Overview
Rotational moulding (often referred to as Rotamoulding or Rotomoulding) is a
process used for producing hollow plastic products. By using additional
post-moulding operations, complex components can be produced enabling the
process to compete effectively with other moulding and extrusion practices.
Rotational
moulding differs from other processing methods in that the heating, melting,
shaping, and cooling stages all occur after the polymer is placed in the mould,
therefore no external pressure is applied during forming.
This provides the following advantages Economically produced
large products, Minimum design constraints, Stress-free products, No polymer
weld lines and Comparatively low mould costs.
Overview
Rotational Moulding (American sp. molding) is a unique process that is very versatile and is virtually unlimited in the shapes and products that can be produced.
Designers and moulders are pushing the limits and demanding a wider variety of materials to meet more challenging applcations.
As the process requires the material to be subject to much longer heat cycles compared to other processes such as injection and blow moulding, materials for Rotational moulding require an enhanced heat stabilisation additive package to prevent oxidation and break down of the material properties. In addition all Rotational moulding grades supplied should contain a UV stabilisation additive package making them ideal for outdoor as well as indoor applications. Therefore materials available on the general market for other processes should not be used for Rotational moulding.
For these reasons and due to the lower volumes used worldwide for the Rotational moulding process, the materials that are available are limited from the thermoplastic suppliers.
Structural Foam
Overview
Structural Foam is a term commonly used to
describe thermoplastic injection moulding components made by the injection
moulding process which have a cellular core. A cellular plastic is one in which
the outer surface is denser than the inner layers. The core of the moulding is
of a honeycomb nature and less dense than the outer surface. The combination
results in a moulding of a high stiffness ratio compared with non-structural
foam (compact) mouldings.