PETpla.net Insider 09 / 2015

Please order your copy at the PETplanet insider book shop: https://www.petpla.net/books Bottles, Preforms and Closures - A Design Guide for PET Packaging Second Edition by Ottmar Brandau € 115,00 180 pages © Copyright Elsevier 2012 CAPPING CLOSURES 40 PET planet insider Vol. 16 No. 09/15 www.petpla.net Different applications, neck finishes for various, part 3 Closure for PET bottles PETplanet Insider is publishing extracts from successive chapters of Ottmar Brandaus’s “Bottle, Preform and Closures”, which was published by hbmedia. A newly revised version is reissued under the Elsevier imprint. 4.2.4 Necks for custom bottles Besides the three beverage cat- egories discussed, there are now thou-sands of bottle types that do not fit into any of these. To give both bottle and cap producers a framework that guarantees that cap and bottle fit together, the Society of the Plas- tics Industry has devised a system that specifies both dimensions and tolerances. The data sheets give both metric and imperial dimensions, whereas nomenclature always refers to the metric number. The name of a neck finish of this type always starts with the letter “M” followed by the size of the neck in millimeters. After that come the letters “SP” followed by the numbers “400,” “410,” or “415.” These refer to 1, 1.5, and 2 thread turns, respectively (Fig. 4.7). Most bottles in this category are still extrusion blow moulded, but the injec- tion process delivers a more precise and repeatable neck finish. Added to this weight savings that may be achieved by using PET and PET’s superior consumer appeal, it is under- standable that many brand owners are looking for ways to convert into PET. Fig. 4.7 A large number of customised neck finishes are available through the SPI (Society of the Plastics Industry) system. Obstacles here are the greater flexibility of extrusion blow-moulded bottle designs, for example, with handles, and the higher tooling costs of the injection stretch blow moulding process. As many custom bottle necks do not feature an NSR, it becomes more difficult, though not impossi- * This article was published in Bottles, Preforms and Closures, Ottmar Brandau, Chapter 4.2 Copyright Elsevier 2012 ble, to guide preforms and bottles through blow moulding machines and conveyor systems. Therefore, many custom bottles are manufactured using the single-stage process, which is also more suitable considering the generally lower yearly volumes.