Rotomolding project showing early gains

The project is being headed by officials from independent rubbers, plastics and composites consultancy Smithers Rapra (Shropshire, England). Others involved include the Queens University Belfast and the University of Minho (Portugal). The aim of the European Union-funded project is to develop novel rotomolding technologies in order to improve cycle times and process efficiency while also facilitating greater flexibility in product design and integrity for rotomolding processors. The EU funding is part of a larger program to strengthen the continent's small-to-mid-sized enterprises.

Smithers Rapra officials say their work has focused on powder flow, and on finding innovative methods for transferring the powder into the rotational mold, ideally in a pre-conditioned state. Materials characterization has also been undertaken on a range of candidate materials, and this will feed into the modeling and simulation work which Smithers Rapra also is conducting. 

The aim is to predict areas of shrinkage and significant stress from a model so that these can be designed out or minimized prior to processing. The other partners are undertaking initial validation work with the test molds used.

The rotomolding experts at Queens University Belfast, meanwhile, have been active over the last 18 months designing and developing an automated material feed/filling system. A full-scale prototype feeding system has been constructed and is fully incorporated into one of the University's rotomolding machines. The system facilitates the precise positioning and stopping of a mold to a pre-determined point, thus enabling the accurate dosing of powders, fillers, and other materials directly to the mold while it remains inside the oven. This will enable the production of reinforced and multilayer parts, with greater control and reduced processing cycle times than currently possible.

Additional research at Queens has focused on experimentally assessing this new technology and developing it to make multi-material/multi-layered parts. MPW coverage of previous work done at the Belfast-based University includes most recently this article. Workers at the University of Minho have been rotomolding sample parts using various processing conditions, and then characterizing these in terms of morphology, mechanical properties (tensile and impact tests) and shrinkage (using a 3D CMM). The results from these tests will provide the baseline data for comparison with the results obtained with the Rotoflex system developed at Queens University Belfast.

Processors interested in learning more or in following the project online can contact [email protected] for further information, or visit www.rotoflex-eu.org to register for free literature alerts relevant to rotomolding.