BOTTLE MAKING 16 PETplanet Insider Vol. 26 No. 11/25 www.petpla.net Enhancing bottle manufacturing with advanced venting and stretching technologies Optimising the blowing process Advances in blow moulding technology continue to focus on improving efficiency, product quality, and energy use. Recent developments by Italian machinery manufacturer SIAPI illustrate how refinements in air distribution, cooling, and heating systems can contribute to more consistent bottle production with lower resource consumption. Through solutions such as enhanced mould venting, improved base cooling, and optimised preform stretching and air recovery systems, the company aims to address key challenges in process stability, material distribution, and energy efficiency in PET container manufacturing. Enhanced venting system In bottle manufacturing, precision and efficiency are key. A recent development in this field is the enhanced venting system (EVS), designed to improve the blow moulding process by reducing pressure and energy demand. The system optimises air evacuation between the preform and the mould cavity, allowing bottles to be manufactured with accuracy and strength. EVS technology features a refined distribution of air vents across the mould surface, preventing the build-up of air pockets that can interfere with proper shaping. Improved venting enhances the overall blowing process, contributing to increased machine performance in terms of production speed, aesthetic and functional quality of the container (such as handle solidity), and lower air and energy consumption. The performance of the blow mould is further improved through a new internal base cooling system, which includes a dedicated air channel to accelerate cooling in the lower part of the bottle, accelerating the formation of the base of blown containers. Preform stretch booster Another advancement is the preform stretch booster (PSB), a process designed to improve the radial stretch ratio during preform blowing through a pre-blowing phase. This results in an intermediate preform that enhances stretching performance, maximising the yield of engravingtexture and handle insertion. SIAPI’s SX2 machines are currently the only models equipped with PSB on a double cavity. To ensure consistent temperature control and process repeatability, SIAPI has implemented thermoregulated heating ovens. These systems are claimed to stabilise thermal conditions and to reduce the influence of external environmental conditions. Thanks to advanced heating system management, the time required to achieve thermal stability is shortened, increasing production efficiency. The heating path is divided into multiple zones, each with dedicated sensors that monitor preform temperature. This allows for rapid and precise adjustment of heating power, resulting in uniform material distribution and consistent bottle quality. Energy efficiency is further addressed with the air recovery system (ARS) 5.0, which reduces air consumption by up to 50% during blow moulding, particularly for largeformat bottles. The system incorporates three recovery phases - two dedicated to blow air recovery - enabling substantial energy savings and a more sustainable production process. Automated control via a PLC ensures consistent performance and eliminates the need for manual parameter adjustments. www.siapi.it BOTTLE MAKING Preform stretch booster (PSB) is a process designed to improve the radial stretch ratio during preform blowing through a pre-blowing phase. Improved venting enhances the overall blowing process, contributing to increased machine performance in terms of production speed, aesthetic and functional quality of the container and lower air and energy consumption.
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