All
| Term | Definition |
|---|---|
| Shrinking Allowance |
The dimensional allowance which must be made in molds to compensate for shrinkage of the plastics compound on cooling. |
| Sintra® |
Sintra is a lightweight yet rigid board of moderately expanded closed-cell polyvinyl chloride (PVC) extruded in a homogenous sheet with a low gloss matte finish. Sintra has print-optimized surfaces; supports faster printing speeds; is lightweight yet rigid and durable; is easily formed using wood and foam board fabrication techniques; is dent and scratch resistant. Sintra is a registered trademarks of Alcan Composites USA. |
| Spiral Mold Cooling |
A method of cooling injection molds or similar molds wherein the cooling medium flows through a spiral cavity in the body of a mold. In injection molds, the cooling medium is introduced at the center of the spiral, near the sprue section, as more heat is localized in this section. |
| Split Cavity Mold |
A mold cavity designed with sections. |
| Split Ring Mold |
A mold in which a split cavity block is assembled in a chase to permit the forming of undercuts in a molded piece. These parts are ejected from the mold and then separated from the piece. |
| Sprue |
In an injection or transfer mold, the main feed channel that connects the mold filling orifice with the runners leading to each cavity gate. The term is also used for the piece of plastic material formed in this channel. |
| Sprue Bushing |
A hardened steel insert in an injection mold, which contains the tapered sprue, hole and has a suitable seat for the nozzle of the injection cylinder. Sometimes called an adapter. |
| Sprue Gate |
A passageway through which molten resin flows from the nozzle to the mold cavity. |
| Sprue Puller |
A pin having a Z-shaped slot undercut in its end, by means of which it serves to pull the sprue out of the sprue bushing. |
| Stabilizer |
Ingredient used in the formulation of some polymers to assist in maintaining the physical and chemical properties of the compounded materials, for example, heat and UV stabilizers. |
| Stack Mold |
Two-level mold (two sets of cores and cavities stacked one above the other) for increased part production rates. Effectively doubles the parts per hour a machine can make. |
| Static Eliminators |
Mechanical devices for removing electrical static charges from plastics articles. Types of static eliminators include static bars, ionizing blowers, and air guns. |
| Stationary Platen |
In an injection molding machine, the large front plate to which the front plate of the mold is secured. This platen does not normally move. |
| Stearamide |
A slip additive used in polyolefins. |
| Stiffness |
The capacity of a material to resist strain where stressed. |
| Strain |
In tensile testing, the ratio of the elongation to the gauge length of the test specimen, that is, the change in length per unit of original length. The term is also used in a broader sense to denote a dimensionless number that characterizes the change in dimensions of an object during a deformation of flow process. |
| Stress |
The force producing or tending to produce deformation divided by the area over which the force is applied. As generally defined in tensile testing (engineering stress), stress is the ratio of applied load to the original cross-sectional area. True stress (instantaneous stress) is applied load per instantaneous cross-sectional area. |
| Stress Concentration |
The amplification of the level of an applied stress in the region of a notch, void, or inclusion. |
| Stripper-Plate |
A plate that strips a molded piece from core pins or force plugs. The plate is actuated by the opening of the mold. |
| Structa-Board™ |
NEW Structa-Board is a lightweight extruded black polystyrene foam board with tough lightweight bright white manmade wood-fiber veneer facers. Structa-Board offers a dent and scratch resistant surface, multi-year Application duration - perfect for point-of-purchase (POP) and interior signage. Structa-Board is a TradeMark of Alcan Composites USA. |
| Styrene-Acrylonitrile Copolymer (San) |
Copolymers of about 70 percent styrene and 30 percent acrylonitrile, with higher strength, rigidity, and chemical resistance than straight polystyrene. They may be blended with butadiene, either as terpolymer or by grafting onto the butadiene, to make ABS resins. |
| Submarine Gate |
Gate where the opening from the runner into the mold is located below the parting line or mold surface; as opposed to conventional edge gating, where the opening is machined into the surface of the mold. With submarine gates, the item is broken from the runner system on ejection. |
| Suck Back |
Technique used to partially clear the resin from the injection nozzle after the injection cycle by pulling the screw rearward, thus drawing the resin back into the injector. |
| Surface Tension |
A fluid in contact with a surface exhibits phenomena, due to molecular attractions, which appears to arise from a tension in the surface of the fluid. It may be expressed a dynes per centimeter or as ergs per square centimeter. |
| Surfactant |
A compound that alters surface tension of a liquid in which it is dissolved to improve contact area between two materials. |
| Surging |
In extrusion, an unstable pressure buildup leading to variable output and waviness of the surface of the extrudate. In extreme cases, the flow of extrudate may even cease momentarily at intervals. |
| Synergism |
A phenomenon wherein the effect of a combination of two additives is greater than the effect that could be expected from the known performance of each additive used singly. |
| Tab Gate |
A small removable tab of approximately the same thickness as the molded item, usually located perpendicularly to the item. The tab is used as a site for edge gate location, usually on items with large flat areas |
| Tack |
The stickiness of an adhesive, measurable as the force required to separate an adherent from it by viscous or plastic flow of the adhesive. |
| Tackifier |
A substance such as a resin ester which is added to synthetic resins or elastomeric adhesives to improve the initial and extended tackiness of the film. |
| Take-Off |
The mechanism for drawing extruded or calendered material away from the extruder or calendar. |
| Talc |
A natural hydrous magnesium silicate, used frequently as a filler such as steatite, talcum, mineral graphite. |
| Tear Propagation Resistance |
Resistance of a material to a force acting to propagate an initiated tear in the material. |
| Tear Resistance |
Resistance of material to a force acting to initiate and then propagate a failure at the edge of a test specimen. |
| Teflon |
Dupont |