Numerical modelling for rotational moulding with non-isothermal heating

Abstract

In the rotational moulding process, the internal air temperature has been widely recognised as a tool to predict an optimum cycle time. This paper presents a new numerical approach to predict the internal air temperature in a two-dimensional (2-D) static model without requiring the consideration of the tumbling motion of polymer powder. The initial non-isothermal heating of the static model is actually formed by two changeable plastic beds (stagnant and mixing beds), which represent the actual stagnant and mixing pools inside a rotating mould respectively. In the numerical approach, the lumped-parameter system and coincident node technique are proposed to incorporate with the Galerkin Finite Element Method in order to account for the complex thermal interaction of the internal air. It helps to overcome the difficulty of multidimensional static models in predicting an accurate internal air temperature during the heating stage of rotationally powdery plastic. Importantly, the predicted temperature profiles of the internal air, oven times for different part thicknesses and process conditions accord with the available experimental results.PRC/2029

Rotational molding of polyethylene composites based on agave fibers

“…Figure 3 shows typical evolutions of the IAT inside the mold as a function of time when the oven temperature was maintained at 260°C. This kind of graphical representation of the rotomolding process has been reported elsewhere [4, 22–29]. In other studies [30, 31], for PVC plastisol prepared by rotational molding, the temperature inside the mold was measured as a function of time to get a better understanding of the curing process.…”

Study on processs and impact strength for a rotationally molded truck fender

“…In this regard, Spence and Gogos did some investigations on the bubble defect in a rotationally molded part [5,6]. Lim et al adopted numerical analysis method to predict the temperature distribution in the mold [7]. Liu [8].…”

Thermal analysis of foamed polyethylene rotational molding followed by internal air temperature profiles

“…. The parts can have a very wide range of dimensions, but are mostly stress‐free and without weld lines . The optimum processing parameters (heating and cooling) in rotational molding have been traditionally determined by trial and error procedures .…”

“…The optimum processing parameters (heating and cooling) in rotational molding have been traditionally determined by trial and error procedures . Nowadays, they can be optimized using internal air temperature (IAT) profiles as a first approximation to infer the state of the material inside the mold during processing . Based on IAT profiles, physical transitions related to heat transfer can be determined .…”