Price Advantage for Thin-Walled Packaging
The injection compression molding (ICM) process, which Netstal-Maschinen AG in Näfels, Switzerland, introduced last year together with their system partners Plastisud and Machines Pagès, enables very thin-walled packaging to be produced. Hereby, the mold is not fully closed during the injection phase – instead of the holding pressure, a compression phase is used to compensate for material shrinkage. This results in lower and more uniform internal mold pressures, which in turn reduces undesirable stresses in the material. According to Netstal, the ICM process permits material savings up to 20 % to be achieved by eliminating the holding pressure phase of the conventional injection process.
A stack mold with four cavities per parting level is used to make the process – a margarine tub of PP for the trade fair application – even more efficient. The tub is labeled by means of an IML solution. In combination with the high-speed label handling, the injection compression process on an Elion 2800-2200 permits cycle times of 5 s for the finished packaging component weighing 10.7 g. In order for the material to be embossed, a short injection phase with high injection speeds (> 800 mm/s) as well as synchronized interaction of injection unit and clamping unit are essential. Injection with the mold open places particularly high demands on plate parallelism and toggle lever design.
Another high-speed application deals with the manufacture of pipette tips for medical use. In a 128-cavity mold (Tanner Formenbau) – the world’s largest of this type – pipette tips are injection molded with a cycle time of 5.6 s. This corresponds to a daily output of some 2 million units. Particular challenges for maintaining the required tolerances are the low component weight of 0.26 g and the wall thickness of 0.38 mm. These demands are met by means of precise control of the injection processes. A handling unit with carbon/aluminum removal gripper (Zubler Handling) performs demolding in 0.9 s, without touching the sensitive collar area or the tips of the pipettes.
Hall 15, booth D24
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