Plastics Technology

MAY 2012

Plastics Technology - Dedicated to improving Plastics Processing.

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...Continued from p. 19 after 10 washing cycles, vs. 15% for PC. The PET bottles passed a 1.2-meter drop test 100% of the time, before and after 10 washing cycles, while PC bottles passed only 60% before washing and 50% after washing. Even more recent is an ultralight 5-gal water cooler for one-way use that Siapi created from new-generation performs as light as 330 g. The finished container has a wall thickness around about 0.45 mm and base thickness around 0.4 mm. Its topload strength is 120 kg (264 lb)—still one-third higher than a PC bottle weighing 130% more. Large PET containers of such light weight require careful bottle and preform design and extremely accurate reheat and stretch-blowing processes. Siapi has collaborated with COM- SOL Group (comsol.com, U.S. office in Burlington, Mass.), a supplier of finite-element mechanical simulation software to design large, ultralight PET containers. However, Siapi notes that bottle design itself is not suffi- cient to guarantee performance of ultralight containers. It is necessary to engineer the complete process, including preform design and the processing parameters, to achieve consistent minimum wall thickness necessary to prevent bottle deforma- tion. Thus, Siapi is also working with Agr International, Inc., Butler, Pa. (agrintl.com), using Agr's PETWall Profiler to man- age the production process for very fine wall-thickness control. Another area of recent application development for Siapi is large stackable PET containers with square bases and volumes of 10, 16, or 20 liters. Developed initially for the North Euro- pean market, such containers are said to be arousing interest now in North and Central America for edible oils and for the chemical industry. One recent example was conversion of an HDPE container for environmentally friendly fuel to PET with a weight reduc- tion of 50%. A special design allows the containers to be stacked four high. In general, Siapi says, 20L stackable containers can weigh For the U.S. market, Siapi recently devel- oped a 5-gal water- cooler container of PET to replace PC. It's lighter but has higher topload strength. Note the injection molded PET handle inserted during the stretch- blowing stage. 480 to 500 g in PET vs. 900 to 1000 g in HDPE. Wall and base thicknesses are around 0.6 and 0.5 mm respectively for PET vs. 2 mm for both in HDPE. Siapi also has been developing its EAWM series of wide- mouth container machines since 2004, largely in response to requests by North American customers. These machines can mold containers up to 12L with neck finishes up to 180 mm diam. in one to four cavities. A major project in North America converted a 500-ml PET jar with a 70-mm neck finish from single-stage (integrated) stretch-blow molding to two-stage reheat technology. The driving force behind this move was a reduction in con- tainer weight of almost 30%. Siapi helped develop the contain- er design and optimize the preform profile. This jar can be molded on Siapi machines at up to 4800/hr. By Matthew H. Naitove, Executive Editor know progress before problems Reduce surprises by knowing the actual performance of your tools: • Alerts for deviations to production activity targets • Verify scheduled PM's are performed consistently Call 1-800-269-6653 to discuss how the CVe Monitor can connect you with your tooling. PROCOMPS.COM/CVe monitor activity. get results. PLASTICS TECHNOLOGY MAY 2012 63

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