Rotational moulding is a technological process used to manufacture one-piece hollow items without welding. This technology allows the manufacture of items with uniform thickness and no internal stress.
It is possible to mould very large items with extremely complex shapes and different surface finishes, but with far more cost-effective tooling than other types of technology.
Currently, the most popular manufacturing materials are linear and cross-linked polyethylene, followed by polypropylene, polyamide and polycarbonate. The peculiarity of this technology regards the fact that the mould rotates about two axes: a main one in a single direction and a secondary one in a variable direction. Throughout the process (excluding the charging and demoulding stages) the mould rotates continuously but always at low speed.
The two movements allow the polymer to come into contact with the entire inner surface of the mould that once heated in the oven begins to melt the polymer that sticks and builds up an even layer over it. In this manner, layer after layer, all the polymer eventually melts, thus creating the finished item.
The polymer does not cover the mould due to the slow speed of rotation and the centrifugal force generated, but only because it melts when touching the walls of the mould.
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