Plastics Technology

JAN 2019

Plastics Technology - Dedicated to improving Plastics Processing.

Issue link:

Contents of this Issue


Page 22 of 60

Despite higher melt temperature than PETG, cycle times with EPET are said to be similar because it sets up faster. Another key consideration, several sources agree, is a need for higher clamp force for EPET in order to get a good pinch-off. Exactly how much more force may be required appears to be a subject of debate, though a ballpark of 20% was suggested by one machinery OEM. Jackson notes this is influenced the boosting of clamp force from 32 tons to 44 tons on Hesta's newest and largest all-electric EBM machine, the Hesta 900. Slenk says uniformity of clamp-force distribution is perhaps equally important, and cites that as one reason the C-Frame clamps on Bekum machines have been very successful in EPET applications. EPET may not be a drop-in for PETG with regard to tooling. Some modifications for sharper pinch-off may be required. Rollend suggests that EPET molds may benefit from deeper flash pockets, sharper knives, prouder edges, and steeper angles. He adds that drying requirements for EPET are very similar to those for standard bottle- grade PET, which typically are more intensive than those for PETG. Equipment suppliers point out that all of the above considerations assume even greater importance when it comes to converting from non-polyester resins, such as HDPE or PVC, to EPET. Here's how: • Double Cross Cutting Action – Reduces Jams and Material Fines • Adjustable Bed and Rotor Knives – Maintain Constant Cutting Circle • Safe, Easy Access to the Grinding Chamber – for Improved Maintenance, Screen Changes and Machine Cleanout • Replaceable Armor Plating in the Cutting Chamber • Faster and Safer Knife Changes – Adjustments are Made in Jig Outside of Granulator • Available Force Feed Mechanisms – Increase Throughput by 50% - 80%, While Reducing Power Consumption We Know Every Day is a Grind That's why we make our granulators so tough 888.612.7774 | Size reduction is tough work that can really do a number on your equipment. At Herbold, we know that granulator performance and durability is critical to your success. That's why we build our equipment to deliver maximum throughput and require minimal maintenance and downtime. Higher clamp force and uniform force distribution are important to achieve a good pinch-off in EPET extrusion blow molding. Bekum's C-clamp, shown here, has been successful in this application. Reduce scrap and improve quality with Per-Fix ® specialty flaw repair coatings. Salvage costly parts with surface imperfections with our permanent flaw repair touch-up coatings. In 60-seconds, Per-Fix instantly repairs the most common visual part defects including knit/flow lines, gloss imperfections, splay and many others. 800-336-9828 • SPRAY-ON PERFECTION Per-Fix ® Clear Transparent coating to fix light to medium flaws. Free evaluation kit. Per-Fix ® Black For deeper flaw repairs. Free evaluation kit. Per-Fix ® Color Match Custom formulated based on full-color analysis of existing products. Free sample match. 20 JANUARY 2019 Plastics Technology E P E T B L O W M O L D I N G Close -Up On Technolog y

Articles in this issue

Links on this page

Archives of this issue

view archives of Plastics Technology - JAN 2019