A general purpose screw that utilizes a typical three-zone style is best for processing RTP Company Long Fiber Compounds. The screw has three sections: feed, compression, and metering. Metering should be done with an L/D ratio of 16:1 to 22:1, with a low compression ratio of 2:1 to 2.5:1.
A 100% ‘Free Flow’ fluted screw tip valve assembly is required to allow smooth melt flow. The nozzle/sprue orifice should have generous dimensions (0.250in/5.56mm) and be without sharp edges or severe convolutions. Do not use internally tapered tips or tips without a constant diameter pathway.
Material construction for screws and barrels can be the same as for standard reinforced materials.
Three Piece Screw Tip Ring Valve
