Estimation of the heat transfer coefficient: (a) model for calculation of parison temperature distribution, (b) measured parison temperature distribution, and (c) Comparison of calculated (lines) and measured (diamond) temperature distribution as a function of distance from die core at the stroke of 30%. The solid and dotted lines indicate calculation results for a heat transfer coefficient of 9.8 W/m²K, and 19.6 W/m²K, respectively.