Compression and transfer molding

Injection Molding Extrusion Blow Molding Thermoforming Reaction Injection Molding Rotational Molding Compression and Transfer Molding Matched Mold Spray-up... 

Molded articles may be prepared from the prepregs by compression and transfer molding. In general, several sheets of the prepreg are cut and stacked in a mold. For example, a prepreg was cured by heating for 80 s at 150-180°C at 100-200 bar. The cured sample had the physical properties shown in Table 11.4. 

A variation of the compression molding technique is to use transfer molding. In this method the liquid polyurethane mix is placed in a pot and allowed to thicken. The polyurethane semi-gel is forced through sprues into the mold, and the air is allowed to escape through vent holes. The part is allowed to cure sufficiently so that it can be removed. Figure 5.2 shows the general layout of a compression and transfer mold. 

They can be processed by techniques commonly used for thermoplastics, such as extrusion, injection molding, rotational molding, dip, slush molding, and powder and fluidized bed coating,16 and can be expanded into foams.17 Compression and transfer molding of FEP resins can be done, but with some difficulty. Extrusion of PEP is used for primary insulation or cable jackets and for tubing and films. 

Fluorel . [3M] Fluoroelastomers for extrusion, inj., compression, and transfer moldings, fuel line hose, seals, o-rings, calendered sheet, rolls. 

The two most widely used methods for molding thermoset are compression and transfer molding. Thermosets, you will recall, undergo a permanent set, i.e., become essentially insoluble and infusible under the action of heat. Consequently, techniques for fabricating thermosets must take due cognizance of and make allowance for the fact that sprues, runners, and gates are not reusable and therefore constitute rejects. 

Phenol-formaldehyde molding compositions are traditionally processed on compression- and transfer-molding machines with a very small amount being extruded. However, the injection-molding process as modified for thermosetting plastics is being increasingly used and it is today the most common method used to process phenolic compounds. The shorter cycle times and low waste factor available with... 

MF compositions are easily molded in conventional compression- and transfer-molding equipment. Molding temperatures from 145°C tol65°C and molding pressures 2-4 tonfrin. (30-60 MPa) are usually employed. In transfer molding, pressures of 5-10 tonf/in. (75-150 MPa) are used. The cure time for an l/8-in.-thick molding is typically 2 1/2 min at 150°C. 

Diallyl Phthalate Resin Thermoset supplied as diallyl phthalate prepolymer or monomer. Has high chemical, heat and water resistance, dimensional stability, and strength. Shrinks during peroxide curing. Processed by injection, compression, and transfer-molding. Used in glass-reinforced tubing, auto parts, and electrical components. Also called DAP. 

Polyphenylene Sulfide High-performance engineering thermoplastic has good chemical, water, fire, and radiation resistance, dimensional stability, and dielectric properties, but decreased impact strength and poor processability. Processed by injection, compression, and transfer molding and extrusion. Used in hydraulic components, bearings, electronic parts, appliances, and auto parts. Also called PPS. 

COMPRESSION AND TRANSFER MOLDING 245 Table 6-3. Examples of Pressure Required to Compression Mold Based on Cavity Depth using Phenolic Molding Compounds (psi Pressure). ... 

PLASTrCS PROCESSING DATA HANDBOOK Compression and Transfer Molding... 

Compression and transfer molding processes are high-volume, high-pressure methods suitable for molding simple to complex parts. (See Chapter 6 for details.)... 

Uses Melt processable high performance thermoplastic for melt extrusion, coating of fine wire and inj. molding of slender, thin-walled, or intricate shapes, compression and transfer molding for pipes, sheets, and cable jackets in elec, wire insulation, industrial fibers, weather-resist, films, mechanical applies., and in chemical service Manuf./Distrib. Aldrich http //www.sigma-aldrich.com... 

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