The molding of plastic materials by rotation is one of the techniques to produce polymer-based items.The items produced by this process are hollow. This process allows us to materialize complex shapes. The thinking behind the design is necessarily valuable all the way to the finished products. The mould design is crucial so as to facilitate the moulding and the demolding of items. At the mould design stage we have to take into account everything that can produce the operations of conformity of the finished product. The rotomoulding application fields are numerous: Public works, waste water management , automobiles , children toys, water sports, road furniture, industrial equipment.
The implementation by rotomolding counts 4 phases:
It is necessary to introduce the powder raw material in the mould. The powder quantity according to the desired thickness. The rotomoulding molds are made of two dismantable partswhich are mainly in Steel Sheet or in Aluminum. The rotomoulding molds are hollow, thin-walled with good thermic and mechanical characteristics in order to withstand production cycles
Once loaded and closed, the mould is rotated around two perpendicular axes during a heating phase. Normally, the heat is brought by gas burners or fuel (hot-air recirculation in the oven ).
In this stage, the mould , always in the rotation , comes out of the oven to cool. Water, cold air or a combination of both (atomized air-water mists) allow the mould cooling and thus the molten material.
The item is finally demolded when the internal air temperature is low enough, i.e., when the item is well-solidified. We then open the arms (between the upper and the lower parts of the mould) and we release the item which exactly reproduces the internal architecture of the mold.