Press insert molding

The principle for both these methods is final shaping by pressing in the molding tool. The film and the melt are inserted prior to production of the molded part. 

FIGURE 3.21 Process chain, press insert molding [48] 

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There are presses that include shuttle (molds in which usually two, or more, are moved so that one mold is positioned to receive material and then moves to the press permitting another mold to receive material with this cycle repeating result is to permit insert molding, reduce molding cycle, etc.), rotary or carousal system, and book opening or tilting press.4 279... 

When the molding cycle is complete, the press opens and the molded part is removed and, if required, trimmed. It is probably moved to a jig for post-cure. This is normally carried out in a vertical press (compression molding), which is also convenient for loading inserts into the molding tool. 

Screw injection and plunger injection molding may be used with vertical presses for insert molding. In such molding, the screw and barrel (or plunger, barrel, and stuffing mechanism) may be positioned vertically above the upward closing mold. After inserts are placed into the open bottom mold half, the press closes the mold, and the plastic is injected into the mold. 

Screw Assembly. Self-tappiag screws are used for joining ETEE parts. Eor maximum hoi ding power, the boss diameter should be about double the screw diameter, and the engagement length about 2.5 times the screw diameter lubricants should be avoided. Threaded inserts can be molded ia place, pressed ia, or driven ia ultrasonicaHy. 

Rubber Plug Molding. Liquid silicone rubber is cast into a female mold cavity and cured. The plug is removed, and layers of mat or fabric are built onto the plug. This assembly is then inserted into the mold cavity, pressed, and heated until cured. 

Moldings with inserts or threads or coring that cannot be formed by the normal functioning of the press require installation of separate or loose details or cores in the mold. These loose members are ejected with the molding. They must be separated from the molding and reinstalled in the mold after every cycle. Duplicate sets are therefore used for efficient operation. 

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