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| Term | Definition |
|---|---|
| Core Pin |
In injection molding, a pin inserted in a mold to produce a hole. May also be used to activate the movement of a sliding core. |
| Corona Discharge |
A method of rendering the surface of inert plastics, such as polyethylene, more receptive to inks, adhesives, or coatings by subjecting their surfaces to an electrical discharge. Typical method is to pass film over a grounded metal cylinder above which a high voltage electrode is spaced to leave a small air gap. The corona discharge oxidizes the film leading to the formation of polar groups. The surface now becomes receptive to the coatings. |
| Coroplast® |
Coroplast's main product is corrugated plastic sheet. The name Coroplast applies to a wide range of extruded twinwall plastic sheet products produced from a high impact polypropylene copolymer. Coroplast comes in a variety of styles, all based upon the Coroplast high quality corrugated plastic sheet. Coroplast is a registered trade mark of Coroplast Inc. |
| Creep |
Creep is the permanent deformation resulting from prolonged application of a stress below the material |
| Crosslinking |
The establishment of chemical bonds between the molecular chains in polymers. Crosslinking can be accomplished by chemical reaction, vulcanization, degradation, and radiation. |
| Crystallinity |
The state of molecular structure in some resins denoting uniformity and compactness of the molecular chain. |
| Cycle |
One full sequence in a molding operation, from a point in the process to the same point in the next sequence. |
| Cyclohexane |
A colorless liquid derived from the catalytic hydrogenation of benzene, used as a solvent in percent extractable testing. |
| Dancer Roll |
A roller used as a tension maintenance device in the production of films and sheeting |
| Daylight Opening |
The maximum distance that can be obtained between the stationary platen and the moving platen in a mold clamping system when the actuating mechanism is fully retracted without ejector box and/or spacers. |
| Deckle |
A rod or plate attached to each end of a cast film or extrusion coating die which is used to adjust the length of the die opening. |
| Deflection Temperature |
The temperature at which a standard ASTM D-648 test bar deflects 0.010 inch under a load of 264-psi. |
| Degree Of Polymerization |
The average number of monomer units per polymer molecule, a measure of molecular weight between the layers. |
| Densetec HDPE® |
Densetec High Density Polyethelyne sheet exhibits the properties of high impact strength, abrasion resistance, and low coefficient of friction. The material is also moisture, stain and odor resistant, and is FDA approved to be used in the food processing industry. The material's durability makes it ideally suited for a variety of applications such as water tanks, chute linings and numerous industrial uses. Densetec HDPE is a registered trade mark of Polymer Industries. |
| Diaphragm Gate |
In injection and transfer molding, a type of gate used for annular or tubular articles. |
| Dibond® |
Dibond is an aluminum composite material (ACM) made of two pre-painted sheets of .012" aluminum with a solid polyethylene core. Dibond is masked on both sides. Dibond offers a very flat panel surface, its superior surface protects expensive digital and screenprinted graphics; provides excellent durability in outdoor applications; won’t bow or oil can; approximately one half the weight of aluminum. Dibond is a registered trade mark of Alcan Composites USA. |
| Die (Extrudate) Swell Ratio |
In extrusion, particularly for blow molding, the ratio of the outer parison diameter (or parison thickness) to the outer diameter of the extrusion die (or die gap). |
| Disc Gate |
Mold gate having the same cross section as the mold runner. |
| Doctor Bar (Blade) |
A flat bar used for regulating the amount of liquid material on the rollers of a coating machine, or to control the thickness of a coating after it is applied to a substrate. |
| Drawdown |
In extrusion, the process of pulling the extrudate away from the die at a linear speed higher than that at which the melt is emerging from the die, thus reducing the cross-sectional dimensions of the extrudate. |
| Drooling |
Leakage of resin from a nozzle or around the nozzle area during the injection step in injection molding or around the screen-pack during extrusion. |
| Ductility |
Amount of strain of material can withstand before it fractures. |
| Duraplex® |
Duraplex is a continuously processed impact modified acrylic sheet. Duraplex has superior impact strength: 40% impact modified acrylic is 5 to 6 times stronger than general purpose acrylic, 10 to 15 times stronger than double strength window glass, and 20 to 30 times stronger than polished wire glass or other glasses. Duraplex is excellent for handling--less breakage in shipment, and is an economical alternative to Polycarbonate. Duraplex is a registered trademark of Plaskolite, Inc. |
| Dwell Time |
A pause in the application of pressure to a mold, made just before the mold is completely closed, to allow for the escape of gas. |
| Ejector Pin |
A pin or thin plate that is driven into a mold cavity from the rear as the mold opens, forcing out the finished piece. |
| Ejector Plate |
A plate which backs up the ejector pins and holds the ejector assembly together. |
| Ejector Return Pins. |
Projections that push back the ejector assembly as the mold closes. |
| Elastic Deformation |
The portion of deformation of an object under load which can be recovered after the load is removed. |
| Elasticity |
The property (of plastic materials) of recovering original size and shape after deformation. |
| Elastomer |
A material which, at room temperature, can be stretched under low stress to at least twice its original length and, upon immediate release of the stress, will return with force to its approximate original length. |
| Elongation |
Deformation caused by stretching; the fractional increase in length of a material stressed in tension. |
| Embossing |
Technique providing a textured surface to roll goods. It is used inline with extruders and calendars of off-line in an unwind, emboss, and rewind operation. The focal point of the equipment is the textured roll which imparts the impression. |
| Endothermic Reaction |
A reaction which is accompanied by the absorption of heat. |
| Entrance Angle |
In extrusion, the maximum angle at which the molten material enters the land area of the die, measured from the centre line of the mandrel. |
| Environmental Stress Cracking |
The susceptibility of a thermoplastic resin to crack or craze when stressed in the presence of surface active agents or other environments. |