Optimisation of Injection Stretch Blow Moulding Process
Fugen Daver, Crescint Tanusetiawan
RMIT University
Australia

Keywords: Injection stretch blow molding, Process optimisation, Polyethylene terephthalate

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The injection stretch blow moulding (ISBM) process is used for the manufacture of hollow plastic parts, primarily bottles and containers. The quality of the final product depends strongly on the processing variables.

In ISBM, an injection moulded preform is cooled above its glass transition temperature prior to its biaxial deformation – axially by means of a stretch rod and radially by means of compressed air – until it takes up the shape of the blow mould. During the deformation of the preform, three processing variables have been identified to have major influence on the properties of the final product: the cooling time of the injection moulded preform; the delay time prior to the activation of the stretch rod; the blow pressure time during the blowing of the preform.

In this study, the central composite design method was employed to study the effect of processing parameters on product quality. Finally, an optimisation technique was used to optimise the ISBM process based on the product performance in terms of wall thickness distribution, top load strength, burst strength and hot fill capabilities.