Vertical heat platens

Lamb et al studied the conversion concept of a crosscurrent moving bed. The PBC system consisted of a trolley filled with a fuel bed of bagasse. The trolley rolled horizontally over a vertical air duct to simulate the moving bed (Figure 3). The speed of the trolley was controlled to keep the flame in a stationary position over the duct. An electrically heated platen, 30x15 cm, was placed horizontally 12 cm above the base of the bed, simulating radiation from furnace walls. 

Sachets can be fabricated from a single web with a centre fold, using a three or four sided seal or two webs using a four sided seal. The reels may be fed horizontally or vertically and be sealed by a series of heated platens or rollers (cylinders) or a combination of the two. In certain ways they are an enlarged version of a strip pack. The sachet seal can also be made peelable by a non-seal part on the web which may involve a pattern lacquer rather than a full heat seal coating. Difficult to tear plies, like PET, can also be used provided a cut or V-notch is added to initiate the tear. 

The top and bottom dies are heated independently to about 120°-150°C (250°-300°F). Dies are of hard tool steel with the part appearance surface mounted on the top platen. A vertical flash design with adequate guide pins, safety stops, and ejector system is suggested. Dies must have a shear edge of about 0.002-0.003 in. to trim the part in station. 

Compression moulding is carried out on moulding powders or sheet moulding compounds (SMC). The presses are vertical, with the hydraulic cylinder above or below the horizontal platens. The mould is heated to between 160 to 200 C, being thermally insulated from the platens (Figure 1.9). The required amount of prepolymer (mixed with catalyst or curing agent) is placed into the open mould it is then closed and pressure is applied to cause the material to flow around the cavity. The mould remains closed until the... 

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