Transfer molding plunger-type

Figure 2.3 shows the molding cycle of pot-type transfer molding, and Figure 2.4 shows plunger-type transfer molding (sometime called auxiliary raw transfer molding). The taper of the sprue is pot-type transfer is such that, when the mold is opened, the sprue remains attached to the disc of material left in the pot, known as cull, and is thus pulled away from the molded part, whereas the latter is lifted out of the cavity by the ejector pins (Figure 2.3c). In plunger-type transfer molding, on the other hand, the cull and the sprue remains with the molded piece when the mold is opened (Figure 2.4c).

FIGURE 2.4 Molding qrcle of a plunger-type transfer mold, (a) An auxiliary ram exerts pressure on the heat-softened material in the pot and (b) forces it into the mold, (c) When the mold is opened, the cull and sprue remain with the molded piece. (After Frados, J. ed. 1976. Plastics Engineering Handbook, 4th Ed., Van Nostrand Reinhold,... 

Figure 1. The molding cycle of a plunger-type transfer mold.

---