Compression Molding of Fluoropolymers

Another example of compression molding was given by Nichias Corporation.1 0 A rectangular platelike part was formed by inserting a stainless steel plate in the mold at the core of the part and surrounding it with a fluoroplastic resin. PTFE bearers (Nos. 

3 and 4 in Fig. 6.48) were positioned between the core material and the mold cavity such that the core was inserted into the mold without contacting the surface of the mold cavity. Essentially, the PTFE bearer resembles a large screw that is threaded (No. 

4 in Fig. 6.48) into the metal core plate (No. 1 in Fig. 6.48). Consequently, the fluoroplastic surface layer could be formed around the core. PTFE did not soften and deform during the molding, leading to its complete encapsulation in the core. 

In the first molding step, half of the fluoroplastic resin was charged into the mold. Next, the bearer and core assembly was set in the mold. Then the other half of the resin was dispensed into the mold. The hold-down plate was used to compress the contents of the cavity while the mold was heated to a temperature above the melting point of the fluoroplastic resin. After cooling, the part can be removed and machined to the required specifications. 

Molding Technique Advantages Disadvantages Typical Process Shear Rate (sec ) 

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