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operation. The cavity is loaded and the plunger forced down, forming 

 the part. Multiple cavity molds cannot be loaded exactly alike and 

 hence some provision must be made for the escape of excess material, 

 forming a flash that must be subsequently removed. Such dies must 

 be carefully designed so that the fin is located for easy trimming and to 

 provide the best appearance. These multicavity molds are frequently 

 called semi-positive molds to differentiate them from a truly positive 

 mold where there is little flash. A typical telephone part made in a 

 semi-positive mold is the handset handle shown in Fig. 2. 



Fig. 2 — Mold for handset handle. 



The recently developed process of injection molding which consists 

 in forcing plastic material through a nozzle into a completely closed die 

 from an external compression chamber is also being used and promises 

 to alter many of the present operations. Since the opening and the 

 closing of the die are not related to the application of pressure, greater 

 freedom of design is possible. Furthermore, since full pressure is not 

 applied by this method until the die cavity is completely filled with 

 material, the material already in the die tends to support inserts and 



