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thin wall moulding | Packaging


Right: Thin wall containers


produced on a Netstal injection moulding


machine using Plastisud’s injection


compression technology


trials with Unilever were said to be ongoing at the time of writing. “Brand owners tell us they want to move to injection moulding for lids,” says Caunègre. “It allows them to get different shapes and provides more versatility in IML decoration.” Coveris currently has only a relatively small presence in North America at present, with two plants, neither of which is involved in thin-wall production. But Sun Capital is understood to have plans to grow its injection moulding business there. Caunègre points out that in 2014, Unilever stopped using thermoformed tubs in the region, switch- ing exclusively to injection moulding. “The trend to injection moulding is picking up in the US, especially with IML tubs versus dry offset printed types,” he says.


Tailored cooperation Plastisud CEO Laurent Buzzo says it took Plastisud, in close cooperation with Netstal and Machines Pagès, four and a half months to develop a stack mould that was tailored specifically to the requirements of the new production process. He says the technology “guaran- tees a perfect balance of the two parting lines with a very low dispersion rate.” Nathalie Fabbro, who handles sales and marketing


Below: Milacron says its Klear Kan co-injection technology is undergoing trials with various food brands


at Plastisud, says: “There is no exclusivity to custom- ers or geographic area. It is new but neither tricky nor complicated. Application areas are mainly packaging, whatever the shape. The technology can be applied to any high performance machine able to inject in a very short time (less than 0.1 second) and able to guarantee a perfect platen parallelism.” Netstal’s manager for packaging applications technol- ogy, Thomas Iten, says he is convinced that the combina- tion of the injection-compression moulding process with a 4+4 stack mould represents a leap forward in innova- tion. “This configuration uncompromisingly combines the advantages of both technologies,” he says. As Iten points out, in the new process the holding


pressure phase of injection moulding is in essence replaced by a compres- sion process. “What might sound simple does in fact demand highest


precision both from machine and mould – es- pecially in cooperation with the stack mould,” he notes. “In order to consistently achieve


a high product quality, all process parameters must be kept within the narrowest


tolerance ranges. The process requires an extremely high repeatability with regard to the injection amount. The injection process and compression stroke must be synchronised extremely precisely. With an injection time of 0.1 seconds, that is a real challenge.” Iten says the limits of the application technology are


not yet clear. “The future will tell us,” he says. “Today, there are lots of open questions. We are just at the beginning and increasing competition will help drive it forward, every year the limits move. At the beginning of the century, the Eurotub weighed 17g; now we are down to 14.5g with standard injection moulding, and I am sure that with injection-compression this is not the end.” He points out, however, that it is a mistake to make


direct comparisons between injection and injection-com- pression moulding on existing applications. “You may have to completely change designs to get the best out of the new process,” he says. “For sure you have some new limitations with injection-compression; you have an extra moving part in the mould, for example, the sliding plate, and not all part designs allow sliding plates.” Injection-compression should also allow the use of thinner labels, Iten says. The Eurotub, which he regards as a very high end application, normally requires very high injection pressures and the shear rates around the gate are high. But if injection is carried out with the mould slightly open, the shear rate will be lower and there will be less risk of label burning, making it possible to use thinner labels. Iten says Coveris is not the only processor that


Netstal and Plastisud are working with on injection- compression. “We are in contact with several custom- ers and we are involved in various projects with them but everything is confidential at the moment,” he says. “And I am sure other mould makers are developing their own technologies as well.”


In the can Several other equipment makers have also announced developments that have particular relevance to thin-walling in recent months, with Arburg, Engel,


16 INJECTION WORLD | January/February 2016 www.injectionworld.com


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