ROTOFAST

Rotational Molding is a very competitive manufacturing method for producing large hollow plastic products. It provides one advantage over other plastic processing technologies: production of seamless articles, with uniform wall thickness and complex shapes for sectors as chemical storage, toys, construction and transports.

However this technology has stuck without major innovative improvements in the last 15 years becoming energy inefficient and costly, and at the same time other techniques which have substantially improved (as injection moulding or blowing moulding) are not suitable for such large pieces. Moreover, it has to face up to the growing market of low cost plastic goods from China and India. As a result, rotational moulding industry with high labour and energy costs becomes one of the most vulnerable sectors of Plastic Processing Industry.

Therefore, this sector needs to research and develop technology innovations in order to provide plastic industry of high value added products which manufacturing will allow it to reduce energy consumption and production costs. The challenge is the development of low energy systems in order to enhance the energy efficiency and reduce the cycle time, without becoming more expensive. The solution proposed is an automatic rotational molding machine with the following systems:

- Induction Heating System. This system will use a medium frequency power supply and helical induction coils to generate heat within the mold. It will integrate a thermal insulating layer between the coil and the mold to avoid heat losses.

- Internal Cooling System. The new technology will be integrated an internal cooling system which it will consist of ionic liquids. This system will remove heat from internal mould atmosphere, reducing the cooling time. In addition, it will provide low pressure to the polymer when it has reached melt point in order to improve the mechanical properties of the final product and to reduce cycle times.

Proposed solution: The IAGs brought a consortium of RTD performers and SMEs, which will innovatively apply two technologies never used before in rotomoulding (induction heating and the use of ionic liquids on internal cooling) to enhance energy consumption up to 70%, increase productivity (45%), decrease the use of raw material in 20% and gain mechanical and aesthetic properties with additional energy efficiency.

Technological Objectives

- Develop an induction heating system to optimize heat generation and to enhance energy efficiency reducing 70% energy consumption.
- Develop a multilayered mould composed by thermal insulation material and magnet flux concentrator in order to get homogeneous heat at all points of the mould, decreasing heat losses up to 80%.
- Develop a rapid prototyping tool able to simulate for a certain mould design, the electromagnetic fields in the system, induced heating, temperature distribution in the mould and mechanical performance.
- Reduce total cycle times up to 50% with respect to the current rotational moulding technique.
- Develop a new internal cooling system with ionic liquids -containing a special cation and counterion- able to produce a cooling curve 20% shorter than present internal cooling without any losses.
- Make the process available for other raw materials (nylons, polypropylene and polycarbonate) and for multiple layers of different materials like ethylene-vinyl alcohol and foams.

plastic
rotomoulding
rotational moulding
induction heating
heat transfer
casting

 

Associations leading the proposal will be:

- IAG1: National Association (IT)
Role: Coordination, Dissemination, training and exploitation activities
Benefits: Members of the Association will be the end user of the technology developed. IPR ownership for the results of the project. Licensing will be the main commercialization strategy after the project.

- IAG2: National Association (ES)
- IAG3: National Association (IR)
- IAG4: National Association (UK)

Roles: Dissemination, training and exploitation activities
Benefits: Members of the Association will be the end user of the technology developed. IPR ownership for the results of the project. Licensing will be the main commercialization strategy after the project.

The RTDs performance already involve in this project are:

- ITAv (ES): It will be in charge of modelling of heat transfer system and simulating flows dynamics . They will study the interaction among polymers with the ionic liquids and its behaviour during the phase-change stage and the process as a whole.
- RTD (IR): Polymer Processing Research Centre will support the design and develop of the cooling system which will provide pressure to the internal part of the mould, and will reduce the cooling time. Moreover, it will test with several raw materials and under different pressures, the whole process in a rotational moulding machine with the new induction heating and cooling system integrated.
- RTD (GE): It will research to find the suitable parameters of the induction heating, and it will develop a rapid prototype of the induction heating system.

The industrial partners will be:

- SME3: Rotational Moulding Plastic Products Manufacturer (UK)
End user of the new technology developed. Role: Trial this new technology in its production. Benefits: Important discount to purchase the new rotational moulding machine which will decrease its production costs, so its profits.

- SME4: Rotational Moulding Plastic Products Manufacturer (Lithuania)
End user of the new technology developed. Role: Trial this new technology in its production. Benefit: Important discount to purchase the new rotational moulding machine which will decrease its production costs, so its profits.

- SME5: Rotational Moulding
Plastic Products Manufacturer (Estonia )
End user of the new technology developed. Role: Trial this new technology in its production. Benefit: Important discount to purchase the new rotational moulding machine which will decrease its production costs, so its profits

- LE (IT) Designing and Manufacturing of the rotational moulding machine. Role: Design and develop of the prototype machine and its moulds
Integrator of the new technology sytems. Benefit: Commercialization of the new rotational moulding machine to plastic process industry.