Global efficiency of innovative rotational mold directly heated by thermal fluid

Abstract

The article is focused on analysis of global efficiency of new mold for rotational molding of plastic parts, being directly heated by thermal fluid. The overall efficiency is based on several items such as reduction of cycle time, better uniformity of heating-cooling and low energy consumption. The new tool takes advantage of additive fabrication and electroforming for making the optimal manifold and cavity shell of the mold. Experimental test of a prototype mold was carried out on an experimental rotational molding machine, developed for this purpose, measuring wall temperature, and internal air temperature, with and without plastic material inside. Results were compared with conventional mold heated into an oven and to theoretical simulations done by Computational Fluid Dynamic software (CFD). The analysis represents considerable improvement of cycle time related to conventional methods (heated by oven) and better thermal uniformity to conventional procedures by direct heating of oil with external channels. In addition to thermal analysis an energetic efficiency study was done. POLYM. ENG.

Estudo dos processos de rotomoldagem e injeção na fabricação de produtos poliméricos termoplásticos

“…Ogila et al (2017) realizaram uma revisão a respeito de melhorias relacionadas a moldes e maquinário, buscando relacioná-los à redução dos tempos de ciclo, que normalmente podem variar de 40 a 80 minutos, dependendo da espessura de parede necessária. Monzón et al (2012) propuseram um novo design de molde construído, a partir de uma casca metálica eletroformada, na qual um fluido térmico pode ser aquecido ou resfriado diretamente. Utilizaram um software de mecânica dos fluídos computacional para simulação numérica.…”

Rotational molding: A review of the models and materials

“…Monzón et al [87] proposed a novel mold design constructed from an electro-formed metallic shell, which a thermal fluid heated and cooled directly. While channels cast integrally with or welded onto the mold supply the heating oil in conventional designs, this design used manifolds with inlet and outlet pipes to supply to and remove externally heated fluid from an open channel.…”

Research on the machining process modeling of a rotational mold using CAM applications

“…A particularity of the rotational molds is that when making the parts the pressure does not intervene but only the heat and a continuous rotation at a low speed [5,6].…”