Heated moulds

Materials World magazine
1 Dec 2008
The Cage System heats the surface of the mould for a higher quality injection

A system for plastic injection that heats and cools the suface of the mould to enable higher quality injection using less pressure is now available from RocTool, based in Bellignat, France. The Cage System uses electromagnetic induction to pre-heat the mould surface from 80 to 140ºC in nine seconds, allowing for a fast cycle time. Cold water lines close to the device allow for rapid cooling.

‘On a conventional [mould], hot materials touch the cold surface, and a lot of pressure is needed to fill the part,’ explains Alexandre Guichard, CEO of RocTool. ‘We have completely changed the rheology/flow [of the plastic] because we pre-heat the mould. [This means] hot materials touch a hot surface.’ This improves flowability and packing, and means 30% less pressure is used, reducing residual stress and product warpage.

For specialised polymers, such as polyetheretherketone or polyetherketone, the mould can be heated to 400ºC to meet filling needs. Guichard says only one per cent of the steel surface is heated, so it does not cause long-term damage. The resulting mould pattern is reproduced more exactly, with a decrease in surface stripes, he adds.

The company has recently used the Cage System to produce 5,000 parts, and has licensed the technology to plastics and aerospace companies as part of its ramp-up.

RocTool is investigating the suitability of the system for other automotive, telecommunications, packaging, and sports and leisure industries.

Further information: RocTool