PACKAGING | TECHNOLOGY
“You can save material, because you are not packing so hard, and you also have better control over part filling. The challenge is the synchronisa- tion of clamping and injection, which requires very good programming. We have some features that enable the process window to be expanded to provide stable production.” KraussMaffei HighPerformance can also suggest
Above: Al Wafa Plastic Industries is using an injection-compression process on a Netstal Elion 3200-2000 to produce IML PP food containers
production. This has been proven to require no major changes on the machine, simply an adjust- ment of process parameters.” Product Manager, Packaging, Marcel Christen, sees the benefits that microcellular foaming can provide in improving flow: he says the company is monitoring developments, but it has not received many demands from customers for using the technology in this way. But he and Härter are not fully sold on the technologies. He has doubts about the levels of material savings achievable in thin-wall products that Netstal machines are primarily used for. On top of this, investment costs in gas dispens- ing and mixing equipment, as well as the costs of the gas, taken together, are not inconsiderable, he says. Finally, demands on process control can be high.
Injection compression Netstal has taken a different route, preferring to use technologies such as injection compression, which it introduced several years ago, and which is now attracting more attention. “We have some interest- ing projects going on, for production of stadium cups for example,” says Härter. She cites one customer, Al Wafa Plastic Industries in Palestine, which is running injection compression on an Elion 3200-2000 to produce IML PP food containers in a 4+4 stack mould. Parts have a wall thickness of around 0.43 mm, and an L:T ratio of 340:1. They are some 25% lighter than equivalent injection moulded containers, Härter says, which would have had to be produced on a 4,500-kN machine, rather than 3,200 kN.
Christen says the benefits of injection compres- sion (ICM) are very similar to those of foaming.
24 INJECTION WORLD | July/August 2021
materials with lower MFIs. “As a limit of ICM, I would take for example MFI 25 and a wall thickness of 0.28 [mm],” says Härter; even lower MFIs can be used, but not at such low wall thicknesses. Lower MFI gives better mechanical stability in parts after moulding, which is useful when parts are stacked for transporting. The company launched its largest Netstal Elios hybrid machine, with a 10,000 kN clamp force, a few months ago. This is targeted at multi-cavity thin-wall moulding. “We think it has the shortest dry cycle in its class, at 2.2s,” says Christen. In the Elios series, the crosshead moving the lever mechanism of the clamping unit is actuated by a combination of a servo-electrically driven rack-and-pinion gear and two hydromechanical synchronised cylinders to provide final locking. The company has also been investing in an
expansion of its Application Center Näfels, Switzer- land, which was officially opened in May. At the same time, it announced a collaboration with SABIC on thin-wall packaging. “The Application Center will enable innovative application, material and pro- cessing solutions in the thin-wall packaging industry through closer collaboration across the segment’s entire value chain,” said SABIC at the time. “With the future knowledge gained from this valuable collaboration, we will further improve our injection moulding technology in terms of usability, process control and performance,” said KM’s Härter at the launch. “In addition, through the close branch exchange of our know-how, we will develop new processes for sustainable packaging solutions together with SABIC.”
CLICK ON THE LINKS FOR MORE INFORMATION: �
https://trexel.com �
https://stackteck.com �
www.yizumi.com/en �
www.haitian.com/en �
www.bockatech.com �
www.arburg.com �
www.sp-protec.com �
www.imflux.com �
www.engelglobal.com �
www.kraussmaffei.com �
www.sabic.com
www.injectionworld.com
IMAGE: KRAUSSMAFFEI
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