Glossary

ABS- Acrylonitrile butadiene styrene is a common thermoplastic used to make light, rigid, molded products such as piping, musical instruments, golf club heads, automotive body parts, wheel covers, enclosures, protective head gear, airsoft BB's and toys.

Acrylic- is a thermoplastic and transparent plastic. It is sold by the trade name Plexiglas.

Carbon Black – A black pigment produced by the incomplete burning of natural gas or oil. It is widely used as a filter, particularly in the rubber industry because it possesses ultra-violet properties.

Coefficient of expansion – The fractional change in length (sometimes volume, specified) of a material for a unit change in temperature. Values for plastics range from 0.01 to 0.2 mils/in., C.

Coefficient of Friction - A number expressing the amount of frictional effect.

Compound – An intimate mixture of (a) polymers with all the materials necessary for the finished product.

Compression molding – A technique of thermo set molding in which the molding compound is placed in the open mold cavity, mold is closed, and heat and pressure are applied until the material has cured.

Crosshead – A device generally employed in wire coating which is attached to the discharge end of the extruded cylinder, designed to facilitate extruding material at an angle. Normally, this is a 90 degree angle to the longitudinal axis of the screw.

Cross-linking –Applied to polymer molecules, the setting-up of chemical links between the molecular chains. When extensive, as in most thermosetting resins, cross-linking makes one infusible super-molecule of all the chains.

Density – Weight per unit volume of substance, expressed in grams per cubic centimeter, pounds per cubic foot, etc.

Draft – The degree of taper of a side wall or the angle of clearance designed to facilitate removal of parts from a mold.

Drape forming – Method of forming thermoplastic sheet in which the sheet is clamped into a movable frame, heated and draped over high points of a male mold.

Draw down ratio –The ratio of the thickness of the die opening to the final thickness of the product.

Durometer – is one of several ways to indicate the hardness of a material, defined as the material's resistance to permanent indentation. Durometer is typically used as a measure of hardness in polymers, elastomers and rubbers.

Dual durometer – combining two dissimilar materials into a single extruded unit. Sometimes called co-extrusion.

Elastomer – A material which at room temperature stretches under low stress to at least twice its length and snaps back to the original length upon release of stress.

Elongation – The fractional increase in length of a material stressed in tension.

Embossing – Techniques used to create depressions of a specific pattern in plastic film sheet and on custom profiles.

Encapsulating – Enclosing an article (usually an electronic component or the like) 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.

Extrusion – The compacting of a plastic material and the forcing of it through an orifice in more or less continuous fashion.

Fabricate – To work a material into a finished form by machining, forming, or other operation or to create end products by sewing, cutting, sealing or other operation.

Family mold – A multi-cavity mold where each of the cavities forms one of the component parts of the assembled finished object.

Flame retardant resin – A resin which is compounded with certain chemicals to reduce or eliminate its tendency to burn.

Flammability – Measure of the extent to which a material will support combustion.

Flexural Modulus – A measure of the strain imposed in the outermost fibers of a bent specimen.

Flexural strength – The strength of a material in blending, expressed as the tensile stress of the outermost fibers of a bent test sample at the instant of failure. With plastics, this value is usually higher than the straight tensile strength.

Foaming agents – Chemicals added to plastics and rubbers that generate inert gases on heating, causing resin to assume cellular structure.

Foil decorating – Molding paper, textile or plastic foils printed with compatible inks directly into a plastic part so that the foil is visible below the surface of the part as integral decoration.

Hardness – The resistance of a plastic material to compression and indentation. Among the most important methods of testing this property are Brinell hardness, Rockwell hardness and shore hardness.

Heat deflected temperature – The temperature at which a standard test bar (ASTM D648) deflects 0 010in. under a stated load of either 66 or 264 psi.

Heat sealing – A method of joining plastic films by simultaneous application of heat and pressure to areas in contact. Heat may be supplied conductively or dielectrically

Hot stamping – Engraving operation for marketing plastics in which roll leaf is stamped with heated metal dies onto the face of plastics.

Impact strength – (1) The ability of a material; to withstand shock loading. (2) The work done in fracturing, under shock loading, a specified test specimen in a specified manner.

Injection mold – A mold into which a plasticized material in introduced from an exterior heating cylinder.

ISO – International Organization of Standardization

Izod impact test – A test designed to determine the resistance of a plastics material to a shock loading. It involves the notching of a specimen, which is then placed in the jaws of the machine and struck with a weighted pendulum

K-Resin- a type of plastic made with butadiene.

Kydex – a durable sheet thermoplastic alloy that can be extruded in a variety of colors and textures.

Notch sensitivity – The extent to which the sensitivity of a material is increased by the presence of a surface in homogeneity such as a face notch, a sudden change in section, a crack or a scratch. Low notch sensitivity is usually associated with ductile materials, and high notch sensitivity with brittle materials.

Pigment – Any colorant, usually an insoluble powdered substance used to produce a desired color of hue.

Plasticizer – Chemical agent added to plastic compositions to make them softer and more flexible

Plastic extrusion – is a high volume manufacturing process in which raw plastic material is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weather stripping, window frames, adhesive tape and wire insulation.

