High Injection Dynamics for Full Flavor
By producing coffee capsules at the Fakuma trade show, Netstal-Maschinen AG, Näfels, Switzerland, and their system partners show the benefits included when using the co-injection molding process to make thin-walled packagings with an aroma-preserving function. An all-electric Elion 1200 with a supplementary Plasdan unit integrated via VNC produces the capsules in a four-cavity test mold by Fostag. Total cycle time is approx. 4.9 s. This is the time the Beck Automation handling system requires to automatically insert the labels provided by Verstraete IML into the mold and remove the decorated PP capsules after injection molding. The finished parts are stacked upside down. Integrated into the demolding robot, an optical inspection system by IMD-Vista checks the EVOH barrier layer for position and thickness. Finally, the Nespresso-compatible capsules are placed into a container as bulk goods.
Applying the multi-layer technique, the melt is injected into the mold cavity from two different aggregates, via the same runner. The material to arrive first forms the exterior layer of the molding, surrounding the core formed by the second component. In the case of the coffee capsules, two layers of PP cover one layer of EVOH, thus constituting an extremely thin sandwich structure with a mere 0.4 mm wall thickness. The EVOH (0.06 mm) acts as an aroma barrier, while the PP (0.17 mm each) protects the EVOH barrier, because the sensitive material would otherwise absorb moisture and lose its barrier effect against gas flow. As a result, the capsules are aroma-proof, requiring no secondary packaging, whatsoever. Thanks to this feature, the plastic capsules represent an alternative to aluminum: While offering outstanding aroma protection, these metal capsules require an enormous amount of energy for production, though.
The application reaches the high level of shot-to-shot consistency required, and this is mainly due to the dynamics and precision of the Elion injection unit. This is based, among other factors, on the principle of double gear rack transmission, as well as highly-precise force measurement integrated into the injection axis.
Fakuma 2017: Hall A7, booth 7304
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