Plastics Technology

JUL 2018

Plastics Technology - Dedicated to improving Plastics Processing.

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OEE (Overall Equipment Effectiveness) statistics, and color-coded machine status. Such data are uploaded to the "cloud" so as to be available to computers and mobile devices anywhere, 24/7. INJECTION MOLDING NEWS Multi-layer injection molding of barrier containers and PET bottle preforms was highlighted by Milacron Inc. (milacron.com) and Husky Injection Molding Systems Ltd. (husky.co). Husky displayed examples of how sandwich molding of three-layer PET preforms can be used for other functional and decorative pur- poses. For example, the center layer could incorporate, instead of a gas barrier, a thermochromic pigment that would signal when a bottle is cold or warm. Fluorescent pigments could be used to make the bottle appear a different color when subjected to UV light. Other decorative effects are possible by continuously varying the thickness of the pigmented middle layer during injection of the preform, so that blown bottles show a transition from clear to colored or between two colors. Another area of technological innovation displayed at NPE was LSR molding. Negri Bossi, (negribossi.com), molded a ping-pong paddle using three materials—PBT for the basic structure, TPE for a soft-touch grip, and LSR in two colors for the resilient faces of the paddles. What made this particularly interesting was the injec- tion of nitrogen gas for microcellular foaming of the PBT and the LSR. In fact, Negri Bossi said it could differentiate the resiliency of the two paddle faces by foaming one face and not the other. There were at least three demonstrations at NPE of LSR/LSR molding in two colors and/or durometers in the same part. As previously reported, two other examples were shown by Arburg (arburg.com). Another was conducted at the booth of Sigma Plastic Services, Schaumburg, Ill., which simulated the process in its Virtual Molding software (virtualmolding.us). What was special about this application was that two-color LSR egg cups were molded on a single- barrel Arburg machine with a single Elmet metering system. Shown for the first time in the U.S., this application used a T-coupling to divert a side stream of LSR to a second static mixer and a side-mounted pneumatic piston pump that delivered the second color. 'ARTISTIC' ROBOT Previous NPE shows have featured robots playing basket- ball and miniature golf. An imaginative display this year was a robot from Star Automation (starautomation.com), using a new three-axis servo head to do Japanese calligraphy. The robot carefully loaded the brush with ink, painted the figure, and then rinsed the brush. Yushin America (yushinamerica.com), put together a complex cell just to demonstrate the versatility of robots for accomplishing multiple tasks in one molding cycle. The cell combined two injection presses, each with a servo linear robot, plus a seven-axis collaborative robot (cobot). The end product was a "shaker cup" for making milk shakes and other mixed beverages. The two presses molded a PP cup and a lid with a flip-top closure attached by a living hinge. The two parts were threaded; the robots each used a servo wrist to unscrew the parts from the molds. The robot that demolded the cup also placed an in-mold label in the mold beforehand and presented the cup to a pad printer after molding. The second robot unscrewed the lid, closed the pour spout, placed information cards inside the cup, and then screwed the cup and lid together. Finally, the cobot placed the assembled product on a conveyor. BLOW MOLDING: THEY SAID IT COULDN'T BE DONE Jomar Corp. (jomarcorp.com), may have opened some eyes to the unsuspected capabilities of injection-blow molding. At NPE, Jomar molded polycar- bonate LED bulbs on its new IntelliDrive 85S servohydraulic injection- blow machine. Molded eight-up in 11.5 sec, the bulbs had only slightly visible gate marks and parting lines—something not supposed to be possible with this process, according to Jomar sales manager Ron Gabriele. He credits both the know-how of Jomar's processing team and the skills of the toolmaker, Lenape Mold in Millville, N.J. An imaginative display this year was a robot using a new three-axis servo head to do Japanese calligraphy. Star Automation programmed a servo robot to paint Japanese calligraphy (inset) after carefully loading the brush with ink and rinsing the brush between demonstrations. Two-color LSR egg cup was molded at Sigma Plastic Services booth using a single-barrel Arburg injection press and a single Elmet pumping system. T-coupling visible here diverted a small stream of LSR to a second static mixer and pneumatic piston pump, where the second color was added. @plastechmag 15 Plastics Technology

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