Hot presses/platens

During the processing of composite materials in a hot press or an autoclave, the laminate is usually kept flat until cure is complete. If the platen surfaces are assumed frictionless, the effect of the constraints is to require that the curvatures K] and k2 be zero throughout cure. To develop the elastic solution under these constrained conditions, the laminated plate theory may be used with conditions of N = 0 and jc, = 0. The resulting midplane strains are given by... 

Once the elastic residual moment from Equation 8.30 or the viscoelastic residual moment history from Equation 8.39 have been determined, the final value may be applied elastically as platens open (hot pressing) or as the applied pressure is released (autoclave processing) to find the resulting cross-ply curvature. This curvature can then be correlated to experimental data. 

The traditional heating processes used to cure epoxy adhesives are fully described in Chap. 17. These traditional curing processes include oven heating, hot presses and platens,... 

Eor certain analyses it may be desirable to ensure that the hot pressed compression molded film is frozen into an amorphous state. This may be achieved by melting a few milligrams between a pair of thin press plates or aluminum sheet, leaving part of the plates exposed from the press platens. This may be... 

Hot press moulding is a mass production method for the manufacture of composite components. A hydraulic press is used capable of applying a pressure of about 100 tonnes/m of platen area. A matched metal tool is located between the platens, the cavity between the tool halves having been machined to produce the shape required. The tool is heated to about 130-170°C either from the heated platens or directly (by cartridge heaters, etc.). 

Hot-pressing n. The pressure-forming, between heated platens, of plywood, laminates, particleboard, fiberboard, etc. usually requires thermosetting resins and heat for curing. 

The picture frame mould at left, which sits on a hot press s lower platen, consolidates multiple thermoplastic matrix composite plies into the laminate at right. 

Pressing Time, pressure and temperature Manual (clamps) roll or platen press. Cold or hot pressing Frames, autoclaves... 

The homogeneous southern pine particleboards with a density of 50 pounds per cubic foot were pressed to 5/8 inch stops using a closing pressure of 500 psi with a platen temperature of 360 F for the prescribed press time of 5, 6, or 7 minutes. A resin solids of 6%, based on oven dry weight chips, was used for all boards. No wax or other material was added. Immediately upon removal from the hot press, boards were stored in an insulated, but unheated, oven for an overnight period of simulated hot stacking. Two duplicate boards were made for each hot press time and resin combination. 

One day after the flakeboards were made, the oak flakeboards having a 120 seconds press time were used to laminate with 1/8 southern pine veneers on face and back to form the 1/2 composite panel by the plywood resin. After 20 minutes close assembly time, the panels were hot pressed at a platen temperature of 300 F for 2 or 3 minutes under 200 psi platen pressure. 

Here, for illustrative purposes, is a sample procedure with manual manipulation of a small mold. This procedure is hot molding of thermosetting granules where both the mold and the press platens are pre-... 

Stronger and more dense products can be obtained by hot compression molding, usually in a flash mold. For phenolics, a press platen temperature of about 165 C is usually used. Such a hot molding cycle can be used either to fix the wheel geometry into a partially cured con-... 

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