Plunger molding

Design factor Bag molding Flexible plunger molding Vacuum injection molding Matched die molding Comp, molding... 

Plunger molding n. A variation of transfer molding in which an auxiliary hydraulic... 

Rubber-plunger molding n. A variation of matched-die molding that employs a deformable rubber plunger and a heated metal concave mold. The process enables the use of high fiber loadings. 

This class of mold is used only in compression molding and is generally used in all compression molds. The landed plunger mold provides a higher density of... 

A variation of the removable plate mold is the removable plunger mold. This is generally used when the stroke of the press does not allow ejection of the molded part because of its length. The plunger may also be removed for loading inserts or for mechanical or hand ejection of the molded parts. 

Transfer, or plunger molding, is a process in which high-flow B-stage resins, such as epoxies, are liquefied under heat and pressure in a transfer pot, after which the resultant liquid resin is transferred under pressure into mold cavities. The transferred resin is then heated to form cured, final parts that are then removed from the mold. Although compression and transfer molding are used principally with thermosetting compounds, the processes are occasionally used with thermoplastic material, often thermoplastic composites. 

Plunger Molding n A variation of Transfer Molding in which an auxiliary hydraulic ram is employed to assist the main ram. The auxiliary ram rapidly forces the material through a small orifice, thereby generating high frictional heat. The higher temperature speeds the cure of the material, which when transferred into the mold by the main ram, cures very soon after the mold is filled. 

Figure 9.7 Schematic illustration of transfer or plunger mold.

In the plunger molding (also called auxiliary ram transfer) process, an auxiliary ram exerts pressure on the molten plastic for transfer to the mold cavity (Fig. 

In this proeess, the plastic is heated and melted in a screw and then dropped into a pot of an inverted plunger mold (Fig. 10.15). The molten polymer is transferred to the mold by the same procedure as shown in Fig. 10.12. The screw transfer method and the sequence of the operational steps are depicted in Figs. 10.15(a) and 10.15(b). Screw transfer molding is an excellent process for full automation. 

Figure 10.14 Schematic drawing of the plunger molding process.

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