PETpla.net Insider 11 / 2011

BOTTLE MAKING 22 PET planet insider Vol. 12 No. 11/11 www.petpla.net New ISBM process by Cypet Where injection moulding meets stretch blow moulding The Cypet process is a new patented single stage injection stretch blow moulding (ISBM) process to produce a wide range of PET bottles and jars. A standard injection moulding machine is converted into a PET ISBM machine by adding injection and blow moulds as well as a blowing station. Invention and challenges The inventor and driving force behind the Cypet process is Con- stantinos Sideris, a former Techni- cal Director of the Interplast/Harwal Group. The reason for developing such a system was the high invest- ment costs related to conventional single stage PET injection stretch blow moulding machines, especially for countries with small market sizes. This led to the idea of using a normal injection moulding machine as a base to achieve the same result at substan- tially lower investment costs Two main challenges were faced during the development phase. First was the mechanical design of the blowing station, which was originally executed in a horizontal arrange- ment and later had to be changed to a vertical arrangement, for a smaller footprint, and a more practical and operator friendly operation. The second main challenge was the opti- misation of the preform design to suit the process. All challenges were faced successfully. Design and process The Cypet process is based on a composite injection-blow mould set, mounted in the clamping unit of a standard injection moulding machine. What makes the Cypet process spe- cial is the arrangement of the injection and blow cavities in relation to each other and in relation to the machine clamping plates. The opening and closing of the clamping plates opens and closes the injection and the blow cavities simultaneously (no need for two separate clamping units). The machine’s clamping force is used to keep all injection and blow cavities securely closed against both the injec- tion pressure and blowing pressure. In a typical production cycle, when the Various containers produced on Cypet machines