Plastic injection molding – is a manufacturing process for producing parts from both thermoplastic and thermosetting plastic materials. Molten plastic is injected at high pressure into a mold, which is the inverse of the product's shape.

Plastics wood composites – A range of materials that resemble wood. It combines the advantages of wood with those of plastic

Plug-and-ring – Method of sheet forming in which a plug, functioning as a male mold, is forced into a heated plastic sheet help in place by a clamping ring.

PVC (rigid and flexible) - Polyvinyl chloride is a widely used thermoplastic polymer. As a hard plastic, it is used as vinyl siding, magnetic stripe cards, window profiles etc. It can be made softer and more flexible by the addition of plasticizers, the most widely-used being phthalates. In this form, it is used to make flexible hoses and tubing, flooring, to roofing membranes, and electrical cable insulation.

Polybutylene – A polymer prepared by the polymerization of butane as the sole monomer

Polycarbonates- are a particular group of thermoplastic polymers. They are easily worked and molded; as such, these plastics are very widely used in the modern chemical industry.

Polyethylene (low, medium and high density) - is a thermoplastic commodity heavily used in consumer products (notably the plastic shopping bag). Over 60 million tons of the material is produced worldwide every year.

Polypropylene- is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including packaging, textiles, stationery, plastic parts, reusable containers of various types and more.

Polystyrene (HIPS) - is one of the most widely used kinds of plastic. It is used, for example, in disposable cutlery, plastic models, CD and DVD cases, and smoke detector housings. Products made from foamed polystyrene are nearly ubiquitous, for example packing materials, insulation, and foam beverage cups.

Polyurethane- Polyurethane products have many uses for example: used for moldings which include door frames, columns, balusters, window headers, pediments, medallions and rosettes to name a few.

Polyurethane Resins- A family of resins produced by reacting diisocyanate with organic compounds containing two or more active hydrogens to form polymers having free isocyanate groups. These groups, under the influence of heat or certain catalysts, will react with each other, or with water, glycols, ECT. to form a thermosetting material

Prototype Mold- A simplified mold construction often made from a light metal casting alloy or from an epoxy resin in order to obtain information for the final mold and/or part design

Shore Hardness- A method of determining the hardness of a plastic material using a scleroscope. This device 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 will be the rebound.

Silk screening – (Screen Printing) is a printing technique that uses a woven mesh to support an ink blocking stencil. The attached stencil forms open areas of mesh that transfer ink as a sharp-edged image onto a substrate. A roller or squeegee is moved across the screen stencil forcing or pumping ink past the threads of the woven mesh in the open areas.

Specific Gravity- The density(mass per unit volume) of any material divided by the water at a standard temperature, usually 4 degrees C. Since water’s density is nearly 1.00 g./cc, density in g./cc and specific gravity are nearly numerically equal.

Stretch Forming- A plastic sheet forming technique in which the heated thermoplastic sheet is stretched over a mold and subsequently cooled.

Tensile Strength- The pulling stress, in psi, required to break a given specimen. Area used in computing strength is usually the original, rather than the necked-down area.

Thermal Expansion Coefficient- The fractional change in length (sometimes volume, specified) of a material for a unit change in temperature. Values for plastics range from 0.01 to 0.2 mils/in, degrees C.

Thermoplastic- Capable of being repeatedly softened by heat and hardened by cooling (n)- A material that will repeatedly soften when heated and harden when cooled. Typical of the thermoplastics family are the styrene polymers and copolymers, acrylics, cellulosics, polyethylenes, vinyls, and the various fluorocarbons materials.

Thermoset- A material the will undergo or has undergone a chemical reaction by the action of hear, catalysts, ultra-violet light, etc. Leading to a relatively in fusible state. Typical of the plastics in the thermosetting family are the aminos (melamine and urea), most polyesters, alkyds, epoxies, and phonemics

TPR (Thermoplastic Rubber) - Thermoplastic elastomers, sometimes referred to as thermoplastic rubbers, are a class of copolymers or a physical mix of polymers (usually a plastic and a rubber) which consist of materials with both thermoplastic and elastomeric properties. Used in applications such as shoe soles, snowmobile tracks, catheters and in adhesives.

Translucent – Descriptive of a material or substance capable of transmitting some light, but not clear enough to be seen through

Transparent – Descriptive of a material or substance capable of a high degree of light transmission, e.g. glass. Some polypropylene films and acrylic moldings are outstanding in this respect.

UHMW – also known as high-modulus polyethylene (HMPE) or high-performance polyethylene (HPPE) is a subset of the thermoplastic polyethylene. A very tough material, with the highest impact strength of any thermoplastic presently made.

Ultimate Strength – Term used to describe the maximum unit stress a material will withstand when subjected to an applied load in a compression, tension or shear test.

Ultimate Sealing – A film sealing method in which sealing is accomplished through the application of vibratory mechanical pressure at ultrasonic frequencies. Electrical energy is converted to ultrasonic vibrations through the use of either a magnetostrictive or piezoelectric transducer. The vibratory pressures at the film interface in the sealing area develop localized heat losses which melt the plastic surfaces affecting the seal.

UV stabilizer – Any chemical compound which, when mixed with a thermoplastic resin, selectively absorbs UV rays.