PETpla.net Insider 12 / 2016

CAPPING / CLOSURES 27 PET planet Insider Vol. 17 No. 12/16 www.petpla.net 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 * This article was published in Bottles, Preforms and Closures, Ottmar Brandau, Copyright Elsevier 2012 4.10.1 Lighter necks The most common necks for water and CSD bottles were the 30/25 and PCO 1810, respectively, drawings of which are shown in chapters 4.2.1 and 4.2.2. The strategy for both appli- cations was slightly different. Let us look at water first.  The diameter was reduced from 30 to 25.84mm  The height was reduced from 16.81 to 12mm  The wall thickness was reduced from 1.4 to between 1.05 and 1.2mm. (Fig. 4.41) Figure 4.41 Thinner walls and a shorter height contribute to the weight savings of this bottle neck for a 26mm closure. (Drawing courtesy of Bericap) This resulted in a weight reduction of the bottle neck from around 4g (as measured to the bottom of the transfer ring) to about 2g. These numbers differ slightly between manufacturers but, nevertheless, show an approxi- mate and astounding 50% weight reduction. It is little wonder that many companies jumped on this opportunity to save substantial amounts of money. Every hundred million bottles thus produced save 200,000kg (440,000lb) of resin, and although the new pre- form tooling required does not come cheap, payback time is short. Figure 4.42 PCO 1810, longer and heavier than the new PCO 1881. Figure 4.43 PCO Corvaglia with tradi- tional thread engagement of 720° Similar efforts were made with CSD necks, and two competing designs have evolved (Figs 4.42 and 4.43).  PCO 1881 with reduced thread engagement of 650°  PCO Corvaglia with traditional thread engagement of 720° (Fig. 4.43) The industry has now standardised on the PCO 1881, and more and more bottles can be found with this neck on your supermarket shelves (Fig. 4.44). Figure 4.44 These 26mm caps for water bottles weigh just 1g. 4.10.2 Lighter caps The new necks require new caps, and designers have used the oppor- tunity to go beyond just fitting a cap on a new neck. Instead, they have pushed the limits of what can be injection or compression moulded and have engineered caps that are truly as light as can be, especially for water. The new water cap features a wall thickness as low as 0.95mm and weighs in just under 1g, down from 1.85g of the tall 30/25 cap (figs 4.45 and 4.46). The requirements for CSD caps are significantly higher as the caps have to withstand the significant internal pressure of the carbonated contents. Nevertheless, the new CSD cap saves 0.6g, reducing the weight from 2.95 to 2.3g. Figure 4.45 This water bottle cap weighs only 1g. (Picture courtesy of Corvaglia Mould AG). Figure 4.46 PCO 1881 (Picture courtesy of Corvaglia Mould AG).