Flexible plunger moldings

This process is a take-off from compression molding that uses solid material male and female matching mold halves. This unique process uses a precision-made, solid shaped heated cavity and a flexible plunger that is usually made of hard rubber or polyurethane. This two-part system can be mounted in a press. Rather excellent product qualities are possible at fairly low production rates. The reinforcement is positioned in the cavity and the liquid TS resin is poured on it. Also used are prepregs, BMC, and SMC. 

The plug is forced into the cavity and the product is cured. The plunger is somewhat deeper and narrower than the cavity. It is tapered in such a manner that contact occurs first in the lowest part of the mold. Ultimate pressure usually used are up to 400 to 700 kPa (58 to 100 psi) in the plunger causes the contact area to expand radially toward the rim of the cavity, thereby forcing the resin and air ahead of it through the reinforcement with the target of developing a void free product. 

The pressure conforms to irregularities in the lay-up, permits wall thickness to be varied within reasonable limits, and makes a good surface possible only against a metal mold surface. The fact that the heat can be applied only from the cavity side leads to longer cure cycles. This factor tends to produce resin richness, and consequendy greater smoothness on the side of the solid mold surface. 

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

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