TECHNOLOGY | THIN-WALL MOULDING
Right:
BMB eKW 45HP/2200, one of the company’s new range of HP Series ma- chines, suited to production of thin-walled containers
injection under accumulator, controlled by a double servo Moog valve. Direct torque motors are used on the clamping and plasticisation units, directly coupled to the toggle and screw rotation movements, without the use of belts or gear reducers. Trexel says its new P-300 SCF system for thin-wall packaging applications supplies nitrogen into the plastic melt on its new TDM (Tip Dosing Module) design MuCell screw. This allows high plasticising capacity with good melt quality. The system uses a high pressure SCF injector which allows elimination of the traditional burst disc. The MuCell system is integrated into the machine controller via VNC (Virtual Network Computing) protocol which allows users to change input via the machine controller. Trexel’s MuCell physical foaming was also
Below: Thin-wall cup production on an Allrounder 1020 H in Packaging version
featured at K2019 by Engel, KraussMaffei, and Nissei. Nissei, for example, was making champagne glass cups from polylactic acid. Trexel notes that in standard PLA moulding processes, it is common to have short shots in thin-wall parts since the fluidity of PLA is very poor. It says Nissei developed a new technology to mix supercritical carbon dioxide into molten PLA to improve the fluidity of the material. “It makes injection moulding of the world’s thinnest level (0.65mm) thin-wall container possible while
achieving super-high transparency,” it claims. Discussing sustainability issues being targeted
by KraussMaffei HighPerformance (which uses the Netstal brand), Christina Härter, Head of Applications Technology, says: “One of our main goals is the concentration on thin wall thickness. Together with our toolmaker partners, we have been pursuing this goal for years. Initially, the focus was on greater performance and therefore higher injection dynamics. This was followed by develop- ments towards lower-viscosity materials by the material manufacturers. And, in recent years, we have focused on the injection-compression moulding of packaging in order to arrive at even thinner walls, like we showed on the [mould maker] Glaroform booth at K2019. An injection moulding process paired with IML is no problem for us with the high-performance machines of the Netstal Elion and Elios series.” She adds: “We are also paving the way in the
direction of bio-based and biodegradable materi- als. Our trade fair application uses a material based on tall oil, a waste material from the manufacture of paper. We also regularly test biodegradable plastics on our Netstal machines, but the market is still cautious in this regard.” The Glaroform stand featured a Netstal machine
producing a packaging cup for cream cheese in a six-cavity mould. The part was IML-decorated and removed by a handling system from Beck Automa- tion. “With a 1:190 wall thickness to flow path ratio, the part does not have the ultimate thin wall thickness because a certain stiffness is required for the prod- uct,” says Härter. “What is sustainable is the polypro- pylene [from SABIC], which is based on tall oil.” Another hybrid machine designed specifically
for packaging that debuted at K 2019 was Arburg’s Allrounder 1020 H. This had a 6,000-kN electric clamp and a tiebar distance of 1,020mm, while the new size-7000 hydraulic injection unit provides shot weights up to 4.2kg (PS). At the show, Arburg had the machine making thin-walled round cups in an 8+8-cavity stack mould.
� 16 INJECTION WORLD | March 2020
www.injectionworld.com
IMAGE: ARBURG
IMAGE: BMB
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