PETpla.net Insider 07+08 / 2016

CAPPING / CLOSURES 34 PET planet insider Vol. 17 No. 07+08/16 www.petpla.net Different applications, neck finishes for various, part 7 Closure for PET bottles & Resins PETplanet insider is publishing extracts from successive chapters of Ottmar Brandau’s “Bottles, Preforms and Closures,” which was published by hbmedia. A newly revised version is reissued under the Elsevier imprint. 4.4.2 Pilfer-proof rings and their construction 4.4.2.2 Folded band  The folded pilfer-proof ring has become famous together with the development of CM machines. Because closures are already ori- entated after the CM process, the pilfer-proof rings can be slit and folded immediately after this opera- tion.  The IM process made this kind of construction inefficient because closures have to be unscrambled and orientated for this second oper- ation. Nevertheless, mould costs seem to put a limit for this solution because prices for closures have become very competitive. 4.4.2.1 Preshaped band  The preshaped pilfer-proof ring has become the most common one for single-component closures. This is because it is easy to produce and has a low maintenance cost on the mould. There is no limit in production speed because of the pilfer-proof ring. Such moulds can run up to 5 years without changing inserts in the moulds.  The disadvantage of this construc- tion is the limited safety in terms of resistance to tampering. Neverthe- less, latest developments show good improvements also in this respect. 4.4.2.3 Inserted band  The inserted pilfer-proof ring has the maximum safety in terms of tampering. This is because it obvi- ously can be produced in a differ- ent material than the closure shell, which is optimally designed for the function of the ring. This type of pil- fer-proof ring was developed for the aluminium roll-on closure and later used also for a similar construc- tion of lined plastic closures. This three-component closure became too expensive in a very early stage and has almost disappeared in the plastic closure market.