Deployment of ultrasonic melt flow enhancement technology to achieve energy savings of 27% across the energy intensive, injection moulded food packaging sector

RPC-Superfos designs, develops and manufactures innovative plastic packaging solutions and the majority of our carbon emissions are linked directly with the manufacturing process. A focus on energy efficiency is a large part of our corporate responsibility - electricity and carbon emissions are reported in our Annual Reports & Accounts and to monitor energy use the energy management system ISO50001 is being rolled out across our sites.

Thermoplastic injection moulding is an energy intensive process, whereby room temperature granules are heated within the screw and barrel of the injection unit until they reach the melt temperature, at which point the viscosity is sufficiently low to inject the material into the cold mould to form the product. Heat is extracted from the molten polymer material into the steel of the mould, the temperature of which is maintained by circulating chilled water through the mould.

The viscosity required to inject molten polymer into the mould is what dictates the minimum melt temperature, as melt viscosity reduces with increasing melt temperature. Melt temperature governs the cooling time; the lower the melt temperature, the less cooling time required, with shorter cycle times improving productivity.

We propose to use an ultrasonic vibration system applied to the melt during injection, which provides a flow enhancement akin to a temporarily reduction in melt viscosity. This reduction in melt viscosity then enables a lower melt temperature, compensating for the otherwise increased viscosity due to the lower temperatures. Testing has shown over 20% reduction in energy consumption per moulding and a 20% productivity improvement.

Our Blackburn manufacturing site operates ~60 injection moulding machines, producing food packaging products, and our vision with this project is to roll out the technology across the site, with a goal of reducing production electricity consumption by over 20%.

Through increasing productivity and reducing our carbon footprint, injection moulders will help to meet the Government's net zero carbon and Clean Growth Strategy targets for industry to "...improve their energy productivity, by at least 20% by 2030", primarily addressing the 'improving business and industry efficiency' theme.