Today's designs allow more than just melting and mixing

摘要

Plasticating screws convey input materials (pellets, color, additives, reinforcements and fillers, etc.) through heated barrels to melt, mix, and deliver them to an injection mold or extrusion die located downstream. There are three zones (illustration, right) that make up the flighted length of a typical screw. 1. In the feed zone, polymer enters and is compacted and driven forward, beginning the melt process. 2. In the transition, or compression zone, the root diameter of the screw increases and the channel depth decreases, increasing compression and accelerating the melting process. 3. In the metering zone, the melt is conveyed forward at a constant depth as it reaches optimal temperature and viscosity for molding.