PETpla.net Insider 03 / 2018

INSPECTION 38 PET planet Insider Vol. 19 No. 03/18 www.petpla.net Preform temperature – the invisible parameter As the world advances towards half a trillion plastic bottles/annum by 2021, productivity is hampered by large inefficiencies frequently caused by temperature variables such as operator subjectivity, environmental changes and variation in material properties. This gives rise to over-engineered bottles, product defects and machine down-time. However, a greater understanding of temperature in the SBM process will lead to more optimised bottle production, greater productivity and reduce energy consumption. It will ensure the consumption of fewer raw materials; generate less waste and decrease product defects, thus reduc- ing trouble-shooting, product deforma- tion, and machine down-time. It will lead to lighter more efficient preforms which can still reach the targeted per- formance standards such as ‘shelf-life’ and ‘top-load’, with greater ease of manufacture. Blow Moulding Technologies (BMT) developing state of the art temperature measurement technology for the stretch blow moulding indus- try. Launched in 2011 as a spin-out from Queen’s University of Belfast ‘Advanced Materials and Manufactur- ing Group’, BMT’s unique products and services are designed to solve problems in production trouble-shoot- ing and to enhance bottle efficiency. BMT’s clients span far and wide, with their products and services in frequent use by major multi-national players across USA, Europe and China. Due to the unique optical charac- teristics of polymers in general, pre- forms develop a different temperature profile inside and outside. Depending on the type of lamp, power, cooling conditions, as well as the grade of the polymer, the difference between the internal and external temperature profile can be 10 degrees or more. Such a difference can be useful as the internal preform wall has to travel and deform further than the external one. However, in certain conditions, mini- mising temperature difference is para- mount, such as, in multilayer preforms where a large difference in tempera- ture profile can lead to localised layer delamination. BMT’s recently launched Ther- moscan 3D is a simple to use offline device which enables the accurate and simultaneous measurement of the internal and external preform temper- ature profile on a longitudinal and/or circumferential (Fig. 1) scan path. As temperature is a non-visual parameter it can be difficult to understand these variations and the impact it has within the process. Without a clear tempera- ture map, managing temperature set- tings can often prove difficult, and can lead to temperatures exceeding the required tolerances desired to achieve the optimum plastic bottle. In addition, BMT developed pro- prietary software to evaluate through thickness temperature distribution (Fig. 2) to allow further in depth preform temperature understanding. Thermoscan 3D provides engineers with the know- ledge and data required to improve their understand- ing of temperature control during the production process. It can be used in both the SBM produc- tion environment, during the bottle R&D phase and facilitates the scale up from the R&D lab to pro- duction. As opposed to pres- sure, pre-blow timing and other machine parameters that affect preform pro- cessing globally, tempera- ture is the only factor that Fig. 1 Fig. 2