From Design for Manufacturability Handbook, Second Edition
Chapter 6.1: Thermosetting-Plastic Parts
Chapter 6.2: Injection-Molded Thermoplastic Parts
Chapter 6.3: Structural-Foam-Molded Parts
Chapter 6.4: Rotationally Molded Plastic Parts
Chapter 6.5: Blow-Molded Plastic Parts
Chapter 6.6: Reinforced-Plastic/Composite (RP/C) Parts
Chapter 6.7: Plastic Profile Extrusions
Chapter 6.8: Thermoformed Plastic Parts
Chapter 6.9: Welded Plastic Assemblies
Chapter 6.10: Rubber Parts
Chapter 6.11: Ceramic and Glass Parts
Chapter 6.12: Plastic-Part Decorations


Robert W. Bainbridge


Occidental Chemical Corp.

Durez Resins & Molding Materials

North Tonawanda, New York


Molding compounds of thermosetting materials, or thermosets, when subjected to heat and pressure within the confines of a mold, cure or set into an infusible mass. An irreversible chemical change, involving the cross-linking of molecules of the material, takes place, and a solid part is formed.

Three basic methods of molding may be selected to process thermosets: compression, transfer (pot or plunger), and injection molding. Compression molding is illustrated in Fig. 6.1.1.

Figure 6.1.1: Schematic illustration of compression molding. A preform of thermosetting material is placed in a mold cavity. Heat softens the preform, and the ram pressure forces the material into all portions of the mold cavity, where it takes the shape of the cavity. The material then sets into a solid part that can be removed from the mold.

The molding operation requires a press large enough to generate the required pressure and a mold mounted into the press and heated by steam, electricity, or hot oil to the recommended temperature. Auxiliary equipment, for preheating the molding compound, loading it,...

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Composite and Fiberglass Molding Services
Composite and fiberglass molding services perform injection molding, blow molding, compression molding, rotationalmolding, thermoforming, and dip molding.
Silicone Molding Services
Silicone molding services produce molded components made from silicone or liquid silicone rubber.
Molding Machines
Molding machines form thermoplastic resin, thermoset polymers, or MIM compounds into finished shapes.
Plastic Molding Services
Plastic molding services use a number of different molding techniques to produce components, including thermoplastic and thermoset injection molding, blow molding (includes injection blow molding), rotational molding, thermoforming, structural foam molding, compression molding, resin transfer molding (RTM), and others.

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