PETpla.net Insider 07+08 / 2013

PREFORM PRODUCTION 20 PET planet insider Vol. 14 No. 07+08/13 www.petpla.net Bottles, preforms and closures, 2nd edition - part 4 From shape to fully-fledged design for a dependable process Ottmar Brandau has newly revised his book, “Bottles, Pre- forms and Closures” first published by hbmedia/PETplanet- Publisher, and now to be re-issued under the Elsevier imprint. PETplanet insider is publishing extracts from successive chapters in a series of articles in forthcoming issues. Once the initial outer appearance of the bottle has been visualised and agreed upon, the shape must be imple- mented in a bottle design that ensures a high level of pro- cess dependability and will also include the wall thickness and its distribution. The first step in this stage is the design of the preform. From the ideal to the real preform Based on the dimensions of the bottle (height, diameter, capacity, and desired weight) and the selected or required neck design, the ideal preform geometry for the bottle is determined. This can be done either “manually” using the experience of a product developer or by applying the defined rules of a computer-aided expert system as described in Part 1. An example of such rules is as fol- lows: The shoulder zone requires 20% more material than the labelling zone, and the bottom zone requires 50% more material than the shoulder zone. The exact values for these rules will be derived from the bottle require- ments defined at an earlier stage of the development process, such as