Plastics Technology

SEP 2018

Plastics Technology - Dedicated to improving Plastics Processing.

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n s i g n E Q U I P M E N T ENSIGNEQ.COM | 616.738.9000 | SALES@ENSIGNEQ.COM • SYSTEMS INTEGRATION • CONTAINER FILLING/UNLOADING • MATERIAL CONVEYING • ADVANCED DUMPING TECHNOLOGY • WEIGH SYSTEMS • MIXING AND BLENDING Smart Solutions To Keep You Moving! BULK MATERIAL H A N D L I N G S Y S T E M S E N S I G N D E S I G N S & M A N U F A C T U R E S zation. Typically, each element is optimized in isolation from the others and, as such, a sub-optimized system is created. 3. Plasticating. The process of creating a homogenous melt and injecting it into the hot runner is a key to being a world- class molder. The screw configuration has a major impact on melt homogeneity, which is closely related to repeating weight precision and melt- temperature uniformity. Type B screws exhibited poorer temperature homoge- neity and larger temperature fluctuations than the Type A screw when molding this grade of PC resin. The high viscosity of this grade led to a high dependence of homoge- neity on screw geometry. The level of homogeneity that is created in the screw is carried into the hot runner and the mold. As the old saying goes, "Garbage in produces garbage out," so creating a good melt is critical. 4. Screw tip to hot-runner inlet. Although it seems like an obvious fact, the interface between the hot runner and the injec- tion unit must match in size and contact radius. Any mismatch in alignment or size can cause flow restrictions, hang-up spots and pressure loss. Any of these, in turn or together, can reduce OEE via slower cycles, increased scrap or greater downtime. FEA particle trace shows that two apparently balanced hot runners yield quite different fill balances. The colors represent melt particles having the same residence time in the melt stream. The single level H-style manifold creates non- uniform shearing in the hot runner, resulting in unbalanced fill. The X-style melt-channel path creates a much more even shearing profile and resulting filling pattern. FIG 7 QUESTIONS ABOUT INJECTION MOLDING? Visit the Injection Molding Zone. FEA Particle Tracers Hot Runner B Hot Runner BD @plastechmag 59 Plastics Technology Melt Management

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