink fixture) A jig or block to hold the shape of a molded part after it is removed from the mold until it is cool enough to retain its shape.

Cooling timer The timer that is used to control cooling after the second stage timer has timed out.

Copolymer A compound resulting from the chemical reaction of two chemically different monomers with each other. An organic compound made from a series of different monomers.

Copolymerization The building up of linear or non-linear macromolecules (co-polymers) in which many monomers, processing molecules having one or many double bonds, have located in every macromolecule of different size which constitutes the copolymerizate, following alternations which may be regular or not.

Core blocks The blocks of steel out of which the core (male half) the mold cavity is machined.

Core pin A pin similar to an ejection pin with distinct differences which is used as a core to make a hole in a molded part.

Core pull A machine control function where mold slides are hydraulically retracted and inserted in the mold by the machine controls.

Core retainer plate See B-plate.

Core A protrusion, or set of matching protrusions, in a plastics forming mold which forms the inner surfaces of the molded articles.

Corona Resistance In an insulated electrical conductor, the resistance of the insulation to breakdown caused by ionized air in voiks existing in the insulation by the current in the conductor.

Corrosion Resistance A broad term applying to the ability of plastics to resist many environments.

Couette Viscometer Rotational type of instrument for the measurement of viscosity. A fluid is placed in the annular space between two concentric cylinders, one of which is rotated. The measurement of torque and velocity gradient can be correlated with viscosity.

Coupling agent Agent acts as an interface between resin and glass fiber or mineral filler to form a chemical bridge between the two.

Covalent Molecule Molecule in which the bond between two atoms is a shared electron pair.

C_p Abbreviation for heat capacity.

Crazing An undesirable defect in plastics articles characterized by distinct surface cracks or minute frost-like, internal cracks, resulting from stresses within the article which exceed the tensile strength of the plastic.

Creaming Separation of an emulsion into two distinct phases, one of which has a higher concentration of the dispersed phase than the original emulsion; the other contains more of the continuous phase. This is a reversible process.

Creep Due to its viscoelastic nature, a plastic subjected to a load for a period of time tends to deform more than it would from the same load released immediately after application, and the degree of this deformation is dependent of the load duration.

Critical Micell Concentration (CMC) Saturation point of surfactant in a water system. The CMC is observable by discontinuities in the curves of physical properties of the system as a function of the amount of surfactant added.

Critical Quantity Minimum or maximum amount of a blended or homogenized material needed to obtain a desired result.

Critical Surface Tension Surface tension of a solid equal to that of the liquid of highest surface tension that will wet the solid.

Critical Velocity Transitional velocity at which the flow of a fluid changes from laminar to turbulent.

Crosslinking The establishing of chemical links between the molecular chains in polymers. Crosslinking can be accomplished by chemical reactions, vulcanization, and electron bombardment.

Crosslinks Bonds linking molecular chains

Cryogenic Pertaining to very low temperatures.

Crystal polystyrene Clear, general purpose polystyrene. Amorphous material.

Crystal A homogeneous solid having an orderly and repetitive three dimensional arrangement of its atoms.

Crystalline melting temperature The temperature at which the crystalline regions break apart and begin to flow.

Crystalline polymers A family of polymers characterized by areas of order in which the molecular chains line up and lay tightly together in an otherwise amorphous mass. More accurately called Semi-crystalline Polymers due to the combination of amorphous and crystalline regions.

Crystalline A characteristic property of polymers that tend to form uniform, compact, and ordered chains.

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.

Crystallization temperature The temperature at which a crystalline resin begins to crystallize upon cooling.

CSA Canadian Standards Association. Similar to U.L. Standard #222.

CTE Coefficient of Thermal Expansion: The change in length of a material for a unit change in temperature, per unit of length.

Cure temperature Temperature at which a thermoset material is subjected to curing.

Cure time In the molding of thermosetting plastics, the time it takes for the material to be properly cured.

Cushion The melted plastic that stays in the barrel after injection.

Custom Molder A firm specializing in the molding of items or components to the specifications of another firm which handles the sale of distribution of the item, or incorporates the custom molded components in one of its own products.

Cut-Back Product Material that has been diluted by adding a solvent.

Cycle time The time elapsing between a particular point in one cycle or production and the same point in the next cycle. The optimum processing cycle calls for a balance between the filling, cooling, and holding requirements set forth by the material and the part.

Cycle One full sequence in a molding operation, from a point in the process to the same point in the next sequence.