Plastics Technology

SEP 2018

Plastics Technology - Dedicated to improving Plastics Processing.

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Part Weight vs. Injection Speed: Any reduced variation in part weight improves the performance of a multi-cavity injection molding workcell. It can be seen Fig. 4 that as injection speed increased, part weight decreased and weight range also decreased. In order to take advantage of this phenom- enon, the system must have a lower pressure drop and an equal fill balance. So if the fill balance and pressure drop in the hot-runner system is optimized, it provides an oppor- tunity to further improve the part cost via lower part weights and faster cycles. Color Change: The fastest color change can be achieved with hot-runner configura- tion D and screw design B, although this combination was not tried together (Fig. 5). Screw B exhibited a 24% improved color-change time compared with screw A, mostly due to reduced channel depths and higher compression ratio. Hot-runner configuration D performed best, as it has ZEISS X-ray family Industrial computed tomography gives you entirely new insights by making it possible to capture the whole volume with all internal structures. With the ZEISS X-ray family, you can successfully perform complex analysis, measuring and inspection jobs with only one scan. Visit the ZEISS booths at IMTS – East Building, 135502 & 135655 (ZEISS X-Ray Solutions). Register for a learning session and a chance to win ZEISS gear! Find out more at www.zeiss.com/imts-2018 Performing complex measuring jobs at a glance. ZEISS Computed Tomography Number of Shots to Change Color Screw A + HR D Screw A + HR C Screw A + HR B Screw B + HR B Screw B + HR A Screw A + HR A 0 5 10 15 20 25 30 35 40 45 50 24% 53% Hot Runner Type A B C D Screw A Screw B 20 15 10 5 3 1 Screw B exhibited a 24% improved color-change time compared with screw A, mostly due to reduced channel depths and higher compression ratio. Hot-runner configuration D performed best, as it has small runner sizes and a contoured channel layout. It is well established that color-change times can be enhanced with higher shear rates (smaller channel and flight depths), as this reduces the residence time of the plastic nearest the barrel and melt-channel walls. FIG 5 Dark-to-Natural Color Change * Based on 100 color changes/yr in a 48-cavity mold running 4 sec. @plastechmag 57 Plastics Technology Melt Management

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