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Processes

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Calendering

The process of forming thermoplastic sheeting or film by passing the material through a series of heated rollers.  The gap between the last pair of heated rollers determines the thickness of the sheet. Subsequent cold rollers cool the sheet.  The plastic compound is usually premixed and plasticated on separate equipment, then fed continuously into the nip of the first pair of calendar rolls.

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).

 

Cast

To form a plastic material into a certain shape by pouring it into a mold and letting it harden without applying external pressure.

 

Centrifugal Casting

The process of forming pipes or other hollow cylindrical objects by introducing a measured amount of fluid resin or resin dispersion into a r­­otable container or mold, rotating the mold about one axis at a speed high enough to force the fluid against all parts of the mold by centrifugal force, maintain such rotation while solidifying the plastic by applicable means such as heating, then cooling if necessary and removing the formed part.  This should not be confused with Rotational casting, which involved rotation at slow speeds about one or more axes and distribution under the force of gravity.

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).

 

Centrifugal Molding

A process similar to centrifugal casting except that the materials are dry, sinterable powders such as polyethylene. Such powders are fused by the application of heat to the rapidly rotating mold. 

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).

 

Chill Roll Extrusion

A term applied to film extrusion in which the extruded film is drawn over cooled rollers, imparting improved gloss.

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).

 

Cold Drawing or Cold Stretching

A stretching process employed to improve the tensile properties of thermoplastic filaments and films.

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).

 

Cold Molding

A procedure in which a composition is shaped at ordinary temperatures and hardened by subsequent baking.

 

Cold Pressing

A bonding operation in which an assembly is subjected to pressure without the application of heat.

 

Compression Molding

A process in which a plastic material is molded into a shape by the application of heat and pressure.

 

Contact Pressure Molding (Contact Molding)

The term encompasses processes for forming shapes of reinforced plastics in which little or no pressure is applied during the forming and curing steps.  It is usually employed in the connection with the processes of Spray-up and Hand Lay-up Molding when such processes do not includes the application of pressure during curing.

 

Continuous Contact Laminating

Process by which laminates bonded with contact pressure resins can, by means of specially developed machinery, by produced on a continuous as opposed to a batch-wise basis.

 

Curtain Coating

A coating process in which the substrate to be coated is a conveyed rapidly through a free-falling liquid “curtain” of a low-viscosity resin, solution, suspension or emulsion.  The coating thickness is governed by the rate of flow of the fluid and the speed of travel of the substrate.

Source: Whittington, Lloyd R.  Whittington's Dictionary of Plastics (Stamford, CT: Technomic, 1968).